Dr. Universe: What materials would you use to make a rocket?

-Freya, Scotland

Dear Freya,

Whether it’s a model rocket you build in the backyard or one that launches a space shuttle, there are lots of materials you could use. So, when I saw your question I grabbed my lab coat and safety goggles, and zoomed over to my friend Jake Leachman’s lab. He’s a rocket scientist and engineer at Washington State University.

“Even a summer sausage could be a rocket,” said Leachman. That is, if you don’t get hungry first.

Rockets use solid fuel or liquid fuel. Sometimes they use both. A summer sausage has a lot of natural nitrates, so its chemistry makes for good solid rocket fuel.

Then there’s the body of the rocket to think about. Model rockets are usually made from lightweight materials. The body tubes can be cardboard with fins made from balsa wood. They usually have plastic nosecones and parachutes. As you get into more high-powered rocketry, you may use thicker wood or composite materials for the body and plywood or even 3-D printed fins.

Still, no matter the kind of fuel or whether the design involves lunchmeat, simple materials or expensive ones, rockets will all have at least one thing in common. Rockets bottle up a lot of pressure and then they release it very quickly to create motion.

If it sounds familiar, you might have heard of Newton’s Third Law of Motion: every action has an equal and opposite reaction.

“Propulsion is throwing something in one direction and allowing it to push something in another direction,” Leachman explained. “If you can create propulsion just from what you have stored on-board, you’ll have a rocket.”

The materials you use can influence not only propulsion, but also the speed, sound, shape, and even smell of the rocket. A summer sausage rocket would obviously smell like burnt meat.

You wouldn’t want to smell rockets that use both hydrogen and fluorine for fuel because it’s toxic. Other rockets, like those that use oxygen and hydrogen, would smell like water. In Leachman’s lab they use hydrogen for rocket fuel.

Hydrogen is the lightest and most chemically reactive fuel in the universe. Both the lightweight quality and reactivity are important to rockets. It means the gas shoots out the back faster and it takes less time to get to its destination.

Sound also changes depending on the materials, so you’ve got to protect your ears.

“Rockets are shaped in many ways like flutes, but explosively powered,” Leachman said. “You don’t want to hit off key.”

So, the materials you choose to use really depend on the kind of rocket you want to build. To start out, you may want to look for a beginner model online or at a local store. You can also look for local clubs or launches in your community and meet other people who are having a blast building rockets.

Sincerely,

Dr. Universe