Calculating thrust from CFM?
1) a radius of 60mm (120mm fan)
2) a CFM of 252.
Basically, I was using this formula:
CFM = Cubic Feet per Minute = Volumetric Flow Rate
Mass Flow Rate = (Density) x (Volumetric Flow Rate)
Newton’s Second Law of Motion: Force = (Mass) x (Acceleration), or F = ma
F = ma = (Mass Flow Rate) x (Velocity), given a constant flow velocity
(i.e., constant propeller speed and pitch angle).
Velocity = (Volumetric Flow Rate) / (Area), where Area = (Pi) x (r^2), the
length of a propeller blade is a good approximation for the radius, r.
Thrust = (Density) x (CFM^2) / ((Pi) x (r^2))
I was alright until they brought density into it. I take it they mean the density of the air?
Anyways, could someone tell me how much weight that fan could lift, and how they got there?