How Does Propeller Diameter Affect Thrust?

How Does Propeller Diameter Affect Thrust?

The team at Premier Aerodynamics put this question to the test using a Tyto Robotics Series 1585 thrust stand, comparing several propellers ranging from 6 to 10 inches in diameter.

While theory predicts that larger propellers should produce more thrust, different models disagree on exactly how much. To see what happens in practice, they measured thrust and efficiency across multiple propeller sizes.

The results were clear:

• Increasing propeller diameter from 6 to 7 inches increased thrust by 49%
• Increasing propeller diameter from 7 to 8 inches increased thrust by 53%
• Increasing propeller diameter from 7 to 10 inches increased thrust by 50%
  

For the smaller propeller pairs, the measured thrust increases fell between the predictions ofactuator disc theory and blade element theory.

Interestingly, the larger propellers produced less thrust than expected. The team noted that motor and battery limitations likely prevented the larger prop from reaching its theoretical performance.

Efficiency was also fairly consistent across most of the tested propellers, with the 10-inch prop showing a small improvement over the 7-inch prop.

This experiment shows how real measurements with a Tyto thrust stand can help validate theoretical predictions and reveal the factors that influence propeller performance.