The Cal-look Lounge

This is something that I have thought about alot of recent times.When i was first getting into making my Cab go quicker the general info seemed to be at 100mph you needed some kind of device to break up the air over the back of the car or you would crash!!
Now as we have seen in recent years this is totally untrue and got me to thinking that maybe its the weight of the vehicle that is critical not the shape?
For example you have several cars running low 11s and high 10s with or without power adders,Paul Bate,Joe Gallagher,Martin[boom boom]Greaves,Anders Roman,Petter Carlberg,Arto Varta .We have several mid to low 12s cars,jason Rew,Frank Hofmann,Greg bishop,Pete Shattock,Phil West,Steve young,Andy Marriot etc  Then the low 10 & 9sec cars,Jussi Jyranko,Martin Taylor,myself,Jyrki Laune and particularly the Skinne brothers car,none of which run any aerodynamic device that I know of.

Now the common theme i see here all these cars are not crisp packet or potato chip cars,they are heavy compared to the similar performance cars from the 80s/90s  so do we really need the wings/spoilers/aerofoils?or do people just copy what everyone else is doing?

Looking at it from here,particularly with what the skinne car just did I have to say No they arent needed,so what do you all think?
anyone tried the same combo with and without? have any or the common designs been anywhere near a wind tunnel? or similar means of testing to see if they actual improve anything?


cheers richie

I just want to mention that the Skinne beetle did have a wing when it did the 9.26 run... mounted just to check if there was any difference. The driver said that the car did feel a bit more stable but they had also mounted 8" DOT slicks. Still he had to let go of the gas in 4th because he felt the car started to drift. Also remember that the Skinne beetle use R track tires in the front.

Best rgs
BB

I would of thought there wouldn't be much air flowing down the back of a bug when your travelling 100+. Big Pete has put a chopped bug in a wind tunnel at a university before.think bernie uses his to stop crap going down the carbs and piece of mind. anyone running wings notice the difference? :)

Kalle,was it a wing that followed the car like is normally used on a bug or stood off from the car in the clean air?

cheers richie

To see why it ran so hot ;) but it didnt have a wing

cheers richie

Wings are for birds ;) :D

somthing i prob have more experamce than most on.
i use the wing and front splitter on my race car and it makes a huge differance for what i do, took just over 6 seconds of a run up prescott hill climb which is under a mile long.
running at north wield i removed the wing for one run, shutting of at the top end @ 96mph the car felt very unstable and i bolted the wing stright back on.
(http://farm4.static.flickr.com/3276/2508725047_c6bd7357c9.jpg)
rear wing is twin element carbon from a f3 lola and the front splitter is alloy with a ply base.
not sure how it would affect flat screen cars as i have not run one with this set up but the 03 responds very well to some lift reduction. have also noticed that the rear wing does not have any affect on my 1/4 times or termanil speeds.
cheers rob

Like a ordinary wing a la Lummus and Tekken..

i noticed a difference at very , very high speeds when fitted to my road car ..

i ended up having to fit a small one on the front to balance it out , and stop it feeling like i was doing an 160mph wheelie .

i dont understand earodynamics , but iirc mines a spoiler , and not a wing ??

an 100,000 lb 737 can take off at less speed than i've done , and that has wings .

i think mine might be a spoiler because it is an upside-down wing ???

what i'm saying is ,,, i dont know what i'm saying  ::)

but it made a big difference to my car , but in a BAD way .
the front one made a small diference that brought it alll back together .

Love this Subject!

I too have been concidering such a dilema Richie.

I have spoken to MIRA the wind tunnal people about this so called problem, and there reply was very long and very helpfull.

with my perticulare setup they were very concerned that it it went past 150 mph then it would become airborn, now that im running data logging on the suspention you can see that the car is actualy starting to lift at the top end of the track. so it would seam that they are correct.

they also let me told me that if i can stop the air going underneath the car then lift forces are greatley reduced, which got me talking to Russ Fellows about his front air dam. now his car isnt as low as mine, but he did say that the car 'feels' planted withthe airdam, and with out its a little sketchy. now i know he's as been past the 150mph mark in his car using the apropriat M56 test track and says the car feels fine.

Now this is all well and good saying it 'feels' ok, but i like facts so. im going to put my car in the MIRA wind tunnal, now this isnt cheap, but im am working on a deal and its down to me getting enough cash together to pay for it.

the car that i know of that have been in the tunnal are Wayne saunders Focus, and the PT bruser. the Focus suffered a little instability at 150 mark, but ford paid for it to go in there tunnal in germany and they fixed it with gurni flap, along with some other little tweeks, they actualy reduced the drag of the car so ineffect it needed less power to go just as fast. The PT Bruser was another car that suffered bad aerodynamics, In the tunnal they found that the car was actualy lifting more at the back than it was at the front, so in effect making it feel like the rear was doing the steering. the also found that the peddle box in the engine compartment was creating lift on one side of the car!. next time you see it a the track take a look at the front of it, and you'll 'see' the fixes they did to it. now the car lifts, but its the same on both axles, they too also reduced its drag and the car went its fastest as soon as it got back onto the track. They had limitations in there body mods due to there sponsorship.

getting back to beetles, yes i think the weight of the cars (mine) is helping it become more stable, but i think its just moved the enevitable further up the MPH scale. now mine 'feels' spot on at 140 even with the car starting to lift.

one good thing about the MIRA deal is that the guys come up from Mira and advise on the car from the start, they you make the bits, and stick them on with tape, the you put the 'finished' car in the tunnal and as the day goes on you take bits off one by one untill you end up with the car bare of aero aids, then they tell you which bits to fit. they can also tell you how much Hp it will take to puch the car through the air.


as soon as i have my car done, It will be shared with anyone who wants to know, all in the aid of making our cars safer, so we can push them harder and harder.


Martin.

could you reduce the lift just by shifting the weight around in the car so you have more up front, I.e battery msd box

you can but your not sorting out the aerodynamic fauts, your just putting it off

What a great thread!
I would presume it must effect the air having a wing as we all know if your decklid is stood off at the bottom this creates a vacuum and  hot air is sucked out of the engine bay. Maybe your on to something with lighter cars lots of the racers in the USA run wings on full chassis cars, but then also is this just the make things look nice as alot of bugs run airboxes to due to the engine being larger raised etc.

I know it sounds shallow but I think wings look great on some cars and that is enough of a reason to run them! As long as they are not actually having an adverse effect!

If you look at all the top NHRA stuff, whether it be funny car, pro mod or pro stock all the cars have wings. Admittedly most of these are front engined.

Rob.

Wasn't the old Herrod Helper design, meant to be tested?  It was said to work!  Let me find the acticle...SPEEDWELL :)

reminds me of a conversation with Jimmy Larson, we asked him if the rear wing worked? his reply, shit its only there to cover the motor!

I feel that the most important part of the wing is the side part of it. This helps the car to go straight as for the top part that for putting your cups of tea on at the track. ;D

Kris Lauffer has gone pretty quick in his convertible without any wings, flaps, rudders-  Maybe cabs don't have the same aero problems that a full roof car does.

That said... Mike Scott has also gone really fast in his silver oval window without any aero "fixes" either- but he also has giant wide porsche wheels/tires on the front.

Hello Richie

Ot O now you've done it LOL !
IRS and a heavy car seem to be much more stable and if ya got the right brakes you can make the first exit  :P

Paul B

1973lbs 11.02 @ the Open Sport Nationals roll on the Hot Rod Drags

Steve,funnily enough I didnt mention Kris because of the unique shape of a cab without roof,i am sure my own car disturbs the air enough to alter any negative effects a regular sedan has,wether i run roof up,down or off it seems to make no difference  :) And I thought about Mike Scott but couldnt remeber his name ::)

Rob,obviously what you are trying to do is totally different,my car is set up to have as little downforce/weight over the front wheels at the top end as possible and I think you proberly have a front rear combo thats works well together

cheers richie

Rob I am not sure about your first point as the decklid stood off at the bottom allows idas to fit without cutting the velocity stack on number 2 and also allows extra air in to make up for the carbs/engine robbing cooling air to the fan,

number 2 is what I fear,that they fit them purely for looks and becaue there rules state that the engine has to be covered/sealed in


number 3 !!! what can I say,i hate the look of a wing on the clean lines of a bug,Mr taylors car looks so much better now he removed that thing from it :o :D

cheers richei

richie
would it be in your interest to make the car more "slippy" ??

flat bottomed , side skirts etc to lower the drag ?

btw , what does that "support" comment mean in your sig. ???
is it refering to women wearing bras ?

Dont believe the hype ;) :D  

You ever heard of anyone claiming there product doesnt work?

chers richie

Ian,I am not sure,it seems to me that if we break up the natural airflow on a bug its alot safer,most of th cars in my original post have the decklid stood off at the top and my observations point to this have a positive effect on stability,just wondering what others have found/seen

cheers richie

And no it has nothing to do with Bras :D

The big killer always seems to be backing of at the top end with the resultant unloading of the rear suspension, especially combined with a cross wind. Unfortunately the cars we have chosen to race are not as ideally suited to the far end of the track as they are to the start line.  Having said that, we wouldn't do it if we didn't get a bit frightened every now and again!

Andy

PS didn't little pete have a herrod helper on his car for a bit, not sure whether he rated it or not?

Andy he did,but now he doesnt,maybe it weighed to much :D   But really i am unsure why he removed it

iirc
to get same speed with less power , or more speed with same power ... you need the front and sides as slippy as poss , and disrupted air at the back .

i guess a nose-down , bumper-less car has the front sorted , and the raised lid is doing the stuff at the back ?

downforce robs speed .....
but would help with wieght transfer on the lift off ??

wouldn't the combination of a smooth underside to the car, and a rear wing help to lift the front wheels at speed.  Hence why beetles crash at the top end of a track when there is a cross wind?  I think a front spoiler would aid traction more than a rear wing.  But Richie you have a rear wing covered in canvas anyway.  What about welding strips along the length of the floorpan to help spped up the airflow.

For traction you want slow speed over the car and fast speed under the car.

A beetle has a similar profile to that of an airplane wing, hence at high speed the car will lift!

porsches have been flat bottomed girls since 1989 ....

a front splitter will force the front end down , this wouldnt help the rear raising on lift-off or traction ?

Wasn't here a whole load of experiments done back in the 60's with bloody great wings and vertical stabilisers hung of the back of a bug?  Didn't work worth a damn and looked very silly. But here was some interesting talk about the centre of pressure on a bug being well behind the car due to it's curves. A squareback would be a better shape to start with but all that titanium needed to get the weight down would even make pete blanche!

andy

Golf balls!  :o

The big advantage that cabrios have is that the air passing over the top is totally disrupted and has no chance to create a low pressure area above the car, it's starting to tumble the secound it goes over the top of the wind screen rail and destroys lift. On a regular sedan this doesn't happen, low pressure builds above (in theory anyway, there are still arguements about how things actually fly) and high pressure builds below, if you could connect the two by venting the roof and floorpan together then it would prevent lift,

andy

What Martin says reminds me of when I spoke to Ron Lummus at Bug Jm or Big Bang some years ago. I asked why people put flaps in the back of the air box, I asked if it were to aid cooling or release pressure etc and he just said "Nah people think they look cool!" lol

In my mind a wing a top end would aid traction of the reat wheel and keep the rear down, but I have never been at the top end speeds like any of you guys so what do I know. ;D

I think certain cars look hard as nails and wings suit them, Like Dave Dinning, Chris' Hembug, Jay Wottons cars all look great and I could't imagine them without thw wing, and in Jays case it add a practical place for him to put the intercooler lol

(http://www.offdrc.co.uk/images/gallery_2008_001/photo_2008_001_006.jpg)

footballs !! :o

Wouldn't work.

ping-pong balls ??

Rob James has not got his intercooler they any more it inside the car. Also i feel you don't need to much air pushing down on the back of the car. As this will make the front end to light at the top end and you don't need that.

yes , but it will help when you lift off over the line ?

How do you work that one out.

 if your suspension unloads violently at the top end when you lift off you or your car is set up wrong :o

cheers richie

Micheal,this is what i have been thinking,a car with a badly designed rear wing and wheelie bars is more likely to crash as the downforce acts to make the extra 2 rear wheels steer the car,I almost wonder if the front wheels have any control at all when a rear wing is used without any front end downforce additions

cheers richie

Some surfers cottoned onto that and used it to great affect  ;)
 let in a few dimples on the underside of their boards , the break in water flow created bubbles under the board breaking the surface tension .
http://www.racecar-engineering.com/allarticles/166403/dimpled-aerodynamic-surfaces.html
Someone has already been thinking along these lines me thinks

allthough lifting off the accelerator will shift wieght to the front , a wing will still be creating downforce to help counter it ?

If you look at the quicker cars with flaps they open quite early on the run,we have experimented with this on my car but you wont see it ;)

But to prove a point I removed the decklid catch from the rear apron and videod what happened,threw the top end the decklid was open by 3/4 inches at the bottom with the air pressure in the engine bay :o and a steel decklid takes some pressure to move it,a normal saloon one with out vents in it would be even worse

cheers richie

I have slowly changed my opinion on Wings over the last 6/8 months deciding where we want to go with our car. Being around the V8's alot, the amount of measurements and scientific shit that goes in to making them is unreal.

We really only wanted our because of the look, but just goes to show we dont really need one, plus i dont drink Tea  ::)  :D

So do you think lifing off the accelerator is a good thing.

yes , once youve done the 1/4 !!!

 ;D

(note , no question marks on this post)

A smooth underside coupled with 'obstacles' on the top such as a Bugs roof or a badly placed wing to a lesser or greater degree creates lift as the air over the top has to travel further than the air along the bottom to meet back at the same spot later on. Fast cars designed with a smooth underside may be smooth on the pan but they'll be doing stuff to the air somewhere, in the case of most (designed) race cars the air doesn't have to go so far over the top in the first place anyway. If you have a surface which increases the distance the air has to travel on the bottom then you counter lift but increase drag. It's complicated by other factors too, apparently. I guess theoretically a body mounted wing higher up the car reduces the amount of distance the air has to travel down the back of the car and therefore slows the air flow a degree reducing lift, you'd probably want to kick the lower air up a bit too though.

Sorry i find that lifing off the accelerator at top end is a bad thing. I tend to just put it into neutral and let the car settle before braking. So having two forces working against each other is a bad thing right. That why a feel a wing is a bad thing and i do not run one.

pm sent

I have been working on the principle that the big dining table on the back of my car is actually a spoiler, not a wing per se. I don't expect to get down force from it, I just expect it to break the flow over the car enough to reduce the uplift generated. Oh, and I like the way it looks  ;)

I am hoping that I'll get the set up right enough in order that the rear end will not be squatting at high speed and the wheelie bars doing the steering as the front goes light  :o ???

I was considering installing a 'V' shaped lip behind the front axle line to divert some flow out from beneath car- I am told on good authority that this does aid the high speed stability. Time will tell- I just need to get my car finished and see whether it works or not.

Got it back from Wayne's today.

Amen But then again... if you skip the 28-30mm torsion bars and the drag only dampers what will then happen to your 60ft times?

if you can make the underside flat with a slight kick up to the rear then that would be of more benefit than a spoiler ( not a wing) you want the air under the car to have the smoothest quickest route to the rear of the car, not the side.
ever car is differant and needs slightly differant tweeks to make it work, hence mine constatly changing.
have videoed mine at speed and it seems to be making some real downforce as the ride hight is about 25cm lower at speeds above 80mph. you could not get any turn in at high speed before i fitted the front splitter.
none of the above is of any use to you guys that just run in a stright line, you all need minimum drag and the front end lift is not so much a problem, not as if you have very heavy braking and a 90* corner 50 meters after the finish line.
its a subject i have spent the last 4 years playing with on my car and am just starting to understand what is happerning and how to change it.
cheers rob

I had a spoiler on the back of my car which was pretty much flat, just a very slight kick up to add some strength to it. As Boom Boom said, the sides are more important - keeps the air over the back end flowing straight and not spilling over the sides. Several Land Speed cars have strips running the length of the car over the roof to keep airflow straight. My car had a spoiler on the front too, don't know if it worked or not but the car always felt quite nicely balanced. True, I was only doing 100 - 110mph over the line, but it never felt squirrely at all. Dad reckoned it kept the trailer straight towing at 85mph too... :o


(http://muchos.co.uk/members/neil hab2/Headstraight - bigbang03.jpg)

There was a beetle running on the salt flats that had abig tube running from the roof to the floor to help extract the air from under the car, it didnt crash, interesting idea though.

yeah, the venturi effect should equalize the pressure top to bottom, and could possibly induce negative pressure under the car to suck it down to the track, all depends on whether this would cause drag, you don't get something for nothing do you!

andy

Love this subject!

From an aerodynamics viewpoint, the Beetle body shape is not good. Looking at it sideways on, the rate at which the roof line tapers down over the rear window and deck lid is far too steep for air to stay attached - it breaks away somwhere around the top of the rear window and creates a huge area of turbulence behind the car. The turbulent air creates drag and slows you down. The faster you go, the worse the problem. Drag increases as the square of speed. Say you double your speed from 60mph to 120mph. Drag just increased by a factor of four.

If your current ETs are around the 120mph mark, it'll take a lot more power to gain an extra 10mph than it will for the someone looking to go from 100mph to 110mph.

I agree with Richie that a heavier Beetle will be more stable at very high speeds than a lighter one. The extra weight is helping keep the car planted to the track (downforce). However, it would be possible for a lighter car to achieve the same level of downforce at high speed by adding the right aerodynamic aids. The advantage would be less overall weight on the startline, where extra weight is of little benefit (makes life easier on the trans), and increasing downforce directly related to vehicle speed ie exactly when you need it. Drag and downforce have to be treated separately as well as together. Reducing drag makes it easier to push a shape through the air but you also need downforce to keep it going in a straight line. Remember the pre rear spolier Audi TT high speed crashes?

A convertible Beetle with the hood down is even worse than a saloon in terms of aerodynamic drag - like andy M explained above. Because the air has no initial roofline area to attach to I believe the turbulent air is distributed and broken up over a much greater area rather than being concentrated mostly in one spot. It no doubt takes more power to push the cabrio with hood down to a given speed than it would with the hood up but it's probably less likely to lose rear wheel downforce as a result.

A low mounted front spoiler can reduce the amount of air getting underneath the car. A smooth underbody allows the air to exit quickly reducing drag and lift. To create genuine downforce you need a properly designed aerofoil section wing hung in clean, non-turbulent air. Airflow must be able to pass over the top and bottom of the wing, otherwise true downforce won't be generated. The trick is to choose a wing profile and angle of attack that generates adequate downforce with minimum drag. The rear tray style engine covers can't deliver the same effect as a wing because air only passes over one side but they can help reduce the strength of the turbulent wake at the rear of the car by breaking it up and gaining some downforce as a result.

I know of a few instances where people have had the rear lexan window pop out at high speed. It's not being blown out from the inside - it's getting sucked out by the drag created at the rear of the car. Similar thing happens with the doors on lightweight Pro Stock style cars. That's why you see helicopter latches fiited in that area. The door starts getting sucked out at the 'A' pillar when you hit a certain speed due to the air going turbulent once it hits the A post and not staying attached around the corner once it leaves the edges of the windscreen. Richie's deck lid is most likey being sucked open by drag induced at the rear of the car, as opposed to being blown open by air pressure in the engine bay.

Air is weird! We can't see it and it does strange things when you start pushing stuff through it. Really keen to hear the results of Martin's trip to MIRA. There should be some interesting lessons learned. But due to numerous variables, what works for Martin's car won't necessarily apply to others.

Airflow/drag/turbulence etc can become critical at high speeds. Hats off to Richie, Russ and the other guys running the big numbers. It takes sheer brute force to push such an aerodynamic disaster through the air at those speeds!

BTW I'm not advocating everyone start fitting huge wings and spoilers. It's a science. Getting it wrong could make things worse. And more importantly, most of them look shit  ;D

 

Do you not think this lid was held open due to the negitive preshure behind it? created by your car making a 140 mph hole in the air?  


as for Jonnys idea of the v's under the car, this is another thing were going to try in the tunnal.




Look at that, start to reply and old Maher jumps in! lol

Its a fascinating science! But to be honest I dont think we will truely know unless someone is willing to spend about £10million researching it! Think of how much the F1 teams invest and how cars with the same engines but different aero packages can be so far apart! Ferrari vs Torro rosso for example!

Even the Top NHRA stuff probably isn't as good as it could be but then its only a $280,000 pro stock car! So they wont invest as much as F1. So when you think you have a £40,000 beetle top end racer your aero bugget is tiny!

I think a wing/spoiler must disrupt the turbulance which should bea good thing. But I could imagine a badly designed with will have a negative effect.
I always wondered about the wing Slush puppie and Beetle Geuise ran I thought that this would make the air run off the back of the car and under it causing lift?

So what about cars running wings and a chute! Surely this is another kettle of fish!

Rob.

the mira package isnt that bad i thought. There top price for 4 hours in the tunnal is £3500 + vat. now some people think nothing about spending that amount on crap for there cars, (technical term) so i feel investing that amount of money in the car is cheep if it keeps the car safe, and ultimatly makes it go faster. bear in mind that less drag means less power to push it the same speed as a car with loads of drag (have you seen what happens to a car with a roof rack?)

Would you spend £3500 on making to motor more powerfull?(yes is the answer) then why not spend that on the tunnal and go faster with the old motor.


Just the way i look at it.


Martin

That is indeed a good price, but how many hours would it take to get it spot on, alot more than 4 I would suspect  :(
I think what you are doing Martin is great and it is a testament to you that you are willing to share. I think overall safety is the main thing racers should thank about, its all good and well going quick but its better to go quick and safe and to over compensate on the safety aspect!

Working at EBI this year was a real eye opener it amazes me how many prople were willing to go down the strip in a quick car with a crap show cage and looked at you like you was a kill joy when you said that they couldn't go down the strip in their shorts and t-shirt lol

Rob.

how does Jim Smiths car behave at the top end, bearing in mind the bottom of his car is realtively smooth?

This will probably have everyone cringing, but when Jonny and I were at University together.... we used to talk about this a great deal with my Engineering tutor who was also our halls warden. Of interest here is perhaps the fact that he was a fluid dynamicist and alongside academic commitments worked on/for the aerodynamics for Ferrari F1 and high speed trains, like the japanese bullet train... Anyway, he always expressed concern about the shape or profile of our Bugs, stating that they must be really unstable due to the lift that is created...

For me, its not so much about creating downforce, but more a question of reducing lift - i.e. using spoilers to break-up airflow over the top of the car and "splitters" or whatver you want to call them to restrict airflow under the car. For example - with Richie's car, undoubtedly the cabrio shape, especially when running without the roof or roof down, will have significantly less lift than a regular hard top sedan as the airflow over the top is disturbed. With Russ Fellows' car, lift is also reduced by restricting airflow under the car at the front. As someone else has already said of downforce, for lift to occur you need airflow over both sides of an "airfoil" section in order to create the pressure differential...

Secondly, regards the issue of weight - this is simple physics according  i.e.  the Force that is "pushing" the car onto the ground (which we all know and feel as gravity) can be quantified by F= MA
For a car; A = gravity and M = the mass of the car.

For argument's sake, let's consider two virtually identical Bugs travelling in a straight line at "high" speed.

Both cars are experiencing an equal "force" upward upon them, caused by aerodynamic "lift" induced by the shape of the car.

However, one car is significantly heavier than the other and is experiencing a different opposing "force" downwards on it according to F=MA. i.e. the heavy car is being pushed down more than the lightweight one.

From this, it is clear to me that a lightweight car is therefore more susceptible to "lift", which we might also call high speed instability, or even (unfortuantely) crashing at the top end. "Lifting-off" merely transfers weight and alters the stability of a car and, as above, will be more of a problem for lightweight cars than heavy ones.

As an illustration of this "lift", with my old Karmann Ghia the all steel and v. heavy decklid would soemtimes lift open and flap about at the top end of a run when I would be doing 110ish mph. Ok it did this because the latch wasn't fitted because the valance wasn't fitted - but it was caused by the pressure differential above and below the car - i.e. LIFT caused by airflow over the top of the car travelling at a greater speed than air below... (oh - after this was observed by startline crew, I cabled tied it shut...)

Martin - good luck with your testing - I think there are many of us fascinated to learn the results...

Morning John,thought you might put your head above the wall for this one :D  

Interesting thoughts,after i wrote about my decklid I thought about it somemore and did come to the conclusion it might be affected by both suction from the rear and the forwrd momentum,you really need to see inside the old package tray area of my carn ow to get an idea of where the pressure is coming from,after removing the package tray to fit the header,turbo intercooler etc the air seems to come along the bottom of the pan into this void and have no escape except out of the engine bay,when I made these changes i lost 5/7mph and have spent the last year and 1/2 trying to find it back again.[there were other changes hat could affect it as well]
Strangley enough the roof up or down doesnt seem to affect mph and my best ever mph was on one of those were it actually opened itself from flex after a hard wheelie/landing

The problem with a double acting true wing is
1 they look so shit
2 the rules seem to deem them illegal

It would be interesting to put my car in a wind tunnel but I feel that as i continuously change stuff which alters what the air will do/does it would be somewhat pointless as the needed changes may no longer have any effect,while Martin doing his may benifit alot more people as they have similar body style/shape.

So anymore thoughts?anyone,this has been mostly usefull so far  :)

cheers richie

Indeed... :)

No idea ben,it been that long since he got a good pass :o :D  But I am not convinced his car is any better than a pan,he still has all the voids we have
Interestingly it did go 5/7mph faster than it ever has before or after when he damaged a rear fender/wing and had to remove them to be able to carry on running which shows the drag and pressure build up in there

thought you'd say that about jims passes ;D

Great thread ;D

I think it might be interesting to this subject to find out what really happend to Håkans car last weekend. He told Tekken by e-mail that he lost traction (don`t know front or rear) at the end of the strip.
The car has the wing and the wheelebars, and is from what I saw at SCC maybe a little to stiff in the rear suspension.

I also think it would be interesting to see how at beetle without a wing, but with a totaly sealed underbody would behave

Nice post JamieL... looking to reduce lift is a great approach.

Again,looking at the Beetle in profile, you could say it resembles a crudely drawn airplane wing ie curved on top and mostly flat on the bottom. If a wing generates lift by forcing air to travel more quickly over the increased surface area on the top side vs the shorter distance on the bottom we can see how a Beetle generates lift. By limiting flow over the underside, lift will be reduced. Spoilers are correctly named - they 'spoil' the airflow rather than treat it aerodynamically. A front spoiler should attempt to direct flow around the sides of the car rather than dam it up in front like a snow plough. Those old Kamei front spoilers actually did something! Time for a revival?  ;)

Reducing ride height also does good things - it reduces the area available for air to flow under tha car and lowers the centre of gravity for better handling/stability. Many years ago Jon Webster built a front spoiler for Paul Sutton's 10sec Beetle (I've probably got a pic somewhere). It worked on the same principle as the one he'd already
made and fitted to Danny Cockerill's Ford Pop. It was flat bottomed and sat approx 3-4" off the ground. It was spaced away from the front body work by a similar distance. It was probably around 6-8" tall IIRC. It leaned back at the top at the same angle as the front valence. It performed two roles. It limited the amount of airflow going under the car simply by closing the gap, same as any other front spoiler. The interesting bit was the gap between itself and the body was supposed to suck up some of the air that made it underneath the spoiler. This worked on the basis there was more airflow going over the top of the car than below, so this would create negative pressure in the gap between body and spoiler. No idea if that's what was actually going on but it looked like a good idea to me at the time. After it was fitted Paul said his car was more stable going through the top end. Ultimately Paul's car crashed but I don't believe that was due in any way to the spoiler - he had other handling issues at the time. Not sure if that design has been repeated on other cars? This is why it's so difficult to evaluate the various aero mods carried out to VW racecars - everyone has a different combination.

Re underside: smoothing it reduces turbulence. Think of all the ugly shaped pieces and void areas under there just wanting to catch the air. Some high end road cars and plenty of single seat race cars have carefully engineered contours on the underside, acting like a venturi, with the closest point to the ground being engineered to apply the most downforce in an area that best benefits handling.

On to the back of the car. The Beetle roof profile could never be reworked to keep airflow attached. You have to make the best of a bad job. Flat rear wings must help as they extend into the area of turbulent air, disrupting/spoiling it and possibly adding a little downforce. The other approach is hanging an aerofoil shaped wing high up, away from the turbulence - it won't work if it's in turbulent airflow. In clean air the wing profile will be upside down compared to the Beetle body profile ie the largest surface area is on the bottom of the wing and the smallest on top, therefore the airflow over the wing generates downforce.

The structure for downforce generating wings needs to be substantial. Many cars have crashed due to broken wing supports. It's hard to believe how much effective weight is being applied to an aerodynamic wing at high speed. For a Beetle it could be equivalent to a couple of people standing on it! If you reckon your wing couldn't support that kind of weight, don't rely on it to stay in place down track.

Martin will get the opportunity to put figures to all this stuff on his MIRA trip. If that doesn't fit within your budget there's a poor man's wind tunnel option racers have
been doing for years: wool tuft testing. You can't measure downforce and you won't get figures but it can show the areas on your bodywork where flow goes turbulent. Check the pic - sorry about the car  :o.   Could also be used to check the effectiveness of aerodynamic wings as it will show if air is correctly attached to both top and underside.

(http://us1.webpublications.com.au/static/images/articles/i1086/108656_6mg.jpg)

Tape wool tufts in the areas you want to investigate and have someone drive alongside with a camera. You can clearly see turbulence around the rear end of the car where some of the wool tufts are inverted and/or flapping in the breeze.

Cool trick with the wool!

Also I have always wondered what about having holes in the front and rear wings/fenders to release air, as surely the air under the curved almost parachute shaped wings causes alot of lift?
Alot of the HiPo cars like R8's and Veyrons have vented wheel arches and rear spiltters.

Rob.

I did give Jim a couple of fibreglass '56-'61 tail-light pods, the idea being to fit them to the rear wings and cut out the wing behind them, also leaving the lenses out as a way of relieving the pressure under the wings after his incident. Don't know if he ever thought about using them or not though.

 Look cool , don't think they work too well , the shape's all wrong but maybe if you change the angle ::)
(http://images.thesamba.com/vw/gallery/pix/363505.jpg)
Some how don't think anyone thought you would see a bug going over 130 mph
and worrying what would happen when you came off the gas when these were made  :o

Well so far I dont see any evidence that what is comercially available actually improves safety or ET in any way that can be proven,hopefully we can get more input from people actually running wings/aerofoils etc

cheers richie

Im with you on that Richie, im sure the wing that i had on before would have created downforce as it was in the 'clean air' above the car, we will never know as i sold it to andy raw and its currently on his funny car.


I'll see if i can capture the screen shot from my data log.




Martin.

did it!

right let me explaine.  the top two graphs are the rear suspention travel, and the bottom is engine speed so you can follow it down the track.

if you look at the far left of the suspention travel lines that is me driving after the burnout so you can take this as level. now as the graph goes up the more the car is squatting and if the line goes bellow then the rear of the car is lifting.

now follow the rpm (i bogged real bad in 1st gear) now you can see the car moving about, now look as im in 3rd and 4th you can see that the car is starting lift a little. on this run i was doing 138 mph over the finish line.


(http://i32.photobucket.com/albums/d18/autocraft/datalogscreenshot.jpg)


hope you can see it!

this log was just at the start of me tuning the dampers, the graph now is a load smoother. but there still is lift at the high speed.

the next thing to do is log the front end and follow that movement (i only has enough $ for the rear sensors so far)




Martin.

Okay I will put my hand up  ;D I have a wing :D When I first got Betelgeuse it had this wing

(http://i.pbase.com/o4/69/341069/1/64135357.J6wEDILU.IMG_5296.jpg)

I took it off and being a fairly light weight car it changed its stabilty at the top end even though it was just going through the traps at 120mph.

I replaced the wing with a big wig and IMHO suits the car and does give top end stabilty. I no longer use the wheelie bars as I think they are partly responsible for damaging gearbox's in this particular car. The downside for me was fitting this wing the engine runs hotter. To be modified
(http://i.pbase.com/o2/69/341069/1/96301907.TVAJESyp.SBF_9503.jpg)

No need to spend any money there,I can tell you exactly what you need to know!!


The front dampers should extend fully on launch then stay extended till just after the finish line when you get of the gas pedal ;) :D ;D

cheers richie

PS I am sure the graph helps but it might as well be in Greek to me ::)

Thankfully the links didnt work so I am not blinded by the monstroserty :D

Did you gain or lose MPH when you removed the first wing?

cheers richie

talking of lifting the front wheels i have a disc here for you

Flatfire is that the same car?
Looks great in the second pic with the big wig wing.

Thankfully the links didnt work so I am not blinded by the monstroserty :D


Did you gain or lose MPH when you removed the first wing?

cheers richie
[/quote]

What you didn't like the wing  ;D

I improved my mph with it removed but probably didn't better Stretchs best MPH.
My aim is to better the cars reliability and its performance.

Jim Bowen created a great car I just need to do it justice

Yes Prowagen its the same car I wish I could change my image as easily.
Thanks for the kind words

Just like you can't step into a shop and buy a replica of your engine, you won't find any "guaranteed to improve the aerodynamics and downforce of your Beetle Cabrio" products on the shelves of your local 'Made in China' VW parts supplier.

The people who've taken the trouble to make or buy and fit rear wings need to convince themselves they work. If they work, how do they know? Seat of the pants testing works for most. The alternative is to admit they wasted their time and money.  Some cars fitted with wings aren't reaching high enough speeds for the wing to make a contribution but the car goes straight therefore it must work....  ???

The fast cars without wings (eg yours) are spoiling it for all the guys who are trying to justify their aerodynamic strap-ons  ;D

Seriously though, the right aero mods will work. It's not so simple physics. Clean up the aero on your car and it will take less force to push it through the air. Add downforce as necessary to keep it stable at speed.

If you want to find something that'll improve the stability/downforce/drag coefficient of your car, you'll probably have to take a route similar to the one taken with your engine i.e. experiment and refine lots of different combinations. Engines can be tested on the dyno or at the track. Aero mods can be tested in a wind tunnel or at the track. If the engine mods go wrong, worst case scenario is you need a new motor. If the aero stuff goes wrong, you could wreck the car and take a ride in an ambulance.

If you come up with a list of mods you think might work and have the funds to take a trip to MIRA, you'll find out what works and learn a lot. But they can only test what you've brung - so there's still no guarantee you'll come away with a positive result. At worst you'll have discovered what doesn't work. MIRA's not an option for most but at the kind of speeds you're running, you'd probably benefit more than most.

If you decide to take the trip, expect to see engine lids bearing the slogan:
"No Nitrous, No Turbo, No EFI, No Wind Tunnel"   ;D  8)

for got to say, we found on the rollers that the tires im using (sportsman pros) grow by over 2 inches past 120 mph. so thats also altering the angle of the car.


Martin

"No Nitrous, No Turbo, No EFI, No Wind Tunnel"...........why go slower lol ;)



(best thread ever)

So does this mean you are coming back out to play? as thats mostly your old slogan :o :) :D

And I have a slightly different approach to find out what will work,no surprise there then i there :)
along the lines of the newbie you posted a pic off and a very long piece of desert ;)  Its cheaper to take it there than Mira,but is kind of spelled the same ;)

cheers richie

Never took that into consideration,obviously you see the fuel car tyres growing but didnt think of it on our scale of things,how much does that affect your 4th gear ratio,is that 2inches taller exactly? or just an estimate? as I assume it would be difficult to measure unless you use known rpm/mph and calc the difference from static?

cheers richie

Just throwing something in here about Cabriolets and centre of gravity - just think of how much weight there is lower down with the sill strengtheners, A-post re-inforcers, the rear seat area, rear windown winder mechanisms and inner quarter panel skins... is that a reason why Richie's cab is so stable?

dont forget richies car changes shape at speed !!!  ;)

If I ever make it, at least one of those statements will have to be scratched out  ;)


I just knew the ball of wool and masking tape option would appeal - you're probably unravelling your cardigan as we speak  ;D

JM

The rollers i use have a speed sensor and you can see as the tire grows the ratio between between engine rpm and road speed increases quite dramaticaly, we plotted it when the car was on a cool down and it was about 10 mph (by just following the graph. its was only a tea break!)

next time i'll film the tire, as the speed goes up the tire gets taller and narrower, that was at 25 psi, chuff know what it does at 11psi!

as for the 2" exactly we were jsut using a tape meashure and sighting it up.

Interesting stuff. I've always had a thing about aerodynamics, but I guess if the truth be told, most of my ideas came from looking at what others did and second-guessing what might or might not work. My elder step-son Mark is a Formula 1 aerodynamicist (worked alongside Ross Brawn at Arrows, then on to Ligier, Lola, Jaguar F1 and the Jaguar Group C team. Now with Honda) and we had many discussions about the subject while I was racing No Mercy (is it really 15 years ago?).

Now No Mercy was very heavy for a tube-chassis car. It weighed 1700lbs with me in it (weighed by Jon Webster) and was powered by a relatively small 2165cc turbo motor. The best time was 9.87 @ 139.8mph. I would like to think some of the aerodynamic bits I tried helped, but of course that may be wishful thinking. Here's what I ended up with...

1 ) Flat floor – aluminium skin under the chassis from front to rear bulkheads
2 ) Roof chop – may or may not have helped
3 ) Flush-mounted windows
4 ) Aluminium plates fitted to windscreen pillars to smooth airflow over gutters (drip-rails) – VW did this on the Mk1 GTI
5 ) 'Adam Wik' front end with deep airdam
6 ) Lips round the front edges of each wheelarch opening to deflect air away from rotating wheel (Mark says that a rotating wheel is one of the biggest sources of drag on any car) – this is commonly done on Funny Cars
7 ) Abbreviated rear fenders to allow air to escape from under back of car
8 ) Hinged 'lid' at bottom of engine cover to allow air to escape, also
9 ) Large spill plates on each side of rear 'spoiler'
10) Adjustable rear edge to spoiler (approx 3in – 75mm – deep)
11) Gurney flap added to rear edge of spoiler (disturbs airflow without increasing drag)
12) Limiting straps on front end

OK, other things that were tried early on included a strut-mounted true airfoil 'wing' from a F5000 Lola mounted up in the clean air above rear of car. This was interesting. The ETs fell by, on average, 0.15secs but the TS also fell by an average of 2mph! I put the former down to increased traction at the top end (there was some evidence of tyre slip at speed) while the latter was down to the increased drag, I guess. The wing was probably too 'severe' for this car – a smaller design might have worked better.

Anyone who remembers seeing the car run will recall how arrow-straight it ran, time after time. It was the easiest car I have ever driven – part of that must be down to the sophisticated four-bar rear end and IRS, but part must ls be don to the aerodynamics. Or is that just wishful thinking? Whatever, if I built a chassis car again, I'd not hesitate to follow a similar route.

No nitrous, No turbos, No fun... ;D

Hi KS,

I must have seen your car go down the track at least a hundred times and agree totally - it always went straight. Only once did I see you have an issue. IIRC that was after you'd fitted a quick acting steering rack. Think it got removed for the next meet  ;)

I believe some of your aero mods had to help - but like you say, how do you prove it? However a car with a ton of consistent passes under its belt is a good basis for evaluating stuff.

Oh God, I'd forgotten about THAT! Seemed like a good idea at the time... quick-ratio, lightweight Stiletto rack'n'pinion made the car undriveable!  :o

I am currently waiting for some unsuspecting old lady to walk past so I can pinch one,even though I am getting on a bit a cardigan is not something I presently own :D

keith I rememeber some of the thinks you mention,will have to have a look at some photos to get them clear in my head,was it only 15 years ago you last raced,seems longer :D

cheers richie

If I were the sort of person who was old enough to have a nice woolly cardigan in the back of my wardrobe, would anyone know how fast you would need to go to get some idea of what is going on. Just wondering if its a 70mph (no faster you understand) in the middle lane of the motorway whilst a couple of equally law abiding citizens video the car? Or is this something that changes with speed so that you need to be going at your maximum trap speed to get a realistic result?

I'm not totally sure what I'm going to do with this if its possible to gain useful information this way, but it sounds like start on what looks to be a very long learning curve.

Just for the record my car (1584lbs with me in it) feels better without a wing (H helper) but my terminal of 107 - 109mph is way down relative to many on here, but as said earlier the weigh relative to speed (lift) also needs to be considered. I'm sure there is some clever maths to sort this out.

Anyone care to comment on the use of the little air deflector used above the rear window by some of the more hardcore German look cars. Form or function?   

Pete,

That's a seriously anorexic street car (and driver???)    :o

The wool tuft test will show relevant info at speeds lower than your 1/4 mile terminals but for best results closer to the real deal is better.
It's a little like cylinder head flow bench testing.....
Industry standard test depression is genarally accepted as being 28" H2O but actual flow demand on a good head at max piston acceleration can be 70" plus.
The only benches capable of pulling that hard tend to be in the hands of the OEMs, F1, NHRA Pro Stock & Nascar. For the rest of us, 28" gives enough valid data to make useful improvements.

Terminal speed is generally a reflection of engine hp i.e. big hp equals higher terminal speeds.
That's why you often see turbo cars with modest ETs but high mph.
If you see a car make a mediocre pass but the terminal is up there, it's a dead giveaway it has some serious bhp.
With your little motor, the  lower bhp number (relatively speaking) delivers slightly smaller mph while the power to weight ratio results in super respectable ETs compared to cars running similar ETs with more cc.

No idea if the rear window deflector works or not but if it's positioned just before the air breaks away from the body it should trip the air enough to make a positive contribution (less drag).
Trick would be to identify the position at which the wool tufts start going crazy and position the lip spoiler just above that point. Should result in less drag (improved ET & mph).
Looking back at that New Beetle pic I posted you can see air stays attached pretty much all the way down the rear window. Don't know what mph the pics were taken at.
Maybe ask Martin to add it to his list of tests for MIRA?  ;)

I run a wing. I have been 111 in the 1/8 without the wing. Car was solid.

I have been 142 in the 1/4 with the wing. Car was rock solid...i'm not about to try it without it just to see.

Does it work? Who cares? Looks cool to me.  ;D

(http://i269.photobucket.com/albums/jj51/lordestroyer/Unlimited1.jpg)

Thats why I figure most people have them ;)
Thankyou for you input,you sure you dont want to take it off and try it? :)

cheers richie

My street car used to squirm a little when I got of the throttle at just 164 km/t, it was then stock height at the rear.
It's now lowered 3 cm but when I go thru traps at 174 km/t it's so solid that I can just lift the throttle. The only other change is that I have fitted a pair of AVO chocks in place of the cofaps that used to be back there. The car weighs 1808 lbs.

Looks daft.  :)

Looks kind of like a two fold ragtop in open position...  ;)

they may be more effective than you think, even if they do look daft! lol

Its another thing we'll be trying.

I only ever drove my old car once without the wing / aerofoil.  It didn't feel as 'planted'.

I never had a problem with the car thru' the top end, although the best terminal was only in the 120mph range.  It also had the brakes jammed on a few times at the top end to avoid breaking out, is that kind of talk aloud on here?   ;) ;D :o

As for looks, I liked the look of the car with the 'big' wing.  Each to there own.  I also love what Pete has done with it.

I have been following this thread with interest and it made me look at my ticket when I had my mishap. It happened at the 1/8th and my speed was 108.20 and my thoughts were for self preservation rather than weight transfer and the aerodynamics of stopping in a straght line etc etc. I have never braked so violently in all my life and the car stopped very quickly in a straght line, felt very stable and planted . I suspect that this was due to the weight, IRS and the setting up rather than any wing/spoiler/tea-tray attachment but with that in mind with the rebuild it will be having another one fitted. I do agree with Ritchie that the weight of a car is an important factor. On the plus side for wings /spoilers they do stop fires from spreading over the roof. ;D Sissy sticks, Ritchie that's another can of worms ;). Bernie

It takes a specific amount of horsepower to push a vehicle through the air at a given speed.
You also have rolling resistance to take into account (friction coefficient of tyres, weight of vehicle, bearing losses etc) but the major issue is wind resistance and power required to overcome it.

The lower the drag coefficient of the vehicle (Cd), the less resistance there is to forward motion.
Cd number is relative to the same frontal area turned into a flat plate as opposed to a contoured body shape...
It takes less energy to push a tear-dropped form with frontal area of 32 sqft through the air than an 8' x 4' sheet of plywood!

A 10 x scale model of a Beetle will have the same Cd as a regular one.
Multiply frontal area by Cd to make comparisons between diffferent sizes and shapes.

From memory a Beetle's Cd is something bad like 0.49. Think New Beetle is 0.38 (crap for modern car).
Not sure what frontal area is - height x width... maybe 25sqft??

25 x 0.49 = 12.25 CdA

Cd of a cabrio with the hood down could be in the 0.6-0.7 range   :o
CdA now becomes 15 (being generous and using 0.6)

Lower the CdA figure and it'll take less hp to travel at speed.
ie make the car slippier and reduce frontal area

When doubling speed, drag increases x 4 but the amount of horsepower required to overcome extra drag goes up by cube of speed - factor of 8
Beetle takes something in the region of 25hp to travel at steady 60mph on a perfectly flat road on a calm day.
Approx 200hp at 120mph

Working off that theory, aiming for 150mph terminal speed when you're used to maxing out at 140mph will require a 23% increase in horsepower  :o  :o
... assuming aero is the factor holding you back - not traction/handling/gearing etc

(150/140 cubed = 23%)

At the bhp level required to run 140mph, dropping CdA might be less expensive than funding a 23% power increase  ;)

Conclusion: Richie needs a New Beetle (with wheelie bars)   ;D

JM

Note: prior to adding this edit, I'd originally calculated the percentage power iincrease reqd as 56% (!!!), rather than 23%. Thanks to Bruce for recognising the error and supplying the correct calculation (see his post on Page 5)

A propos the New Beetle, this is interesting:
http://www.evworld.com/article.cfm?archive=1&storyid=911&first=2412&end=2411 (http://www.evworld.com/article.cfm?archive=1&storyid=911&first=2412&end=2411)

And the Audi A2 has a Cd of just 0.25 – how about racing one of those? Perfect for the VWDRC... ;)

And John, you're right about the Beetle: 0.38–0.39

I know the Karmann Ghia is almost as bad – in fact, the Type 25/Vanagon has a lower Cd than a Ghia, but I can't find the figures at present. If I recall, the Ghia coupé is around 0.36, the convertible about 0.40.

It would be interesting to know what difference the 'snow plow' front end made to the handling of the outlaw anglias

(http://www.outlaw-anglia.co.uk/images/pwright2_ddhrd03.jpg)

Interesting article. Despite the Cd improvement it's yet more evidence for the "wings look shit" posse  ;)

Seriously though, the wing position confirms placement in an area normally subject to turbulent flow decreases drag (see wool tuft pic posted previously).


Yeah... it'd fit right in with the Golf, Polo and Skoda.

All they need now is a Netto Car Park sign in the pit area and it'd look perfect   :D

hey john
how yoiu doin .

when you say a beetles cd is bad , this figure is for a standard trim car yes ?

with bumpers removed and front end lowered the cd would come down .

how much , i dont know ???

i also suggested earlier that richies car changes shape at speed .
as the roof bellows up , this would also effect the slipstream in a good way ?

(as long as he remembers to latch it ):D

Not sure if he's allowed to run the roof anymore, that's why he had a haircut due to lower the CD the ponytail caused ;D

shoulda kept the tail , would have helped with the "wool-tuft" experiment :D

i suspect with the roof down , air will be going over richies head , and tumbling back in towards the windscreen ;)

helping to push him along !!! :)

Mmmm so I need 56% more power,ok I think I can find that :D

I actually thought a ghia was better  than that? starting to wonder now if my Fridolin is such a goos idea :o ;) :-X

cheers richie

Not sure if its helping me go forward but I already proved that one when the breather box burped a little!!! oil and it ended up coming over me onto the windscreen

cheers richie

i could have warned you about this one .... 
had my directions writ on a piece of a4 on the passenger seat .....
they did a couple of loop-de-loops and shot out of the car at 120 on the m62  ::)

brainwave !!!

you seen the mesh screens that mount behind the seats on modern cabrios to stop wind blasting the back of your neck ?

you could make one easy enough and do back-to-backs to see if times alter !!

SOME CARS use a polycarb one i think , so this HAS to affect earodynamics ;)

I am sorry but using the word boxter in the same sentence as anything I own is deeply offensive >:(

cheers richie

SORTED !!!  ;D

With all this talk of cabrios, Boxsters, pony-tails being cut off, hair blowing in the wind.....
I reckon there's a frustrated hairdresser itching to come out

Coming soon: Richie's new styling salon.....

HAIR-O-DYNAMIC    ;)

"Not working today?"
"Been on holiday yet?"

The PERFECT name for Richie's racer!  8)

lmao! :D :D :D :D

John, the car is actually quite heavy, but with the excitement of a days racing ahead, I normally loose a few pounds in the morning before getting in the car!

FFS John you have had me in stitches with a couple of your posts ;D What a grreat addition to the lounge!

I figured 1584lb inc driver was pretty light for a street car....  unless you're the totally wasted, strung out junkie type  ;)
I know worshipping the weight God can be seriously addictive

(http://www.talkingretail.com/a/main/063D8AEA-1B92-11D9-A258-B96F2D727A86/A7E96EA8-4106-11DC-829F-3626640B077D/D4852EA4-45AA-11DC-BCB4-1363640B077D.jpg)

 ;D

Probably more in keeping if fitted with a Subaru engine  ;)

Q.  What's black and yellow and full of shit?

A.  A Netto bag   ;D

Hot Rod Magazine had some interesting articles about the subject:
http://www.hotrod.com/techarticles/body/hdrp_0609_aero_tricks_tips/index.html
... and...
http://www.hotrod.com/techarticles/body/113_0703_car_aerodynamics/index.html

Thanks stephan,at last we are getting back on track ::)


cheers richie

<Serious head back on>

Great articles. Thanks for posting the links. Printing them off to add to the library.
Looks like they cover just about everything under discussion on this thread, and more.

Here's a link to the A2 wind tunnel mentioned in the feature
http://www.a2wt.com/Wind%20Tunnel%20Testing.htm

Shame we don't have such a facility in the UK: $345 per hour for the first 2 hours!

 

years ago,drag beetles uses to have the metal covers over the a post gutters?
was that for aerodynamics? ???

See post on page 3...  ;)

thanks!  8)

This is correct.
However, you haven't applied the math correctly here.
(150/140)cubed is the factor.  In this case it is 1.2299, or 23% more hp.

Thanks Bruce, you're absolutely right   :-[

Maybe best not to inform Richie.... if he increases power by 56% we may yet see a full 1/4 on two wheels  :D

JM

Oops, never thought of that!  If he did increase hp by 56%, he'd be up to 162mph.

Mmmm,I will stick with the 56% extra just to make sure :D   box is geared for 164mph@8000rpm in 4th so sounds about right,and all that without any hideous wings?


cheers richie

Now thats what I'm talking about! lol

just found this.

AERODYNAMICS
The Cx of the Beetle, measured in the wind tunnel of the Polytechnic of Stoccarda on the final prototype, measured just 0,385. This datum increased to 0,41 in the mass-production, but in any case it remained an exceptionally low value for the epoch (we were in '38!); you have to think that the aerodynamic Lancia Aprilia hardly reached the 0,47 (0,44 a Fiat127 and 0,41 the first model of the Golf). The datum was also confirmed by the particularly low value of the absorbed power to travel to 100 km/h: only 15 CV. To make a comparison you have to think that a modern Volkswagen Pole first series absorbs 17,2 CV at the same speed. Anyway, you have to notice that the aesthetic modifications introduced in the '67 (squared bumpers and vertical headlights) made the Cd of the Beetle meaningfully worse and in the last models it appeared to be equal to 0,48.

http://www.maggiolinoweb.it/technique.html#cx


Just some more ifo to throw into the pot.


Bit more info...

Found this site with a Aerodynamics database, shame the beetle isnt on it. but take a look and you can see the lift at speed created .

http://www.mulsannescorner.com/data.html

Wasn't the "beetle" originally designed to have lift in order to allow a "high" top speed with a low power requirement by reducing the rolling resistance/friction - along with the whole "maximum speed is cruising speed" thing...?

I was at the track this weekend and only managed one high speed run the others were in the 130's more findings for you from the data logs

over the finish line 145.68 mph the suspention logs say that the car is at the same ride hight as 130, its a little higer than normal ride hight. but it felt diferant. All i can put this down to is as the tires have gotten taller the castor has reduced making the car feel a little less directed. Im going to try and increase the caster to see if this cures this little odd feeling.

going to put the suspention sensors on the front next to see what the ride hight of the car is at the top end. might try and inclanometer, but i think the G's will confuse it.

Other than thats it felt fine, but man the breaks are rubbish!! lol

Doubtful.  Any change in the friction in the bearings and tires is microscopic compared to the wind resistance at 60mph.

145! what times were you running?

10.10 with a 1.68 60ft, going to be working real hard on the 60 ft at night of fire

the axles stayed together then!

Has Boom Boom been teaching you how to launch? :D
Seriously, what sort of 60ft times are you expecting out of the car eventually? I know street tyres are a limiting factor, but 1.40's can't be far off? :)

See you don't need low 60ft's to go quick. ;D

yeah but there nice!

1.68 60 ft is still very quick by my standards  :D

What tires do you use Martin?

micky Thompson sportsman pro's, its about the only option for street eliminator as i feel the drag radials are far too heavy for my axles to cope with.
there no problem with traction

OK i think along all the pages it has been said that if you fit a way it should be done with the aid off a windtunnel as there are too many things to consider. however i want to put my damn heavy car at your disposal Richie if you bring the trans and engine and see what happens. i'll let you even drive once in a while to continue your studies and observations.

But on a more serious note i do think that aerodynamics are a strange thing when you look at dragrace cars covering the 1/4mile. your car Richie does wheelies and catches a LOT off air and wind on the first gears and still manages to go fast. it isn't lowered that much so i guess it takes a lot off wind under the car as well. so i believe there are a few ways around the problem and depending on the car different solutions will be found. and indeed on most cars the wing is a teacup stand and not much else.

Wind resistance is trivial at the speeds where Richie is showing off.

Hello.
First I will admit that I have not read the entire thread closely, only scanned it. So if i repeat what someone else have said, I appologize.

That said, I did a lot of testing on this subject back in the early 90ies. - Both when we were racing at Avon and more on fast street cars.
Our race car was a bit odd, being a 1303 with a 1200 flip front and front beam. The fastest we ever went was 11,21 with a big shot of NOS. We had  a Scat racing wing attached to the rear. (I seem to remember that they were the ones that sold them anyway) It was mounted under the rear window. It was aboiut 12" long ans had a "lip" on the rear. It also had vertical side pieces that was approx 6" tall and narrowing down to about 2" to the rear of the wing. It sat in an angle of about 15 degrees. The weight of the car was 640 kg w.o. driver.

Now at Avon there was often some sidewinds at the final 100 yards of the quater, because the dirt wall ended there. (I think they have changed that now) Many of the faster cars had stability problems when passing that point. We never had that, apart from one time where we had the wing off because of some repair. And Carsten who drove the car said that it felt squirrely when letting off the throttle. We put the wing back on and it was back to normal. Another thing was, that there was a big difference in "efficiency" of the wing, compared to the angle of the wing. 12 degrees was wirtually worthless. 15 degrees gave a significant difference. We had a relatively low front part on the flipfront, allowing less air under the car. That was made because I had some experience from fast street cars with a Kamei or Kamei style front spoiler, that got way more high speed stability with these on. We experimented somewhat with front wheel adjustment in all 3 angles. But I have fogotten how we ended up in numbers. I do remember that we had 5,5 degree caster on it.

The total set up of the wheels front and rear has a lot to do with all over stabilty. Much mare than most people realize.

Now, how much is needed, and when? That is the big question. As we have seen over and over again, beetles nowadays often have trap speeds around 120 mph. and gets away with it. But going from 120 to say 140 mph or more makes a huuuge difference. Then you really have to begin working with the airflow around the car.
From my point of view, I would seriusly begin to think of a front spoiler when hitting speeds at or above 115 mph. I saw a test many years back from Kamei, that showed just how much more weight was kept on the wheels both front and rear simply by adding their spoiler. I forgot the numbers, but do remember that It was a signifincant number at 120 mph. - Russ Fellows`  front spoiler migh not be the prettiest in the hood, but I´m sure it does what it was intended for.

Another thing that was very clear on street cars was, that with the front spoiler the car got much more steady in crosswinds. Especially above 70 mph. To the point of getting very close to front engined cars.

Hope this helps in  shedding more light on the subject.
T

At 145mph, you got mid nine second potential there.

I'm not sure if you can make much of this, but the old school jumper finally got it and Ian C, Lee M and I had a bit of a comedy moment filming the Woolly Bug! The first link (assuming it works my first time at this) is with no wing but as you can see the car has a raised deck lid which will obviously have an effect, the second is with a bit of an effort at a sort of "German look wing" and the third is with a helper.

I'm sure we need to have another go on a road with less traffic on a dry day at higher speed as the filming was difficult to get close enough on a busy road and with hindsight we could have done with thicker wool to make it easy to see but one thing that was a surprise was the effect of the rear window rubber!

I'm not sure what people made of the cars new fashion accessories but it seamed to amuse most!

http://s384.photobucket.com/albums/oo284/petershattock/?action=view&current=WoolyBug004.flv

http://s384.photobucket.com/albums/oo284/petershattock/?action=view&current=WoolyBug005.flv

http://s384.photobucket.com/albums/oo284/petershattock/?action=view&current=WoolyBug009.flv

Peter

That last one is quite a difference isn't it? I presume by the fact the wool is limp that you have create a lower pressure area?

Neat!!

Difficult to make out exactly what's going on in the web movies (assume original footage is clearer?) but there appear to be different things going on in each test...

Looks like the Herod Helper style wing creates more turbulence around the rear window than without??
Roof mounted lip spoiler looks like it may be better (from an aerodynamics viewpoint)
Weird stuff going on around the rear light unit!

Wonder how far down the rear of the car air would stay attached if the engine lid was fully closed?
Maybe the propped open lid is contributing to turbulence around the rear light housing?

See.... the problem with this stuff is you end up with more questions than answers  ;)

Hi John,

We came to the same conclusion about there being more questions than answers, when we started to try and think about it, we all got very confused and decided that we better put the kettle on and have a bit of cake!

As you suggest, there are a few things going on which are a unexplained, but I think we need to have another go with some more serious wool, not so much school kids cardigan, but more fisherman’s jumper (they must do a god line in big woolly jumpers in your neck of the woods), so the results show up a bit better on film (although the original clips are better). If I'm feeling up to the inevitable piss taking, I might have a go at the track some time next year, so the speed is more realistic, although the filming might prove to be a challenge.

I'm not sure what there is to gain from this, for me though, as I'm not about to change the look of the car with some great big strap on...... but I hope it’s of some interest to others, even if it’s just for the comedy value.

So I think I'll go for plan B for 2009. That class A drug habit you were talking about, should save some weight and it sounds much cheaper than the Titanium, Magnesium and Inconol!

Hope to see you at the track this year, don't for get your jumper, we might need it! 
 

Hi Peter,
All I can say is that i LOOOOOVVE your car,
with or without wool! :)

It was a school jumper you say? You sure it wasn't something that you got for Christmas?  :P  ;D

Thanks ruff, "Woollook" it could be the new thing for 2009, what do you recon we could be onto a new thing? That said I went for a razz round yesterday, to blow out the Christmas cobwebs and felt a lot less self consensus without the wool!

Nice Mat, fortunately this Christmas's knitwere selection was restricted to socks!

Happy New Year, roll on warm weather and sunshine!

Well have been thinking about this on a fairly regular basis,got this idea from Der express and as my car needed a new rear apron anyway thought i would try it,managed to get this one from Ppomona last weekend for $35 so perfect for my butchery :D

I have added a couple of other little changes to the car and am still looking at ways to get air out from underneath more easily

cheers richie

Making room for wheelie bars...?  :D ;D

Nice work!

I was going to say something but that's probably how rumours start!

:o  :P  ;D

oh nice
even if don't own a bug. that is how i would make the apron on my car. it looks good too. did you use the original cutouts as starting point. i figured i would have made the cutout wider... but this looks really nice.

!
so are you fitting wheelybars?





repeat the lie, that makes it true.  ;D

I knew I was starting a trend when a late night trash resulted in a rear apron like this on "the fieldcar".... ;) ;D

But It got me thinking, what would this look like if you did it right... now I know, and I like it big time in combination with the 67 lid, it sort of has the same design language as the lid.

In your case, the metal you cut away is whats stopping you from flipping over in the SCC 2008 movie...  now is that a really cleaver move, or a even better idea?  :)
(http://vdub2you.com/gallery/d/8224-1/Richie-Take-off.jpg)

Great video's Peter! Good to see, even if it makes more questions than answers.

Nice.
My fasty´s apron looks like that,perfect for wheeliebars and chute :)
and with your new engine im sure you are gonna need to join the sixwheelers
that brakes with some type of umbrellas ;D

 ::) :o :D  No chance,


not on this car anyway ;) 

Oh,is that how rumours start :D


Patte,didnt think about the chute  mount but it does look like it will make it easier


cheers richie

 ;D

Well I made several changes over the last couple of months but am still not sure if they helped or not,but it sure is stable at 150+mph,on my last pass weekend I was still on it after the finish line and going on the rpm recall in the ECU it went 155ishmph before i got of the go pedal,this is a view from Pat Mcdermotts fiat ont eh 9.33/149mph run and it looks good to my untrained eye :)



http://www.youtube.com/watch?v=1jy2BC3BIr8&feature=channel


cheers richie,uk

That video is fucking bonkers. I can't even begin to imagine going that fast side by side with another car. Especially seeing how much work Pat is doing to keep the thing on the straight and narrow!!

Looks good,

You can see the front end just dip down (may be as you come off the power) if anything the rear end looks a little bouncy? maybe needs a little more rebound control.

just a thought.



Martin

I had a few people come by after that run with obsevations on it being a little bouncy in 4th,I actually softened it up next pass as i felt it was to stiff,but only got one more pass which wasnt conclusive >:( 

cheers richie,uk

Now on Fiat 600 when they road race them (especially in ABARTH trim) they prop open the rear deck flat and the have a really cool looking front piece they attach out front -- They have rally lights mounted on this one.

http://www.youtube.com/watch?v=P2gsTvP1pVI&NR=1

Check out some more of the videos on the bottom and you will see the struts holding the lid up better --- Cheap rear spoiler huh!!!!!

Pat's car and Jon Scheers' car really started behaving when they went to the hardest settings on the shocks

Are you on single adjustable shocks? as the compression looks like its working for you, just not the rebound?

You'll be able to adjust the rebound with a double adjustable shock. This would help the control further down the track...



Martin

Just singles,its only a simple street car,nothing fancy here ;) :D


cheers richie,uk

ok, but you dont want that bounce developing into a hop!. not for the price of a pair of shocks anyways.


good luck.



Martin

Just been going over the data from the weekend,

It would seam that the whole car is starting to lift, more so at the front end. 

Going to try a front air dam and splitter first, might even have to spalsh out on a stint in the wind tunnell


Martin

Its funny you drag this post back up,I was thinking of doing the same,after driving the EBI car on a bumpy track and feeling no negative issues at 130ish mph and seeing that Matt Keene survived unscathed at similar MPH this weekend first time out in a new car both without any aero devices I am still not convinced that any off the shelf stuff helps.

 Given that Hector Urias and Frank Estradas cars dont have any frontal aero devices and seem to manage at 160 mph respectively what is happening under your car to make it so unstable?

Is it possible the larger and taller rear tyres you use are causing some strange problem? with that tall a tyre you just cant get it as low as someone using a 26 inch tall tyre and that upsets the balance of the car more?  just thinking aloud really :D


cheers richie,uk

From the Data, you can see that the front of the car is lifting , and creeps higher as the speed increeces, as soon as i lift a little on the throttle it comes back down.

but even with the car accelerating real hard in 4th, the back of the car is lifting as well. My tires grow 2" past 120 mph so you would asume that the front end would get pushed down.   Its not

the car is going faster than it has ever done (MPH) i was off the throttle at the 1000' mark on all the runs, along with the 10 - 15 mph head wind, the car was 'seeing' over 150 mph.

as for under the car, its just a pan with the forks cut off, just like a regular beetle.


i think the only think keeping it on the grown is the weight of the car!


going to try and stop the air from going under the car first, then if this calms it all down I'll stick with this, dont really want to put a tea tray on the rear.

I'm still of the opinion that you need something to seperate the air cleanly from the rear of the vehicle, don't think this needs to be a tea tray just a sharp edge maybe.

I see the same thing happening on my car Martin,the rear end lifts when the speed increases.On full throttle at maybe 150mph,the rear end is higher than before we leave the line.We're going to adjust the flap on the rear spoiler before the next race to see if we get any result.

I'd be very interested in your results.

as i can see us reaching speeds inexcess of 150mph very soon!

Martin

I know his may only be a trivial point, but thats the thing with aerodynamics, the little things count, like the german look roof strips, but has anyone done any back to back testing (ie same car, same track conditions) with rear wings(fenders, not aerofoils). On an original german rear wing, there is a return lip that runs all the way around the edge of the panel, and is quite deep at the rear, where it comes down to meet the rear valance, but some of the glass race weight wings dont have that return lip, that must have an effect on the air flowing under the car or trying to escape out the back. Would be interesting to see the wool test done to see if the turbulence around the tail lights stays the same as on Pete's videos a few pages back.

Front splitter is being made this week at Websters to stop the air from going under the car.

I'll post some pictures when its done.

I'll be testing it at the eurofinals to see what effects it will have on the lift.

Martin

So its been a couple of years since this was last replied to,so what did we learn since then? for me its still clear as mud :o 

I have seen new devices tried[the skinne front splitter & big wing as an example,but its still using most of the track]  I have heard so many opinions as to why we must have a wing/spoiler and  then some that say it doesnt help at all.
The biggest gain for most of us is cheap small video cameras[go pro is the best example] that allow us some data logging without all the expense and ability needed to actually understand it,the data could potentially make it worse if you read it the wrong way,which is possible,a video is alot easier to understand.
Stians idea with the double plane rear wing looks like it will give some gains,and as his times improve and mph goes up the benifits should show more,but again you need to understand what any adjustment will do.Its to easy to get it wrong and you wont know for sure until you are going to fast already.

I think the front splitter will become more common,instead of adding weight to the front of the car you can use the spliiter to provide the downforce to keep the wheels on the ground[boring to watch but less underwear needed for the driver ;) ]   Then the rear wing may not be needed? if the air doesnt travel under the car what affects will that have? will anyone actually try running a tube from the floor up throught the roof? the theory is there? I did think that it would be possible to run it to a plastic rear window instead of cutting a hole in the roof,would this have the same affect?
Then there are Sill plates,do we need to try some really big ones,and where to put them,yes they are ugly but we all want to go quicker and sometimes compromises have to be made.

There are lots of knowlegable people who visit this site,  it doesn't have to just be "happy birthday ???? whoever" or similar bullsh##t threads does it?  ;) :o :D



cheers richie

Why did you have to bring this topic back up. I am already banging my head on the table whether or not to add a wing and now you start again on all the other mods. thank you!! ;D ;D
Hopefully it will get interesting again.

Michael

Your car is a perfect candidate for some aero mods,it is still a light car and some downforce would make it so much safer and then quicker 8)  Now you dont have to bang your head anymore,just sit back with a beverage of your choice and read what works and what doesnt :D

cheers richie

Oh and its winter,time or making changes and improvements ready for next year just like you are ;)

cheers richie

The biggest gain for most of us is cheap small video cameras[go pro is the best example] that allow us some data logging without all the expense and ability needed to actually understand it,the data could potentially make it worse if you read it the wrong way,which is possible,a video is alot easier to understand.

cheers richie

Thanks for bringing this thread back to life again Richie. This is how the Turbo Town guys use their Go Pro cameras to "log" what is going on with their wing at high speed. Please note that the car in the video is a 1953 Volvo PV and in some ways it have a similar body shape as our beetles:

http://youtu.be/b1hVJKTLGdM

A while back I watched a video of a beetle in a air tunnel and it showed that there is no air following the rear end of the roof. In other words, if you are going to fit a wing you need to place it far up on the roof for it to have any down force effect. But the video also showed that the "side" panels on a wing will have a effect on the stability no matter where the wing is placed. Another example, at SCC my rear lid was kicked open on one of my launches and it was held up by the original springs at 125 mph... need I say more  :)

I think it is the angle of the roof and the longer roof section on the Volvo that makes all the difference.

Front splitters... ugly but they work.

-BB-

Nice to see this subject brought back up.

for me personaly, the front spliter has had the best results so far, 150 mph and the car isnt trying to lift, according to the damper logs.

I have had a rear wing made by Keeno, with higher spill plates (side plates) but im going to try with out and with at the easter meeting and pay close attention to wheel speed / damper extention.

I can only say that so far, the splitter has made the most "seat of the pants" improvments to date.

I personaly think the only proper way foraward with this subject is to allow 5K in the race budget to take the car to MIRA, i have gotten some really helpfull information from them on the subject.
and lets face it, if your willing to spend 20K+ on a motor whats another 5 to keep it on the ground. My next car has this included into the budget.


just a note, we have to remember that increasing downforce can increase drag, but it is posible to increase downforce and reduce drag at the same time... Drag is also the enemy as its costing HP to overcome it.

I do work for a GT3 team, and they have spent 80k+ on aero package, and its very interesting seeing what they come up with, some things you would have never have thought of. with this package they have increased downforce by over 30% and drag has only increased by 5%, dont think thats a bad trade off for what they are trying to do.


Best get savin ;)

I run mainly track days and a time-attack event (and high speeds on the Autobahn), so I am very interested in what might be transferable from the flat beetle to our original beetles  :D
Any sneak peaks or pointers you could give me on the above things I am sure have indeed not thought off?

Tnx,
Walter

Me 2!!!

Sorry Guy's im not allowed, i could lose there work. but hell its very smart. ;)

How about a photo of your front splitter that has worked so well???
Love to see it ...
TxT

Hello Tom,

here it is from above....
(http://i32.photobucket.com/albums/d18/autocraft/52-3.jpg)


And front on.
(http://i32.photobucket.com/albums/d18/autocraft/52.jpg)

as you can see mine follows the lline of the bumper, its now satin black, and you dont notice its there. ;)

Im in the prosses of making it a little longer, 2" from the floor are the rules in the uk, but that can effect the timing lights. so were pitching it 2.5" off the ground.

mines removable for road duty.

hope it helps

Kalle,

good link,thats a good example of what I am talking about,given your own progress this year,and you to Trond,both now running 10s without any aero aids,how does your cars feel at MPH?

cheers richie

Hey Martin,
You tease!  :D
but that's not a splitter your showing, but an airdam!
Oh wait, its on a split, therefore it's probably a splitter  :D

I actually did put a real splitter on mine under the airdam, but its on a super, so its 'verboten' on this forum  ;D

[attachment=2]a different approach to the same idea


[attachment=3]Stians wing/spoiler


[attachment=4]Kalles wing ;)


[attachment=1]Skinne car spliiter,need a better picture but this is all i could find

Thanks to fabian for the pics ;D

and Jyrki's version ;)[attachment=1]

Stable as a train but then again I have not been near the top speed that you and the fast guys are doing when crossing the beam.

http://youtu.be/i8H-g4p0_5w

But rumour has it you cant go over 100mph in a beetle without crashing unless you have a big picnic table :D  So how do you manage

cheers richie 

sorry this is an old picture, the new one has a splitter on the lower edge. ;)

Must not have been an express train since you were going so slow?  ;D

I was going over the line at 125mph or something, and it felt like a beetle: Noisy and old. But seriously, it was undramatic and felt straight and safe.
That said, I'm still replacing my drumstick rollcage for a more proper one this winter. That will add some weight, so I guess I have to loose some to still be able to repeat another 10 sec next year.

So.. what is the conclusion? Or are we able to conclude? I just wish I could find the wind tunnel video again.

What we know:

1) A beetle lifts both the front and the rear at high speed. This is confirmed by Martin and Tekkens log.
2) A beetle with a somewhat correct wheel allignment and classic rake is stable up to at least 125 mph. I have been told that it should be stable up to around 135 - 140mph.
3) A wing, unless mounted high up or a wing like Tekken, will not produce downforce but the side wings will make for a more stable car at high speed. Or?
4) A front splitter is a good idea because it prevent lift due to less air going under the car. After all our cars are shaped like a airplane wing

Enclosed are some pictures of the amazing Volvo in the video above. I talked to the owner and he told me that the car felt more stable after he fitted the wing and he would not race it again without it. I believe his top speed is around 175 mph.

[attachment=1]

[attachment=2]

-BB-

Maybe it's time for me to try to contribute to this excellent discussion. Aerodynamics is one of the most difficult topics to design & test, and to make it even more difficult, suspension geometry should be mixed in. Sometimes it is really hard to tell if the root cause is in aero or suspension!

I have never had any aero help in my street car (unless the deck lid stand offs is considered one). At speeds below 200km/h there were never any issues, but the first season with appr. 400hp was scary. The car would try to go sideways on 10.5" dots in 3rd gear on a prepped track, and the car felt really unstable in 4th gear. Best timeslip was 10.36sec / 220km/h. The traction problem was fixed by raising the torsion housing (was just a raised transmission), but it was still really unstable above 200km/h. Finally we found a cure; the steering geometry had to be changed to minimise bump steer. A lot better but not yet perfect. The next issue was violent wheelies, which was fixed by back-halfing the car. The 32" ladder bars made all the difference in launching, and it also made the car stable at high speed!! I mean all of a sudden the car was very easy to drive with speeds around 230 km/h. The datalog showed that the front end did not lift at all at high speed!!! Maybe the more appropriate link point with the ladder bars contributed in reducing front end lift at high speed (car was still accelerating in 4th)?? Also, being an the heavy side helps; 930kg race ready, with battery, oil tank and some ballast in front of front beam.

I am convinced that a spoiler and splitter help a lot, yet here are all the aero mods I have planned for my new car  ;)
[attachment=1]

Jyrki

The rear of the beetle is to steep for it to have an effect perhaps?

(http://www.gerrelt.nl/roofspoiler/VW_beetle_teardrop.jpg)

(http://www.gerrelt.nl/roofspoiler/beetle_windtunnel_test.jpg)

So the wing would have to be fit on the end of the wheelie bars to have an effect :-D

Here is some more slightly related info (new beetle)
http://www.autospeed.com/A_108675/cms/article.html

Or we can make a deflector on our roofs that will force the wind to a wing:

[attachment=1]

"And for something even more extreme, just look at the V6 Beetle RSi. Its huge rear spoiler and flow-directing upper window attachment are said to give 77kg of downforce at a massive 250 km/h - a pretty academic figure when that's apparently 25 km/h faster than the car can actually power itself to.... Drag also rises from the factory 0.39 to 0.40! But again, the wool tuft testing shows why the huge spoiler is both needed and why it is positioned where it is. Incidentally, one media test of the massively spoiler'd RSi Beetle said that on the autobahn the car still "displays a lack of stability"!

Brilliant picture and info Trond, thanks for sharing.

So this proves it, unless you mount your wing above the rear window and/or make it very long you can just as well forget about the downforce effect. What you cant see in the picture is that the wind is actually going upwards further down towards the rear lid. This explains why you see a lower engine temp when lifting the bottom end of the lid instead of mounting a so called "cool air". The cool air kit will allow heat out of the engine bay but lifting it up at the low side will allow more air into the bay. But only as much air as you can get out.

-BB-

can anyone remember how fast the Stahl land speed beetle goes?

Looking at the great wind tunnal picture, looks like an effective wing is going to have to go above the rear window, or under the rear window but about 2M long! lol
it would be interesting seeing it with its nose down....but saying that, my cars front end is still high at the top end of the track.


link might work, if not give it a google
http://blu.stb.s-msn.com/i/FD/135EADC1632ED3AEB9D8B51CD8249

Thanks guys the posts from the last few days made it all clearer to me.
My car is in the workshop at the moment and talked to Jim about this subject. I wondered if he could make one. All I have to do is give him an example but I don't think google will come up with a picture of a wing fitted above the rear window.

Michael

Michael, be careful, if you mount the rear wing above the rear window it may cause people physical harm to their eyes, or induce vomiting.  I personally really like it, but, hey thats just me.   ;)

Anyway, looks like the wing may have been in the 'correct' position, whether it's aesthetically pleasing or not.   ::)

Hope the pic helps.

(http://i30.photobucket.com/albums/c342/vw71/58781263IMG_6535.jpg)

That guy  has been in a wind tunnel for sure

Thinking about it: A small, plastic wing mounted on the upper window rubber can make all the difference in the world on our cars. It will create less drag and create down force. It should be easy to make too. If I remember correctly the wind starts loosing it's "grip" at angles around 25-30 degrees.

Hmmmmmm...

My car in 1992...

[attachment=1][attachment=2]

I do remember a wing like that on Martin's split some years ago while it was visiting Spa-francorchamp (Lebug show)  ::)
It didn't look that out of place compared to those ugly(er) dragcar 'geisha' extensions (back packs)  ;)
I ran an (also ugly looking) small rear wing halfway of the rear window for a trackday, but couldn''t really tell a difference with or without it. Did give me more confidence though...

You can just spot it there:
(http://i174.photobucket.com/albums/w112/fusca03/1303/IMG_0799.jpg)

There are a lot of talk about downforce in this thread, and I ask myself, is that whats needed?  The problem as I read it in this thread is that the body shape produces lift? Isn't it enough just to get rid of the lift?

That being said, maybe thats exactly what people have been achiving with the wings in the normal low position on the bugs? I mean, when I look at the Volvo PV video I can't see any evidence that the wingplane is seeing any force from the wind, it's hardly bending at all, and you can see from the vibration that this wing is pretty thin. I bet it would bend more from placing a bag of groceries on it.
But here comes the twist, these wings still work... But they are not producing actual downforce... Maybe they change the profile enough to eliminate the lift. Maybe they create a pillow of turbulence ontop of the wing... So the airflow  rides over that....   ???

Ofcourse, you can keep a airplane on the ground by adding spoilers creating downforce, just seems much smarter to take the wings off.;D

Just some thoughts on the subject.

So you are saying we should take the roof of....?  :P

Yes, or make a little sharp wedge shaped spoiler on the rear part of the roof, to get the air to break free... I can't remember where I got it from, but I saw it described somewhere.

Nooooo,I dont want to see the pits full of roofless cars,they look sh#te :D


Keep it coming everyone,lots of things to think about and the more input the better,that pic Trond posted really shows how little effect the conventional wing has,now if we could just get the same thing[picture] with a front splitter on it to see what happens as a comparison it would be perfect


And the report of the new beetle makes me even surer that most wings on beetles are pointless for downforce


cheers richie

But they make a cool place to rest a cup of tea...

Pjuh, that's a relief, now I can skip making a wing for my racecar, and make a invisible splitter instead ;)

This is what I am getting inspired from and my Beetle will get the wing for sure this summer.
A CF wing has waited for two years. Stream lined profile struts and support arms in to the roof.
High enough but just not too extreme.

Fun Cup website. Nope, not aircooled but looks good. Everything can be bought from a pricelist. Every single component. Not cheap though.

http://www.funcup.co.uk/default.asp

(http://i153.photobucket.com/albums/s207/Frallan2/0501ec_08zVolkswagen_BeetleDiver_Side.jpg)

corrected it for you Keith ;)

My understanding of a Beetle's aerodynamics is to disrupt the airflow at the rear to stop the car's natural tendency to lift the rear at speed. Excessive downforce at the rear should be avoided because the moment you create downforce at the rear the front will rise makIng it go unstable.

My own experience with my car led me to create a wing that sat beneath the rear window to disrupt flow. Now I don't have any fancy data loggers, so I can't baffle you with numbers and science. But I have a 'butt-o-meter' which registered that prior to the wing the car was undrivable above 135 mph - the rear was steering all over the place the moment I backed off or pulled the 'chute. It was downright dangerous. Since I fitted the wing - and made no other changes! - the car has driven arrow straight at speed. 146 mph feels so stable I don't even bother with the 'chute. Now I am not suggesting I have invented the wheel or anything; simply conveying my experience on my car, which will be setup differently to every other car.

My advice to others would be don't dismiss the simple rear wing beneath the window as it works in certain applications. Try it and see for yourselves.

AND


Gentlemen, I believe you have pointed out the essential!!!
Jyrki

Bob Stahls 65 Bug did a 155.828 mph in 2004 at Bonneville (see pic below):

(http://i494.photobucket.com/albums/rr301/36hplandspeedracer/BobStahls65Bughasbeento159mphSmall-1.jpg)
Bobs large wing is essential to stabiilty in any VW Bug at speeds above 110 miles per hour! Photo by Burly Burlile.

Here is my two cents worth. Back in 91 and 92, my partner Kerry Hart and I built a stock bodied (no wing or aero!) Super Beetle to run on the Bonneville Salt Flats with a goal speed of 133 miles per hour. Kerry made it to 131.296 mph and I hit a high speed of 129 mph. I can personnally verify it was down right "scary" at those speeds with the rear end lifting and dancing around even with 500 lbs of ADDED ballast (200 front/300 rear) and another 200 lbs of added safety gear and dry oil sump system. Kerry later did three 360 degree spins on the salt at 115 mph because the car had no rear wing. The 700 plus pounds of added ballast and the lack of walls down Bonnevilles long black line meant he did not roll or hit anything with the SB. See pic below:

(http://i494.photobucket.com/albums/rr301/36hplandspeedracer/DaveTaylor_004Small.jpg)
Burlile/Hart stock bodied Super Beetle in 1992. Photo by Dave Taylor.

Dean Lowry's last racing effort, another land speed racing Super Beetle was topping out around 130 mph at El Mirage before he added a simple old VW accessory called a Herrods Helper, an aluminum wing that clamps onto the air slots under the rear window. Once the HH was installed, the added stability allowed him to jump up to speeds in the low 140's. Unfortunately he passed away before realizing the full potential of his winged VW. Although Deans Super Beetle was esseentially stock bodied, the addition of the rear wing placed him in and altered land speed racing category: See pic below:

(http://i494.photobucket.com/albums/rr301/36hplandspeedracer/scan0003.jpg)
You can see the simple bolt-on Herrods Helper just behind Deans head in the photograph. Photographer unknown?

To date the fastest stock bodied Beetle in land speed racing belongs to the Hicks/Forlano 61 bug set in 1991 with a top speed of 132.100 miles per hour. See pic below:

(http://i494.photobucket.com/albums/rr301/36hplandspeedracer/HicksForlano_003Medium.jpg)
A year after this photo (photographer unkown) was taken, they added a rear wing and their speed immediatley jumped up to 141.242 mph on the idrt at El Mirage.

I would strongly reccommend anyone expecting their Beetle to exceed 110 miles per hour in drag racing or land speed racing (or on the street!) to add a rear wing, even if it is something as simple as the new replica Herrods Helpers currently available. This aerodynamic improvement will greatly reduce the chance of aero related instability.

Burly  (36hp Challenge)

hm...intresting thread.. :o

I was working on some professional racecars in the windtunnel before.
All had some nice looking wings (Designed and calculated before) which most times didn´t work at the first time.
It was ALLWAYS a long day with a lot of meassurments to find a solution
which really helps the car.

The wing of the Fun cup car is in my opinion just for the show and
I think it will be faster without it...

just my 2 cent...

Cheers,
Basti

It should be possible to make a small size cabinet, add a air compressor and some smoke and take it from there like this guy:

http://www.youtube.com/watch?v=vsFwU4T_qe8

Interestingly enough it is a cabriolet  :)

That is so simple,but so usefull,well to me anyway :D 
I would have never believed that putting the roof down would make so much difference,the way it follows the roof line rather than just get forced up in the air from the windscreen has got me really puzzled,why doesnt it hit the screen and go upwards when the roof is up like when the roof is down? I understand it will change the way the air moves,but not how drastically it does?
Anyone explain?

cheers richie

So we need to brake the wing effect the beetle has, by not letting the air go under the car, and not follow the back of the car down to the ground.
Easiest done this way ?

 

Check this one out:

[attachment=1]

Decrease in aerodynamic drag coefficient: minus 4 %
Increase in top speed: plus 2.3 %
Reduction of fuel consumption: minus 1.5 %
Decrease in lift coefficient on front axle : minus 64 %

Front axle lift at 125 kph / 80 mph is reduced from 2 cm to 0,5 cm.

There is quite a lot of interesting info to be found on the web, especially from people trying to reduce the drag to improve the fuel consumption (believe it or not). Roof wing:

http://www.gerrelt.nl/section-aerodynamics/roofspoiler-explanation.html

A little more on drag and performance:

http://www.autospeed.com/cms/A_3058/article.html

http://www.autospeed.com/cms/A_3059/article.html

http://www.autospeed.com/cms/A_3060/article.html

And the conclusion is really interesting:

http://www.autospeed.com/cms/A_3061/article.html

-BB-

Keith did you notice much difference with that wing as opposed to the more tradiational spoiler you had before?at what point was the front piece added?


cheers richie

I   wonder how different the Stahl car would behave without the scoop so high up,it must have a major effect up there,also those spill plates look like they will do some good.

cheers richie

So having had a few days to digest all the info[and to much turkey :D ] I have started to make what I think a beetle needs,a front spoiler/splitter and spill plates for the back,I am not convinced by any rear spoiler that i have seen so far,so I will ignore that for now.
I have made a card template for the front,and will transfer this to alluminium this week hopefully time permitting,the spill plates will take more time as I havent got a clear idea in my head yet of size,shape and location.
I am doing this on a beetle saloon,not a cabrio 1st of all as the info should be more usefull to everyone,I have an idea I intend to use to fix the front splitter without any drilling or welding to the base car so as to make it totally removable in approx 10mins,if it works then I will share it,if it doesnt then I will keep quiet :o ;)

cheers richie

In my touring around the pits at a local VW race and talking to a couple of guys, I started looking at one of the cars that is quite fast in naturally aspriated form and the gentleman was running vortex generators on the roof of his car. I casually asked him about them and he said he was experimenting with them and didn't know if they helped or not. Well, knowing this gentleman and his legacy, I'd say that he doesn't do anything by chance and they were on there by design and the location was well thought out in advance.

These might be a solution to the problem without going to a wing.

http://www.youtube.com/watch?v=We8LWkqjdX4

http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/2004/16E_03.pdf

Anyway ::)

Been watching some wind tunnel videos,heres a few I found interesting


http://www.youtube.com/watch?v=8PoIoQNIoMQ&feature=endscreen&NR=1 (http://www.youtube.com/watch?v=8PoIoQNIoMQ&feature=endscreen&NR=1)

http://www.youtube.com/watch?NR=1&feature=fvwp&v=7Xc5TjtZh34 (http://www.youtube.com/watch?NR=1&feature=fvwp&v=7Xc5TjtZh34)

http://www.youtube.com/watch?NR=1&feature=endscreen&v=3EjFkPL_H_4 (http://www.youtube.com/watch?NR=1&feature=endscreen&v=3EjFkPL_H_4)


cheers richie

Great videos Richie,thanks!

Talking about wings and splitters...: http://hellafunctional.com/?p=369 (http://hellafunctional.com/?p=369)  

Here is a idea to think about...  :D

[attachment=1]

Nice really subtle :D 

cheers richie

So on the subject of splitters/front chin spoilers. I wonder how effective the old 70's affairs made by companies like Kamei etc. are?

Does any info/data exist for these? and would they be any use for a drag racing application?

Something to think about.

Look at my reply earlier in this thread where I have enclosed a tech sheet for the Kamei front spoiler.

Thanks BB

I have just re-read this thread and couldn't find your post ???

Wings/airfoils.  Are they really needed?

The poor soul driving this car "turned turtle" at 180 mph. Though I suspect he rotated and was wheels up long before that point  ;D

 Page 8, scroll down. 

And if I'm not mistaken the Black Widow ended up as a wreck after a terrible crash. The driver survived and there is a picture of him standing next to the wreck with a big smile on his face. Probably smiling because he realised how lucky he was...

Thanks BB, the German confused me!

Look at the front wheels, expesially towards the end of the run.I think the car is lifting, what do you think?

http://www.youtube.com/watch?v=5d4bcRA4Odw&feature=player_embedded

could this be,because of the parachute that is deployed?

henk!!!

Or 1025 whp and too much down force at the rear?

You can see the car turn left before the line.Do you think it's loose in the rear, or is it the front starting to float..?? To me it looks like he then pulls the chute and you see the front come back down.The thing is I have experienced the car du a turn like this many times myself,expesially with the old car.The speed has been slower like 235-250km/h but with really light car with no weight at the front.Could also see it on the linear shock sensors that it was lifting a lot.This VWP car is almost 1000kg with driver, but also higher speed like 280-300km/t.
I know the big HP numbers, but still don't think that is the problem.
Talked to Eric/Red Baron.He uses a splitter type fibre glass front,but don't have this problem.The car is actually lower in the front at top speed.

Thanks for sharing Stian,

I do believe Kris mentioned that it started to drift to the left due to side wind. If it had more down force at the front it would perhaps stayed on the track? I find this very interesting. Perhaps you can share what you`re log is showing you? Does your car lift at top speed? If so, how much?

-BB-

I had linear sensors on the RPM logger in the previous racecar.I don't remember how many mm, but when I passed 220-230km/h on full throttle the car had the same height as standing still.From there to 250km/h the car keept lifting and lifting.At approx +240km/h the car could suddeny turn to one side, had to pull the chute right away and step of the pedal to get it straight.

An example from SCC 2009.Look at the end of the run, and you'll see the car starting to float and suddenly turn to the right.Not a good feeling in +230km/h..

http://www.youtube.com/watch?v=Nn0b70Gma5A&feature=plcp&context=C3eb1b1bUDOEgsToPDskI8ovWOGh9arwzJaHC5ueM-

But this car had a really low weight, maybe 700kg with driver and no weight at all on the front wheels.
We added a lot of weight on the new car to get a better balanse.The plan is to install linear sensors before the season starts so we can see if the weight and wing makes any difference.We are also thinking about making a small splitter.The car now is really different to drive with the better weight distribution, feels a lot more stabile and safe.

Dam! Thanks for sharing Stian and please play safe!!

Kris's car is a strange one,until he posted that video I had never noticed how much it lifts at the front,under power there can be no steering possible in at least the first 3 gears. But the car has a huge amount of weight in the front,this obviously isnt enough to overcome the torque that the engine is pushing through the chassis trying to lift the front.It does look like some front downforce would help,the front end on his car is also an unusual shape,but guessing on aerodynamics on our slower cars is risky enough,but with his mph would you really want to try something new that may or may not work?
I will also try the height sensors this year,but I will definatley be adding a front splitter/spoiler proberly before the 1st outing and have a couple of other ideas to help air escape from underneath and inside the wings[fenders]


Stian,that video looks just like a pan car with to much power and not enough track ;)

[attachment=1]How porsche do it on a 911 cabrio
[attachment=2]can we apply anything here to a beetle?

I'm not sure if this contributes to the topic but what about making holes in the backside of the front fenders. Some one asked me if I was going to add them.To be honest I don't like the look of it but does anyone know if it actually works?

Michael

Micheal,

this is something I wondered about as well,when you cut away alot of bodywork from under the front[even more so on a tube car with flip front] and dont have any device to stop the air getting under there[splitter or similar] there has to be alot of trapped air under there trying to get out,and consequently causing lift,as I have some extra wings/fenders available, I will use them to experiment with,I also dont like the look of plain holes,my idea is to make some trap doors in the back of the wings,hinged shut normally,try to make them blend in as well as I can so they are not noticable when the car is just parked and use the go pro camera to video what happens on a pass :)
If they do nothing then I will just put the other wings/fenders back on.

Keep the ideas coming ;D

cheers richie

Bernie Ecclestone had a good idea back in 78 with the Gordon Murray designed The Brabham BT46B Formula One racing car,
(http://i149.photobucket.com/albums/s60/JenkinsComp/Random%20Cars/brabham-bt46b01-1.jpg)
It didn't go down very well with the rest of formula that race which it won and was banned for the next race .
It was claimed by the Brabham team to be there to be an aid to the heat exchangers , but it proved to be a bloody good way to hold you car to the track .
 Not something I'd bolt to the back of my own car but I the theory is sound , think about it in a car with the rear fire wall removed and paneled out as many race cars are just add the fan and a bit of rubber skit around the pan and you have hoover bug  ::) keep the engine cool too  ;) after your run ;D

Who jacked it from Jim Hall  ;D

(http://1.bp.blogspot.com/-aiNwar27bgo/TljrUq9gFTI/AAAAAAAADBA/tsvjf9NBhKc/s1600/chaparral-sucker-2.jpg)

Back in 2001 or so when I was doing my post-grad teacher training I was sharing a house with an undergraduate on an aerospace degree. He raised that very same question about a belly pan under the front end but his thought was that the trapped air is "less bad" than a smooth belly pan. Yes, it's a disruption to smooth flowing air, but with the curved top to the Beetle, a flat bottom would make it the whole car into a wing profile and generate more lift. The biggest problems that he saw were the wheels - he said that he'd fit a type of Moon disc inside and out of the wheels, and even try to enclose the wheels with cycle fenders within the Beetle arches to allow the air moving through to remain as un-disturbed as possible. :o
I told him I was only running high 15's at the time and so it didn't affect me... :D

Even the quickest cars get updates,Kris's car from this weekends vegas meet had these mods added,the 1st car I saw this done to was Frank Estradas turbo car,I have seen it on some VW Pro stock cars as well and have considered it for mine,something for the winter maybe as i have a spare pair of front wings to try on



[attachment=1]front fender vent

Most DTM and other circuit racers all use that too. I was wondering why no-one in the drag scene used this. Cool pic and well spotted!

I used some lower placed vents in the front wings this year for the first time like some others have done with round holes. Hard to notice the difference without actually measuring pressure in the wings. The higher placed vent on Kris' front fender seems more in line what track racers do though.

(http://i174.photobucket.com/albums/w112/fusca03/1303/Aerodynamica003.jpg)

Do we know if there is any positive pressure in that area?

thinking out loud i supose you could measure the preshure with a map sensor and place the tube in various points around the area. but i dont think this would give you a difinative result you may fined pockets of pressure hi and low....

The front susoension sensors will give you a reading to see if theres any lift created by positive pressure trapped unter there.

But I keep going back to, the only definative answer, is to get to the Wind Tunnel and test it. Then you would know if there was any more drag created by trapped air...

The Wind tunnal costs 4.5K last time i got a price from MIRA for half a days usage. Put it into perspective it can produce cheep HP via less drag and you'll have a good handle on what the cars going to be like at 160 - 180 mph




Martin....... 

(is it easter yet?)

Looking at the model in a wind tunnel video I'd be inclined to put a spoiler on the front of the roof above the windscreen at a similar rake to the screen. You'd need to play with the height but essentially you just want to unstick the air in the same way you saw when the roof was missing.

By spoiler I mean a device to disrupt air, just a flat piece sticking up.

I know nothing about aerodynamics BTW just applying common sense to what the video showed.

That looks really neat,nice idea :)

cheers richie

I had another picture of that car at speed and the tires are so compressed that it looks almost like the car is running on the rims
[attachment=1]

My buddy has a NASCAR road course car here are some pictures of its aeros

(http://i586.photobucket.com/albums/ss306/Fiatdude/photobucket-11485-1350665688760.jpg)
(http://i586.photobucket.com/albums/ss306/Fiatdude/photobucket-5763-1350665631417.jpg)
(http://i586.photobucket.com/albums/ss306/Fiatdude/photobucket-2943-1350665645342.jpg)
(http://i586.photobucket.com/albums/ss306/Fiatdude/photobucket-11944-1350665603599.jpg)
(http://i586.photobucket.com/albums/ss306/Fiatdude/photobucket-4855-1350665616636.jpg)

and another friends car

[attachment=2]
[attachment=3]

not at the same level but now we are doing 96+mph driver had to lift of at last gamblers race as car started to turn left and when she tried to correct there was no feeling in steering and more worring no response.stock hight at front and lower profile slicks and first time into a head wind.have got narrow(2inch)adjustable beam to fit over winter ,thinking of mk2 polo rack so itwill keep stock(ish)  track rods . was thinking of chin spoiler but have a beaver tail trailer so may foul  ::)

I really wouldn't go for rack and pinion, especially with the narrowed beam! Had one on my car when I bought it and it was horrible even at 30 mph! I bought a brand new steering box and it transformed it.
If I had your car, I'd put the new beam on and point the front end down a bit, at least until it's level but preferably slightly nose down. 2 sets of caster shims will make the car feel more stable at speed too, so it shouldn't feel so twitchy. Ask Holly to describe exactly what happens at speed - does it start to get "waggy" or just drift off in a gentle arc? What is the play in the steering box like? Did it feel like a crosswind had hit the car?
If you remember my old car, it had the little chin spoiler on the flip front and the big wing on the back and always seemed stable at 100mph+. Ok, it was chopped and de-guttered too, but I think that was a smaller part in its stability. You could have the chin spoiler Dzus'd onto the front wings so that it is removeable for transport?

Neil, there are nothing wrong with racks, they just need to be fitted correctly.

Martin

I know, mine wasn't! Not by me, I have to add! :D
On a 13 second pan car I don't see much point in re-inventing the wheel though. On a beam front chassis car I'd seriously consider it, or maybe even if the beam position was getting moved with a framehead raise, but as Holly's car is essentially stock, it seems like an un-necessary modification.

dont want to get of subject but using polo rack I can keep stock geometary ,is it worth it???dont know but wanted to try and its reversable if it dont work.as to castor ,yes was going to put in lots.and did think about removable spoiler/splitter.taking some weight out,ali fuel tank,perspex windows,headlamp bowls ect.dont want it to light though reading these posts.

I cant remember,does it have a spool in it now?  sounds like either a side wind or the track was cold,definately get some improvement from getting the front lower, why do you want to fit a narrower beam?

I have a similar problem getting the car on and off trailers,I have a spare pair of front wheels now with a taller tyre to get clearance just to load and unload it and I made the front airdam removable with dzus fasteners,not that i actually used it yet

cheers richie

This car has it all figured out :o

is this the first pici of your 10 second street car?????  :)

found play in a trackrod end,didnt show with it jacked up so cant be that much.why the narrowed beam,thats cos the only beam I had spare had adjusters welded in that had siezed so cut them out and welded in new coz I had some.No spool yet thats a winter project if we can get one cheap ,also thinking of lower 3rd and 4th as stock ratios at the mo.also need adjustable coil overs to stop rear squat ,anyone got some cheap????back to the thread ,will have a go at areo aids as well ,watch this space ;D

the only thing similar to my car is the colour ;D

Snow plow

V8

Hello everyone
A number of years ago and was tested in the Volvo car vindtunel that was built on rolling floor
So we got strange results
Was the reason was that the air flow between the floor was so that the car had to lift
We changed the car height in the rear (1.5 degrees) decreased lift in rear
If the airfoil is straight can be increased lift due to poor air around the vehicle
Then one of the worst arodynamiska problem is the tires
Often a vw's side open and where would the air flow going in and lift the car in the rear
And the car becomes unstable at high speeds
Then I'm surprised how to mount wings on the cars
I want to give you a tip to buy the book
Race Car aerodynamik:
Designa för Speed
//// Micke

Hi everyone ,

hey Ritchie , this is quite a hot issue when you start poking around .
My bug isn't that fast (low 13s) that it needs much aerodynamics allthough it gets very unstable when you come off the throttle at the end of the 1/4er.

I still want to make this point :  when the first Audi TT coupe (little roud ass ...) was launched , it had a bad reputation for unstable behaviour at higher speeds.
therefor I think Audi introduced the little rear boot spoiler and solved the problem of instability . I wonder if that's not the same with our bugs at higher speeds. Maybe a well placed Herrods Helper could have the same effect on stability ...

Greetz
Marc

If your bug is getting unstable when coming of the power you really need to look at limit straps or rebound stop mod as its probably getting unstable to rear end lift/positive camber.

With rebound stop mod, my car feels great coming off power, as it did today when I was we'll over 90mph and someone decided they wanted the fast lane too :o

Lee

According to this wind tunnel test, the VW Beetle is more aerodynamic when driven backwards......

http://www.youtube.com/watch?v=IsDUVXscCGg&feature=youtu.be (http://www.youtube.com/watch?v=IsDUVXscCGg&feature=youtu.be)

Maybe Geordie McAvoy (sp?) had a point all those years ago with his backwards Beetle! :D

Only if you do not have a wing  :)

John,

I am not sure it will help,I have seen a couple of bugs go through the finish line backwards and it didn't end well :o ;)

I had heard the stories about it for a long time,just never seen any evidence before

cheers Richie

Been there, done that - didn't work for me either!  ;)

Wasn't going to mention any names :D

I have the "Larrys old volks home" land speed ghia here at the moent,it has some interesting things done to it,I will take some pics later and post them up

cheers Richie

Land speed ghia,it has been high 160mph,not huge by drag race standards but sustaining the speed needs more control[attachment=1]some records it held[attachment=2]more records it held[attachment=3]simple but very effective and soemthing not used for drag racing[attachment=4]to hold the windows in? 

The ducting in the car is different,1st they duct it from behind the nose grills through vents pressed into the bonnet[attachment=1]you can just about see the tubes to vent air away[attachment=2]these tubes would be conncted by hose[attachment=3] to these tubes into the boxes and out through the vents[attachment=4]bonnet vents

Then there are these vents letting air out,from the article I read it was supposed to have ducting to let air from underneath but I cant see any evidence of that

Then there are the roof rails,pretty standard I think,
[attachment=1]covers on vents[attachment=2]vents [attachment=3]roof rails[attachment=4]unsure of what this is for

there is this inside the package area which I havent figured out what it does yet

Very cool pictures and explanation to go with it!
"I love Bonnie" !  ;D

Maybe the floor pan shows some hints of what the duct openings in the parcel tray, that end under the rear window, are for?
It also could be that the pan or other parts of the car were replaced making those ducts obsolete?
Just wild guessing.

Thanks for sharing Richie  ;)

Not a wing or an aerofoil but I found myself in a VW showroom at the weekend and had a look under a new Polo and found they have a golf ball like finish on the under trays and floor which I'm sure was not for fun. All sorts of other aero bits under there too.

Peter

Pete

interesting, and as you mention VW don't spend time and money on something like that for no reason, maybe you could "test drive" one and get it on a ramp to take pictures quickly ? ;D 

Hopefully I will get a chance to try some "add ons" I have made this weekend and get enough track time to see some difference or not

cheers Richie

In talking to some of the people racing ghias, they use those 'vents' on the package tray to get additional air to the engine and help remove air from the back of the cabin, but remember they run with no side windows in their cars -- -- also a few of them stated at higher speeds the air flow started reversing and they were getting hot air back into the cabin -- my car has the dual front ducting also but mine is directed at the front brakes

i know sweet fanny about drag racing,  but i see most drivers that are suffering from unstable handling at high speed all have one thing in common, they're cars are too high from the ground, but they seem transfixed on this idea and quote the magic words ' weight transfer', then they bolt a b/d work mate on the back and go slower. the Beetle has a very good basis for establishing ground effect right from the showroom, being flat bottomed is a designers dream, and the basis is pretty good as stock, and can be improved on even further with properly designed side pods and under trays to increase the area, the magic number is 40mm ground clearance at the floor pans, this also just happens to be the regulation ground clearance for the circuit racing which i am addicted to,  40mm is good aerodynamically offering good downforce without the problems of instability found on very low cars when cresting rises or track undulations for example,  i notice all the quick cars, including Richies ar running nice and low, so im hopefull i will never need a b/decker on mine, tho my top speeds are lower than drag cars, but we do have to toss it into turns at high spped, and i can run with be winged 911's no trouble, just the free grip from physics, i may go 13" inch wheels to give more scope, not yet set in stone, as the brakes may need changing,  Richies car was rock steady right through the 8 second run, congratulations on that are due, big respect, it looked almost like it would give my track car a good race lol :D  ;D  in my view, wings belong on aircraft and have done more to spoill racing than any other 'invention'  .
well done again on the 8.

Here is some discussion about beetle aerodynamics


http://www.germanlook.net/forums/showthread.php?t=2820


I plan to add front spoiler and small rear spoiler over rearwindow like these:

(http://www.day-of-thunder.com/assets/images/Bild_Rennkafer.jpg)

(http://www.kerscher-tuning.de/images/dynpic.php?file=L2thZWZlci9ncmFmaWtlbi9zdG9zc2ZhZW5nZXJfbV9zcG9pbGVyLmpwZw==&width=500)

(http://www.laperformance.co.uk/blog/wp-content/uploads/2010/05/DSC02597-1.jpg)

Time for my dumb question of the week.  :)

I know those small aerofoil lips over the top of the back window do wonders for stability at speed and I've heard even lowering the Cd, but just by their very design don't they also rob valuable cooling air from the engine compartment vents below it?

the yellow car shows exactly my point, it has this that and the other, but it needs to come down 2"..

As requested a golf ball floor on new a new VW.

 [attachment=1]

Interesting little vortex type deflector at the back of the floor too. If its intended to prevent the need for an enclosed floor to the rear it could be good for us as it would mean the area at the back of the car could remain open so as not to cause any potential cooling drams by extending the flat floor to the rear of the car. That said I'm not at all sure that is what its for but rest assured it will not have been done for fun!

[attachment=2]

As ever more questions than answers.....

Peter

This is interesting Pete, as when I raced a boat (quite a few years ago) there was a theory that the golf ball effect on the underside of the hull would create pockets of air that would lift the boat thus less drag.  I did try it once on a jet ski but I could not feel a difference.  VW might have made the floor like this for strength and these shapes could be cheaper to press, tooling wise.

So did you reach any conclusions from the wool testing at EBI ? or was that just to keep the car warm ;D


cheers Richie

Yes! The wool tufts were to long.

Round 2 at Bugjam all being well.

Assuming I have anything worth sharing I'll post it here.

That said it looks like the top of the rear window rubber is the end of the attached flow over the roof and the rear window air flow remained disrupted down the rear window. Hopefully I'll be able to confirm in a couple of weeks.

Peter

That is absolutely correct and if you search you will find wind tunnel pictures proving it.

-BB-

Pointless fact - the guy that runs our local trailer hire place (BDS trailers) told me he used to race power boats with you Mr Newbury :)

Check out the bottom rear of the front wings in this video, an interesting approach

http://www.youtube.com/watch?v=_Vo-ikdgQGQ

I like his dash :) it would be interesting to find out how much the air is opening the vents

Cheers Andy

Interesting flaps on the back of the wing. There is clearly air wanting to escape from under the wheel arch which makes good sense given all the air rushing under the front of the car assuming there is no floor and wheel arch covers to reduce the amount of air getting in there. Where this turbulent air goes once it exits the flap and what effect positive or negative it has on the remainder of the cars aero who knows.
I didn't get round to checking this on my car last time out but one other thing I've been thinking about is the shape of the front and rear wings, as in principal they are not dissimilar to the whole car wing shape. I was going to do some wool tuft testing on the wings to see where the air detaches. Assuming this is correct we could expect each wing to create lift given the high speed low pressure air over the top of the wing and what is at best atmospheric if not high pressure under the wing. Clearly the area this pressure differential is acting on is far less than the roof but none the less it must be significant as the LMP cars all have wing top vents these days and the regulators have sought to control their size and shape in the classes where they are permitted. Again there is the issue of where the turbulent air then goes once it exits the wing top and what effect that then has on the lift and drag.
If you look at the wheel arches of a lot of the touring cars and rally cars they have big cutaway sections behind the wheel arch extensions used to cover the increase in track. This is perhaps similar also to our wings which extend from the main body line.  They again clearly have seen some benefit as the regs control their shape location and size which supports the need for the flaps and holes on the wing backs
For what its worth I think the first thing to do is reduce the amount of air getting under the car (lower the car with the added benifit of reducing the c of g) to reduce the problem at its source. Then if you can stomach the compromise of the look, fit an air dam. What ever you decide to do above then enclose the area's in front and behind the floor pan linking them with either the air dam / front valance / front wing lips and a diffuser at the rear. This I think would help reduce the effect of the turbulent air (less drag) and tidy and speed up the air under the car. Assuming this can be done to a point where it creates some negative pressure with the now high speed air which is acting over a large area (the whole of the underside of the car) could create some significant negative lift with little additional or potentially reduced drag.
Wouldn't it be nice to keep the same look externally and reduce drag and lift in the process! Certainly would be a lot better than having a big strap on on the back of the car (if it works).
All very well in theory but need less to say in practice it will be a bit more difficult as although we do in a standard car have a good start with the floor pan the rest is a bit of a mess. That with the need to get the exhaust and the hot engine air out from the back of the car (blown diffuser?), assuming its not a drag only car, sump extensions (unless you are dry sump) air in to coolers etc makes it all a bit of a challenge in practice when you start really looking at it. That said it would be an obvious thing to try and include an oil catch tray with a diffuser at the back of the car.
To end my ramblings on a positive callook note a nose down rake on the car is a good thing in fact that is understating it as at speed a nose up stance could be very dangerous so it does need to be kept this way when the car is under load too.
So there it is callook is safe!
Peter

Few ideas I've had no idea if they will work and nothing to compare to, stripped the guts from the heater chanels to vent from front to rear to feed the turbos

(http://i71.photobucket.com/albums/i149/gluemixer/661D6758-2AB5-4ACB-AC73-1A94797945E0-1139-000000A0DFFB55A0.jpg) (http://s71.photobucket.com/user/gluemixer/media/661D6758-2AB5-4ACB-AC73-1A94797945E0-1139-000000A0DFFB55A0.jpg.html)

(http://i71.photobucket.com/albums/i149/gluemixer/28C3D7C5-61E5-4C9C-A2A8-4CD6456347F7-1139-000000A101329919.jpg) (http://s71.photobucket.com/user/gluemixer/media/28C3D7C5-61E5-4C9C-A2A8-4CD6456347F7-1139-000000A101329919.jpg.html)

Thinking this when fitted correctly will release preaur from the top of the wings

(http://i71.photobucket.com/albums/i149/gluemixer/28C3D7C5-61E5-4C9C-A2A8-4CD6456347F7-1139-000000A101329919.jpg) (http://s71.photobucket.com/user/gluemixer/media/28C3D7C5-61E5-4C9C-A2A8-4CD6456347F7-1139-000000A101329919.jpg.html)

(http://i71.photobucket.com/albums/i149/gluemixer/garys%20picnic%202010/null_zpsbb0b7672.jpg) (http://s71.photobucket.com/user/gluemixer/media/garys%20picnic%202010/null_zpsbb0b7672.jpg.html)

Just thought I'd share my thoughts on aero as my flat floor, tube frame build continues...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/rob009_zpse706859f.jpg)

I'll be running a Wikk style front end with splitter and a roof mounted lip spoiler to aide cleaner separation in preparation for the air to meet my home made wing.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/workshop033.jpg)

A chance meeting with an aerodynamicist with access to CFD used by Airbus found him offering to help design a wing for me based on the parameters I gave and my choice to stick to a single element for ease of construction and setup simplicity. In clean air at 150mph it is calculated to produce 236 kg of downforce at 13 degrees AOA with soft stall occurring at 16 degrees.

Armed with the profile, and in the absence of an autoclave, this is what I made...

Given that the wing needs to support the weight of three adults + safety margin, I set about designing something I hope will be strong enough...

I started to make the the outer end spars which will be the template formers for the hot wire cut foam core and ultimately the end fence mounts.

To ensure a uniform airfoil section it is essential that these two templates are the same. In this vein, I cut out the paper template supplied by Mr CFD and copied this onto some 64th marine ply which I then transferred onto my 6mm billet plate. I've got a bigger off cut for the main centre spars.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00216.jpg)

The trailing edge extends a good 2" beyond the pointy end of the templates, but this will just be a sandwich where the upper and lower skin meet and continue up and back towards a Gurney flap.

Once I'd rough cut these to shape, I clamped, then drilled and tapped them together so they could be cut out and finished 'as one' and hence be exactly the same shape. The tapped holes will be where lightening holes will go further down the line.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00218.jpg)

I then used my flat bed belt sander to get the profile almost perfect, but then finished of by hand with progressively finer files, and finaly emery cloth on various blocks.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00219.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00221.jpg)

Pretty pleased with how they've come out as now I know I can do it, it'll save me the expense having to get them machined or laser cut, and what I save on the swings, I can spend on the motor...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00222.jpg)

Next job was to cut the centre spars which also double as the main mounting spars, hence the extended lower edges.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00284.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00285.jpg)

Again, these were bolted up to the end spars to ensure they are all perfectly the same profile.

To join the four spars together and give strength to the wing, they are all joined with four aluminium tubes of varying sizes.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00286.jpg)

I contemplated how I was going to fold the aluminium skin round the leading edge of the wing in a uniform and even manner without getting witness marks, kinks or creases around the spars given that the foam centre is likely to give a little during the skin forming process.

To overcome this I decided it would be a good idea to have a mandrel at the leading edge in the form of a tube running along the length of the nose to bend the skin round, so I cut an appropriately sized recess in the leading edge...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00288.jpg)

To hold the front tube like so...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00289.jpg)

Then it was a case of cutting the strengthening tube holes in the spars...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00290.jpg)

And then some strategically placed lightening holes, leaving me with these.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/DSC00291.jpg)

Which fit together like this...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/spar3.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/spar4.jpg)

Quite please with how it looks so far as it's already pretty rigid even in it's skeleton form and very light indeed. The body of the wing will be cut with a hot wire and made from blue high density styrofoam, then skinned and bonded in aluminium skin with the tubes running through the foam like bones.

Firstly, apologies for the poor quality pictures - I dropped my regular camera one time too many ans it's now officially dead, so until such time as a replacement is found, I'm stuck with a crappy phone camera.

Anyway, I 'borrowed' some 50mm thick styrofoam from Dad, which not being quite thick enough will need to be laminated, which isn't a bad thing as it allows me to solve a problem - more of this in a moment.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0504.jpg)

Luckily it was 610mm wide, which as my spar is 300mm, allowed me to cut it down the middle to laminate leaving me with a 305mm block.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0505.jpg)

Now what of this problem? I pondered how to cut perfectly straight, true and accurate holes down the length of the foam for the three aluminium tubes to go through without cutting through to the edge of either the spar or the foam which would compromise the strength of the structure.

I then came up with a cunning plan whilst staring at the laminated halves. Firstly, I pinned the spars to the end of the laminate where it will sit for the cutting, strategically placing the three tube holes over the join in the foam.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0506.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0507.jpg)

I Then marked down the length of one of the halves where the tubes will sit.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0508.jpg)

Next, I clamped a long steel rule to the foam and modified my soldering gun by adding a depth gauge and used the tip of the soldering gun to carve a little hole all the way down the length of one of the foam halves which will allow me to feed the hot wire through the foam and use the holes in the spar as the hot wire template to cut perfect fitting holes for the tubes.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0509.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0512.jpg)

It worked really well and left me with a perfect little slot to feed the hot wire through when the two halves are bonded together.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0514.jpg)

I then smeared the halves with polyurethane adhesive and let them bond under the weight of a couple of old car batteries and a tool box.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0516.jpg)

You can see in that picture that I have done this process twice - one piece for the longer centre section and the shorter piece for the outer ends which will be cut in half when finished.

I also got my 2 x 1 sheet of aluminium sheet for the outer skin.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0517.jpg)

Next job is to mount the spars on the ends of the
foam block laminates and hot wire the foam to shape.

I carried on making the rear wing, concentrating on cutting the foam centre sections to make sure everything is going to fit together with precision before I kin it in aluminium.

Pleased with how its turning out so far, just the main centre piece to cut now.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/w2.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/w1.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/w3.jpg)

The wing mounting spars needed some clevis' machining - here's what happened next. A solidworks drawing was made...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995618.jpg)

And also a stainless clevis pin, as shown in green, here...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995617.jpg)

A program for the CNC lathe using gibbscam after the solidworks rendering was complete.

...then chucked up the aluminum in the lathe.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995616.jpg)

The green button left the machine do it's thing.

Here's the final pass "in action".

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995615.jpg)

Done!

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995614.jpg)

I need four of them...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995613.jpg)

Next, the part was turned around and chucked it up in the lathe.

Then drilled and tapped to 8mm x 1.25 thread x 20mm as seen below.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995612.jpg)

Repeat three more times...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995611.jpg)

Everything on the lathe is finished.

On to the mill...

A fixture was made out of Delrin to hold the part in the vice.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995610.jpg)

To machine the slot in the aluminum....

Placed the aluminum in the fixture and mounted it onto the vice on the mill.

Here we are after the slot has been cut.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995609.jpg)

Next, a 1/2" end mill machines the flat portions on either side of the slot.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995624.jpg)

Then turned the part 90º to machine the holes for the clevis pin.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995623.jpg)

After the holes were milled, the bottom portion of the blind hole was tapped with an 8mm x 1.25 thread tap.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995622.jpg)

Here's the finished part along with the stainless steel clevis pin. No pictures of these being made, sorry.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995621.jpg)

Close up of the shouldered pin mounted in the clevis...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995619.jpg)

The final product!

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/995620.jpg)

A wise man once said, "I'd rather be born lucky than good", a theory I've subscribed to many times in my life.... this isn't one of them.

Still, I'm soldiering on as best as I can despite my ability bankruptcy status.

Since the last time, I had wrestled the alligator by hand and skinned the wing in 20swg aluminium sheet. I'm sure if I'd had a roller, the skin would have followed the contour of my foam core beautifully with silky flowing lines.... however, I am pleased to report than when forming the skin by hand, it follows the form of the core a bit like a child's first attempt at clay modelling.

Needless to say, a 'waffer thin mint' of filler was required after I'd spent two and a half ice ages with my dollies and hammers getting it to resemble something like the air foil section hidden beneath it's 'house of mirrors' surface.

Here we are in the final stages of prep where I've blocked it to death and am working the final contour of the upper concave surface.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing8.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing7.jpg)

And after I'd just applied a final very light skim of surface stopper before I etch prime then 2K seal and prime it.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing3.jpeg)

I'm having to go to these lengths as my good painter friend, Bruce from WRP Paint and Restoration who will be doing all the body and paint on the car deserves better than to be handed a 'creation' to work with that is too far below spec. I want him to have at least something workable as he applies his show car utter perfection.

Thankfully, the underside with it's continuous convex surface will require somewhat less prep - thank goodness.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing6.jpg)

The mounting lugs work well...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing5.jpg)

Fitting perfectly onto the spar mounting lugs...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing4.jpg)

Finally got the underside of the wing in primer. Might not look much, but part of my soul is lost forever in those uniform curves.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing9.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/wing91.jpg)

Just in case I forget to mention it at a later date, I really hate doing body work prep. Just sayin'

At this point, and after consultation with my CDF bod, I decided to add a Gurney flap to the wing for reasons I'll not bore you with now, but it required me to split open the rear of the wing and add the flap at the heavily researched size...

The adhesive set on the Gurney flap, so I started to re-do the body work on the wing where I split the rear skin join to fit it. I'm very please with how it's turned out.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0563_zps16cb7af0.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0565_zpsd1b55bae.jpg)

Still lots of prep to be done, but it's close.

Meanwhile, I've been itching to cut the wing end plates. You'll have to trust me on the shape and wait to see what they look like on the wing when mounted on the car - all will become clear.

I transferred my design pattern onto a 500mm square of 1.5mm aluminium plate

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0560_zps39c2348b-1_zpsca986ab1.jpg)

Then carefully cut them out with a jigsaw

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0561_zps079b4d5e.jpg)

The final position is yet to be decided, but this will give flavour...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0566_zps2be378c4.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0567_zpsdef7bfcd.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0568_zpsffb544f5.jpg)

Since I inserted my Gurney flap, I've had to re-do some of the body work on the wing so I blocked it all back, and am guide coating and block sanding it all again to get it perfect. Also finally got my new camera with a wider angle lens I wanted to try out.
*
Just a few shots of how it looks as of yesterday...

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/LX0095_zps4985663d.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/LX0092_zpse3b8659e.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/LX0093_zpsd3945eb0.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/LX0094_zpse1f8bca0.jpg)

Despite a streaming cold, I did a bit more on the rear wing. Further research and after consultation with my CFD guy, it was considered advantageous to add a central wing fence on the high pressure upper side of the wing.

First I took a deep breath and took a cutting wheel to the top surface of the wing to give the fence a slot to fit in for strength and support.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1000997_zpsf23e857a.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1000996_zps0e31612e.jpg)


A trial and error, cut and trim session followed leaving me with a correct cardboard template...


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1000998_zps6270b3f3.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1000999_zps82800b10.jpg)


Which was then transferred to 1.5mm thick aluminium sheet - the same as the main end fences.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010002_zps382b3835.jpg)


Leaving me with this...


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010003_zps86f80550.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010004_zpsd093ee8a.jpg)


It's now resting whilst the adhesive bonds before final finishing. The profile of the trailing end will match up with the shape and angles of the main end fences so it looks 'correct' when viewed from the ends.

Another small step. :)

All that was left to do was mount the rear wing end fences.

First I had to make sure that when the top edge of the end fence is parallel to the reference plain (floor) of the car, the wing would be at my desired angle of attack which already takes into account a small amount of rake and also the angle of the air being presented to the wing from the roof, based on VW's own wind tunnel data.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0584.jpg)


Then I strategically drilled and tapped the end spars to mount the fences.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0583.jpg)


And hey presto, other than rounding off the end fence corners, it's done


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0585.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0588.jpg)

All that was left to do was mount the rear wing end fences.

First I had to make sure that when the top edge of the end fence is parallel to the reference plain (floor) of the car, the wing would be at my desired angle of attack which already takes into account a small amount of rake and also the angle of the air being presented to the wing from the roof, based on VW's own wind tunnel data.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0584.jpg)


Then I strategically drilled and tapped the end spars to mount the fences.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0583.jpg)


And hey presto, other than rounding off the end fence corners, it's done


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0585.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/IMG_0588.jpg)

Tonight I decided to make a start on the rear roof spoiler which is designed to provide a clean and defined airflow separation point above the rear window before natural turbulence occurs and to provide the rear wing with cleaner, more effective and less turbulent flow.

First, I cut to aluminium templates to the required shape. The two holes are to fix the template to the blue foam core. Notice the slight under curve on the bottom surface to match the longitudinal radius of the Beetle roof.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010035.jpg)


I then selected a chunk of blue foam to cut the spoiler out of using my home made hot wire foam cutter.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010039.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010040.jpg)


Here is my home made cutter, fabricated from some stainless rod, bowed to keep the Ni-Cr resistance wire under tension. It's nothing fancy but it does the job admirably.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010037.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010036.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010038.jpg)


To provide the correct amount of current (heat) through the resistance wire, I hook it up to a 12V car battery which works out perfect for the length of wire I'm using.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010041.jpg)


Using the aluminium templates at each end, it's simply a case of carefully cutting the foam to shape...


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010042.jpg)


Once you know the correct speed, heat and gauge wire to use, this technique car leave very neat accurate profiles.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010043.jpg)

Due to the length of the foam available and the capacity of my wire cutter, I had to make the spoiler in two halves, which isn't a problem, as joining the foam is very easy. It's also preferred to keep the lengths shorter if possible as the longer the profile cut, the less accurate the shape in the middle as the wire drags behind during the cut. Here's the two pieces end to end which is the correct width between the gutters on a Beetle roof above the rear window.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010044.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010045.jpg)


So.... why the slot cut down the rear edge?

Obviously there is quire a tight lateral radius in a beetle roof and the spoiler will need bending to the right shape. The blue foam is surprisingly strong and whilst flexible enough to follow the contour, I'd not be happy trying to 'adhere' it to the roof under permenant tension to straighten out.

So I thought the best thing to do would be to give it a back bone. After some experimentation, I discovered that the best material that would bend and more importantly stay bent afterwards giving the spoiler the correct shape and a bit of strength was 10mm diameter copper micro bore tubing, which even if I say so myself, works really well.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010051.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010050.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010049.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010048.jpg)


That is only roughly formed to shape at the moment, but it'll be very easy to get it perfect once I've got a roof to use as an accurate template. Once bent to perfect shape, I'll coat the entire spoiler is an epoxy glass cloth to provide a stable and tough substrate for finishing. Also, I can use the rear off cut from the tube slot cut in half to plug the gap behind the tube to seal it in position.

Still plenty to do, but it's well on it's way. Not bad for an evening's work.

With the car being over 150 miles away, it was difficult to guess the correct curve of a Beetle roof to set the exact profile of the rear spoiler so I can skin it in epoxy GRP.

To this end I made a visit to my good friend Mr Smull on the basis that he'd let me meddle with the roof of his Beetle as long as I meddled with the set up of his engine whilst I was there. Done deal.

Firstly, I measured and marked with a small section of masking tape where the top of the rear window on an Oval beetle is which can be seen near the top of the rear window in the first picture. Then it was a case of examining the flow data from Volkswagens wind tunnel research which shows that the top of the rear window is where the air flow begins to separate from the roof causing turbulence and drag, so just above this point was chosen to position the roof spoiler. This is a little below the level that the rear wing will sit to ensure the rear wing is fed with the best possible, least turbulent air flow.

The positions were marked with tape and the copper tube 'bone' of the spoiler was carefully bent to match the profile of the roof.

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010053.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010052.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010055.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010054.jpg)


Once happy, I inserted the tube into the spoiler and offered it up to the roof.


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010058.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010057.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010059.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010060.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010061.jpg)


It needs final trimming and a load of work to skin then finish it, but as a concept I'm really pleased with the results.

During a recent visit to Rob's to see the car, I made a profile template of the roof from blue styrofoam to take home with me...


(http://i83.photobucket.com/albums/j301/last_triumph/IMG_0696_zpsb9514f4d.jpg)


As Smull's Mexis is still an hours drive away from me, it made sense to make my own roof 'buck' to work from, so using the blue styrofoam template, I cut two matching templates out of 18mm MDF and boxed these up so I had my very own replica roof section to work from...


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010686_zps778c542f.jpg)


Which allowed me to screw down the spoiler into position so it adopts the perfect (or near as matters) curvature of the roof...


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010687_zps455dd624.jpg)

(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010688_zpsc001359b.jpg)


Which when at the correct angle will give me something like this for the air flow to deal with, leading nicely onto the main rear wing...


(http://i83.photobucket.com/albums/j301/last_triumph/Race%20Car/P1010690_zps38a635f6.jpg)


I'll tidy the ends up with small and neat end fences - nothing too hideous. Now it's fixed in the correct shape, I'll apply several thin laminates of glass cloth and resin to not only form a tough skin to apply a final profile and finish to, but will set and hold the spoiler in the correct curved shape so that when I release the screws at the ends, it won't just spring back straight again. I can live with a little flex as it will be tiger seal/bonded into position on the roof, but I didn't want too much excessive pull at each end that might risk the bond failing under vibration or aerodynamic load.

I'll skin it up with 3 layers of 6 oz cloth and resin and see how rigid it is by slowly releasing the screws - if it straightens too much, I'll add another layer or two until it doesn't.

:)

Andy,

That looks like a lot of work! Hats of to you for making the wing from scratch though and nice fabrication work too. Hope it does what it was designed to when you get it on the car.

Do you have something planned at the front of the car to balance it over all?
 
Peter

Hi Peter,

The main purpose of the wing is to improve high end stability at the top end, which along with the IRS 4 bar should keep things pointing the right way,

Up front I'll be running the nose as low as possible with a large splitter to help balance the aero load as well as wheel arch lips and high pressure vents etc to try and reduce drag.

Like everything though, we'll just have to see.

I'll probably just stuff it into the barrier on the first run though.

https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-frc3/p480x480/971260_267693070035364_1515860515_n.jpg
Ive gone a different route with my circuit car, here in the winter o/h,  its working towards a diffuser, but its developing to that stage from just creating all the flat bottom area i can squeeze in,  its mainly to clean up the underside air flow drag wise, all the lumps and bumps have gone, ie, jack points, lower rear shock mounts etc,the exhaust is high mounted anyway for track use and kerb hoping, the diffusor will extend into the rear bumper,  i also run various fairings on the front axle to clean up the torsion arms and the lower t/tube and shock mounts, the front ARB is high mounted between the axle tubes for the same reason, this car is pure bug, with no Porsche parts or double wishbone conversions in sight, its doing ok as it is, thats the fun of it,  the big problem with a circuit race bug is the front, the more power it can put down, the harder it is to get the thing to turn, the back is easy to get working.
the problem with added aero, the more so if it really does work and you can make it effective, is if the dependency on it is removed suddenly for any reason, cresting a rise, or a big slide for example, you can then fly, this is the reason Sports cars/ LMP etc, have a raised splitter section to maintain airflow at all times, rather than a sudden 'underflow' that will lift the car as we saw with Peter Dumbreck's Mercedes at LeMans 10 or more years ago. Subtle does it....

Andy,

This is a copy of a KaeferCup-design roof extention that I want to try for next years top speed event at Elvington (1-mile land speed racing). Haven't done any high speed testing with it though as the car is back in storage already.

(http://i174.photobucket.com/albums/w112/fusca03/1303/IMG_0360_zpsda258ac4.jpg) (http://s174.photobucket.com/user/fusca03/media/1303/IMG_0360_zpsda258ac4.jpg.html)

(http://i174.photobucket.com/albums/w112/fusca03/1303/IMG_0369_zpsb5b9fd0b.jpg) (http://s174.photobucket.com/user/fusca03/media/1303/IMG_0369_zpsb5b9fd0b.jpg.html)

Cheers,
Walter

Good morning Walter

Can I ask where you got your rear wings from ? I really like the shape over regular wide wings.

Plus what speed are you expecting over the mile ?

Thanks
Darren

Thanks Darren.
The black roof extension was a custom project of Gerrelt. It as it was too much work to sell these on, he said..
http://www.gerrelt.nl/section-aerodynamics.html

I really don't know what speed mine will do as I have no working engine atm. My mate's n/a 1303 did 131mph and he has 220hp.
There is very little reference yet for the top speed racing sport.
For more info see our FB page: www.facebook.com/TheElvingtonMile

Hi Walter, thanks for the info and the link to the gerrelt site. Some nice items and thinking there.

When I asked about your rear wings, I should have said rear fenders I guess, my mistake.
Lost in translation huh

Thanks
Darren

Oeps, sorry mate: they're from Kerscher, germany.
Rears are +7cm (inner +4cm, outer lip +3cm), so almost 3"wider then stock, which doesn't help areodynamics much though.. ::)

Some new data to the old topic. I am still running with no aero help; 1953 body, about 85mm ground clearance below front apron, 940kg (heavier on front than typical), sensors in rear and front suspension. Car ran 240.4 km/h in quarter, and peak speed according to GPS was 244 after finish line. Rear of the car was at neutral height through 4th gear and after pulling the chute (same without chute), front is about +40mm higher than neutral at the end of the pass at 240+km/h, and drops to -20mm after pulling the chute. Chute anchor point is a bit too low.
No drama  8)
Jyrki

 My mate's n/a 1303 did 131mph and he has 220hp.
[/quote]

228hp?
 ;D

Gents, You have to look no further than NASCAR to see how well almost pure wingless race cars can work, they have a very bad underside by regulation, lots of cavities, chassis members and cross braces, suspension parts and a big diff and rear axle, exhaust pipes both sides, very bad for a Venturi,  yet they work at over 200 mph and in close formation with other cars, how is it done?
Well they exclude almost all underside airflow with a very low front air dam, you can see the ride height decrease with speed gain even on the TV,  they also use very low side skirts which help, but I see these mainly as a safety feature to stop underside lift when in a side slip or a spin, almost common in NASCAR, but the big winner here is the rear spoiler, their primary function is apparently obvious, but what they really do is less so, it energises that dreadfull underside airflow by killing the would be spoiler less and un controlled vortexes and stagnant eddy pools  behind the cars, and converts the erratic flow into a smother, controlled and upwards direction, linking with the spoiler controlled 'over the top ' flow,  joining the  two elements and so pulling air out from the otherwise stagnant underside.
 If the cars were smoother and properly venturyied underneath, the spoiler size and drag could be decreased, but they have what they have by regulation and it's working superbly.
There are no experts in aero, if you are an 'expert' you will follow like sheep, nothing new will happen, all you can do is look at what's working and try to understand why it works, then put your needs to it, the EXPERT aerodynamicists said the B1 stealth bomber would have no lift and would never work, well it had too much, it was a pig to land as ground effect came into play,  OK, it's computer aided flight, but it broke rules and worked.
Jerki's above post, seems to do ok with a bare set up, but he's quite low at 85mm, way to go is low low low, keep that air outa the underside, then control what does go under, I run spoiler blades on my lower torsion arms to expel air into my brake discs, these are vented again so may account for the increase in brake dust over the wheels outsides I never had before. Also the oil temperature lost a huge 8* C since they went on, the cooler is in the front, so that's got more air going through it, it's so cool now, I've had to tape 1/2 the cooler, ......regards, spanners

Jeff Volk's New Front Air Dam


(http://i586.photobucket.com/albums/ss306/Fiatdude/Ghia/jeffVolksfrontairdam_zps5bf37e42.jpg) (http://s586.photobucket.com/user/Fiatdude/media/Ghia/jeffVolksfrontairdam_zps5bf37e42.jpg.html)

So was 2015 the year some of the "theory" and "must have" parts was proved wrong?  Lots of progress was made by different cars, built and driven in different countries and no 2 were the same in terms of aero, while the cabrio's have there own unique aero so I will leave them out for now others also proved wings, airdams and splitters weren't actually needed to even run 8s with Jyrki's car the best example.
The Skinne beetle even has removed there front splitter airdam and it seems to make little or no difference running 8.03@268kph.

So in 2016 with all the advances does a beetle really need a wing to run 11s[ see so many fitted it must do surely ?  :o ] or maybe 10s it needs it? or is it just mph/kph? must need it to run 9s right?  Well maybe not :o

cheers Richie

Edited it to correct Skinne beetle kph ;)

As I've said before, mine was just somewhere for my dad to put his tea mug! ;)

Seriously though, most 11 second cars with wings will be torsion bar, swing axle, stock rear ride height (or close to it) whereas a 9 second car is more likely to be either IRS, ladder bar or something else along those lines. Maybe the wing is compensating for the stock(ish) rear suspension?

So solution for badly set up suspension = a wing?  :o and as daft as it sounds I recently see someone thinking this exact thing, wing will solve everything :o

  I think this is one of the biggest issues, everyone blamed the shape forever, early cars crashed and everyone since thought it was normal but things improved a lot since then from when they were hacked up light as possible beasts :o We now know so much more and better parts are available as reasonable money :)



cheers Richie

 

The need for a wing has little to do with the ET – it's the terminal speed that is the major factor. Yes a car capable of a low ET will (possibly) need one, but then the lower the ET generally the higher the speeds achieved. Aerodynamics have relatively little effect on a VW at under 100mph and most street cars only exceed that for a relatively short period of time. I would venture far enough to say that I believe any instability problems on a car that runs 11s or slower are down to suspension set-up more than aerodynamics.

In reality, it's a combination of factors that make up a fast and stable car: enough power to get the job done, the right suspension to let you get the power down and keep the car straight, and the right aero to keep the car stable at speed.

Keith, totally agree but its easy/simpler to say a certain ET needs a certain aero or not, says 8s need a wing as an example, speeds are usually going to be over 150mph by then, so does it need a wing at 150mph and not 148mph? hard to say so I simplified it ;)






Again I totally agree :o ;D  but I am starting to think that its quicker than that even, 10s for sure and now 9s






So relevant that I highlighted it, I really do think its all about power management, and the biggest problem I see is peoples lack of understanding of the clutch in all this, so often I see people wanting & changing to stiffer torsions/shocks/coil overs whichever because there car "squats/bogs to much" or sump hits ground etc  but that's not really the issue in my mind, its launch rpm, rear tyre size and pressure, boost control if turbo, nitrous delay if that power adder and then clutch control[ all power management ]  that nearly always cause these problems, and we all know that if the launch is shit then the pass is done, a lot of times a car out of control is more down to the launch that anything else, its so difficult to recover from it but still people [ me included sometimes >:( ] keep our foot in it to long and then bad stuff happens and no wing or aero device can cure that

cheers Richie

I had a lightened baja in the late-80s (ahem, as you do, it was even aqua blue.....), and I'd lowered it a bit over 14s so it had a couple of degrees negative camber at the back at rest.
At 80 - 90mph though, the back had lifted up enough to create a very strong positive camber on the back noticed by the guys cruising behind me, so I rekn about a 3" lift easily.
At 100mph it was........interesting!
 ;D

Apart from that I got nothing.  ;)

Sh*t, did Richie just agree with me on most points? Yee-hah! I made the grade!  ;D

My point exactly! Both the old cab and the '67 seem really planted at the top end with no aero mods, but they are IRS cars. I remember us joking at Shakey many years ago about putting your motor in my car and you said something along the lines of not until it was changed to IRS! Is swing axle and stock rear ride height the limiting factor? Not badly set up, just inherently compromised?

I'm not surprised at the sort of lift it apparently achieved! A Baha doesn't have much going for it aerodynamically with a front cut up high to evade rocks and sand dunes, no aero favours from that, then no running boards allowing air to get at the rear wheels and the wakes produced by huge tyres energising the rear underbody, then no eddy control at all at the rear with a naked rear engine shrouded in steel tubing, so you did well in the bravery awards not ejecting at a ton really. 🔝😳

[/quote]

My point exactly! Both the old cab and the '67 seem really planted at the top end with no aero mods, but they are IRS cars.
[/quote]

I see well thought out handling and aero mods on both cars, subtle, yes, IRS being the final game changer with better camber control, giving more chance of recovery if things do get lively.

Is it more difficult to keep within acceptable camber changes? Yes, but if its set up correct and rest of car is then no reason it should be dangerous, it comes back to power management again, if you hit it with lots of power and to much clutch, to big a slick it will bog and go to lots of negative camber, but get it right and it wont, there have been 150mph plus swingaxle cars and they didn't crash so no reason a slower car should.

As for compromised, well we are talking about a rear engine short wheelbase VW so yes :D

cheers Richie     

My point exactly! Both the old cab and the '67 seem really planted at the top end with no aero mods, but they are IRS cars.
[/quote]

I see well thought out handling and aero mods on both cars, subtle, yes, IRS being the final game changer with better camber control, giving more chance of recovery if things do get lively.
[/quote]


That's why I wasn't focusing on the cabrios, they are too different to most people for comparison , but more on what other normal beetle saloons are doing, my 67 showed me what I already believed that you can go low 10s at 120mph plus with no wings or junk, then Jyrki's car running in the 8s with nothing either really got me thinking and its swingaxle :o 

cheers Richie

Some people just like the look of a race car with a wing.

When I had Wayne fabricate the wing for Betelgeuse it was because I wanted a race car with a wing on the back.  That car handled perfectly (Jim had spent a lot of time on the chassis making it work) and i have no doubt that it would have been completely manageable at the speeds I was crossing the line at (approx. 120mph) without the wing.  In fact it probably would have been quicker & faster due to less drag.

Would I put a wing on my oval.  No !!!!

Maybe it's just down to personal preference & aesthetics?

Good a reason as any :) I am sure yours had plenty of thought in it from Wayne :)



 Its the one size fits all kits I see being sold that worry me the most, no thought, design or testing by looks of it, just someone who can cut aluminium sheet, they could well make the car worse ??? 


cheers Richie

Some common sense in setting up the mechanical integrity properly, and some honesty admitting to a fashion fetish for wings, 😋..
I don't subscribe to the "Beetle shape is a wing waiting to fly" theory, it forgets one factor, the ground is part of the wing, although airspeed at ground level maybe zero, relative to the underside of the wing, the car floor, and we have a very good one by good fortune rather than aerodynamic design, assuming some attempt at handling and aerodynamic attention to the stock high ride height, it's speed is high enough to start reducing pressure at only 40 mph, at higher speeds, say over 70mph, the pressure is so low, any lift inducing separation over the roof will be overcome, the nearer the air gap is to 40mm, ideal, the better, 80mm is around the point things start to happen, below 40mm, as far as proper designed race cars go, things start to get, " professional" you may have seen LeMans this year with Audis violent porpoising frequency caused by a combination of tyre wear and a suspension fault, enough violence to wreck the car and damage a driver. We won't get to that point but it illustrates the power of the forces we have at our disposal, you can Use it to advantage even on our humble machines, ask yourself why you can do 40 with little effort on a bike behind a bus, probably twice the speed you'd manage in clear and still air, bring on Guy Martin.

all I know is my car feels planted at 135 with the RLR wing ( bug 1850 lbs w/driver / pan /swingaxle )  , and I would not take it off to see what it feels like without it

Yap, 251.xx km/h (156mph) without any aero help.
Suspension data shows rear is stable all the way, front is 30-40mm up at full speed and comes down once I pull the chute.
Full steel car (930kg), swingaxle, ladder  bars, K&L front beam.
I have a GoPro clip from the fastest pass - straight all the way. No drama!!! Not sure if I want to run any faster though  ???
Jyrki

Update from 2015 and 2016. The car now runs over 250km/h (GPS peak 252km/h). Suspension data looks the same as at 240km/h - still no drama!
No wing, no splitter, nothing at all.
Jyrki

BOOM! Says it all...basically.

-BB-

So it didn't increase from 240 -> 250, good!. But it still raised 4cm ahead of 240...

Hi...

Check out the movement of my frontsplitter at high speed...
causing nasty vibrations on the steering wheel...

www.youtube.com/watch?v=8Mz0TVfHADY&list=PL9qfqvlBjJyAvG0_IMwymitXc-Ce3ukdr&index=2

At the bottom of the screen you can see the suspension data. Rear suspension height is in blue and front suspension height is in red. Rather steady through 3rd and 4th gears:

[attachment=1]

Thanks for sharing :-)
It's a bit hard to see, but how much does the blue(rear) actually go up as speed increases? I would imagine having a rear wing would/could prevent this. But maby it is so little as it doesn't matter?
Or perhaps it is actually pushed down by power and just returns to neutral?

I'd like to see the same data for a stock style suspension cal looker - I suspect the suspension on Jyrki's car plays a part in its smoothness.

Jyrki: can you put a bathroom scale on your floor jack and lift your front 40 mm?
It would be interesting to see the lift force!

Indeed it does, or should do, and the old Skool cal look reference is significant,  a USA show on UK TV last night called "Jay Lennos garage" featured a "wheelie car" think it was a mustang with lots of rear Wright bias, mid mounted supercharged V8, big power, big tyres, narrow track and high CoG, just like our old Skool lookers, he was a pro driver, retired big name drag driver, he did his wheelie demo, got off the gas and bang, over it went, big time, they were lucky, very lucky having been grasping the A pillar durung the run, no window nets and arms flung about as expected, all shown by In car footage, the point was the cars high setup as mentioned above, and dropping the throttle! It snap over steered, got onto the edge of the tall drag slick and was history, by that time it looked like it was on track banking and it just kept going over, big accident, thankfully no injury to anyone. The point of no return as I saw it, was dropping the throttle, I have to say I cringe when I hear of drivers not only dropping the throttle but also going neutral and coasting after a run, I've spun in top more than once after taking the flag for doing just that, at least in the early days and with swing axle cars, and they were likely lower than a drag car of the day, tho I 'spose drag cars parachute is big savour on a proper fast bug, then, when it's REALY gone sideways, IRS COULD be got back, if you got swing axle back I guess a big dose of luck was involved, I've had swing do the oddest things in physics you could emagine, even sorted with ALL the quick tricks, sometimes they remind you who's boss, having said that, there are a couple of tracks were I would chose swing over IRS For a quick lap, I love em for grins factor, but dropping the throttle is bad if you have no room to get back on it to squat it down again.
Then we come to aero on jyrki's car, he's got down force from underfloor activity with low pressure, witness the flutter on the splitter, can't tell wether air dam or proper splitter with front Venturi from the vid, but it may be getting too low with the air then going viscous and into stall, pushing the front back up into fluid flow and back to downforce and so on, it may not react on the suspension potentiometers if it's flexing the bodywork.  Next time you see a car on the motorway with the front under tray fluttering madly you'll know what's going on lol! Harness that power and f@#k the wings.
The vid of course I refer to was mexx's.

Here you go:

https://www.youtube.com/watch?v=LabX19ocJZA (https://www.youtube.com/watch?v=LabX19ocJZA)

The problem here was not that he got off the throttle. It is the huge dump they hit that makes the car jump and the fact that they had to do the turn to avoid hitting the wall.

-BB-

Exactly, it is pushed down by power and just returns to neutral. This just shows that the car is lacking power ;) 
At the end of 3rd gear the rear suspension is -5mm from neutral, at the end of 4th gear (250km/h) it is +-1mm from neutral height, and after the pass it raises 5-10mm (which is not what I want it to do).

We will have to wait for the measurements a few months; the engine and transmission are out.

Jyrki

ps. I always pull the chute first, then push clutch and drop to neutral, let it coast a while, and then gently apply the brakes. However, without the chute the suspension data is similar (in SCC this year the chute droped under wheelie bars, speed was almost 250km/h), just need to brake a bit sooner and harder  ::)

Picked up a front air dam to try on my street-strip Beetle.  It's a close reproduction of the rarely available Kamei product (that usually sells at high prices on Ebay):

http://www.thesamba.com/vw/classifieds/detail.php?id=1976266

I did find with the Mk2 version of the front airdam/splitter I made this year for the new cabrio that the front ride height dropped downwards a lot more than needed after 1/8mile mark [135-140mph], so much so that I was able to reduce the lead ballast I have in front of car by 75lbs  :o, it still lowers the front ride height more than needed so I will reduce the splitter size gradually and see what difference that makes.

cheers Richie

This was a great topic with lots of terrific information.
I recently build and tested a front air-dam. Easy to remove and install .
When I was staging the car I found it was tripping the staging bulbs quickly with the air-dam, so I will need to trim
A bit off the bottom.
One thing I don’t have on the air-dam on the bottom
Edge which I see many having is a fwd lip 90 deg to the air-dam that appears to be about
1” in length .
Should I add that once I trim the bottom 1/2”. I take it the idea is to not allow any air to roll under
The air dam . Any input always appreciated
(https://www.thesamba.com/vw/gallery/pix/2421550.jpg)

I think the lip helps in 2 ways, 1st to stop air roll under off the airdam and 2 to add some strength along edge of airdam but this is dependant on how it is attached.

The regs most of places i have raced at require 3inches ground clearance minimum on front of car, and beams are usually about 1.6-2inches off ground so something must be pretty low to flicker beams on?


cheers Richie 

The aerodynamics thing, there are many ways to look at it
Front surface (in square meters) and what happens there is as you think it is
Many forget what happens when the air flows under the car and you create lift even behind the part, it can be tricky to get rid of lift from the air that flows under the fenders
Happened to be part of Volvo's wind tunnel with a racing car during a few weekends Then you got food for thought how the air went There were several things that you had to change your mind
Adding a simulation of how the air can go on a Vw Typ1
/// Micke
https://www.youtube.com/watch?v=LtXOUrTc_dA&ab_channel=Ramooo25

Thanks for the input.
Now that I have a prototype and even better the pattern,
I will make another air-dam and add the forward lower lip,
Makes total sense for not allowing air to easily roll off and under the air-dam and add rigidity.

- I found out what’s triggering the staging lights .
After my burnout I come out fast and Finnish hard on brakes .
This ends up loading the frt suspension and causing it to drop .
Now my air-dam is lower by about 1 to 1.5 inches.
I tested The frt end and yep if i push down on the frt end it drops but does not
Spring back up , but if I lift the frt end  it comes up easily .
I’ve regreased the beam , but figured this is due to the urethane bushings .
Maybe time for a needle bearing beam
 

If I were you, I would check how the air can get into the front fender then under the car which creates lift
It is not only in the front surface that the air enters
One thing I learned in Volvo's wind tunnel is that you have to have a small angle on the car so that the air atom cannot grow in size due to the heat created by the resistance, so it becomes an air cushion under the car, then you create lift
There is a damn good book about Aero that might be worth buying
Race Car Aerodynamics: Designing for Speed
Book
/// Micke

This winter I will also add front and rear level sensors.
And Work on my frt suspension movement.

Will look up that book sounds like a great resource.

I have made some card stock mock up inner fender wells to fill
behind the frt wheels . They look like big air scoops
I think this is what you are talking about.
(https://www.thesamba.com/vw/gallery/pix/2422671.jpg)