Re: LPP Postal Challenge

From: <dgbj_at_aol.com>
Date: Fri, 23 Mar 2007 19:38:41 EDT

"This has been an interesting discussion & I am sure it will continue to be.
But, I hope you two don't actually think this will be a meaningful
"experiment". There will be way too many variables to attribute the victory
to any one
thing.

Gary Hodson"
 
I agree, and if I could figure out what conventional practice was, I would
fly it with the same plane for comparison. When you ask experts for advice,
you get contradictory results. There are so many variables, some pointing one
way, some the other, that unless you actually measure everything, you can't
tell what is an improvement. Perhaps I could start with the common
assumptions and derive a corresponding best practice guideline. That could
demonstrate different outcomes for different practices. Another approach is to compare
nondimensional duration coefficients for each aircraft; how much duration
for weight and unit of energy carried, for example.
 
I have looked at the AMA LPP specification and can see that I am going to
run into trouble with the length of the motor. This is a much lighter plane
with a much bigger prop, turning much more slowly and with only a slightly
longer hook distance. This tells me that I am going to need a much longer motor.
 I would consider a geared prop for this plane, except that it is
prohibited. Braiding the motor comes to mind, with the compromises that entails. That
means torque tests on various braided motors to find the best fit. I will
do the best I can within the limitations specified.
 
I've gotta get some work done in the garden while the sun shines, so I will
respond to other comments later.
 
I am going to ask the CD for a clarification of the flaring prop rule for
purposes of this postal. I can go either way.
 
Gary Hinze



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Received on Fri Mar 23 2007 - 16:38:56 CET

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