There are several important things to keep in mind when designing and building your balloon racer.
The first thing to do is choose the material to build the chassis or body of the car.
The chassis should be both light and sturdy, for this reason Styrofoam makes a very good chassis.
It is also important to design a chassis that is long enough. Short cars tend to spin out more often
than longer ones. A good car should be about 30 cm long.
The second thing to do is build and mount the wheels.
Wheels can be made out of about anything that is round, such as CDs caps and lids.
The hard part, however, is getting them mounted straight with little friction.
If the wheels are not mounted straight or are not free to spin smoothly, the car will not perform well.
Once the wheels are mounted on the chassis it is time to put a balloon onto the car.
Having the balloon attached to a pen barrel so that the air comes out in a smooth manner helps.
Another helpful approach is to double up a balloon so that it is twice as thick.
If the car has a sturdy but light body, free moving wheels and a good power supply,
you are well on your way to being a balloon racer champion.