Calculate propeller thrust, air density, cross-sectional area, exit velocity, or aircraft velocity from four inputs in metric or imperial units.
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Propeller Thrust Formula
The following formula is used to calculate a propeller thrust.
F = .5 * p * A * (Ve^2 - Vo^2)
- Where F is the propeller thrust/force (N)
- p is the density of the air (kg/m^3)
- A is the cross-sectional area of the propeller (m^2)
- Ve is the exit velocity of the air (m/s)
- Vo is the velocity of the aircraft (m/s)
To calculate the propeller thrust, multiply the density by the cross-sectional area, then multiply the difference of the squares of the exit velocity and aircraft velocity, then divide by 2.
What is propeller thrust?
Definition:
A propeller thrust is the total amount of force generated by a rotating propeller on an aircraft that causes forward motion.
How to calculate propeller thrust?
Example Problem:
The following example problem outlines the steps and information needed to calculate a propeller thrust.
First, determine the cross-sectional area of the propeller. This is the cross-sectional area from tip to tip of the propeller. For this example, the cross-sectional area is measured to be 3 m^2.
Next, determine the density of the fluid. In this case, we will assume air at standard temperature and pressure. This has a density of 1.225 kg/m^3.
Next, determine the exit velocity of the air moving out of the propeller enclosure. In this example, the exit velocity is 75 m/s.
Next, determine the speed of the aircraft. This aircraft is moving at a speed of 50 m/s.
Finally, calculate the propeller thrust using the formula above:
F = .5 * p * A * (Ve^2 – Vo^2)
F = .5 * 1.225 *3 * (75^2 – 50^2)
F = 5742.1875 N
