TOPIC: Rocket staging
OBJECTIVE: To demonstrate how several stages of of a rocket can operate in steps to propel a rocket.
DESCRIPTION: Two inflated balloons are joined in a way simulate a multistage rocket launch as they slide along a fishing line on the thrust produced by escaping air.
CONTRIBUTED BY: Gregory Vogt, OSU
EDITED BY: Roger Storm, NASA Glenn Research Center
MATERIALS and TOOLS:
- 2 long party balloons (round balloon will not work)
- Nylon monofilament fishing line (any weight)
- 2 Plastic straws (milkshake size, non-bendable)
- Styrofoam cup
- Masking tape
- Thread the fishing line through the two straws. Stretch the fishing line snugly across a room and secure its ends. Make sure the line is just high enough for people to pass safely underneath.
- Cut the cup in half so that the lip of the cup forms a continuous ring.
- Loosen the balloons by preinflating them. Inflate the first balloon about 3/4 full of air and squeeze its nozzle tight. Pull the nozzle through the ring. While someone assists you, inflate the second balloon. The front end of the second balloon should extend through the ring a short distance. As the second balloon inflates it will press against the nozzle of the first balloon and take over the job of holding it shut. it may take a bit of practice to achieve this.
- Take the balloons to one end of the fishing line and tape each balloon to a straw. The balloons should be pointed along the length of the fishing line.
- If you wish, do a rocket countdown and release the second balloon you inflated. The escaping gas will propel both balloons along the fishing line. When the first balloon released runs out of air, it will release the other balloon to continue the trip.
Travel into outer space takes enormous amounts of energy. Much of that energy is used to lift rocket propellants that will be used for later phases of the rocket's flight. To eliminate the technological problems and cost of building giant one-piece rockets to reach outer space, NASA, as well as all other space fairing nations of the world have chosen to use a rocket technique that was invented by 16th-century fireworks maker Johann Schmidlap. To reach higher altitudes with his aerial displays, Schmidlap attached smaller rockets to the top of larger ones. When the larger rockets were exhausted, the smaller rocket climbed to even higher altitudes. Schmidlap called his invention a "step rocket."
NASA utilizes Schmidlap's invention through "multi staging." A large first stage rocket carries the smaller upper stages for the first minute or two of flight. When the first stage is exhausted, it is released to return to the Earth. In doing so, the upper stages are much more efficient and are able to reach much higher attitudes than they would have been able to do simply because they do not have to carry the expired engines and empty propellant tanks that make up the first stage. Space rockets are often designed with three or four stages that each fire in turn to send a payload into orbit.