# Can anyone confirm this equation? Prop. Thrust

nickpark83
can anyone confirm this equation?? Prop. Thrust

there are many websites that calculate propeller Thrust, and they never show any formulas for it... and i somehow manage to find the formula from NASA website, but when i compare the result with each other, i get totally different numbers...

Thrust = (density)(pi)(radius of prop)^2(2)[(2Vk(RPM) + k(RPM^2)]

where k is coefficient of efficiency of prop.
V = speed, V=0 when static

if i just work with the units only, i get the force unit no problem, but the result is way off from the number from websites..
anyone know which one is correct?

You might want to try this one:

$$T=P_{io}^{2/3}(2 \rho A)^{1/3}$$ where

$$T$$ = thrust
$$P_{io}$$ = (induced) power of the engine
$$\rho$$ = density
$$A$$ = propeller area

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