Workshops: Rocket Transportation

Engineers and scientists have met many challenges to reach outer space with various spacecraft. The mass of a rocket can make the difference between a successful flight and a rocket that just sits on a launch pad. As a basic principle of rocket flight, a rocket will leave the ground when the engine produces a thrust that is greater than the total mass of a vehicle. Large rockets, able to carry a spacecraft into space, have serious weight problems. To reach space and propel orbital velocities, a great deal of propellant is needed: therefore, the tanks, engines and associated hardware become larger. Up to a point, bigger rockets fly farther than smaller rockets, but when they become too large their structures weigh them down too much.

A variety of propulsion techniques may be used to propel a spacecraft to and from Mars. In this activity, you'll get to use a down-to-earth propulsion system - compressed air. Although a system of this type probably won't propel a Mars mission, it will generate plenty of fun and exploration.

MATERIALS

1. balloon
1. drinking straw
1. fishing line
1. tape
1. scissors
1. clothes pin
1. colored construction paper

PROCEDURE

1. Cut a length of fishing line about 5 meters long and thread it through a drinking straw.
2. Tie each end of the line to chairs that have been positioned on opposite ends of the classroom. Make sure the line is taut.
3. Inflate a balloon, but do not tie it.
4. Utilize the clothes pin to prevent the air from escaping, tape the balloon to the straw.
5. Release the balloon and observe its motion along the fishing line track.

QUESTIONS

1. What is the propellant?
2. What factors determine the distance traveled by the balloon?

CONTEST

Design a balloon rocket that can travel the greatest distance. You can add extra balloons, change the length/position/number of straw segments, etc., in your quest to construct the best propelled vehicle! You will be judged on:

Performance: The rocket that travels the greatest distance.