REAR WING WIDTH

[V8Dom]

Anyone know why the rear wing isnt as wide as the car.

looking at lots of photos recently most race cars the wings are as wide as the car?

Edited by V8Dom on Tuesday 10th June 23:58

[deadscoob]

They're race cars...

Can't think of any other road car that has a wing as wide as the car.

One for the factory I guess.

[macgtech]

V8Dom said:

Anyone know why the rear wing isnt as wide as the car.

looking at lots of photos recently most race cars the wings are as wide as the car?

Edited by V8Dom on Tuesday 10th June 23:58

Point 1, as mentioned, it is not a race car.

Point 2, it is about aero balance - the wider the wing, the more downforce at the rear - this has got to be balanced at the front otherwise you end up with frontend lightness at speed - not pleasant!

[drivin_me_nuts]

Does the addition of cannards actually make a discernible difference to the Ultima? The ones I've seen seem to be so small. Also, if you do add them to balance the front downforce, is it a case of wind tunnel testing to determine the best angle, or are there general guidlines.

[macgtech]

drivin_me_nuts said:

Does the addition of cannards actually make a discernible difference to the Ultima? The ones I've seen seem to be so small. Also, if you do add them to balance the front downforce, is it a case of wind tunnel testing to determine the best angle, or are there general guidlines.

Proper testing is required to optimise these things, however the general theory by which they work will make a tangible difference.

There are lots of devices on the front of GT cars such as splitter end plates, canards, diffusers etc which all do similar jobs - improving front splitter performance, sealing the underfloor with vortices and extracting high pressure air from under the clam.

Fitting of 'generic' small canards on GT type cars in the wind tunnel generally shows a ~5% or more shift of the aero balance forward.

[V8Dom]

at what speed does the 5% apply?

[macgtech]

V8Dom said:

at what speed does the 5% apply?

I would have to look through the data again but it is going to be 80mph+

Take a look a this article, which is a forerunner to one RCE did more recently about dive planes:

http://www.reverie.ltd.uk/Downloads/Aerobytes-Oct0...

If you notice on our car, we have move the canards much further down this year to avoid the wake impinging on the rear wing and avoid the loss of efficiency - the effect of which is highly visible in the wet which we saw in testing earlier in the year.

[ROWDYRENAULT]

Mag Tech as usual your comments and links are some of the best we have here. The article was well written. So far I have added a front splitter and side canards mounted very low on the side of the nose. Also I have added a divider that runs 90 degrees to the outlet of the radiator and parallel to the floor of the outlet. I have opened the outlets o the front wheels and intend on adding front fender vents in the future. To balance all of this I run the rear wing second element at a fairly aggressive angle and will eventually add rear wheel vents and lower the wing element. So far I have not seen a high speed oversteer problem. One could add to this that I probably don't attack really high speed corners hard enough. Of course this is in the context that I don't care about drag, that's why mother Chevy makes lots of horse power. Thank you for staying engaged I very much look forward to your posts. Lee

[deadscoob]

Done the same as Lee, plus the side boards, top arch vents on front clam, rear arch vents, enlarged rear vents under lights plus a couple right at the bottom and a full width wing. Is great on track.

[UltimaCH]

Talking of wing vents have you seen that the WEC LMP1 and probably 2's, don't have vents any more just bloody big holes.

[ROWDYRENAULT]

The sanctioning body mandated the size of the hole after a couple of blow over events. They are ugly but I think the idea is it does not allow room for designers trying to meet the letter of the rule and not the spirit. Lee

[V8Dom]

the biggest problem with drag i see is the under tray... after the cabin there isnt one and air can enter the engine bay, and the rear clip acts as a massive passasute... im looking at adding read wheel arches and tray each side of engine annd behuind rear wheels... withit only open under engine and box and that air will be less to enter out of the back... i also dont run rear grill

|Dom

[macgtech]

Rear arch venting should be done at the rear of the car and/or the sides behind the rear wheels - not above the arches, as the HP air escaping interferes with the clean airflow over the rear wing.

[macgtech]

ROWDYRENAULT said:

Mag Tech as usual your comments and links are some of the best we have here. The article was well written. So far I have added a front splitter and side canards mounted very low on the side of the nose. Also I have added a divider that runs 90 degrees to the outlet of the radiator and parallel to the floor of the outlet. I have opened the outlets o the front wheels and intend on adding front fender vents in the future. To balance all of this I run the rear wing second element at a fairly aggressive angle and will eventually add rear wheel vents and lower the wing element. So far I have not seen a high speed oversteer problem. One could add to this that I probably don't attack really high speed corners hard enough. Of course this is in the context that I don't care about drag, that's why mother Chevy makes lots of horse power. Thank you for staying engaged I very much look forward to your posts. Lee

Hi Lee,

Sounds good - post a pic!

[drivin_me_nuts]

macgtech said:

Rear arch venting should be done at the rear of the car and/or the sides behind the rear wheels - not above the arches, as the HP air escaping interferes with the clean airflow over the rear wing.

Is that the reason why some cars have vertical slats cut into the bodywork behind the rear arches rather than have vents on top.

ETA, what do you think would be the effect of venting the horizontal surfaces below the rear wing?

Edited by drivin_me_nuts on Friday 13th June 13:46

[macgtech]

drivin_me_nuts said:

Is that the reason why some cars have vertical slats cut into the bodywork behind the rear arches rather than have vents on top.

ETA, what do you think would be the effect of venting the horizontal surfaces below the rear wing?

Edited by drivin_me_nuts on Friday 13th June 13:46

Yes it is - if you vent the top surface you are using the LP air under the wing to vent the clam, thus reducing the effectivity of the rear wing. Obviously you reduce arch pressure which is good - I can't say what the overall delta would be but I suspect a loss in DF.