[Bluepen]

OK folks I have gotten trapped (kidding) into helping my daughter build a mouse trap car for her sicence class. The kind where a string off a mouse trap turns a drive wheel/axle and the car moves, has to move at least 20'. We built the frame, wheels and drive wheel today. Its going to look more like a top fueler than a car.
Anyway the help I need is with the drive wheel. The rear wheels are 5 1/2" dia and the drive wheel is 4 1/2"dia, long slow turns more distance, Now am I thinking this wrong, it should be a smaller dia like 1" to get more turns faster. I should know this I'm building a truck for gods sake and I can't figure this stupid little thing out.
Help me out please

David

[Ghetto Jet]

I remember doing one of those in school. I used round pieces of plastic that were about 3 inches in diameter. I beat everyone in the class for distance. To get traction I put a rubber band around the surface of the "wheel".

[FieroBob5]

I did one of these last year in physics. I used a sheet of that pink styrofoam insulation. I made the wheels really big, and i don't know if this is allowed in your projest, but i put a dowel oin the trap with the string tied to the end of the dowell. It allowed the string to pull for a longer time on the wheels and due to the extra torque needed, it pulled much slower, with much better traction. The cars with the smaller wheels just spun like crazy, with little to no grip.

My $.02
Rob

[Weimer]

Here you go...
Here too...
Here's a nice little video of one
Later,
WEIMER

[k2mooch]

The best one in our class back in '98 hit the other side of the gym.

Don't make a 'body' with wheels. Make the 'wheels' the car. It's the only way to keep the momentum going.

Get two old records and out some rubber strip on the edges. Mount an axle that will keep them parallel that the mousetrap will 'float' on. Use a CD in the middle as a 'slow gear' to use as a pedal for the motion of the spring. Fix a stud on one place on the circumference of the CD gear and tie a kite string to that and the mousetrap bar.

When activated, it will accelerate VERY slowly and evenly as the spring's bar pulls the CD gear attached to the axle. MAKE SURE you use a good rubber on the wheels to grip the launch and still be smooth enough to reduce resistance. If you can get a good bead of hi-temp silicone to smooth out on the records, you're in business, but it's REALLY hard to get the bumps out.

It is SOOO important that the wheels of a car like this design are perfectly round. Good Luck.



MoocH