Aerodynamics - Splitters and Wings

Aerodynamics - Splitters and Wings

Author
Discussion

Adam Kindness

Original Poster:

656 posts

223 months

Monday 22nd December 2008
quotequote all
I'll be fitting a front splitter, canards and a GT wing to the R32 for Fiona to use in TimeAttack next year.

I'm after a bit of info/help on angles for the Cannards in particular. Can anyone give a good angle to fit them at.... i.e most downforce, least drag? I know this is very dependant on air flow paths round the front of the car, and canard shape etc.... but if someone knows something I dont, I'd appreciate the help LOL

Canards


small and a larger set, 1 each per side.

The rear spoiler - I can adjust the fin angle.... and play about with oil droplets on the wing to see where the oil is going.

Splitter - Aiming to have it poking out past the front bumper by about 70mm. Sound ok? I think any further would prob give too much downforce/drag etc

sam919

1,078 posts

202 months

Tuesday 23rd December 2008
quotequote all
Does the car really need it, where are you going to run it, is most of the heavy cornering done over 100mph?

They fitted canards to the caterham to stop the front lifting around 130 odd mph.

Adam Kindness

Original Poster:

656 posts

223 months

Tuesday 23rd December 2008
quotequote all
KH, Donington, Silverstone, Oulton, Brands and Snetterton.

The car will have about 550bhp, and hopefully just short of 1300kg.

VetteG

3,236 posts

250 months

Tuesday 23rd December 2008
quotequote all
Can you not make the splitter adjustable? I have seen several that were by means of slotted 'holes' for the fixings.

G

360 detailing

1,036 posts

206 months

Tuesday 23rd December 2008
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Drop absolutely a pm, I'm sure he studied aerodynamics or design or something?

e21jason

717 posts

225 months

Tuesday 23rd December 2008
quotequote all
Hi

The optimum angle depends on the profile of the wing, so with out the actual data it s a bit of trail and error, best book I have on the subject is katz, Simon McBeath is a bit more focused on single seaters. If you get it right you need to alter your brake basis and stiffen the springs,and there are some good articles on DIY aero testing.

But haven seen the Skyline at KH there is more you can do other than botl on aero to condition the airflow

Jason



Edited by e21jason on Tuesday 23 December 12:10

Adam Kindness

Original Poster:

656 posts

223 months

Tuesday 23rd December 2008
quotequote all
such as?

Its getting a fair bit more power and losing more weight this winter....

It was lapping in high 58's in the summer with just short of 400bhp and around 1400kg.

I'm aware we need a fair bit more adjustabilty in the front castor/camber - thats on the list to do too.

A new or even just new plates in the rear LSD too LOL

The list is actually endless :/

GreenV8S

30,424 posts

290 months

Tuesday 23rd December 2008
quotequote all
Mods like this have the potential to change the handling balance of the car at high speed but on their own are not going to change the total grip significantly. So if you have high speed handling problems this sort of thing can be useful. The crucial thing is to know what the handling problems are and address those, rather than change things and see what happens iyswim.

I don't know what your high speed handling is like, but it seems typical for rear end lift to promote high speed oversteer. Be cautious about the front splitter. It's quite easy to generate enough downforce on a splitter to change the balance of the car significantly, and usually as you increase the front downforce it actually makes the rear end lift worse both factors encouraging high speed oversteer. Fine if you're tackling an understeer problem, but otherwise it could get you into trouble unless you're also taking steps to reduce the rear end lift.

sam919

1,078 posts

202 months

Tuesday 23rd December 2008
quotequote all
Adam Kindness said:
KH, Donington, Silverstone, Oulton, Brands and Snetterton.

The car will have about 550bhp, and hopefully just short of 1300kg.
I suppose then it would depend the circuit, % of fast corners, % of slow corners, more downforce less top end etc. Was that 58's at knockhill? Single seater aerodynamics, like someone already mentioned, and adjustability would be the areas to look at for inspiration or more accuratly, calculations. One will have an effect on the other, but could be dialed out with a change to something else, suspension set-up etc.

Edited by sam919 on Tuesday 23 December 12:07

e21jason

717 posts

225 months

Tuesday 23rd December 2008
quotequote all
Hi

On a saloon car it is easy to get front down force with a splitter, the canards you have are anti dive planes basically to keep the nose up during braking as the effect of the front splitter can be very sensitive to ride height, The easy way for rear down force is a big 6” spoiler as per nascar but it will create a load of drag.

A rear wing works if it is in clear air and has decent end plates to ensure you get the flow over it.

For the skyline, have you ducted the intercooler and rad from intake to discharge, cleaned up the under side of the car, drop the skirts etc to make a tunnel, so more air goes over the car than over, add a rear diffuser. I image the regs for Time attack are quite liberal so creating a full tunnel on the car would be possible.


A bit of background reading

http://www.sportcompactcarweb.com/tech/0607_sccp_a...

http://www.sportcompactcarweb.com/tech/0610sccp_au...
Jason


Edited by e21jason on Tuesday 23 December 12:37


Edited by e21jason on Tuesday 23 December 12:42

Adam Kindness

Original Poster:

656 posts

223 months

Tuesday 23rd December 2008
quotequote all
flat bottoming it isnt an easy task.... i've thought about it, but a fair amount hangs down (diffs, exhausts etc) so a lot of work would be involved.

Adding a fuel cell and flatbottoming the rear with a diffuser is on the cards though... but then we'd really need the middle flat to complete it.

The car does suffer a bit on power with high speed oversteer.

understeer at the moment was largely dependant on tyres... we need more castor/camber to get the tyres working better as they getting the outside edges too hot.