How calculate propeller efficiency if I know propeller trust?
How calculate propeller efficiency if I know propeller trust ant motor power and motor efficienty?

Re: How calculate propeller efficiency if I know propeller trust?
convert thrust to watts (or any standardized unit of energy), motor output power is motor input power times efficiency, convert to the same standardized unit, Then thrust power divided by motor output power, and you have your propeller efficiency

Re: How calculate propeller efficiency if I know propeller trust?
You cant covert thrust to watts. Thrust is not power.

Re: How calculate propeller efficiency if I know propeller trust?
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Side: It's spelled convert. 
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Thrust is power and it is expressed as either Jules / Second, horsepower, Footpounds / Second, or of course Watts. all of these are easily convertible. 
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Re: How calculate propeller efficiency if I know propeller trust?
You need a speed to convert thrust to a power.

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To answer the OP you need to know the aircraft speed to calculate the efficiency: [tex]\eta_p = \frac{T*u}{P_{shaft}}[/tex] where: [tex]\eta_p[/tex] = propeller efficiency [tex]T[/tex] = thrust [tex]u[/tex] = aircraft speed [tex]P_{shaft}[/tex] = shaft horsepower provided by the engine to the propeller 
Re: How calculate propeller efficiency if I know propeller trust?
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So to correct, I assumed that by "I have thrust of the propeller" he meant, I have the thrust power, and it was expressed as such, other wise to calculate the efficiency we also need a speed giving us Nm/s a.k.a. Watts. Seeing as he is from Europe, has broken English, and didn't provide an air speed or say he was given that variable, I think my first assumption is probably correct. None the less I shouldn't have repeated his mistake and called it "thrust" instead of "thrust power" If it was expressed as a force than Great, it better have a speed along with it... well or a crazy slew of other variables so that a theoretical air speed can be calculated, fortunately due to the fact that we have "power in" we would not need to calculate the theoretical max power assuming no drag. vissarion.eu we really need more info. what are the variables (at least as units) that you were provided. 
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Re: How calculate propeller efficiency if I know propeller trust?
No, sorry, that's wrong too. A plane with no time isn't getting anywhere, even if it has speed!

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How is your equation not about plane efficiency it is using aircraft speed what if the propeller he is talking about is in a fan, or say a pump.....[edited] 
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Anyway, it only takes a relatively slight modification of that equation to change it to describe a desk fan. 
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(2 kg * 30 m/s) / 1 HP = 60 procents? 
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http://img21.imageshack.us/img21/5701/orast.png Then air created by propeller push plane to opposite direction than fly plane... 
Re: How calculate propeller efficiency if I know propeller trust?
You have way, way, too many significant digits.
1 HP = 745.7W Also, why did you use metric units, and then throw in HP? The denominator should be in watts. Side: It's spelled percent. (No o, or s) 
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