Talk:Momentum theory

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Aviation: Rotorcraft

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Questions

Someone needs to add an example, including all the units - as it stands, this formula is unusable to us.

Does the density of the air, ρ, change when the rotors start spinning, or is ρ the density of the air (without the rotors)? Also, is the area the area of the entire circle (or "disk"?) encompassed by the spinning rotory wings, or is it the area of the actual rotor wings? BriEnBest (talk) 23:21, 24 January 2012 (UTC)[reply]

@BriEnBest - area is the swept area of the disc. Good question about the density! I'd guess is is without the effect of the rotors though, otherwise it's a constant in a formula which depends on its own formula, which would not make sense.

This article is complete fraud, genuine author of this formula is Andrija Radovic and the genuine derivation is available on http://www.andrijar.com/thrusters/index.html. This is flagrant violation of the true author’s copyright without any solid proof that Rankin has ever derived this formula. — Preceding unsigned comment added by 85.222.167.187 (talk) 23:00, 10 July 2013 (UTC)[reply]