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<DIV><FONT face=Arial size=2>I've just installed +1.4* upthrust, measured at the
prop hub face, referenced to firewall. The really INTERESTING thing is
that now the spinner is dead center in the cowling (it was off slightly before)
and the prop clears the cowling front lip equally all the way around. I
had to think through this awhile before I remembered - the cowling is "pre
drilled", with the blind nuts premounted. It would seem that it LOOKS
right with the upthrust.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Will fly it Wednesday and report back, FWIW.<BR>I
left the elevator trim alone, so I will know on TAKEOFF if this was a good/not
good thing to do... </FONT></DIV>
<DIV><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></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=rcaerobob@cox.net
href="mailto:rcaerobob@cox.net">rcaerobob@cox.net</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 2:38 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Thrust
Line Trimming</DIV>
<DIV><BR></DIV>
<DIV>
<P>Thanks, everyone. Consensus seems to be "try the thrust change".... and
I'll do that. Good points and things to refresh memory about dynamic effects
when changing throttle settings. </P>
<P>Happy Monday! </P>
<P>Bob<BR>---- "george w. kennie" <<A
href="mailto:geobet@gis.net">geobet@gis.net</A>> wrote:<BR>>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.<BR>>G.<BR>><BR>><BR>>----- Original Message
-----<BR>>From: Bob Pastorello<BR>>To: NSRCA Mailing List<BR>>Sent:
Monday, May 22, 2006 6:53 AM<BR>>Subject: [NSRCA-discussion] Thrust Line
Trimming<BR>><BR>><BR>>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.<BR>><BR>>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.<BR>><BR>>I have
measured, and there is currently NO up or down thrust in the motor referenced
to centerline.<BR>><BR>>Could these planes actually need some UP
thrust??<BR>><BR>>Bob
Pastorello<BR>>www.rcaerobats.net<BR>>rcaerobob@cox.net<BR>><BR>><BR>>------------------------------------------------------------------------------
<BR>><BR>><BR>>_______________________________________________<BR>>NSRCA-discussion
mailing
list<BR>>NSRCA-discussion@lists.nsrca.org<BR>>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion<BR><BR>--<BR>Bob
Pastorello, El Reno, OK,
USA<BR>rcaerobob@cox.net<BR>www.rcaerobats.net<BR></P></DIV>
<P>
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