PPo

Maybe I missed this earlier in the thread, and I apologize if I did...

Assume indentical chord length, and assume the end plates are 100% efficient, at the same constant speed, on the same car, does changing the wing airfoil profile impact the downforce/drag ratio?

SundayDriver

Yes. Not only L/D ratio but total downforce. Different profiles work better at different speeds. A jet airplane wing profile is not at all what you want for a race car.

SundayDriver

I am curious - how are most of you measuring wing angles (AOA)?

Larry Herman

A straight wing? A straight wing!! Seems to me someone here with a lot of practical knowledge suggested that a straight wing was probably best back on page 3. Wonder who that was?

winders

At this point, in the absence of any concrete data for my specific application for other wings, I am most likely to use the 70" Predator from GT Racing. This wing is known to work well on race cars with the same aerodynamic profile and speeds as mine.

I had hoped there would be more relevant data out there. Oh well.....

Larry, I was never considering using anything but a straight wing. Where I will mount the wing is too high in relation to the deck lid to benefit from an asymmetric profile. And that Crawford "Banana" wing is fugly!

Scott

JackOlsen

Although if rules weren't so strict about overall width, you might see this (relatively recent) airplane innovation on race car wings.

SundayDriver

I have seen wings like that on jets. Is there any data that shows it is effective at the Reynolds numbers we see on race cars?

PPo

That's what I thought... to me that means the variables in wing design are immense... some of the conversation here is rather pointless. Doing what the fast guys do, testing at the track, and making incremental improvements on a classic functional design makes sense to me. Isn't that what Mr.Olsen is doing?

mark kibort

Was that me??? Yep , you did say this, but I was saying we were just fretting too much about differences between wing designs with very little difference between much of them in the same size range. However, Scott has pointed out that a siilar sized cup car wing from a wing manufacturer, has produced a high lift wing. However, it looks very tempermental as far as adjustablility, in areas of large changes for small adjustments.

what does angling the end plates supposed to do? I know the end plates, by reducing the wing tip vortecies, effectively widened the wing's effective lifting area. without them, the wing tip vortecies at the ends cancel out a lot of lift for the end portion of the wings. on airplanes, this is very important to lower stall speeds of the airplane during take off and landings, as well as stability control.

that was my question too, and are the effective , or more effective than standard end plates.

Hey, Ive done a lot of this grass roots testing too. you must of missed some of my tufts, splitter-cam video as well as spring scale testing of downforce on empty highways at 120mph.

I think what I have learned from all this, is that the lift to drag ratios are not that different for a given downforce, but some designs can really be high lift, without the use of gurney flaps, or high lift profile NACA designs. I think it doesnt matter too much, what wing you use to start. however, some have max lift limitations , and some could have too much lift (or downforce I should say) that could cause serious problems at high speed. The front of the car needs almost as much attention. splitters, hood vents, duct work, all help with keeping the front end planted around high speed turns.
The interesting thing here is that most turns are not that fast, besides the kink at RA, and other kink like quick turns. 100mph around the carocel? sure you need downforce, but if you come out of it and want to go 170mph down the following straight, you better weigh the trade offs.

Thats the fun of this sport, such a packing of so many different types of technology and knowledge. Is there any other sport so complex? I dont think so.

333pg333

That's one way to dry out Whitebait fish.

kurt M

Zing! this is the key and has been lost in the charts and graphs parade. Just as we tune a motor with a cam wings can be tuned to a car. the AoA is part of the tuning. The wings sweetspot is another.

compound wings seem to beyond the basic level of the off the shelf racer. It seems to me that they have to be planned out from A to Z for a car and use. car shape and wing placement are far more complex. Unless you can do this straight wing in clean air seems to be the safest bet. Tuning the wing to the car is the real question.

Carefull that your testing is not altering the test itself too.

SundayDriver

If you are interested in another view and some education (especially about CFD), you can read this thread. Is is sports racer centric and looks a lot at the underfloor, but interesting stuff for some of you with production cars:

DSR Forum Discussion

BTW - Ren is the design part of Dauntless and a former SCCA FA champ.

mark kibort

Do they? (the point was made that some wings work better at certain speeds)

I think if you have a downforce or lift value at a slow speed and a L/D ratio, it will follow it to near supersonic speeds. I think the main differences as I mentioned, was its ability to create lift. (some wings are high lift, like the GTC300) and some are not for similar area. but, as I remember, the lift, (downforce) and drag all go up with the square of the speed. if you look at the charts for the GTC300, you see that it almost follows this multiplier exactly.

So, I dont know if that is the main reason we look at different wings.

I still feel that you want a shape that provides tune-ability. meaning, you dont want one degree to totally throw off your balance, also, the cars attitude through bumps and turns has to be taken into consideration there too. going through sebring with a soft suspension, and a lot of bumping through the last turn could give you lots of grip and then very little grip, all of the sudden and that would be bad.

Someone mentioned "jet wings" and what came to mind was the F16 which is conditionally unstable, compared to a cessna wing, which is just the opposite.
This is what I am talking about with tune-ability and stability. too high strung of a wing , could make it conditioally unstable, so when the car does change attitide under braking, bumps or turns, large changes in its characteristics can be found. this might not be all good.

Also, regarding the compound wings. they should follow the air flow patterns of the car. a straight wing will not, if it is in this path, however, what happens, is part of the wing is operating at a different AOA than the others. the down side, is that the overall efficiency is compromised, but what is the "real" value of this efficiency loss. I would bet it is so small its off the charts. It would be debatable if there was any value of a compound wing vs a straight wing any track with top speeds less than 120mph. (given the same L/D ratio , and sized wing)

just a few thoughts.

Mahler9th

It doesn't surprise me that Max Crawford commented that the banana wing isn't as effective as some of the straight wings available. I do recall that the Crawford wing was a result of rules and the shape of the car's ***...I just cannot remember the particulars. I must be getting old.

Anyway, I wonder what straight wing he'd recommend for this kind of application.

Johninrsf, which wing did you use?

I found this picture of a red car somewhere some time ago and I am curious about the front and rear aero work they did and why.

The white car is the Brule car that KMR did years back.. I think Crawford did the bodywork. I am pretty sure this car was designed to comply with PCA GT rules. Note the tail and wing. Lots of aero tweaks on this bodywork.

I'd be talking with Max Crawford and/or the Stone bros at KMR if I wanted to get the best info.... I suggested that to Scott before he posted here.

- MM

Mahler9th

Oh and a heads up to Scott:

If you go poking around that link that Mark provided, you will see that those forums have some Porsche guys participating... and an old friend, David Ferguson. He and Ellen have done some wing testing in the sports racer world.