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Hybrid project

A student researched and developed hybrid rocket engine

What's the big deal?

The purpose of a rocket is to deliver a payload to its destination somewhere off the ground - be it fireworks, an atmospheric experiment, a satellite or even humans. The rocket must be as powerful and fast as gravity and aerodynamic forces are relentless, and as reliable as the payload is valuable. The rocket goes nowhere without a engine/motor. The science behind rocket engines/motors, some have been known to say, is the very heart of rocket science itself.

Rocket motors & engines 101

There are two main categories of rocket engines: liquid and hybrid engines, and those using solid propellant are called rocket motors. Each of them have their advantages and drawbacks. Liquid engines are what most larger rockets use as their main engines, such as the Space Shuttle, Soyuz/Proton or Falcon 9. They mix two liquid or gaseous propellants in a burn chamber in order to produce thrust, which makes for some interesting challenges with plumbing and flow control. Solid rocket motors are what you find in fireworks, or indeed as “booster” stages for the Space Shuttle or upcoming SLS - they are the white cylinders you can see strapped to the sides. Here, the propellant is designed so that you need only add a bit of sparks and you’ll be on your way. There’s no off switch, you better make sure you’re aiming in the right direction before igniting it!

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Our project

At Propulse NTNU, we are designing and building a hybrid rocket engine. The idea is to fuse the relative simplicity of a solid motor with the safety and sophistication of a liquid engine. We do this by having one liquid propellant component stored in a tank, and injecting it into a burn chamber filled with a solid component. As you may recall from various safety courses, a fire needs heat, an oxygen source and a fuel in order to thrive. Usually, as is the case with our engine as well, the liquid is the “oxidizer” and the solid component is the fuel. The hybrid concept is not a new one, but it is only lately that it has started to become popular outside of amateur rocketry with appliances such as atmospheric research and cubesat-sized payloads to LEO. Our engine runs on a mix of nitrous oxide (N2O) and paraffin wax. When heated, the N2O decomposes exothermically into N2 and O2, and the O2 reacts with the paraffin to make a good, old-fashioned fire. Said fire is directed out through the nozzle at the bottom, and there you have it -  a rocket engine.


Any questions are welcome at

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