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Type: Posts; User: David J. Gall

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    Of course, we all recognize that you meant "a...

    Of course, we all recognize that you meant "a finer pitch in climb and a coarser pitch in cruise." Thanks for the great link!
  2. I read somewhere that composite aircraft...

    I read somewhere that composite aircraft engineering generally calls for a minimum safety factor of 2.0.
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    Bob, I think you misunderstood my post. ...

    Bob,

    I think you misunderstood my post.

    Good luck with your Dragonfly.
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    Bob, First of all, you don't say how you...

    Bob,

    First of all, you don't say how you arrived at your effficiency numbers. J = V / (n*d) is only one of the formulae needed for propeller calculations. Further, the test for efficiency is not...
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    Vince, you're looking at the wrong curve. Don't...

    Vince, you're looking at the wrong curve. Don't look at the efficiency curve, look at the power absorption curve. It goes as the cube of the RPM with minor variations for airspeed and propeller...
  6. Thanks for the kind words, Howard. I applaud...

    Thanks for the kind words, Howard. I applaud your real-world efforts to measure and quantify. Please carry on!
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    steveinindy, in answer to your question about...

    steveinindy, in answer to your question about composite spec'ing: I found Jim Marske's excellent but terse Composite Design Manual (http://marskeaircraft.com/) to be very helpful, and Andy Marshall's...
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    ...and the 1.5 safety factor only applies to...

    ...and the 1.5 safety factor only applies to metals and wood; composites need to go to 2X, various parts of the airplane even more.... See Neal Willford's article on stress analysis and safety...
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    Yes, sadly, NASAD is long defunct.

    Yes, sadly, NASAD is long defunct.
  10. Howard, Nice work! Regarding your horsepower...

    Howard,

    Nice work! Regarding your horsepower measurement issues, may I recommend Arthur P. Fraas' "Aircraft Power Plants" (1943) as an excellent reference.

    See you at Oshkosh next year,
    ...
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    Static propeller balancing without finding the...

    Static propeller balancing without finding the center of rotation seems like a waste of time to me. Just "hanging" the prop on a piece of drill rod presupposes that the center bore of the prop is...
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