<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2873" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>IMO it sounds like the center line of the engine
shaft is above the center line of the wing acting like down thrust.
Additionally, as I recall, don't those Yaks have really long gear legs,
?......this would produce additional drag producing even more down thrust
effect, then when you cut the power all of these force factors are effectively
removed, which the elev setting has been overpowering at
normal R.P.M. Without these factors in effect, the up elev now
produces enough force to cause ballooning at the reduced setting. You will
probably need to add a couple of degrees of up-thrust in the engine and this
should not make it pitch to the belly, if anything I would expect it to
exacerbate the canopy pitch requiring additional corrective mix, but like I
say, just MO.</FONT></DIV>
<DIV><FONT face=Arial size=2>G.</FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE
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=rcaerobob@cox.net href="mailto:rcaerobob@cox.net">Bob Pastorello</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 Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, May 22, 2006 6:53 AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] Thrust Line
Trimming</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>Hello - I have a BME 30% Yak, (and had a
TOC/Aviation Models Yak), and both pitch to the canopy when power is reduced
in vertical climbs (also on level cruise power deceleration, too).
Elsewhere, fly well, and doesn't exhibit bizarre incidence problems,
and both needed UP elev. trim for level upright flight.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>ON the RCU threads on these two, owners report
needing to carry up elev trim, also, but haven't gotten any insights on the
engine thrust question.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have measured, and there is currently NO up or
down thrust in the motor referenced to centerline.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Could these planes actually need some UP
thrust??</FONT></DIV>
<DIV><FONT face=Arial size=2><BR>Bob Pastorello<BR><A
href="http://www.rcaerobats.net">www.rcaerobats.net</A><BR><A
href="mailto:rcaerobob@cox.net">rcaerobob@cox.net</A></FONT></DIV>
<P>
<HR>
<P></P>_______________________________________________<BR>NSRCA-discussion
mailing
list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE></BODY></HTML>