Quote:
Originally Posted by A-Snake
David,
This is such an interesting subject I had to do some homework. I received this information from a computational aerodynamicist on one of the F1 teams.
[i]"While the PEAK value of longitudinal acceleration on a Cobra is approximately the same as the PEAK value of its deceleration, maximum acceleration tails-off as speed increases, whereas maximum deceleration remains nearly constant.
|
Not to change the subject...but I have a little problem with your "expert" here. (Granted, I may misunderstand what you have written as well.)
I must take issue with his "whereas maximum deceleration remains nearly constant" comment.
NO it does NOT!
Drag INCREASES with the square of the velocity whether (Jamo
) you are driving a Cobra, an F1, or a Pinto!
seen NASA website:
http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html
Again, RUN THE THOUGHT EXPERIMENT IN YOUR OWN MIND...DO NOT TRUST ME TO POUR KNOWLEDGE IN YOUR HEAD. If you are driving down the road at 10 miles and hour and you lift off the gas (assume car in in neutral and you are on a flat road) you will barely be able to feel the car decelerate from wind resistance. (You will most likely only feel tire resistance and bearing/drive train resistance slowing you down). Now, drive down the road at 150 mph (legally of course on a race track
) and let off the gas again...notice the IMMEDIATE braking effect of the wind as your anti-submarine belt tightens up on your family jewels
Back to our F1 cars. The F1 car can only accelerate at 1.5 g's because that is all the grip the tires can achieve (assuming low speeds where aerodynamic drag and down force is not significant to screw up the numbers). Now, the tires have basically the same grip accelerating, decelerating, or cornering (that is known as the traction circle). Therefore, an F1 car can only brake at 1.5 g's before the tires say no more! No more? But wait, why can an F1 pilot brake at 4, 5, or even 6 g's? Aerodynamic drag! An F1 can NOT brake at 6 g's when he is going 20 mph--the tires simply don't have that much grip. But he can certainly brake at 6 g's (I am taking your word for it here on the 6 g part) when he is bombing down the straight at 200+ mph and looking at a concrete barrier coming up to say hello because aerodynamic drag is "helping" him slow down.
Back to nuts.
David
(edit) ps. I have a clarification comment below. As I re-read this, I can see I didn't explain it very well.