Hey, Yet another propeller question on this board. I have done my research, both here & on google, but I cannot seem to find an answer. Lets say I have a motor on wich I mount a propeller. This motor is static (not moving like on a flying airplane), so say its a small ventilator standing on my desk. What I want to know is the volume flow of air its generating at a certain motor rpm. This is what I do: Prop pitch = 6" Prop dia. = 9" Motor rpm = 2000rpm For 1 rotation, the prop moves the air 6" For 2000 rotations, this means 12000". So the theoretical airflow speed would be 1000ft/min. The disk area works out to 0,44 square foot. So this would mean a volume flow of 440 CFM Now my question; in how far is this value representative for the real flow? Does there exist a coefficient which takes this into account? If someone could tell me a rough value this would also be good for giving me an idea..