Planetary Lander Ship Class
Overview
Small, lightweight lander designed for Luna surface operations. Descends from medium orbit to the surface with controlled hover/descent, lands on visual landing legs, and returns to orbit after surface refueling.
Key: planetary_lander
Physical Properties
| Property | Value | Notes |
|---|---|---|
| Dry mass | 3,000 kg | Lightest ship class |
| Fuel capacity | 2,000 kg | Sufficient for orbit-to-surface + ascent after refuel |
| Total mass (full) | 5,000 kg |
Main Engine (Bipropellant Thruster Array)
Four gimballed descent engines arranged symmetrically around the base, providing throttleable thrust for hover and controlled descent.
| Property | Value | Notes |
|---|---|---|
| Thrust | 50 kN | 4 × 12.5 kN engines |
| Specific impulse | 3,000 s | Chemical-class efficiency, high thrust priority |
| Fuel consumption | 1.70 kg/s | At full throttle |
Fuel consumption formula:
fuel_rate = thrust / (isp × g₀)
= 50,000 / (3,000 × 9.80665)
= 1.70 kg/s
Performance (Full Fuel)
| Metric | Value |
|---|---|
| Acceleration (full) | 10.0 m/s² |
| Acceleration (empty) | 16.7 m/s² |
| Lunar TWR (full, surface) | 6.2 |
| Lunar TWR (empty, surface) | 10.3 |
| Delta-v (total) | ~15,100 m/s |
| Full-throttle burn time | 1,176 s (~20 min) |
Delta-v formula:
Δv = isp × g₀ × ln(m_wet / m_dry)
= 3,000 × 9.80665 × ln(5,000 / 3,000)
= 29,420 × 0.5108
≈ 15,100 m/s
Lunar surface gravity: 1.625 m/s²
Attitude Control
| System | Specification |
|---|---|
| Reaction wheels | Max torque: 200 N·m per axis |
| Reaction wheel capacity | 2,000 N·m·s angular momentum per axis |
| RCS thrusters | Max torque: 5,000 N·m per axis |
| RCS total thrust | 5 kN (distributed across thruster pairs) |
| RCS fuel | Shared with main propellant |
| RCS specific impulse | 3,000 s |
| RCS fuel consumption | 0.17 kg/s at full thrust |
| ω_n | 0.5 rad/s (matches fast frigate — small inertia makes it responsive) |
RCS fuel consumption formula (at full thrust):
rcs_fuel_rate_max = rcs_thrust / (rcs_isp × g₀)
= 5,000 / (3,000 × 9.80665)
= 0.17 kg/s
RCS Translation
| Property | Value | Notes |
|---|---|---|
| RCS translation thrust | 2.5 kN per axis | Half of 5 kN total RCS thrust |
| RCS translation fuel rate | 0.085 kg/s | At full thrust on one axis |
| RCS specific impulse | 3,000 s | Same as rotational RCS |
Combined Fuel Consumption
| Scenario | Fuel Rate |
|---|---|
| Full thrust, no rotation | 1.70 kg/s |
| No thrust, full rotational RCS | 0.10 kg/s |
| Full thrust + full rotational RCS | 1.87 kg/s |
| No thrust, full translation 1 axis | 0.085 kg/s |
| Full thrust + full rot RCS + full trans 3 axes | 2.13 kg/s (maximum) |
Inertia Tensor
Compact upright body — symmetric about Z axis (thrust axis), wider at base due to landing legs.
Dry (empty) inertia tensor:
I_dry = | 6,000 0 0 | kg·m²
| 0 6,000 0 |
| 0 0 3,000 |
Full (with fuel) inertia tensor:
I_full = | 10,000 0 0 | kg·m²
| 0 10,000 0 |
| 0 0 5,000 |
Atmospheric Drag
| Property | Value |
|---|---|
| Drag coefficient | 2.0 |
| Drag area | 8 m² |
Dimensions
| Property | Value |
|---|---|
| Height | 8 m |
| Width (legs deployed) | 6 m |
| Width (body) | 4 m |
Visual Design
Upright lander with clear vertical orientation:
- Descent stage: Wide octagonal base with 4 landing legs extending outward/downward
- Ascent stage: Upper cylindrical crew cabin with viewports
- Engines: 4 engine bells visible at base between landing legs
- Landing legs: Splayed outward with foot pads, clearly indicating “down” direction
- Forward (+Z): Points UP when landed (thrust axis = up)
- RCS pods: 8 pods in 2 rings (upper and lower)
RCS Pod Positions (Body Frame)
"rcs_pods": [
[2, 2, 3],
[-2, 2, 3],
[2, -2, 3],
[-2, -2, 3],
[2, 2, -2],
[-2, 2, -2],
[2, -2, -2],
[-2, -2, -2]
]
Spawn Altitude
Uses existing spawn altitude table. Spawns at Luna: 100 km orbit.