Homemade Hybrid Rocket Motor: Test #2

This is the first successful test firing of my homemade hybrid rocket, constructed from a standard pneumatic cylinder. The fuel is paraffin wax mixed with charcoal; the oxidizer is liquid nitrous oxide. The ignition source is a party sparkler and the valve is hand-operated via long strings. Everything is bolted to a 12-kilogram concrete block, which actually moves during the test.

Watch the exhaust plume carefully: you can see shock diamonds forming, indicating that the stream is going supersonic.

Category:

Science & Technology

Tags:

• Hybrid rocket
• shock diamonds
• homemade
• amateur science

[CanadianMacGyver]

To answer your questions in order:

#1: The fuel mixture was approximately 15% charcoal by volume.

#2: Wax ejection was never a problem: all engines burned cleanly.

#3: I have not had the time to experiment with new fuel mixtures: I will have to build a more refined engine first

#4: The engine was built from a standard pneumatic cylinder, so the injector size was already fixed.

I am working on building more sophisticated, purpose-built engines, so stay tuned!

[abond1007i]

That's impressive, I'm assuming you burned quite a bit of nitrous oxide. What type of mixture ratio of coal & paraffin did you use? Did the previous test have problems with ejecting balls of wax? If so have you tried adding other wax types, vybar or stearic acid to raise the melting point? Also, when sizing your injector, how close was your first guess?