Help / KnownX MPT / Propagation
Propulsion and attitude
Thrust from a throttled engine, the propellant it uses, and where the spacecraft points.
Status: Implemented.
Thrust and propellant
thrust = maximum thrust × throttle
mass flow = thrust / (Isp · g₀)The mass of the spacecraft falls as propellant is used, so the same thrust produces more acceleration late in a burn. If the propellant runs out part-way through a step, thrust is reduced in proportion for that step.
| Property | Meaning |
|---|---|
| Maximum thrust | Thrust at full throttle, in newtons |
| Specific impulse (Isp) | Engine efficiency, in seconds |
| Dry mass | Mass without propellant |
| Propellant capacity | Propellant mass when full |
Attitude
Attitude is commanded: the spacecraft turns at the rate asked of it. In a mission sequence an attitude target can be prograde, retrograde, normal, anti-normal, radial out, radial in, or a custom direction.
In the application
- W and S raise and lower the throttle; X cuts it.
- T toggles the engine; holding Space fires it while held.
- Arrow keys pitch and yaw; Q and E roll.
- The Inspector shows thrust, throttle and propellant remaining.
Scope
A vehicle has one engine with a fixed specific impulse. Staging, and attitude dynamics driven by torque and inertia, are not in this release.