If you've been following the news updates on the website "Kiwi 2 Space" you'll know that
we are now experimenting in the world of Hybrid propulsion, the same stuff that propelled Space Ship One into space.
So for now it was Back to testing.I have a R.A.T.T works L600 rocket engine at home which is perfect for doing fuel tests, easy to setup and fire quickly. I decided to pursue Polyurethane as a fuel after following the Copenhagen Suborbital guys, I easily cast up a replica grain for the engine using some old exhaust pipe and SS pipe for mandrels, I got some flooring glue of Trademe for dirt cheap and away I went. Once dry and after a bit of hitting with a large hammer to remove the mandrels we were good to go! The 2000lbf load cell had not yet arrived and as not wanting to modify the motor casing for a pressure port this test was purely going to be a visual and post analysis after the burn.
This seemed to burn alot dirtier and furious than the standard polypropylene fuel that is meant to be used, and as you can see in the pictures in the link below, left the engine very dirty inside, although I do put this down to the burning of the fuel as the residual gas left the tank (no valve on this engine).
All in all a good test, polyurethane is easy to cast, easy to machine and easy to fire in a hybrid! Now to try it in the big beast!!