I had intended to do three tests, only got one done.
I fired the 3D printed motor with larger diameter plumbing on the main valve and a turbine flow meter so I can measure C* and ISP.
Results are mixed....
The test stand I'm using is an amalgamation of an old test stand and a bunch of valves from the silver ball. In short it is a mess. I worked on making it better this week. (largely why I only got one of my tests done) We hydroed the basic structure and tested the relief valve a few weeks ago, and all of that is solid. The new valves and arrangements form the main outlet to the motor are solid.
The valves for the fuel side and the pressurization system are 100% Silver ball leftovers.
They largely worked two weeks ago when we ran it, this weekend two of the fuel side valves were frozen and the actuators died. I had one spare actuator with me so I replaced the fuel valve actuator and changed the fuel side vent to manual operations.
The 2nd deficiency of the system is that all the wiring is an unreliable mess. I hope to clean that up repackage the electronics and make it all a solid solution before I use the stand again.
I left the test stand at FAR but brought all the valves and sensors home.
The actuators are all dynamixel RX-64, 18V actuators run off a 5 cell lipo and an ac power supply to keep things topped up. I have a nice 40V 13.8V AC powered supply, thinking about trading the RX-64 for MX-64 that would be happy running at 13.8V. This is a $1K decision, I need to sleep on that.
My old sureflow pump for loading oxidizer died this year. I bought an air powered diaphram pump from McMaster car to replace it as the model of sureflow pump is not longer made.
The problem with this pump is that is really pulses, the flow is not smooth so hoses jump around and do unpredictable things. I mounted the pump to a 3 hp roll around aircompressor and added a remote dead man switch activated valve to turn the pump on/off. I also changed the loading procedure form opening the top of the tank to having a separate valve and a hard connection on the bottom for fueling, no ladders involved. These changes mostly worked as designed and I'm happy with them. much less risk drama in oxidizer loading. I need to do something similar for the fuel side and will do so. I still have hope that I can find a good steady electric self priming oxidizer pump..... I've ordered a couple of candidates, we will see how they turn out.
The firing ran well about 78 seconds. The CAT pack worked well and I got good data. The feed pressure was up about 20 psi from last time, the chamber pressure was up about 10, not sure where the other 10psi went.... motor ran at about 180 PSI target is 200. On shutdown the fuel feed pressure stayed up witht he fuel valve closed. So I suspect that rebuilding the fuel side of the system in the mojave dust introduced enough material to clog the fuel orfices. I've ordered a small sintered 10 micron fuel filter to add to the system. Well see when I examine the engine this week....
I forgot to do a final last minute tightness check on all the plumbing. Got distracted by a rocket launch that required everyone under cover and for got to tighten one pressure transducer... sprayed peroxide all over everything...this part was after the main valve so was not part of the pre-fill leak check.
Then wheil disassembling things I dumped fuel all over the open ox inlet port on the motor.
So before I run it again it needs to come apart and be properly lcleaned for oxidizer service.
Things to do before next test:
Rebuild and test all the valves and actuators.
Package the electronics in a more robust manner.
Add flow meter to the fuel side.
I'll probably run another motor test the first FAR event of January that should be Jan 2nd
For the Far event on the 19th of December I'm going to try and fly my GPS experiment and test the little TJ-20A turbine as a potential first stage motor.
I'll try and post some of the test data when I have looked at it later this week.