10 lb. Thrust Pulse Jet Engine......VIDEO

[Rocket Man]

Here is a 10 lb. thrust pulse jet engine that I finished yesterday. I ran it several times for a total of 20 minutes until the reed valve broke. Today the new reed valve only lasted 1 min 20 seconds. It is running on propane with a fuel injector with 4 fuel orfices 1 inch in front of the reed valves. I electronically etched the reed valves in a salt water bath for 1 hour using a car battery. Reed valves are pretty easy to make but come out with ruff edges. I think the ruff edges contribute to the low life of the valves. I used the electric belt sander to sand the reed valve edges smooth on the one I used yesterday that may be why it lasted 20 minutes. I did not sand the reed valve I used today. The engine is about 50% throttable. It is running on 3.5 psi of propane gas pressure. It is throttable from 2 psi to 4 psi. Above 4 psi and below 2 psi the engine stops running. Below 3.5 psi the frequency sounds like it stays the same the only difference is the engine runs quieter and produces less thrust on lower gas pressure. I read the German V1 research data several times and learned something new each time. I also read several research data papers written by 2 different college students that built and tested several pulse jet engines. I have a lot of good information to learn from. I have worked out some formulas for building engines so they are correct and will start easy, run good, and have good valve life. The fuel injector keeps the flame forward and keeps the reed valves from getting hot. After examining the broken reed valves they both broke off at the narrow section near the bolt where the valve hinges. Only 1 pedal out of 8 pedals shows signs of getting hot and that is about 1/32" along the tip edge.

http://www.youtube.com/watch?v=u2apj002QwY