Air Brake for RX8?
09-15-2005, 10:27 AM
#26
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Originally Posted by woodysjh
Does anybody have a DIY for the RX8 that is like the Mercedes SLR McLaren air brake on the trunk of the car?
09-15-2005, 12:51 PM
#27
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Originally Posted by Glyphon
AH. that does clear it up. the edmunds 60-0 distances were for the rx-8 (they didn't have number for the mclaren that i could find).
so, to clear things up, according to edmunds, the rx-8 does 60-0 in 108 ft, or equal that of the mclaren :D
so, to clear things up, according to edmunds, the rx-8 does 60-0 in 108 ft, or equal that of the mclaren :D
10-31-2005, 11:02 PM
#28
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I built an air brake system using a wing on my 86 MR2. I was actuated by an electric window motor. The wing cord would tilt almost to vertical. With a couple of limit switches and a hookup to the brake light, it worked OK. Not very sophisticated, but it certainly got attention. I've been thinking of a version for my RX8, but it's still just floating around in my head...
11-09-2005, 07:31 AM
#30
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Originally Posted by TeamRX8
rig the hood to open instead, it will catch more air and slow you down faster ... 
It "deployed" at 60 mph... The stopping power was a disappointment though since it just folded neatly over the windscreen and the roof... 
Cheers, Niclas
Last edited by nicce12; 11-09-2005 at 07:34 AM.
11-14-2005, 11:03 AM
#32
Oil Injection
Originally Posted by woodysjh
So from what I see here in all this chatter is that the air brake does provide some help with stopping.
On the Merc/McLaren SLR the air brake not only adds drag, slowing the car down, it also adds downforce to the rear of the car, A LOT of downforce, that helps to give more grip to the rear tiers allowing them to use a large rear brake with more force.
Normaly when you hit the brakes hard, a lot of the weight shifts to the front of the car, with little weight on the rear, the brakes out back cant be used as much. In a car with-out ABS you might even see (from a highspeed stop) the rear brakes lock up before the front brakes.
Giving more grip (weight) to the rear tires allows more braking force.
So the airbrake does help, although most of the stoping power on the 3800lb car is from the huge ceramic multi-piston disc brakes on the car.
06-27-2009, 12:01 PM
#34
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I don't know how big an air brake we're talking, but let's say 2 sq feet...
F = 1/2 ρ CD A v^2
ρ (Greek letter "rho") is the density of air = 0.002377 slugs/foot3
CD for a flat plate is 1.28
So F in lbf = 0.00304256 * (Velocity Squared in FPS)
So braking force is:
30 MPH ~ 44 fps 2.7 lbf
90 MPH ~ 132 fps 24 lbf
120MPH ~ 176 fps 94 lbf
You could design a plate to have more drag than a simple plate, such as vanes, create lift (downforce) adding induced drag on top of the parasitic drag. Or you could increase the surface area.
F = 1/2 ρ CD A v^2
ρ (Greek letter "rho") is the density of air = 0.002377 slugs/foot3
CD for a flat plate is 1.28
So F in lbf = 0.00304256 * (Velocity Squared in FPS)
So braking force is:
30 MPH ~ 44 fps 2.7 lbf
90 MPH ~ 132 fps 24 lbf
120MPH ~ 176 fps 94 lbf
You could design a plate to have more drag than a simple plate, such as vanes, create lift (downforce) adding induced drag on top of the parasitic drag. Or you could increase the surface area.
Why the hell are you working in slugs lol. I freakin' hate them.
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