Building a Sand-Travelling Car that Fires a Projectile

[Cryotube]

Homework Statement

Build an elastic-powered or gravitational-powered car that traverses on sand for 2 meters, then fires a projectile perpendicular to the car into a target 2 meters away.

The car + projectile is marked based on:
Distance traveled before firing (as close as possible to 2 meters)
Firing accuracy
Weight of car (1 kg / (1 + mass))

The car must fit within 20 centimeters in both length and width of the dock
-It doesn't have to stop before firing

Homework Equations

-None really

The Attempt at a Solution

The current car I have built is only a base, but it refuses to run on sand at all.
-I used retractable badge clips as the source of elastic energy, instead of rubber bands.

The car runs perfectly fine on solid ground, but the sand is so fine that it resists all initial movement by the car so it simply can't build any momentum.

Even after modification and adding on a total of 3 retractable badge clips the car still can't muster enough power to begin running.

Any suggestions or advice would be highly appreciated!

 

[gneill]

Have you determined where the friction is coming from? Is it because the vehicle has to climb out of the depressions in the sand? You didn't mention what the interface is between the vehicle and the sand. Is it wheels? Are the front wheels acting like snowplows?

 

[Cryotube]

I've modified the car so that it's running on both the nametags and rubber bands now. I've also switched out the back wheels for a bulldozer front end - like a giant ski.

It seems to work better (resists less) so it can run, but now I'm unable to control the turning of the car in the sand (it rotates slightly so the shot is now off)