<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML xmlns:o = "urn:schemas-microsoft-com:office:office"><HEAD>
<META http-equiv=Content-Type content="text/html; charset=UTF-8">
<META content="MSHTML 6.00.2900.2523" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY id=role_body style="FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY: Arial"
bottomMargin=7 bgColor=#ffffff leftMargin=7 topMargin=7 rightMargin=7>
<DIV>Anyone would have (lengthy) difficulties trying to measure the pitch
distribution without a pitch guage similar to the Prather. The only problem with
the Prather is that it was designed for props of max diameter of 16 ins and with
it you can only measure out to 5.5 ins max ( about 70% of 16 ). I
referred to the pitch distribution as being proprietary however it is there for
anyone to measure. The blade area distribution would also come into play in
determining pitch distribution, and also probably the section
distribution, so I suspect it is more art than science. We can thank
APC for perservering.</DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=Rcmaster199@aol.com
href="mailto:Rcmaster199@aol.com">Rcmaster199@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, October 16, 2004 9:52
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Propeller Pitch gauge
calibration</DIV>
<DIV><BR></DIV><FONT id=role_document face=Arial color=#000000 size=2>
<DIV>
<DIV>Nat, so if someone were to reverse engineer the famous APC prop blade
pitch distribution, one could start by making a bunch of cardboard right
triangles fit under the blade, at, say, 1" intervals, moving out from center.
Then one can determine what the pitch at each station is by simple graphical
means from the triangles, and plot that against radius (stations). I would
hazzard to guess a parabollic distribution.</DIV>
<DIV> </DIV>
<DIV>Of course, if one isn't so inclined, he can always call Tony and buy the
sucker, but what has he learned?? LOL. Tongue planted firmly in cheek.</DIV>
<DIV> </DIV>
<DIV>MattK, pontificating again, but what the hell. BTW isn't that what the
rubber band wielding free flighters do with the props they build from
sticks?</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><FONT style="BACKGROUND-COLOR: transparent" face=Arial color=#000000
size=2>Matt, you are correct. Feel free to help clarify my
comments.
Nat</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid">
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mailto:Rcmaster199@aol.com
href="mailto:Rcmaster199@aol.com">Rcmaster199@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=mailto:discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, October 16, 2004
12:02 AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Propeller Pitch gauge
calibration</DIV>
<DIV><BR></DIV><FONT face=Arial color=#000000 size=2>
<DIV>
<DIV>Nat, taking a hypothetical example of a 20x10 prop, the radius is 10
inches and coincidentally so is the pitch at the 70% station of the prop.
</DIV>
<DIV>The 70% point is 7" from center. </DIV>
<DIV>The circumference of the circle at that station is 2x(7")x Pi. </DIV>
<DIV>The right triangle would then have a base of 2R x Pi and a height of
10"(prop pitch). </DIV>
<DIV>The hypotenuse inscribes angle which is the true pitch angle at the
70% station. </DIV>
<DIV>(Reducing the triangle down to say 5% of the original makes it
manageable.)</DIV>
<DIV>Is this what you mean?</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Matt</DIV>
<DIV> </DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>
<DIV><FONT face=Arial size=2>Peter,</FONT></DIV>
<DIV><FONT face=Arial size=2>Prop pitch is measured at the 70%
station.Pitch distribution along the span ( deviation from true pitch )
is proprietary and is, in the case of APC, what accounts for their
excellent performance and low noise.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>A way to calibrate your gauge is to make a
template , a triangle with the x axis equal to the circumference
at a given blade station and a slope of ,say, 10 inches and check
this against the guage reading at that station.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>i.e. at each station a prop will "twist"
forward the same amount in one revolution if it has true pitch ( no
slippage ).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>You do not need to express inches of pitch
as degrees.</FONT></DIV>
<DIV><FONT face=Arial size=2>When are you going to give me a report on
the Alliance trim !!</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mailto:pentagon.systems@bigpond.com
href="mailto:pentagon.systems@bigpond.com">Peter Pennisi</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=mailto:discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, October 15, 2004
5:18 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Propeller Pitch gauge
calibration</DIV>
<DIV><BR></DIV>
<DIV class=Section1>
<DIV>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Hi
Guys,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I have
modified a propeller pitch gauge to accommodate larger propellers. The
gauge I have is a very old prop shop
model.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I have
decided to check my APC props because I was getting mixed performance
results between all my prop sizes.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Anyway I
thought I would check my gauge with a new prop to see how accurate it
was and the numbers I got were different to what was on the prop. I
tried another new prop of exactly the same size I got a different
result again. Anyway I am shocked to find that what is displayed on
the prop is different to my measurements.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">What part of
the prop should I be measuring my pitch as this varies slightly over
the length of the blade?<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Secondly, how
would I go about calibrating my unit because I can’t do it with new
props because there all different.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">How do I
express for example 13 inches of pitch as
degrees?</SPAN></FONT></P></DIV></DIV></BLOCKQUOTE></FONT></BLOCKQUOTE></DIV></FONT></BLOCKQUOTE></FONT></BLOCKQUOTE></DIV>
<DIV></DIV>
<DIV> </DIV></BLOCKQUOTE></FONT></BODY></HTML>