Science Forums 2

[Turtle]

Originally Posted by modest

Great idea Turtle, but I think it might be most-useful for a speed race. In that case you could lessen the torque at the start of the race so the wheels don't spin out then increase the torque.

I'm not sure how such a transmission could be used when you're going for distance. In that case you want the least amount of string used (or movement of the weight) per distance the car travels. This would mean having a large drive wheel and a small axle. There is a point where the torque is so small that the car won't move, or it will start moving, but stop at some point down the track. You want to get as close to that point as possible without reaching it. Perhaps Turtle's idea could be used to assure that the car is always just barely moving, but never picks up any real speed or never stops completely. Maybe starting with enough torque to get the car moving from a standstill then lowering the torque so that it's always just barely enough to keep it moving would be useful—which is how the spindle is depicted in Turtle's pic.

~modest

EDIT: here's a link: Mousetrap Car and Racer Propulsion Theory

Here again I point out these specific instructions mention the car should be able to coast once the weight is down, so my thinking is to reach top speed just as the string comes off the drive cone and then you get the best coast distance. The cone acts as a constant transmission, starting in low and ending in high "gear" like a dragster.

Your link gives a description for speed vs. distance vehicles, but makes no mention of combining the advantages of both.
Mousetrap Car and Racer Propulsion Theory

Originally Posted by Doc Fizzix

What is the difference between a good speed-trap racer and a good distance traveler?
A good distance car will not be a good speed-trap car and so on. When you build a mouse-trap car for distance, you want a small energy consumption per second or a small power usage. Smaller power outputs will produce less wasted energy and have greater efficiency. When you build a vehicle for speed, you want to use your energy quickly or at a high power output. ...

Originally Posted by Freezter

Good ideas all around! It raises a question for me. Hopefully this is beneficial to the OP.

For a distance race, would it be better to have FWD or RWD? Where should the pulley system be mounted? Intuitively, it seems that you would want everything centered as much as possible to thwart inertia due to mass. But, perhaps there's a better way...
What is the best way to distribute weight to achieve the best distance?

I think centered weight as far as possible. As to front or rear wheel drive, you could just turn the vehicle around and wind the string the opposite way to try both with one setup.