Travel Limiters

[BillyShope]

While this probably isn't necessary, please forgive me while I review some principles, just to be certain we're talking the same language.

Energy has the dimensions of force-distance. It is a force acting through a distance. Common units are inch-pounds or foot-pounds. (While torque is expressed in the same units, rotational energy involves a rotational displacement. Since radians...the measure of rotational displacement...have no dimensions, rotational energy ends up with the same force-distance dimensions.)

Energy takes many forms. If you pick up a wrench from the shop floor, you've increased its potential energy relative to the floor. To calculate the potential energy, you'd multiply the weight of the wrench times the elevation. If you then drop it, that potential energy is converted to kinetic energy, making it possible to calculate the impact velocity based on the height from which its dropped. Kinetic energy is equal to half the wrench mass times the square of the velocity.

A compressed (or extended) linear spring has potential energy equal to half the spring rate times the square of the amount of compression (or extension).

Now, consider a car which, on launch, loses 1000 pounds at the front. Supposing that the individual wheel rate is 150 pounds per inch, that would mean a total of 300 pounds per inch total front spring rate. Equating the potential energy increase with the loss of spring energy, we can solve and find that the front would rise three and a third inches.

But, we get that three and a third answer if we simply consider that 1000 pounds to be extending a spring with a rate of 300 pounds per inch.

In other words, we get the same answer, whether we consider the energy involved or whether we consider the force acting on a spring. The energy consideration is a valid perspective, but it merely complicates matters. (This is what I meant by the wrong rabbit trail.)

On launch, a vertical force is dynamically removed from the front. Since a weight is sitting on a spring up there, that weight pops up in the air and the spring is extended. That's all there is to it.

The potential energy of an enclosed gas is equal to the pressure times the volume. Suppose that 1000 pounds had been supported by a blowoff valve on a gas filled container. On launch, there would be no front end rise; there would merely be a loss of gas from the pressure container.

But, in all these cases, there is no loss (or possible addition) to the energy driving the car forward.

[F1Fever]

That's correct. I maybe need to clarify what I meant when I said the ground lost would be 1.5"..that is simply because as the tires come off the ground and the car rotates around the rear axle (or contact patch) it's effective wheelbase is shortened.

When the Tq is decreased and the front settles back to the ground it's effective wheelbase is lengthened by the equal distance, so unless the tires are carried all the way until the finshline the only concern is with wind resistance.