Comments by "ke6gwf - Ben Blackburn" (@ke6gwf) on "" video.

  1.  @bobroberts2371  burst discs are common in high precision applications, from rockets to particle accelerators to potato cannons lol They can be designed to not shed any material, and it's very easy to put a in line filter just downstream if needed to catch any debris from it. But considering that it would first go into a large tank, then through high flow plumbing and out a rocket engine, no pumps or turbines along the way, it would have to be a pretty large piece to cause a problem, and that would be throughly tested first.
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  2.    be better just to design the system so that the NTO doesn't go where it isn't supposed to be!
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  3. How would burst discs function you ask? Glad you asked! ;) Burst discs are a thin metal plate of a precision calibrated thickness and usually scored or shaped to hold pressure up to their rating, and then burst instantly when the pressure reaches their design rating. By putting them on the pressurization ports on the low pressure fuel and oxidizer tanks, they would prevent any fuel from getting into the helium plumbing. Then when the SD thrusters were fired, the helium system valves would be opened and instantly burst the discs allowing the tanks to be pressurized. The only times this would happen would be in the event of an in flight abort, and at that point the helium pressure would never be turned off until it was on the ground, so no fuel could get into the helium lines. If they ever do propulsive landings, sane idea, the discs would be burst just before landing, and it would stay pressurized until it was on the ground. All the other valves would remain the same to turn the engines on and off etc, this is just the shrink wrap over the package to keep it sterile until first use so to speak. For long term redesign, I would either move the helium control valves directly to the end of the fuel and oxidizer tanks totally preventing the situation, or add a second set of valves directly at the tanks that actuate at the same time as the existing helium valves. This would preserve the ability to ground test, while preventing the problem of fuel leaking back into the system.
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  4. If I were doing it, I would put the burst disc at the pressurization port on the tank, so that no fuel can enter the plumbing at all while the system is in standby mode. Then if the system is needed, open the helium valves, the discs burst, and the engines fire. The only times the disc would be burst is on an actual abort, or propulsive landing, and in either case the helium pressure is going to be maintained until its on the ground a few minutes later. So there would be no problem with relighting them because the rest of the plumbing is the same, and there wouldn't be any chance of leakage past the check valve because the pressure would always higher once the burst disc was breached.
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