Reaction Control Thruster Calculator
Size reaction control system thrusters based on spacecraft inertia, slew requirements, and propellant budget.
Inputs
lb
ft
°/s
°
s
Results
Required Thruster Force
0.93 N
Total Propellant (1000 maneuvers)
25.89 kg
≈ 7 gallons of milk
Propellant per Maneuver0.03 kg
Recommended Thrusters8
How to Use This Calculator
- Enter spacecraft mass (kg) and the moment arm distance (m) from CG to thruster.
- Set the required slew rate (deg/s) and total slew angle (degrees) for the maneuver.
- Enter thruster specific impulse (Isp in sec).
- Review required thruster force (N), propellant consumed per maneuver (g), and recommended thruster count.
- Use total propellant mass for 1,000 maneuvers to verify RCS propellant budget adequacy.
How the result changes with Required Slew Rate
| Required Slew Rate | Required Thruster Force | Total Propellant (1000 maneuvers) |
|---|---|---|
| 1.01 | 0.95 N | 26.15 kg |
| 3.51 | 11.47 N | 90.86 kg |
| 6.5 | 39.33 N | 168.27 kg |
| 9 | 75.4 N | 232.98 kg |
What each input means
- Spacecraft Mass
- Total mass of the spacecraft for moment of inertia estimation.
- Thruster Moment Arm
- Distance from the spacecraft center of mass to the thruster location.
- Required Slew Rate
- Maximum angular rate the spacecraft must achieve during a maneuver.
- Slew Angle
- Total angular displacement for a typical attitude maneuver.
- Thruster Specific Impulse
- Specific impulse of the RCS thrusters. Hydrazine mono-prop: ~220s, biprop: ~290s.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersSpacecraft Mass = 2000, Thruster Moment Arm = 2, Required Slew Rate = 1, Slew Angle = 30 = 5 input(s) provided
- Calculate Required Thruster ForceRequired Thruster Force0.931 = 0.931
- Calculate Total PropellantTotal Propellant25.89 = 25.89
- Calculate Propellant per ManeuverPropellant per Maneuver0.0259 = 0.0259
- Calculate Recommended ThrustersRecommended Thrusters8 = 8
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