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From: "Bill Bradburry" <bbradburry@bellsouth.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
References: <list-6505368@logan.com>
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Subject: Prop and PSRU efficiency
Date: Mon, 7 Oct 2013 13:18:18 -0400
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I have asked this question a couple of times and no one has hazarded a
guess.

How much HP is lost from our engines due to the PSRU?  I have been
interested in determining what the HP output of my engine is and that info
would be needed for that estimation.

They tell me that most props are about 80-85% efficient, so to calculate the
hp, you take the difference between your climb rate and your glide descent
rate at the same airspeed, multiplied by the weight, and then divided by
33000.

Wt * V / 33000 = HP

This would be the prop HP, so to get the prop flange HP, you would divide by
the prop efficiency, between .8 and .85.

To get the engine flywheel HP, you would have to add something for the loss
of the PSRU.

Is anyone willing to take a shot at that number??  Third or forth chance!
:>)

Bill B