Only three countries have managed to send humans into space via rockets, but you can easily build simple model rockets at home. Ask Science explains the science behind how model rockets work and offers tips on how to construct your own with easy science experiments.
Hi, I’m Sabrina Stierwalt, and I’m Ask Science bringing you Quick and Dirty Tips to help you make sense of science.
Rockets are truly fascinating because they are both extremely simple and very complicated. They are also so complex that only three countries have actually managed to send humans into space in a rocket. At the same time, science experiments with model rockets at home is as easy as going to the nearest hobby shop to purchase your own kit.
How to Perform the Experiment
The best way to get started with building model rockets is to purchase a kit. This will include all the parts you need to construct your rocket as well as detailed instructions.
Take advantage of the fact that you can launch and re-launch your rocket by experimenting with different constructions. Do the number or angle of fin attachments you apply change your rocket’s trajectory? What happens if you put a small weight in the nose of the rocket?
You will also need to purchase a commercially-made rocket engine. For first time rocket makers, the best engine to use is type A8-3. They are the lowest power, but don't worry—they still provide an impressive launch. You can count on them to go so high that you lose track of them on a clear day. There are also B and C type engines, but for those rockets you will need some kind of binoculars and a couple of extra friends so that you can keep track of your rocket. Don't forget to put a stop inside your rocket so that the engine doesn't just shoot right through it or catch fire. It also helps if you buy the rocket engines before you construct your rocket, so that you can tell exactly how big your rocket body needs to be.
Notes on Safety
- Always launch rockets in wide open spaces, far from houses and other buildings, and at a time when the wind is <20 miles per hour.
- Always use the remote to launch your rocket so that you (and everyone else) are at least fifteen feet away from the rocket when it launches.
- Learn when to let go—don't climb trees to collect a lost rocket if it is too dangerous.
- Make sure no young children or pets have access to your rocket parts at home, especially the rocket engines.
For more tips on being safe, check out the Model Rocket Safety Code put together by the National Association of Rocketry.
The Science Behind the Experiment: How Model Rockets Work
Newton's Third Law says that for every action, there is an equal and opposite reaction. Let's think about what this means in non-rocket terms by looking at two examples. First, when you let the air out of a balloon, the balloon doesn't just sit there—it flies around the room. The action is the air rushing out of the balloon, and the reaction is the balloon being forced in the opposite direction.
Second, imagine you are standing on a skateboard and you throw a football as hard as you can to your friend. You won't just sit there—you will roll a bit in the opposite direction of your throw. The action is your throwing the football, and the reaction is your movement in the other direction.
Rockets work in a similar way: mass in the form of fuel is accelerated out the back (the action), and thus the rocket is forced to move forward (the reaction). The strength of the force pushing the rocket forward is called the "thrust." The faster the fuel is thrown out the back of the rocket and the more fuel that is thrown, the faster the rocket will be forced to move forward and thus the greater the thrust.
Similarly, if you throw the football to your friend gently, you won't roll as far on the skateboard as you would if you threw the football really hard.
So, what makes model rockets so much simpler than actual space-traveling rockets?