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<< Lancair Builders' Mail List >>
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Gosh Jack, I wasn't making any claims at all. Certainly did not intend
to tread on the "common cause of greater knowledge". All I have is
piece of paper from Lycon that says the HP at 2750 rpm, 29 inches, using
a Lycon exhaust, air inlet and test club, is 185.877 and when corrected
to a 60 degree day is 196.107. The (new) parallel-valve cylinders were
ported and flow balanced and Lycon 9.5:1 pistons installed. It has a
Airflow Performance fuel injection system. The engine runs like a top,
and whether it is 175HP or 195HP, I am very pleased with it.
As for my data, here is what I said:
> Data is from linear trend lines fitted to a large number of data points
> taken on different days at different altitudes and temperatures.
I made no attempt to determine the power being applied to the prop,
rather am simply comparing the speed achieved with different props
in the range of RPMs where I normally operate.
What I did is put a bunch of raw data points (IAS, RPM, Altitude) into a
spreadsheet, calculate TAS, and make a graph. Then I looked at the trend
line (that's what Excel calls it, I would say its a least squares
straight line fit) and read the TAS shown on the graph at 2700 rpm. I
never said all 3 props max out at 2700, in fact they will all go
faster, I don't know how much because I don't intentionally
run the engine above 2700.
I calculated TAS from a simple formula which uses ONLY IAS and altitude
and is at best good to a few percent. This is not "lab quality" data,
but I think it does average out the errors and makes a valid comparison
between different propellers on a real Lancair, under real flight
conditions.
I hope others will contribute to this thread. Judging from the speed
numbers, the Performance prop was a better match to my airplane.
The Felix prop has more pull at low RPM, (I have to relly mash the
brakes during runup) and it feels smoother.
The Warnke 2 blade has too little ground clearance for the 235, but it
climbed better than either of the other two. I decided to try the
Felix prop because the price/delivery time was better.
Bob Belshe
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LML website: http://www.olsusa.com/mkaye/maillist.html
LML Builders' Bookstore: http://www.buildersbooks.com/lancair
Please send your photos and drawings to marvkaye@olsusa.com.
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