Weight powered car

[TEguy]

because everything is really light weight and only limited amount of input energy is allowed, drag will play a big part in slowing it down. Make sure you minimise that, otherwise it will stop real quick. As you already know ( I hope) what you are doing is converting potential energy to kinetic energy. Make sure you set it up so that the conversion rate is very slow, you want the weight to drop slowly and propel the car as it decends. Having one quick burst of energy will not be good in my opinion. The reason is the same - drag. High speed means lots of drag, keep the speed low and this will keep the drag low. Same applies to friction in the moving components. It is not a speed race, it is a distance race.
That is my opinion anyway. Oh and you really need to do something about your spelling
Good luck

[arkain101]

Honestly, you could use spaghetti sticks glued together to build your frame.

It was a quick thought, maybe glue will soften the sticks? I don't know. It's easy enough to test.

I don't know what spaghetti costs these days, but it could be the quick cheap route your looking for.

[Turtle]

Originally Posted by TEguy

because everything is really light weight and only limited amount of input energy is allowed, drag will play a big part in slowing it down. Make sure you minimise that, otherwise it will stop real quick.

Good point. Powdered graphite or light oil with powdered graphite makes car go good.

Originally Posted by TeaEeDude

As you already know ( I hope) what you are doing is converting potential energy to kinetic energy. Make sure you set it up so that the conversion rate is very slow, you want the weight to drop slowly and propel the car as it decends. Having one quick burst of energy will not be good in my opinion. The reason is the same - drag. High speed means lots of drag, keep the speed low and this will keep the drag low. Same applies to friction in the moving components. It is not a speed race, it is a distance race.
That is my opinion anyway. Oh and you really need to do something about your spelling
Good luck

So I have a bit of a different take. First, note the rules specify the car should be able to coast after the weight is down. So to begin with you have to engineer the thing to let the string loose from the axle. I think simply wrapping it tight should suffice.
Then to me, the faster a car is going the farther it can coast, oui/no? So what I have in mind is basically as in Craig's drawing, but having the axle cone shaped with the string wrapped starting at the small end and then progressively toward the fatter end so the car gets more torque at first and then less as it accelerates to higher speed. At the very least, I wager no other cars have this design feature and it might get some credit for ingenuity.

[Pyrotex]

Originally Posted by Turtle

...Powdered graphite or light oil with powdered graphite... but having the axle cone shaped... I wager no other cars have this design feature and it might get some credit for ingenuity.

Powdered graphit can be bought at any good drug store, auto parts store or Home Depot / Leow's. It comes in a toothpaste tube and is generally sold for lubricating locks for external house doors and car doors. Careful, it is the messiest substance on the planet!

Turtle, I have to credit you for ingenuity! Bravo!

[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: http://www.docfizzix.com/mousetrap-faqs.shtml

[freeztar]

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?

[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.

[arkain101]

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

Aha. but how fast will the car get moving? And, thus we ask, how far will it coast after the weight has stopped pulling?

I can smell a physics equation in here that has to do with

Force Momentum and Coefficient of friction.

Somewhere in there is a golden zone.

Speed is surely a key factor!

Yet, will a dangling weight start swinging if acceleration is too harsh? A swinging power source would be an all around no no. right right?

[freeztar]

Originally Posted by arkain101

A swinging power source would be an all around no no. right right?

That's one of the ideas I was trying to draw out. What if the weight did swing? Perhaps it is possible to put the horizontal movement to work, as well as the vertical dropping?

For this type of assignment, it's probably not a good idea but it's a fun idea to think about...

[arkain101]

Right! As long as the movement of the weight was perpendicular to the direction of travel you could gain some extra mmph moments. Good Call. Ah, but you would lose some mmph on the upper swings.. too bad so sad

I guess to keep this in perspective...

We have 1 force to do work for us here. And that is gravity. (as long as we dont start whipping the weight around in a circle, and create centrifugal force)

As we all know, you can't get more out than was put in. So, the max is 9.8newtons, for 10cm.

w = f x d (if i remember)