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Every fitting connecting to the ASI is a copper crush except the fitting that connects it to the main injector, which is an ORB fitting. We chose an ORB fitting here mostly due to the fact that it'd make installation and clocking way easier, and also because we already had an ORB porting tool of the right size lol. However, we recently de-integrated the ASI and observed some O-ring melting. Currently our potential solutions are are buying FFKM O-rings which are rated to 600 F (previous high temp silicone O-rings are rated to 450 F) or just burning for less time. However, we are concerned that the FFKM can decompose into toxic chemicals (HF) if it still melts.
Nozzle
add cross sections
The "nozzle" is not really a traditional rocket nozzle, as it does not have a diverging section. Its converging angle is also not optimized because we wanted it to be easy to manufacture (just drill with two different sizes to get a converging geometry). There isn't really a reason why the igniter flame needs supersonic – if they come in sonic that's fine. So, we didn't see a need to drill on the other side for a diverging section. .
The flame travels through the nozzle and goes through the main injector before coming out into the main chamber. The whole ASI assembly is at an angle so that it can shoot out the flame closer to where the nitrous exits the pintle orifices to maximize ignition probability. The nitrous itself should regen cool the pintle enough that it doesn't melt due to the ASI flame temp, but we do want to test whether or not the ASI plume would melt the pintle if the valves failed to open for whatever reason. This could be a major problem, as if we have a failed ignition during a hot fire attempt where the ASI fires but the throttle valves don't open, we may not know whether the pintle melted or not. We have an extra pintle tip that we'll try to test this on ASAP.