I have managed to put the accumulator together and carry out a test on the rocket. Here is the setup
- The accumulator piston was moved up to the top so the N2O chamber was as small as possible and the bottom chamber pressurised to 500 Psi
- I applied 500 psi to the bottom chamber with N2 and attached the full N2O bottle to the top chamber.
- The N2O bottle was opened and the pressure in the lower chamber was seen to increase to the N2O pressure of 650 psi
- The pressure in the lower chamber was bled to 0 and this allowed the liquid N2O to decant into the top of the accumulator.
- The top valve was closed and the N2O bottle removed and weighed to ensure it was fully empty
- N2 was applied to the lower chamber and re pressurised to 1100 psi. This returned all the N2O to liquid with no gas
- The rocket was attached and ignited
Here is a video of the test. The main camera didn't work past ignition but it was captured on my mates phone
The results were as follows
Thrust = 12-15lbs
Burn time 12 seconds
The fuel grain was all gone and it was pretty obvious the injector was too big. The next test will be with a smaller injector and maybe 1/2 the N2O