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Discussion Starter #1
i believe the stock wing makes 66lbs at 90mph... does anyone know the numbers on the RMM wing at its most agressive setting (i believe it has 3)... thanks, brian
 

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Have someone video tape you drive by at 90mph with the wing on. Then come to a stop and add weight until the ride height is the same as it was at 90mph. It's a po-dunk way to check, but it should be good within ~30lbs if you're careful...
 

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TX2K7 roadrace champion
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lol, thats the guettoist thing evar,

you could drive threw a tractor trailer weigh station at 90mph, see what it weighs. lol
 

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Hey how about this? Go buy a bunch of really big shop fans and blow them on the supra and measure the windspeed with a handheld anemometer while you have the Supra on four digital scales. Being from the South I highly recommend the Dixie cup method http://sln.fi.edu/tfi/units/energy/dixie.html
Barry H.
ma71supraturbo said:
Have someone video tape you drive by at 90mph with the wing on. Then come to a stop and add weight until the ride height is the same as it was at 90mph. It's a po-dunk way to check, but it should be good within ~30lbs if you're careful...
 

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lol too much work. I don't see why you'd need to know what the actual #'s of downforce are anyway -- I'd suspect it would be something you would want to tune based on the handling of your car at speed.
 

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Discussion Starter #10
id just like to know and i would prefer that it was a higher value than the factory wing
 
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The RMM wing makes more downforce than the stock wing at low/medium speeds. Don't believe me? Just pick both of them up! ;-)

I don't know about high speeds. It would be interesting, but I doubt we'll ever have a number...

Jim
 
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To know for sure you could do this.

Buy one of those devices that lets RV owners know how close they are to something when they are backing up.

Mount this unit so it is facing the ground at the rear of the car directly over the centerline of the axles so you don't have to include other factors. Make sure it's mounted to the body of the car or something that gets close to the ground when you compress the rear springs. You want to know as close as possible the distance the springs compress.

Drive whatever speed you want to know the downforce of your wing at. While driving this speed read the distance the device shows you.

Take another distance reading while you are standing still (with you in the car).

Record the difference of these two values.

Now find out your rear spring constant (spring rate).

You know the distance you compressed the spring (the difference you recorded) so you can determine how much force it requires to compress the spring that distance. That force will be your down force.

Say (purely for example not real numbers) you have 800N/M rear springs. Your measured difference is say .02 meters.

2 x 800 = 1600N/M total rear spring constant = k
distance compressed = .02 meters = x

Down Force = k*x. In our make believe case that would be approximately 32 N or 7.19 LBs of force.

Be sure you use appropriate units of measure for the formula.

-k is in N/M (newtons/meters)

x is in Meters

The formula for future reference is,

Force = -k*x

Since we know it's compressing we can forget about the - sign. If the device wasn't directly over the centerline of the rear axles you would need to know the exact angle in which is was off of center. Since that would be no fun to measure.. just make sure it's directly above the axle as close as possible.

Also be sure you are driving on as level ground as possible that is as smooth as possible to get stable readings.

You obviously won't get an exact number.. but if you do this same procedure for both the stock wing and the wing being tested you can set up a ratio between the two.

Good luck!

-Russ T
97 T6
 

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Discussion Starter #13
that sounds harder than something i feel likedoing but thanks
 

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jtanner said:
The RMM wing makes more downforce than the stock wing at low/medium speeds. Don't believe me? Just pick both of them up! ;-)

I don't know about high speeds. It would be interesting, but I doubt we'll ever have a number...

Jim
If it makes more downforce at lower speeds, it will for sure make more down force at higher speeds. Unless the wing creates a lot of separation at higher speeds which is not likely at all. Looking at the wing, it isn't high cambered, i'd say it works more on netwon's than bernoulli's.
 
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Yup. Someone (Dinan?) once said "all wings produce downforce equal to their weight" or some such...

Jim
 

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jtanner said:
Yup. Someone (Dinan?) once said "all wings produce downforce equal to their weight" or some such...

Jim
That is not true at all. Look at the F1 wings, i bet they weigh no more than 30 kg (this could be an underestimate), but can generate up to 2000kg of down force. Downforce has nothing to do with weight, ... well, aerodynamic downforce has nothing to do with weight. None of the wings you see on the street are really high downforce wings. Rarely any of them are inverted airfoils or have much camber in them. Most wings run off reaction forces more than bernoulli's principles.

Anyway, i've been working on a wing design for the supra but haven't had time to follow through on it yet. I was doing the aeropackage for the Formula SAE team here and i thought why not design a supra wing as while i'm at it. I've been kept quite busy and haven't had much time. The initial design is a dual airfoil design, basically a main wing with a highly cambered detached flap. I was also in the process of a diffuser and maybe something for the front. But that would be a lot harder without actually changing the front bumper.

Speaking of which, would anyone be interested in such a wing? I was hoping to make 300-500lbs at 90mph. maybe i should start a new thread.. lol

lol I think he was talking about it being heavier than the stocker
hehe, yah i just re-read his post, my bad. :D
 
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JuPa, you're right of course. I butchered the quote pretty badly. It was more along the lines of a wing makes at least downforce equal to it's weight.

Jim
 
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