Rockets

CHEMICAL ROCKETS

A chemical rocket requires two things to work, fuel and an oxidizer. The fuel is worthless without an oxidizer for it is the oxidizer that chemically reacts with the fuel to create the combustion, and thus the thrust.

Many chemicals can act as an oxidizer. The most common is oxygen. Fluorine could also be used as an oxidizer, but its very poisonous and dangerous. Nitrogen peroxide would also be a good choice. It is a liquid at room temperature, which makes it pretty easy to handle. Liquid oxygen must be pumped into the tanks at countdown due to it being a gas at room temperature.

The two main types of rockets are liquid and solid rockets. The big difference between them is that liquid rockets use liquid fuel and oxidizers, while solid rockets use solid propellants. (See, rocket science isn?t that hard J )

The Space Shuttle uses both kinds. Its main rockets on the tail of the body are liquid rockets, while the big red rockets (usually called the boosters) used for the launch are solid rockets.

Solid fuel rockets are very simple. Just insert the solid fuel and oxidizer, attach a fuse, light and run. J People who are into model rockets use solid fuel engines. The space shuttle?s solid propellant is made of ammonium perchlorate (70%, the oxidizer), aluminum (16%, the fuel) and polybutadine plastic (14%, binds the fuel to the oxidizer). Aluminum is a very good fuel because it burns well.

The major set back with solid rockets is that you can control the thrust. Once you light the fuse, it burns away wildly until it runs out of fuel. This is the major advantage of liquid rockets; you can have a throttle control.

Liquid rockets store the chemicals in tanks. When you are ready to ignite, you pump the two chemicals together. Because you have to have separate tanks for the different chemicals, a chamber where you ignite the chemicals, plus the pipes that take the chemicals to the chamber, etc. etc. it results in liquid rocket systems being much more complex than solid rockets. However, with liquid rockets, you can get much more thrust than with solids.

NUCLEAR ROCKETS

A little note on nuclear rockets here. I assume that most people know a simple explanation of nuclear power plants so I won?t go into the details of nuclear reactions.

The advantage of nuclear rockets over chemical rockets is that you get much more thrust with a lot less fuel. Therefore, nuclear rockets can be small and very efficient.

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