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<DIV><FONT size=2 face=Arial>Dqave:</FONT></DIV>
<DIV><FONT size=2 face=Arial>Agreeing here with Bob. I always make hard
copies of in-depth stuff by the highly qualified guys, and file it away for
rainy-day reading!<G> Well worth the paper and drawer space.
(And no, it isn't filed and forgotten!)</FONT></DIV>
<DIV><FONT size=2 face=Arial>Bill Glaze</FONT></DIV>
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style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=getterflash@yahoo.com href="mailto:getterflash@yahoo.com">Bob
Kane</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">General pattern discussion</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, September 08, 2009 9:29
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Electric
props vs. standard pattern</DIV>
<DIV><BR></DIV>
<DIV
style="FONT-FAMILY: times new roman,new york,times,serif; FONT-SIZE: 12pt">Nice
analysis, thanks for sharing.<BR>
<DIV> </DIV>Bob Kane<BR><A
href="mailto:getterflash@yahoo.com">getterflash@yahoo.com</A>
<DIV><BR></DIV>
<DIV
style="FONT-FAMILY: times new roman,new york,times,serif; FONT-SIZE: 12pt"><BR>
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style="FONT-FAMILY: times new roman,new york,times,serif; FONT-SIZE: 12pt"><FONT
size=2 face=Tahoma>
<HR SIZE=1>
<B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> Dave <<A
href="mailto:DaveL322@comcast.net">DaveL322@comcast.net</A>><BR><B><SPAN
style="FONT-WEIGHT: bold">To:</SPAN></B> General pattern discussion <<A
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>><BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Tuesday, September 8, 2009 1:06:03
AM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re:
[NSRCA-discussion] Electric props vs. standard pattern<BR></FONT><BR>
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<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Dave,</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">The ideal prop
airfoil shape is compromised to provide the needed structural integrity to
withstand aerodynamic, gyroscopic, and impulse loads (from firing of
combustion engines, and even pulses from electric motors). Ideal in this
context meaning most thrust and/or speed for least amount of input power.
Because the impulse loads from an electric motor are lower, and
electrics are generally run at lower RPM (primarily to take advantage of
larger more efficient props), it is possible to design a prop that is closer
to the ideal shape and lighter while still having the needed structural
integrity.</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Several years ago, I
played with a very high RPM outrunner (295 KV) and checked many different
props, including some E vs glow prop comparisons –</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">16x10E – 8400 RPM, 79
amps</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">16x10 – 8800 RPM, 69
amps</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Performance in the
air was very similar, but the E prop was much lighter (about 65% the weight of
the glow prop). I preferred the glow prop because it afforded the same
performance with cooler motor, ESC, and lipo temps (less mah discharged for an
equal flight).</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">I’ve run high RPM
(7500 – 8000) outrunners in pattern quite a bit, and had always found the glow
props to be better – in terms of lower input watts needed and fewer mah
consumed for equal flights…..and I had a theory why…..but never “proved” it to
myself until this past year. I laminated a number of E props of various
sizes for various motors/RPMs with CF cloth, and found on the higher RPM
setups, the E props with CF would turn more RPM and draw less amps….and in the
air they indeed performed better than a stock E prop or a similar sized glow
prop. With respect to pattern sized motors/power…..I saw very little
improvement at <6500 RPM, but noticeable improvement >7000
RPM.</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">The vast majority of
electrics being used in pattern are <6500 RPM (and the unload in the air is
a reduction in amps, but very little increase in RPM), while the majority of
glow stuff is running between 7400 and 8400 (and can unload to ~+10% RPM in
the air)…….so the difference in 6500 and 8700 (unloaded) is pretty substantial
when you start looking at prop structure needed to eliminate
flexing.</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Regards,</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Dave
Lockhart</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"><A
href="mailto:DaveL322@comcast.net" rel=nofollow target=_blank
ymailto="mailto:DaveL322@comcast.net">DaveL322@comcast.net</A></SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
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<P class=MsoNormal><B><FONT size=2 face=Tahoma><SPAN
style="FONT-FAMILY: Tahoma; FONT-SIZE: 10pt; FONT-WEIGHT: bold">From:</SPAN></FONT></B><FONT
size=2 face=Tahoma><SPAN style="FONT-FAMILY: Tahoma; FONT-SIZE: 10pt">
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org] <B><SPAN
style="FONT-WEIGHT: bold">On Behalf Of </SPAN></B>Ken Velez<BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Monday, September 07, 2009 11:41
PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> ' General pattern
discussion '<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re:
[NSRCA-discussion] Electric props vs. standard pattern</SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT size=3 face="Times New Roman"><SPAN
style="FONT-SIZE: 12pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Hi
Dave,</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">It seems to me that
the electrics are not turning comparable numbers. Most setups are turning in
the low to mid 6000 and only 1 or 2 set ups are in the 7000 and none in the
8000 that I know of. This is based on what I have observed only; so there
could be a setup turning higher numbers; and on a 10S battery. If you go to
more cells = more Volts = more RPM’s also more Amps. FAI is caped to 10 cells
not sure about AMA. My Hacker A-60 is on the mid 7000 and we were using the
18.1X10-11-12 glow props; while it flies very nice with these props the plane
is very slow for top classes and or wind. So right now I’m using an E prop;
huge difference. It’s also my understanding that the E props are more
efficient than the regular glow props not 100% sure but pretty certain about
it but you are correct about the stiffer is more efficient when comparing 2
identical props lets say one plastic and one carbon but not equal when
comparing different airfoils. An APC 20X10 E will be more efficient than a 20
X10 Glow and if you can make the APC 20X10E in Carbon it will be more
efficient than the original 20X10E etc… Just my observations.
</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt">Ken</SPAN></FONT></P>
<P class=MsoNormal><FONT color=navy size=2 face=Arial><SPAN
style="FONT-FAMILY: Arial; COLOR: navy; FONT-SIZE: 10pt"></SPAN></FONT> </P>
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<P class=MsoNormal><B><FONT size=2 face=Tahoma><SPAN
style="FONT-FAMILY: Tahoma; FONT-SIZE: 10pt; FONT-WEIGHT: bold">From:</SPAN></FONT></B><FONT
size=2 face=Tahoma><SPAN style="FONT-FAMILY: Tahoma; FONT-SIZE: 10pt">
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org] <B><SPAN
style="FONT-WEIGHT: bold">On Behalf Of </SPAN></B>Dave Burton<BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Monday, September 07, 2009 11:04
PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> ' General pattern
discussion '<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re:
[NSRCA-discussion] Electric props vs. standard pattern</SPAN></FONT></P></DIV>
<P class=MsoNormal><FONT size=3 face="Times New Roman"><SPAN
style="FONT-SIZE: 12pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT size=2 face=Verdana><SPAN
style="FONT-FAMILY: Verdana; FONT-SIZE: 10pt">Why are we using the Electric
style APC props on electric powered pattern planes rather than the standard
pattern props? We are turning the electric motors at comparable RPMs to a glow
engine. The standard pattern props are stiffer and should be more efficient it
seems to me. I can understand a little weight savings if needed but is that
the only reason for using the E-props? What am I missing? Anyone compared
similar E and standard props in the same sizes? What results did you find?
<BR>Dave Burton</SPAN></FONT><FONT color=#1f497d size=2 face=Calibri><SPAN
style="FONT-FAMILY: Calibri; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN></FONT></P></DIV></DIV></DIV></DIV><BR>
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