Help! Model car build...

[pikestabber]

I guess this is as good a place as any to post this. When my nephew asked for help with a school project, me and my big mouth bit off more than I could chew... Here's the rules, and it's due Wednesday. Any ideas? Sorry it's sideways... Not sure how to change that.

[ZapMan]

I turned the pic. for you.

[ZapMan]

my son did this a few years ago. Foggy on how. Cantilever pole hooked to a rubber band rolled on an axel. wheels made if cd's. Ill look for pic.

[ZapMan]

This isn't exactly but, close. once you watch this link, there are more on you tube to get ideas from.

[delcecchi]

The use of cd's for wheels is a good one. Rubber band is one propulsion method. I would have to look at rules again to see if solar cell and motor would be legal. A weight and string that lowers down and the string is wound around axle. A propeller and rubber band like in those balsa airplanes.

In fact, here is my first proposed design. A cardboard mailing tube with two threaded rods, and the correct size bushings to fit the hole in a cd, And on the top a couple of screw eyes and a rubber band and a propeller made out of a piece of metal cut out of a can. Wind it up about 500 turns and it will go a long ways, at least if it goes straight.

Make the track wide enough so it doesn't fall over.

[littlebear]

Helped a roomate in college on a vehicle build like this, however his was propelled by a mouse trap, which is not allowed in this project

we did use CD's for wheels, and glued rubber bands around the outside for traction, as the mouse trap turned the rear wheels with a string. If this will not be propelled by the wheels, I wouldn't worry about it, but when the mouse trap pulled, the CD's spun and lost traction. I believe we just used pieces of rubber epoxied to the center of the cd's for a hub, and axle punched through the rubber and expoxied. we were careful to center the hole, otherwise the cd was out of balance

we used balsa for the frame, lightweight and strong enough. I don't recall, but I believe it was prob 1/4-3/8" width, and 1/8" thick. Used 2 pieces spaced the mousetrap apart, and two on each end for support. The balsa was vertical (width up/down). The length was as long as allowed (don't recall) but through trial/error on length, the longer vehicle went farther (also due to some mods of the mouse trap engine.

used hollow brass for axle housing (small pieces 1/2" or so) with a 1 piece metal rod inserted through the brass for the axle, running to both wheels. Used powdered graphite for lubrication inside the brass housing. Hollow brass ran through the balsa frame, hole punched through it by a drill bit.

I would guess you could use some of the hollow brass and aluminum, with the propeller and rubber band assembly as described above and a small frame to propel the vehicle.

Hopefully some of this helps.....

[delcecchi]

Hopefully a CD isn't considered a "pre-made wheel"

oooo ooo another idea. A 2 liter soda bottle with baking soda and vinegar or equivilent (mcgyver bomb) with a small hole in the lid to make a rocket effect.

2 axles and cd wheels. bada bin. blast off.

[pikestabber]

Thanks, everyone, for all the good replies (and thanks, Zap, for turning the pic).

[delcecchi]

Let us know the design, and how he did, I am curious

[pikestabber]

Let us know the design, and how he did, I am curious

Found out I get to help two nephews now I'll try to remember to get some pics and let you know.

[Tom7227]

My grandpa used to make a little rig out of a thread spool, two wooden matches and a rubber band. Break one of the matches in half. Thread the band through the spool and put a match on each end wind the thing up. The longer match dragged on the ground and caused the rig to move. I wonder if you could do something like this and get where you have to go and then maybe a foot further.

[bobbymalone]

My grandpa used to make a little rig out of a thread spool, two wooden matches and a rubber band.

http://www-tc.pbskids.org/zoom/printables/activities/pdfs/spoolracer.pdf

[delcecchi]

Found out I get to help two nephews now I'll try to remember to get some pics and let you know.

Cool, two different designs. Rocket man and Propeller man and rubber band man. wait, that is three designs. Will they let you have a turn?

[delcecchi]

How did it come out? Pictures? What did you do?

[pikestabber]

How did it come out? Pictures? What did you do?

I was afraid you might ask... I apologize for not having pics, but just imagine a rough cut 5"x8" piece of cardboard with wobbly wheels and strips of duct tape plastered all over it, and you have a pretty good idea

Both cars were made with 1/4" dowels and CDs for wheels. A rubber band ran from the front axle to the rear axle. The rear axle was spun several times to wind the band and create tension. After securing enough weight to the front of the car, it ran consistently just over a meter (the minimum required was a meter). I used plastic bushings between the wheels and the body and some plastic "c" clips to attach the axle to the underbody. It wasn't pretty (hence no evidence...aka, pictures), but it worked.

Car 2 used a long (24") piece of cardboard about 3" high that was formed into a necked down trapezoid shape. The same general rubber band mechanism was employed, but this one barely got out of the starting gate before spinning out. The axles were not lined up properly, the wheels were wobbly, and the engineer was angry and tired and really, really impatient by this point...

Lesson learned? Take more time to design, secure (putty) the wheels on PERFECTLY straight, measure 10x before doing any cutting, etc. And don't do two of these after 6pm the night before they're due.