Armadillo Aerospace News: Miscellanious, Cabin temperature tests, Open catalyst tests

We performed some very interesting tests, running engines with the nozzle removed so we could directly watch the catalyst surface during operation.
We tested the 4” thick ceramic catalyst on the new spreading plate engine first. In tests with the propane preheat, we still needed 10 20 mesh screens between the spreading plate and the catalyst block to avoid any noticeable hot spots as the catalyst heated. This was a bit of a surprise, because that was the same number needed on the previous spreading plate that had only a quarter the hole count, with holes four times as big.
We used a small cavitating venturi to limit the flow to about 140 g/s, since the engine was obviously not going to have any back pressure.
We wound up with a richer than usual propellant mixture, because I didn’t bother pumping more peroxide out to make it perfect, but there was a HUGE amount of flames coming from the catalyst pack on our tests, especially considering that we were only flowing the equivalent of about 50 lbf thrust worth of peroxide if there had been a nozzle on. I’m curious how much of the difference is due to the richness versus the fact that nozzle exhaust is a lot cooler than catalyst exhaust. Read More