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−Table of Contents
Space Drives
Fuel Types
For a typical chemical rocket, the fuel and propellant are the same thing. For Nuclear rockets the fuel and propellant are different things. The fuel powers the reactor, and the propellant is thrown out the back.
LOX / RP1
Density: 14
Impulse: 4.0
Liquid Oxygen and RP-1. Denser and requires less cryogenic cooling than liquid hydrogen.
LOX / Hydrogen
Density: 2
Impulse: 5.2
Liquid Oxygen and Liquid Hydrogen. Very low density but high efficiency without being insanely dangerous. The cryogenic needs complicate things though.
LOX / Methane
Density: 10
Impulse: 4.5
Liquid Hydrogen
Density: 1
Impulse: ~
Generally used as propellant in nuclear or plasma engines.
Real Tech (TL 8)
Real Stats
From: https://youtu.be/D4SaofKCYwo?t=2180
| Engine | J-2 | J-2S | J-2T (250K) | XRS-2200 | RS-2200 | RS-25 | Raptor |
|---|---|---|---|---|---|---|---|
| Type | Bell | Bell | Aerospike/C | Aerospike/L | Aerospike/L | Bell | Bell |
| Fuel | Hydrogen | Hydrogen | Hydrogen | Hydrogen | Hydrogen | Hydrogen | Methane |
| Thrust (sl) | 486kN | – | 731kN | 909kN | 1,917kN | 1,859kN | 1,960kN |
| Thrust (vac) | 1,033kN | 1,138kN | 1,112kN | 1,184kN | 2,201kN | 2,278kN | 2,150kN |
| Isp (sl) | 200s | – | 290s | 339s | 347s | 363s | 330s |
| Isp (vac) | 424s | 436s | 441s | 436s | 455s | 453s | 355s |
| Expansion | 27:1 | 40:1 | 80:1 | 58:1 | 173:1 | 69:1 | 35:1 |
| TWR | 73:1 | 69:1 | 63:1 | 35:1 | 83:1 | 73:1 | 107:1 |
| Dimensions | 3.4h2.1d | 2mh | 4.2h2.4d | 3.1h1.3d | |||
| Weight | 1.8t | 3.5t | 1.5t |
Game Stats
The following drive types are based on real technology, simplified for purposes of the game.
| Engine | Mass (dt) | Thrust/dt | I(sl) | I(vac) | Fuel Type | Density |
|---|---|---|---|---|---|---|
| F-1 | 3 | 2,600 | 2.6 | 3.0 | LOX/RP1 | 14 |
| J-2 | 1 | 1,000 | 1.0 | 4.2 | LOX/LH | 2 |
| RS-25 | 1 | 3870 | 3.7 | 4.5 | LOX/LH | 2 |
| Merlin | ½ | 980 | 2.8 | 3.1 | LOX/RP1 | 14 |
| Raptor | 1 | 2,400 | 3.3 | 3.8 | LOX/CH4 | 10 |
| NERVA | 2 | 250 | - | 8.4 | Hydrogen | 1 |
The Thrust is multiplied by the total mass of the drive. So a single F-1 rocket has a mass of 5, so gives a total thrust of 7,750. 9 Merlin engines have a mass of 4.5, so give a thrust of 4,410.
Fuels
- CH4/O2
- H2/F2
- H1/O2
- H2/O2
- RP-1/O2
- UDMH/NTO
- MMH/NTO
Plausible Future (TL 9)
The “/a” and “/v” engines are variants designed for optimal atmosphere (sea level) and vacuum operation.
The environment is where the engine is actually being used. “/a” engines tend to operate in both environments, though are less suited to vacuum. Most “/v” engines perform self-disassembly at sea level.
Aerospikes work well in both environments.
| Engine | Mass (dt) | Thrust | Impulse | Fuel Type | Density | Environment |
|---|---|---|---|---|---|---|
| Chem-S/a | 1 | 2,500 | 3.5 | Methane | 10 | Atmosphere |
| Chem-S/a | 1 | 2,500 | 3.8 | Methane | 10 | Vacuum |
| Chem-S/v | 3 | 2,750 | 4.2 | Methane | 10 | Vacuum |
| Aerospike | 3 | 1,500 | 3.7 | Methane | 10 | Atmosphere |
| Aerospike | 3 | 1,500 | 4.0 | Methane | 10 | Atmosphere |
| Chem-3 | 3 | 7,500 | 4.0 | Methane | 10 | Vacuum |
| Chem-3X | 3 | 5,000 | 4.2 | Methane | 10 | Vacuum |
| Nuclear-3 | 3 | 500 | 8.0 | Hydrogen | 2 | Vacuum |
Implausible Future (TL 10)
| Engine | Mass (dt) | Thrust | Impulse | Fuel Type | Density | Environment |
|---|---|---|---|---|---|---|
| Chem-1 | 1 | 7,500 | 4.2 | Methane | 10 | Atmosphere |
| Chem-3 | 3 | 7,000 | 4.5 | Methane | 10 | Vacuum |
| Nuclear-3 | 3 | 700 | 12.0 | Hydrogen | 2 | Vacuum |
Far Future (TL 11)
| Engine | Mass (dt) | Thrust/dt | Impulse | Fuel Type | Density | Environment |
|---|---|---|---|---|---|---|
| Nuclear-3 | 3 | 950 | 20.0 | Hydrogen | 2 | Vacuum |