TWR Calculator
Calculate the Thrust-to-Weight Ratio (TWR) for aircraft or rockets. TWR determines whether a vehicle can achieve vertical flight and provides insight into acceleration capabilities.
Thrust-to-Weight Ratio
TWR = T / W = T / (m × g)
Where T is thrust, W is weight, m is mass, and g is gravity
Where:
- TWRThrust-to-Weight Ratio (dimensionless)
- TThrust force produced by the engine
- WWeight of the vehicle (mass × gravity)
- mMass of the vehicle
- gGravitational acceleration (9.80665 m/s² on Earth)
TWR Guidelines:
- TWR > 1: Vehicle can hover and accelerate vertically (rockets, helicopters)
- TWR = 1: Vehicle can hover but cannot accelerate vertically
- TWR < 1: Vehicle requires horizontal motion for lift (airplanes)
- Rockets typically need TWR > 1.2 at liftoff to overcome gravity and drag
- Aircraft typically have TWR < 0.5, relying on aerodynamic lift
- Higher TWR provides better acceleration but requires more fuel
Typical TWR Values:
- Commercial Aircraft: 0.2 - 0.4
- Military Aircraft: 0.5 - 1.0
- Helicopters: 1.1 - 1.5
- Rockets (Liftoff): 1.2 - 2.0
- Space Shuttle: ~1.5
- Saturn V: ~1.2
Thrust-to-Weight Ratio Theory & Notes
- The Thrust-to-Weight Ratio (TWR) is a dimensionless parameter that compares the thrust force produced by an engine to the weight of the vehicle.
- It is defined as the ratio of thrust (
T) to weight (W):TWR = T / W = T / (m × g) - Where
mis the mass of the vehicle andgis the gravitational acceleration (9.80665 m/s² on Earth). - TWR > 1: The vehicle can accelerate vertically upward and hover in place.
- TWR = 1: The vehicle can hover but cannot accelerate vertically upward.
- TWR < 1: The vehicle cannot hover or take off vertically; it requires horizontal motion for lift (like airplanes).
- For rockets, TWR typically ranges from 1.2 to 2.0 at liftoff, allowing for acceleration against gravity and atmospheric drag.
- For aircraft, TWR is usually much less than 1, as they rely on aerodynamic lift rather than thrust for vertical support.
- Higher TWR values provide better acceleration and maneuverability but require more powerful engines and more fuel consumption.
- The TWR changes during flight as fuel is consumed and mass decreases, often improving throughout the flight for rockets.
Open Source & Transparent
This tool is open source and the underlying logic is fully transparent. You can view the source code, understand the calculations, and even contribute improvements to make it better for everyone.
View Source Code