pyroman2498 Posted May 9, 2016 Share Posted May 9, 2016 So I'm building a small hybrid engine for a demo. And I was challenged to do it from hardware store parts. So this is what I came up with after a bit of research . I have one question . The engine is 6 " long with a 3/8" ID , will be powers by vinyl tube that I bought at the hardware store and a oxygen tank from an oxy. Acetylene touch . It will also run off roofing tar when I can get some . The throat diameter is 1/8" and I'm questioning the size of it being to small. Stay Safe and Stay Green ~Steven Link to comment Share on other sites More sharing options...
pyroman2498 Posted May 9, 2016 Author Share Posted May 9, 2016 (edited) Here is a picture Edited May 9, 2016 by pyroman2498 Link to comment Share on other sites More sharing options...
MadMat Posted May 11, 2016 Share Posted May 11, 2016 (edited) Just a few humble thoughts on your design. Am I correct in assuming that you plan to use the vinyl tubing to supply the oxygen? If so, there are two problems I see; 1. your combustion chamber is going to get extremely hot, extremely fast, and I don't think the vinyl tubing is going to stand up to the heat. In fact, unless the burn time is going to be very short, I wouldn't even trust the brass fitting to hold up to the heat. If I were building it, I would feel safer with stainless steel parts as they will handle the heat better. 2. You are going to need a check valve of some sort on your oxygen injection or the vinyl tubing won't even have a chance to heat up because it will likely blow up from the back-pressure. The check valve isn't a hard thing to fabricate from hardware parts and if you search around you may just find a suitable one already made (Think spring loaded ball in a seat.) Lastly, I have seen a number of hybrid rocket designs, and they all seem to use nitrous oxide instead of oxygen for the oxidizer. I'm not sure why its done like this (possibly because N2O is cooler? or the nitrogen adds mass to the exhaust?) Many years ago, I built a model land speed rocket car that was powered by a liquid fueled rocket engine. It wasn't a true fueled engine as the two components were Albone peroxide and a saturated solution of sodium borohydride. It worked quite well. I just wish I had put more effort into a guidance device of some sort (a surplus gyro of some sort comes to mind) because the car crashed on its maiden run. I did have a lot of fun with the test runs of the engine though. Edited May 11, 2016 by MadMat 1 Link to comment Share on other sites More sharing options...
Jsugarlog Posted September 21, 2016 Share Posted September 21, 2016 Hey I just saw this, but for the future something I would suggest is a standard fuel injector from a car to use to control your flow of oxygen. They have a valve that is opened by an electric current, then when the current is removed it shuts. And they are built to withstand heat and pressure. Link to comment Share on other sites More sharing options...
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