Question: How are rockets made?

Drew Rae answered on 14 Jun 2011:

Hi CrunchieJelly. I had a look at your profile – I’ve never heard of Ferdinand Verbiest before, so I looked him up. I see he may have invented the first ever car in 1681!

All rockets work by throwing things out the back to make them go forward. This is based on Newton’s third law of motion, and is one of the few ways to move without something to push against. To send a constant stream of things out, you need two types of fuel:
1) Something to throw
2) Something to throw it with

A simple rocket can use pressure to do the throwing. That’s why you can pump pressure into a rocket full of water or air, and then it shoots off throwing the water or air out the back. You can also use a chemical reaction to make the pressure. If you put vinegar and baking soda into a plastic bottle with a small hole, it will build up pressure and fly about.

Space rockets burn fuel to create pressure through increased heat. There’s no air in space, so they carry oxygen with them. One way is to carry liquid oxygen and liquid helium, and mix them together. This creates water and heat. There are also solid fuels that have oxygen in them so that they can burn even without air. These are usually a bit safer.

So that’s the basic idea of making a rocket. You get a hollow container (usually a tube), and fill most of it with fuel. You add fins to make it fly straight, and there you are.