Message-ID: <3B840B92.F19B5E5B@home.com>
Date: Wed, 22 Aug 2001 12:44:18 -0700
From: Bob <rbelshe@home.com>
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To: lancair.list@olsusa.com
Subject: Re: LNC2 Fixed Pitch Propeller Survey
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Reply-To: lancair.list@olsusa.com

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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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