Building A Model Car

[oOAndrewOo]

Hi, here's the deal.

 

I'm in year 9 (3rd year of highschool). Currently I'm doing a Student Research Project.

 

I've chosen an experiment to do which is the following:

I'm going to build a model car. I will use a balloon to supply thrust to the car. I am going to change the wheel size of the model car to see if it affects the distance it travels with the energy supplied by the balloon. (ofcourse the size of the balloon would be controlled, and I would do this by measuring the circumference).

 

My question is this:

 

What would be a suitable material to build my model car with? It would have to be light enough so that the balloon could easily move it, but heavy enough so that it doesn't just blow off into random directions.

 

A possible material I was thinking of was plywood?

I can't use lego as I need a material which would be easy to construct wheels of different sizes with.

 

Thankyou in advance for any help.

[insane_alien]

plywood would be fine. it would be better to build it with very light materials but then add some ballast afterwards. this means you can adjust how heavy it is so you get a good balance betwen speed and control. and mainly because you don't want to test it and have it just sit there and not move.

 

i'd recommend balsa wood for the frame. it is light and strong and easy to work with(i've built model bridges and planes out of it.)

[CaptainPanic]

a very easy construction material is polystyrene foam (that ordinary packaging material).

 

You can "cut" it by making some piece of metal hot. Anything above 100 deg C will melt itself through the foam, so if you have some circular shapes that can be heated, that could be an easy way to make wheels. Make sure you strengthen the wheels where you attach the axis (foam is easy, but not the strongest material in the world).

 

the car itself... I would suggest you make it as light as possible, while keeping it robust. Making things heavier is usually the easy part. Wood, or plastic (something like a lunchbox?) or again more foam can be used. I don't understand why you cannot use Lego for the body of the car. Lego rules imho, although it can become a little heavy.

 

Finally some suggestions: if you have a lab at school, fill your balloon with helium, and see how far the car gets with that light gas. If possible, also test it with CO2.

[YT2095]

CDs with a broad elastic band around the edge make great drive wheels (if you`r going to use a horizontal blade turbine).

[Klaynos]

I once one a competition for building a car type thing....

 

It was powered by an elastic band, but a balloon would have worked well...

 

It was a single piece of quite thin wood, light, plywood would be fine. With simple plastic wheels at the front.

 

But the drive wheels were polystyrene with elastic bands around the edge for grip, they were held on the powered axel using a pair of cogs that were pushed into the polystyrene then screewed onto the axil.

[DJBruce]

I have competed in the Boy Scouts pine wood derby. It was a 6 inch long block of probably a 21/2 by 21/2 inches. That would work well you can pick these kits up of the Internet or from a Boy Scout store.

[CaptainPanic]

Is 21/2 inches the same as 10.5 inches?