Thrust to Weight Ratio Calculator

By Rahul Dhari
Last updated: Jul 20, 2021

This thrust to weight ratio calculator assists engineers in estimating the thrust to weight ratio of a vehicle. The thrust to weight ratio is crucial data when it comes to designing an aircraft, be it the smaller remote-controlled (RC) drone or a full-fledged passenger jet. For instance, the thrust to weight ratio parameter will tell us about the maneuverability of an aircraft. Read on to understanding how to calculate thrust to weight ratio of different aircraft.

Thrust to weight ratio

The thrust to weight ratio is defined as the ratio of the thrust available to the mass of the aircraft. It is a dimensionless quantity. In order to obtain the thrust to weight ratio, both values should be in appropriate units. For instance, if the thrust is in Newtons (N), and the weight is in kilograms (kg), the weight must be converted to mass to obtain the right answer. However, if the thrust is in pounds-force (lbf) and weight is in pounds (lb), the formula will give the correct answer. Mathematically, the ratio can be given by the equation:

Thrust to weight ratio = Thrust available / Weight

The thrust to weight ratio can have multiple variations because of the different types of thrusts, and weights. For instance:

  • Thrust — Could either be available value during normal engine conditions, maximum available value or in the afterburner conditions, where the thrust available is maximum.
  • Weight — There are different types of aircraft weights such as gross weight, the maximum take-off weight, weight at different fuel levels, say 50% or 100%, and empty weight.

The thrust to weight ratio can alternatively be defined as the inverse of the lift to drag ratio in cruise flight conditions. Mathematically, this is given as:

Thrust to weight ratio = 1 / (Lift / Drag)cruise

How to calculate thrust to weight ratio?

To calculate thrust to weight ratio:

  1. Enter the appropriate thrust value.
  2. Insert the weight of the aircraft.
  3. The calculator will return the thrust to weight ratio.

Note: You can use the advanced mode of this calculator to directly pick the names of the aircraft or engines to find out their thrust to weight ratio parameter.

Example: Using the thrust to weight ratio calculator

There are two modes of this calculator — single mode or compare mode, if you want to calculate the thrust to weight ratio of an aircraft, you can pick single mode. If you wish to compare the thrust to weight parameter of two different aircraft, you can pick the compare mode.

Using the single mode: Estimate the thrust to weight ratio of an aircraft weighing 10,000 kg and having 2 engines capable of producing a thrust of 40 kN each.

  1. First of all, since the aircraft has two engines, we find the total thrust available, such that:
Thrust available = 2 * 40 = 80 kN
  1. Enter the thrust available in the calculator as 80 kN.
  2. Enter the weight of the aircraft as 10000 kg.
  3. The thrust to weight ratio calculator will now return the value of thrust to weight ratio as 0.82.

Using the compare mode: This mode is used to compare two different configurations. Say, for example, you want to compare the thrust to weight ratio of an F-16 Block 52 and HAL Tejas aircraft.

  1. Set the mode to compare and advanced to see the list of different aircraft and engines.
  2. Select F-16 Block 52 from the list as Aircraft 1.
  3. Select HAL LCA Tejas Mk1 from the list as Aircraft 2.
  4. The calculator will now calculate the thrust to weight ratio and compare them to tell you which configuration has a higher thrust to weight ratio.

Similarly, if you have your own data, you can calculate the thrust to weight ratio of commercial aircraft or drones too.

FAQ

What is the thrust to weight ratio?

Thrust to weight ratio is defined as the ratio of thrust available or maximum thrust to the weight of the aircraft. The weight could either be gross weight, the maximum take-off weight, or at different fuel levels.

What is the thrust to weight ratio of an F-16?

The F 16's thrust to weight ratio, considering its gross weight and thrust produced by the engines with afterburner is equal to 29,560 lbf / 26,500 lb, i.e., 1.11. The result may vary if you consider different types of weight or thrust.

What is the thrust to weight ratio of HAL Tejas?

The thrust to weight ratio of HAL Tejas Mk1, considering its gross weight and thrust produced by the engines with afterburner is equal to 20,200 lbf / 26,500 lb, i.e., 0.94. The result may vary if you consider different types of weight or thrust.

What is the thrust to weight ratio of JF-17 Thunder?

The thrust to weight ratio of JF-17 block 2, considering its weight at 50% fuel and thrust produced by the engines with afterburner is equal to 19,000 lbf / 20,000 lb, i.e., 0.95. The result may vary if you consider different types of weight or thrust.

Rahul Dhari
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