Question about F-1 Steering

[hippocow]

I have a question about the suspensions on F-1 cars. I was watching a race on T.V. the other day and I noticed that Indy cars seem to use equal length control arms. This would mean an Indy car would have no SAI (Steering axis inclination) meaning the driver would have to steer the car straight after taking a corner instead of the car having a tendency to steer its self straight. Is this the reason that Indy cars use so much camber on the front wheels? Do they use equal arm suspensions to prevent the cars center of gravity from shifting while cornering? Or is there SAI built into the suspension somehow? These are to only race cars that I have seen with this kind of set up, usually there is about 4-10 degrees of SAI built into must race cars suspensions

 

[GilesGuthrie]

IndyCars tend not to use the self centering because they spend so much time travelling around constant-radius curves. Also, the front wheel camber is used to offset roll, which will alter the wheel angle. Basically, you set the camber so that as the car rolls into a corner, the camber cancels out the roll at the wheel, and you get the whole contact patch of the outer tyre onto the road.

I don't know about F1 cars having SAI. My guess is that they would not.

 

[Mike Rotch]

Originally posted by hippocow
I have a question about the suspensions on F-1 cars. I was watching a race on T.V. the other day and I noticed that Indy cars seem to use equal length control arms. This would mean an Indy car would have no SAI (Steering axis inclination) meaning the driver would have to steer the car straight after taking a corner instead of the car having a tendency to steer its self straight. Is this the reason that Indy cars use so much camber on the front wheels? Do they use equal arm suspensions to prevent the cars center of gravity from shifting while cornering? Or is there SAI built into the suspension somehow? These are to only race cars that I have seen with this kind of set up, usually there is about 4-10 degrees of SAI built into must race cars suspensions

Thats is a very good question - how refreshing

 

[hippocow]

Thanks for the reply GilesGuthrie; I did some thinking about it. I think I know why F-1 cars can't rely on SAI to center the wheels after a turn. The principle of SAI(amongst other things) is that when the wheels turn, the vehicle's spindles will be forced down and the cars body height will rise, so that the potential energy of the body's weight will eventually return the wheels to the straight ahead. Now image this principle at work on an Indy car with about 2 tones of down force coming off a fast sweeping corner. I think that might make things a little hairy.
Also a note of interest about camber, caster and slip angles. when we do short track racing if we get the setup right, and our driver is brave enough, the car could drive itself around the track with nothing but the throttle. (provided conditions were perfect) Makes you wonder how an oval track driver could ever take credit for winning a race!