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Spacecraft
YAGS SciFi is all about spacecraft and travel between worlds, so having a system for defining spacecraft is important.
The statistics used are simplified from real world values to make the maths of designing craft easier. Mostly, this involves including all the constants in the basic statistics.
Definitions
Mass: Total size of the vehicle, in displacement tonnes. Each dt is 14m³ (one tonne of liquid hydrogen), and is assumed to have an actual mass of 1 tonne.
Thrust: How powerful a drive is, per displacement tonne. The higher this is, the faster a spacecraft can accelerate. This is based on Newtons of force produced by the drive, multiplied by a magic number.
Impulse: How efficient a drive is. The higher this is, a spacecraft can accelerate for longer. This is based on the specific impulse (seconds) of the drive, multiplied by a magic number.
The Total Thrust is the thrust of the engines times their total mass.
The Acceleration is the Total Thrust divided by the Ship Mass, in m/s².
| Engine | Mass (dt) | Thrust (kN) | SI (s) | Thrust | Impulse | Density |
|---|---|---|---|---|---|---|
| F-1 (LOX/RP1) | 5 | 7,770 | 260 | 2.6 | 14 | |
| J-2 (LOH) | 1 | 1,000 | 421 | 4.2 | 2 | |
| Raptor (LOX/RP1) | 1 | 2,400 | 380 | 3.8 | 14 | |
| Merlin (Methane) | 1 | 981 | 311 | 3.1 | 10 | |
| Nerva (H) | 2 | 246 | 841 | 8.4 | 1 |
Total Wet Mass is equal to the ship Mass, plus the mass of fuel times its density.