What I want is something like a tail-hook that I can deploy from underneath the car in an emergency situation that will just drag along the ground grabbing on to whatever it can get a grip on, whether that's snow, dirt, or asphalt. If I change my main point of contact with the supporting surface from rolling rubber to a metal spike (or something like that) I'm gonna slow down a hell of a lot faster than I would otherwise.
Re:Through the snow as if on rails
by etrautmann on Wednesday December 04, 2019 @08:53PM
(#21709275)
I’m not seeing how this could work on most driving surfaces. On asphalt you would have to penetrate the surface, which would require extreme force, or somehow apply additional downforce to a friction device, which would reduce braking friction to the other wheels.
> you would have to penetrate the surface
No, you just have to push down hard enough to take some of the pressure off the tires. (In an extreme case you would lift the tires entirely off the ground. A nice side effect is that you would no longer need a tire jack. Hm, I am beginning to understand why car manufacturers don't implement this :-)
Huh? Taking pressure off the tires reduces traction.
Not if that pressure is moved to something pointy that digs in better than tires, or has more friction.
Re:Through the snow as if on rails
by throwaway1777 on Wednesday December 04, 2019 @10:14PM
(#21709660)
Sounds like a good way to destroy our roads.
> An uncontrolled vehicle would quickly understeer in this situation. In other words, the driver initiates the turn, but the vehicle slides in a straight line without slowing down. The control software in the e-SUV immediately puts an end to understeering. In a left-hand turn, it would brake the rear left wheel and accelerate the right one until a neutral driving situation was restored.
Braking the left rear wheel won’t do much if there isn’t enough traction to correct the understeer.
Even if you imagine the car has a magic gyroscope that can arbitrarily control yaw, if you try to make an 0.2g turn when none of your tires have 0.2g of traction, it’s not happening. You won’t oversteer, and you won’t understeer. You will, however, steer less than you wanted, and you’ll go off the road.