Propeller Static & Dynamic Thrust Calculation
By: Gabriel Staples
Written: 16 July 2013
Last Updated: 13 April 2014
--made a minor correction to an example, & added a plot
--added many more statistical details in order to better explain the accuracy of the equation.
--added Simplified form of eqn. too. - 15 Oct. 2013
--added links to Part 2 of this article - 13 Apr. 2014
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DOWNLOAD MY EXCEL SPREADSHEET THRUST CALCULATOR HERE (click link, then go to File --> Download)I have been interested in propellers for a very long time. I've also been interested in how they produce thrust, and how forward velocity affects that thrust. Therefore, I've done a lot of thinking about it, and put a lot of time into understanding them better. Here is an equation that I came up with to quantify the thrust produced by propellers. I wanted it to be a simple approximation, with a minimal number of inputs. Therefore, it uses only the propeller's pitch and diameter (from the numbers on the front of the prop), and the RPMs at which the prop is spinning (this can be measured from a basic optical tachometer such as the one shown in the picture to the left). That's it!
Figure 1: a preview of what is to come - Static Thrust (left) & Dynamic Thrust (right).
Here is the equation.
The expanded form is shown to help you see where some of the numbers come from. The simplified form is shown to help you put the equation into a calculator or Excel spreadsheet easier.