>>13446688Starship
Theoretical payload: 100-150 tons
Theoretical dry mass of vehicle’s body: 120 tons
Theoretical dry mass of body+payload: 220-270 tons
Theoretical propellant mass: 1200 tons
Theoretical wet mass without payload: 1320 tons
Theoretical wet mass with payload: 1420-1470 tons
ISP of 380 with vacuum raptors
Theoretical delta/v with no payload: 8935
With payload: 6949-6314
Let’s imagine a comparable nuclear-thermal vehicle, and assume NERVA’s 900 ISP since we’re talking about a much larger scale vehicle. Also, let’s assume 20% heavier propellant tanks, since we’re using hydrogen, and even assume that the vehicle uses a single solid-core nuclear rocket which weighs 50 tons.
Raptors supposedly weigh 1.5 tons, so out of Starship’s 120 ton dry mass, the nine raptors should be 13.5 tons out of that, so the rest is the tanks and stuff. So Starship’s fuel tanks weigh, let’s say, 107 tons. If the tanks were 20% heavier, they’d be about 130 tons. So, we’ve got 130 tons of fuel tank combined with 50 tons of thruster for 180 tons dry mass total.
Hypothetical Nukeship
Payload 100-150 tons
Dry mass of vehicle’s body: 180 tons
Dry mass of vehicle+payload: 280-330
Propellant mass: 1200 tons
Wet mass mass with no payload: 1380
Wet mass with payload: 1480-1530
ISP of 900 with imagined 50 ton solid-core NTR
Theoretical delta/v with no payload: 17977. THAT’S A LOT
Theoretical delta/v with payload: 14695-13538
So a nuclear version of Starship has way better delta/v. You can drop the total mass to 800 tons, keep the dry mass of 330 tons, and still get 7815 delta/v.
