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Combustion Vortex Block

Posted: Sun Jan 03, 2010 1:08 pm
by kjjohn
I was doing some research for my upcoming pulse jet project (I'll be starting as soon as I'm done with my piston hybrid), when I thought of an idea. A pulse jet is an extremely simple engine, and could be constructed with just few different sized pipes and a check valve. It could also run off of propane or MAPP, along with a venturi to get the correct amount of air in.

My idea is, a pulse jet could be used as a pressure source for a vortex block BBMG instead of a compressor or CO2. It would provide a fairly consistent air source, combusting about 30 times every second. It could also be used with copper BBs to make a slightly "more powerful" BBMG.

This probably could not actually be used for airsoft, but I believe it would work with the right materials.

Posted: Sun Jan 03, 2010 1:23 pm
by rcman50166
Interesting theory, but putting something in front of a pulse jet may cause it to stall, especially if the engine is small enough to feed a vortex block. What I'm saying is the only method I can think of in order to make the idea work is to make a full sized (the ones that are all over youtube) and partially feed a small percentage of the exhaust so the flow isn't restricted to greatly. This will obviously cause problems with portability though.

Another problem I foresee is heat dissipation. Have you seen a homemade pulse just run before? They can get white hot. You need to channel a lot of heat away really quickly in order to make it work.

Example
[youtube][/youtube]

Posted: Sun Jan 03, 2010 1:26 pm
by spudtyrrant
its been thought of before,i'm looking for the link as we speak.
EDIT: here we are http://www.spudfiles.com/forums/the-com ... 18958.html

Posted: Sun Jan 03, 2010 3:10 pm
by jrrdw
Better be heat resistant...

Posted: Sun Jan 03, 2010 3:44 pm
by Brian the brain
It will also need to be able to stall and restart at the push of a button.
These jets don't do that.

The only way I see a combustion bbmg happening is when you use a small gasoline engine to run a small compressor.

Rip up a gasoline RC car, hook it up to a fridgepump and fill a tank with it.
Not very convenient if you ask me...

Posted: Sun Jan 03, 2010 8:13 pm
by inonickname
Pulse jets are very touchy. If you choke the airflow or exhaust the engine will not appreciate it and stall immediately. You will not be able to use a check valve either (you will need a reed valve). Most standard check valves won't take these kinds of temperatures, and don't have the airflow needed to fill that chamber nearly 50 times a second.

Pulsejets are very inefficient. They make a lot of heat, and a lot of noise. The cooling system needed to be able to have this man portable would be immense.
The only way I see a combustion bbmg happening is when you use a small gasoline engine to run a small compressor.
Or use the exhaust gasses (after the mechanism has enough energy to cycle) to power the BB, or using the engine to power a mechanical gun. (Centrifugal force).
Rip up a gasoline RC car, hook it up to a fridgepump and fill a tank with it.
Definitely not. Just buy an old whippersnipper (line cutter, brushcutter, weed eater) to use. Decent RC car engines aren't particularly cheap
And that's not even a very big engine. Nitromethane is also a wee bit more expensive than gas.