Wing building.

MarcusMcRae · **Posted:** Sun May 31, 2009 10:53 am

That looks like the same template that peter bull used. He posted his chord lenght was 10.25. I will pass that along.

My dad actually knew Bob Liebeck. He did some of the original testing on Dan Gurney's "Gurney flap".

MarcusMcRae · **Posted:** Mon Jun 01, 2009 3:08 pm

My dad said these are really general numbers.

At Cl (lift coef. on the 63-520 graph in his blog) of 2, approx force would be 80 lbs at 60 mph (99lbs at 2.5); 312 lbs at 120mph (391lbs
at 2.5)

The way the air flows over the car will actually change the angle of attack and without knowing that you can't predict how much downforce you will have. He mentioned you may actually have stall at the middle of the wing which will decrease the total amount of downforce. He said you can do a "tuft test" to see if you are getting stall on any part of the wing and find the best angle of attack.

Tuft test = gluing/attaching 20 or so peices of string along the bottom-back half of the wing. The string should lay perfectly flat with good down force. If it is moving around/flapping then you are getting stall on that section of the wing. I guess you could mount a camera back there some where to watch the string. If you do this, you definitely have to post the video.

I realize you already got some of this info on your other threads. I was curious about the whole process and figured I would regurgitate some of what my dad told me.

Patrice Bousquet · **Posted:** Mon Jun 01, 2009 4:51 pm

That what's I was thinking, a few hundred pounds. I didn't invent anything, the guy on the Pelican forum did all the testing on the wing profile. What I did is make it movable but like I said in the tread I will need a stronger motor because above 120mph its having a hard time moving the wing.
Anyhow I will test it at CMP, I will start with no wing and then install it to see the difference.

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

Did you buy new springs for it too? At 200-300lbs of down force you may just sit it down on the bump stops. If your tires are very close to rubbing you may also push the body down on them.

Wish I could come down to see the test. Unfortunately I have to work that weekend.

MarcusMcRae · **Posted:** Mon Jun 01, 2009 7:59 pm

Patrice Bousquet wrote:

Anyhow I will test it at CMP, I will start with no wing and then install it to see the difference.

Will you only be looking at lap times or will you be doing something like the tuft test?

Chris Landi · **Joined:** Mon Mar 08, 2004 6:31 pm **Posts:** 579

Marcus, what did your dad say about the wing on your STi? Or, did he just point and laugh?

MarcusMcRae · **Posted:** Mon Jun 01, 2009 10:08 pm

Chris Landi wrote:

Marcus, what did your dad say about the wing on your STi? Or, did he just point and laugh?

Pretty much. I have taken quite a bit of grief from him about the STi.

Donnie Barnes · **Posted:** Tue Jun 02, 2009 3:48 am

Marcus, if you want wing education 101 from a DIY type, click the first link in Patrice's first post. You'll see pictures and video of a large amount of smoke and tuft tests done by the guy who came up with the profile that Patrice is using. Pretty sure every question you could ask will be answered there.

Warning, that thread is VERY long. It's also VERY good.

--Donnie

MarcusMcRae · **Posted:** Tue Jun 02, 2009 10:10 am

Donnie Barnes wrote:

Marcus, if you want wing education 101 from a DIY type, click the first link in Patrice's first post. You'll see pictures and video of a large amount of smoke and tuft tests done by the guy who came up with the profile that Patrice is using. Pretty sure every question you could ask will be answered there.

Warning, that thread is VERY long. It's also VERY good.

--Donnie

That dood has like 8 different threads about biuilding that wing. F%@K. The tuft testing thread is pretty cool.

Patrice,

The only post I saw that he actually mentioned the wing angles said 14 and 24 degrees. Did he tell you 0 and 12 were the ones to go with or are those angles in relation to a different plane?

Patrice Bousquet · **Posted:** Tue Jun 02, 2009 1:05 pm

There is lot of informations in those treads. The angle is coming from these 2 pictures, its actually on the 1st page of my tread. From the testing that he did it look like you can go at a greater angle and still have more downforce???. I change the spring (torsion bar) on the car last year so I should be ok. I want to compare the data from a data acq. system if I can get it in time for CMP.

12 -13 deg is for max down force.

Around 0 deg or even minus is where the drag is low.

MarcusMcRae · **Posted:** Tue Jun 02, 2009 2:56 pm

The angles I saw were on the testing of his first wing in this thread :oops:

.

http://forums.pelicanparts.com/showthre ... light=tuft

This is a quote from Peter Bull regarding the graphs.
"The results are from theoretical analysis so I would not take them too literally. They do, however, give an indication to which profiles to start testing."

So, that settles it. You are going to have to do some high speed tuft testing to find the best angle to use. Highway 64 should give some straight flat stretches to test on. I will happily volunteer to be the chase car.

Patrice Bousquet · **Posted:** Tue Jun 02, 2009 4:17 pm

Laurinburg is a better place but the next PCA AX might be only this fall. We have usually the main runway clear and we can do high speed pass.
2 weeks ago I got the car to 6000rpm in 5th with the tire size on the car that translate to a little above 130mph. So at least the wing and support seem to be strong enough. I will see what kind of testing I can do at CMP.

RobLupella · **Posted:** Tue Jun 02, 2009 4:20 pm

Patrice Bousquet wrote:

Laurinburg is a better place but the next PCA AX might be only this fall. We have usually the main runway clear and we can do high speed pass.
2 weeks ago I got the car to 6000rpm in 5th with the tire size on the car that translate to a little above 130mph. So at least the wing and support seem to be strong enough. I will see what kind of testing I can do at CMP.

You could always try to run with ECTA if they have an event there

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