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<DIV><FONT size=2>not sure if the Heli tachs will read high enough... but they
use a method which can give you the RPM from any distance you can see the
blades.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>A strobo-tach will also work at any distance that you can see
the blades.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>Both use momentary light (the heli tach uses a shutter wheel)
and you adjust the tack until you "see the blades stop" Then you read the
numbers from your settings on the tach. You have to make a judgement to
decide if you have the tach set for an exact multiple of the rpm... (it will be
2X, or 1/2X or some other power of 2)</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>None of the tachs we usually use with glow engines will really
be dependable at 5 ft. You CAN get a reading further than that if you have
the plane pointed directly at the sun and the tack directly behind the
plane. Alignment is increasingly important as you increase
distance. </FONT><FONT size=2> At some distance.. the light
going around the prop will be more infulential on the tach than the light being
interrupted by the prop... at that point, the tach will quit readin with any
accuracy.</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>You can read the frequency of the AC current supplying an
incandescent bulb and get an idea of the potential range of your tach if you can
get the tach, prop and light source (Sun) properly aligned, and can keep the
light going around the prop from interfering.</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=brian_w_young@yahoo.com href="mailto:brian_w_young@yahoo.com">brian
young</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, December 03, 2006 10:56
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] Tachs</DIV>
<DIV><BR></DIV>
<DIV>Anyone know of a reliable tach that will read a prop from 5-6 feet
away?</DIV>
<DIV> </DIV>
<DIV>Brian</DIV>
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