Quote:
Originally Posted by kach22i
In a word, "Lateral Stability" or Longitudinal Control" become factors long before braking and cornering when the forces of momentum caused by mass rear their ugly heads.
If there is a magic ratio of friction to mass/weight which is in-between that of a 400 lb hovercraft + 175 lb operator, and an automobile I personally have no faith in finding it if safety and control are at all considerations.
Conclusion: Anything that lifts weight off the car be it at 1/2 mph, 20 mph or 200 mph leads to compromised vehicle control.
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Anything you do to the car compromises control in some way, whether it is steering, braking, adding downforce, removing downforce, adding lift or taking passengers. It is about the safety envelope, as long as you are within that you are okay.
The magic ratio as you say would depend on so many things, cornering radius, car speed, weight distribution, moment of inertia, headwind speed, crosswind speed, centre of pressure, coefficients of front lift and rear lift, coefficients of sideways lift on the front and also rear of the car under yaw conditions, turbulence and many other factors.
That ratio also changes constantly, it wouldn't be wise to have a lifting car in a strong crosswind, or when cornering heavily, or in turbulent conditions. But when the conditions are right, it may be possible to do so, to get closer to the edge of the envelope.
Whilst maths supports the concept, and it is theoretically possible to design a car that can: have variable amounts of lift based on conditions, is stable under mild cornering when lifted, has a centre of pressure that doesn't cause the car to be unstable, has front and rear coefficients of lift that are balanced, has the ability to pitch down and create negative lift under crosswind or heavy cornering/braking, it would be not only difficult to do, but the design priorities would very rarely line up such that it would ever be worth it.
Partial lift has been employed by solar cars, but these cars had high front lift and low rear lift in a straight line and low front lift and high rear lift in a cross -wind. The aerodynamic and form priorities of a solar car would not easily align with the aerodynamic and form priorities of a partially lifting body car.
Designing a car that could be clever enough to recognise the times/parameters when high lift would be beneficial and where high lift would be unsafe and go into reduced/no/negative lift would be difficult, and this isn't considering all the fine aerodynamic balances that would need to be maintained at various speeds.
Do I think this concept is useless or flawed? No, of course not, I started this debate to find out why it hadn't been done, because I thought it was possible. Do I think that this concept is practically applicable? Given the right conditions, priorities and restrictions yes I do. Do I think that those will ever arise? No, I don't.
I have explored as far as I wanted to with this topic and so I will not be likely to comment further unless new information is presented. I wanted a debate, I got a debate.