namelessfly wrote:You would not use brass for a rocket nozzle because it could not tolerate prolonged heat.
You would not use a thin disc because you cant form a proper expansion nozzle.
The angled slots rather than a single orifice are also problematic to machine.
This is the breach plate for some type of recoiless, rocket artillery. The brass need endure only brief heat while the projectile clears the barrel. The angled slots disperse the exhaust plume. Using brass rather than iron or steel enables sealing a breEch.
Reason the Temple would use brass is that one can cast it and the technology is well developed for plumbing fixtures. The Temple knows nothing about converging-diverging nozzles so a hole is the place to start. The propellant is black powder with a burn time of less than 2-3 seconds so melting may not be a problem. The Type 4 rocket has a range of 2400 meters with a muzzle velocity of 175 m/sec. Assuming a modern propellant with a ISP of 200sec the black power version with a ISP of 80 is going to proved 40% of the energy and a muzzle velocity of 110 m/sec. Assuming vacuumed dynamics the flight time will be 15.5 second and a maximum range of 1700 meters. Minimum range assuming a 75 deg angle is going to be 600 meters.
RFC put this snippet out there and I assume he is using it for a sanity check not that I have all that much sanity.