[Spaceships] Can't find the right propulsion system

AlexanderHowl · 08-09-2020, 06:27 PM

Well, destructive potential is a related to thrust and delta-v. Doubling thrust usually means doubling mass flow or doubling exhaust velocity. Increasing mass flow will decrease delta-v proportionally to the increase in thrust while increasing exhaust velocity will increase delta-v proportionally to the increase in thrust. Energy is proportional to the square of exhaust increase.

For example, compare the TL9 HEDM rocket (2g/0.5 mps) to the TL9 fission thermal rocket (0.5g/0.45 mps). The former possesses ~2x the exhaust velocity, burns twice as much reaction mass per second, so it is putting out ~8x the energy of latter. While a TL9+ HEDM rocket has exhaust with a temperature of over 26,000 K, the fission rocket is only running at around 6,500 K. While dangerous to unprotected systems, a TL9+ fission thermal rocket is much safer than the TL9 HEDM rocket, dealing ~1/3 as much damage to anything caught in its exhaust flow.

08-09-2020, 06:27 PM	#19
AlexanderHowl Join Date: Feb 2016	Re: [Spaceships] Can't find the right propulsion system Well, destructive potential is a related to thrust and delta-v. Doubling thrust usually means doubling mass flow or doubling exhaust velocity. Increasing mass flow will decrease delta-v proportionally to the increase in thrust while increasing exhaust velocity will increase delta-v proportionally to the increase in thrust. Energy is proportional to the square of exhaust increase. For example, compare the TL9 HEDM rocket (2g/0.5 mps) to the TL9 fission thermal rocket (0.5g/0.45 mps). The former possesses ~2x the exhaust velocity, burns twice as much reaction mass per second, so it is putting out ~8x the energy of latter. While a TL9+ HEDM rocket has exhaust with a temperature of over 26,000 K, the fission rocket is only running at around 6,500 K. While dangerous to unprotected systems, a TL9+ fission thermal rocket is much safer than the TL9 HEDM rocket, dealing ~1/3 as much damage to anything caught in its exhaust flow.