ROCKETS AND LAUNCH VEHICLES

« direction is balanced by an equal force in the opposite direction.

This principle is well shown by the backward movement, or recoil, of a cannon when it fires a cannonball. The English genius Isaac Newton first stated the reaction principle as his third law of motion: "to every action there is an equal and opposite reaction." Rockets are often called reaction engines. 2.Solid propellants The fuel and oxidizer in a rocket are called its propellants, because when they burn they produce the gases to propel the rocket.

The propulsive force developed by a rocket is called its thrust. The simplest kinds of rocket use solid propellants.

The original rocket, invented by the Chinese about 900 years ago, used gunpowder as a solid propellant.

We still use this in our fireworks rockets today.

It is a combination of powdered charcoal, sulphur and saltpetre, or potassium nitrate.

Charcoal (a form of carbon) and sulphur make up the fuel, and saltpetre is the oxidizer. In a firework rocket, the nose contains chemicals to produce coloured stars and streamers.

The gunpowder is packed into a cardboard tube, which forms the combustion chamber.

At the rear of the tube is a twist of chemically treated 'touch paper', which acts as a fuse.

The tube is attached to a long stick, which helps the rocket travel straight. To set off the rocket, you light the touch paper.

This ignites the gunpowder and produces a stream of hot gases.

This shoots out of the open end of the tube and propels the rocket into the sky.. »