<div>I tend to agree. So what's the best way to neutralize that effect? Is there a way to set-up the airplane so that the trim changes as the airspeed/air density changes will be minimized? </div> <div> </div> <div>I get the feeling that there are set-ups that are conditions specific and those that are more versatile.</div> <div> </div> <div>Which are the key variables for lift/pitch and airspeed....cg, wing incidence, tail incidence, engine thrust line, aileron droop etc.? </div> <div> </div> <div>I'm going to play with cg and aileron droop this weekend. I assume it will be a bit cold...it is Canada after all.</div> <div> </div> <div>Colin.</div> <div> </div> <div>Colin.<BR><BR><B><I>Amar Shan <shan@telus.net></I></B> wrote:</div> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid"> <META content="MSHTML 6.00.2900.2963" name=GENERATOR> <DIV><SPAN class=876030100-12092006>Tom had
exactly the right idea when he thought it was an "air density" thing.</SPAN></DIV> <DIV><SPAN class=876030100-12092006></SPAN> </DIV> <DIV><SPAN class=876030100-12092006>To begin with, the air density *does* change substantially in going from 15C to 30C. It's the equivalent of moving from sea level to 1700 feet altitude!</SPAN></DIV><SPAN class=876030100-12092006> <DIV><BR>The second thing to realize is that the plane's air speed (indicated air speed to the full scale pilots out there) changes with changing air density. In other words, if the plane<SPAN class=876030100-12092006> appears to be moving at the same speed on a 15C day as a 30C day FROM THE GROUND, the airflow over the wings is actually much greater on the cooler (15C) day.</SPAN></DIV> <DIV><SPAN class=876030100-12092006></SPAN> </DIV> <DIV><SPAN class=876030100-12092006><FONT face="Lucida Sans">Now, when you trim a plane for flight, you trim for its indicated air speed (ie, the
amount of airflow over its wings). If you are flying slower, you need a greater AOA, of course. When you take a plane trimmed for 30C weather, and fly it on a 15C day, the airflow over the wings is much greater - hence, you need much less AOA, and you have to trim with more down elevator.</FONT></SPAN></DIV> <DIV><SPAN class=876030100-12092006></SPAN> </DIV> <DIV><SPAN class=876030100-12092006><FONT face="Lucida Sans">Cheers,</FONT></SPAN></DIV> <DIV><SPAN class=876030100-12092006></SPAN> </DIV> <DIV><SPAN class=876030100-12092006><FONT face="Lucida Sans">Amar</FONT></SPAN></SPAN></DIV> <BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px"> <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> nsrca-discussion-bounces@lists.nsrca.org [mailto:nsrca-discussion-bounces@lists.nsrca.org]<B>On Behalf Of </B>Ed Miller<BR><B>Sent:</B> September 11, 2006 4:54 PM<BR><B>To:</B> NSRCA Mailing
List<BR><B>Subject:</B> Re: [NSRCA-discussion] Trimming question.<BR><BR></FONT></DIV> <DIV><FONT face=Arial>I have the same issue with the EMC I'm flying. At summers 90+ temperatures using a Futaba 9ZAP radio I have 2% up elevator with right rudder and 4% up with left rudder for straight knife edge flight. I noticed when the temps cooled to the 70's lately I had to put 2 % down elevator trim in to fly straight and level at horizontal flight cruise rpm.. Because of that touch of down elevator trim in cool weather, I end up with a slight push to the belly in knife edge in both directions. Plane has the DEPS system installed. I think what is happening is the difference in growth between the fiberglass/wood fuse and carbon fiber pushrods is causing the slight elevator trim change during the temperature change which affects the knife edge flight. Or maybe the cooler denser air requires less AOA in the wing. I
don't see how enabling the trim function in the rudder to elevator mix will fix this as the rudder is the master channel. Unless I misunderstand, only a rudder trim change would effect the elevator movement in the mix. I'm open for suggestions...........</FONT></DIV> <DIV><FONT face=Arial>TIA.....Ed M. </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=trexlesh@msn.com href="mailto:trexlesh@msn.com">Rex LESHER</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, September 11, 2006 6:08 PM</DIV> <DIV style="FONT: 10pt
arial"><B>Subject:</B> Re: [NSRCA-discussion] Trimming question.</DIV> <DIV><BR></DIV><!--[gte IE 5]><?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> <DIV style="FONT-WEIGHT: normal; FONT-SIZE: 12pt; COLOR: #000000; FONT-FAMILY: Lucida Sans"> <DIV>actually, I think I confused myself... I meant to say, all offset will be based from the current trim setting, not from the original setup position....</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="FONT: 10pt arial"><B>From:</B> <A title=mailto:trexlesh@msn.com href="mailto:trexlesh@msn.com">Rex LESHER</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A title=mailto: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, September 11, 2006 3:02 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Trimming question.</DIV> <DIV><BR></DIV><!--[gte IE 5]><?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> <DIV> <DIV>Just curious.... what radio are you using? Do you have mixes set up for roll coupling? If so, do you have the trims set to "active" in the mixes? If not, this could be the reason for the pitching. Without active trim in the mixes, all offset will be based from the original servo position in setup, not from the current flying position after the trim was moved.</DIV> <DIV> </DIV> <DIV>Rex</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="FONT: 10pt arial"><B>From:</B> <A title=mailto:Tom.Koenig@actewagl.com.au
href="mailto:Tom.Koenig@actewagl.com.au">Koenig, Tom</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A title=mailto: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, September 11, 2006 2:42 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Trimming question.</DIV> <DIV><BR></DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff>All-Dean,</FONT></SPAN></DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff></FONT></SPAN> </DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff>I think you could be onto something there. I like to fly on the edge of nose heavy, and I could sympathize with Colin. My Synergy exhibits almost the same tendencies. It is not a heavy plane at 4.7 kg, but the CG is forward. Hmmmmmmm-you boys have me thinking
again. I notice it biggest when travelling as every field I go to is at lower altitude. The biggest and costliest time was during the Trans Tasman comp in New Zealand-it was like flying through soup!</FONT></SPAN></DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff></FONT></SPAN> </DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff>I have always assumed it was an air density thing. I have experienced exactly what Colin describes.</FONT></SPAN></DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff></FONT></SPAN> </DIV> <DIV><SPAN class=573513321-11092006><FONT face="Comic Sans MS" color=#0000ff>Tom</FONT></SPAN></DIV> <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> nsrca-discussion-bounces@lists.nsrca.org [mailto:nsrca-discussion-bounces@lists.nsrca.org]<B>On Behalf Of </B>Dean Pappas<BR><B>Sent:</B>
Tuesday, 12 September 2006 3:36 AM<BR><B>To:</B> NSRCA Mailing List<BR><B>Subject:</B> Re: [NSRCA-discussion] Trimming question.<BR><BR></FONT></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>Hi Colin,</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>By any chance, is your plane relatively heavy, have a particularly high wing loading, propped to fly very slowly, or set up relatively nose-heavy?</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>The reason I ask is that back in the late eighties, I clipped the wings of one of my early Turnaround designs </FONT></SPAN><SPAN class=571581117-11092006><FONT face=Arial size=2>in order to fly faster.</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><SPAN class=571581117-11092006><FONT face=Arial size=2>This was back when we were in the middle of a wild overcorrection from flying slow and small in this country to flying fast,
fast, fast! Then things started to settle down.</FONT></SPAN></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>Actually, I clipped it twice, once from 68" span to 64" and then to 60. I should have left the plane at 64" span. When I made the second clip, the plane developed </FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>almost the same </FONT></SPAN><SPAN class=571581117-11092006><FONT face=Arial size=2>symptom you described. It pulled to the canopy in the vertical down line when the elevator was trimmed for a hot day.</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>It also looked like it flew droopy-drawered (tail low) on hot days. I moved the CG back until the elevators looked like they were in exactly the same spot, and lived with what little was left.</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>There was no suitable electronic
fix back then, with either a Futaba PCM 512 or a JR PCM9.</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>My hypothesis is that the sensitivity to air density happens when the plane requires lots of "up" trim to fly. What do the elevators look like when trimmed on a hot day?</FONT></SPAN></DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2></FONT></SPAN> </DIV> <DIV><SPAN class=571581117-11092006><FONT face=Arial size=2>later,</FONT></SPAN></DIV> <div><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT face="Times New Roman">Kodeos Communications</FONT> <BR><FONT face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT face="Times New
Roman">d.pappas@kodeos.com</FONT> </div> <BLOCKQUOTE> <DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> nsrca-discussion-bounces@lists.nsrca.org [mailto:nsrca-discussion-bounces@lists.nsrca.org]<B>On Behalf Of </B>colin chariandy<BR><B>Sent:</B> Monday, September 11, 2006 9:53 AM<BR><B>To:</B> NSRCA Mailing List<BR><B>Subject:</B> Re: [NSRCA-discussion] Trimming question.<BR><BR></FONT></DIV> <DIV>No, I'm using the MK bellcrank.</DIV> <DIV> </DIV> <DIV>If the problem was only related to the length of the pushrods, then when I re-trim the knife edge performance should return to normal. Thats not the case. The plane pushes to the bottom in the cold and is dead straight on hot days.</DIV> <DIV> </DIV> <DIV>Colin.<BR><BR><B><I>Lance Van Nostrand <patterndude@comcast.net></I></B> wrote:</DIV> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px
solid"> <META content="MSHTML 6.00.2900.2963" name=GENERATOR> <STYLE></STYLE> <DIV><FONT face=Arial size=2>My guess is you have the deps system. carbon fiber does not have as much shrinkage as the rest of your plane.</FONT></DIV> <DIV><FONT face=Arial size=2>--Lance</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=mailto:cchariandy@yahoo.ca href="mailto:cchariandy@yahoo.ca">colin chariandy</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A title=mailto: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> Sunday, September 10, 2006 11:09 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B>
[NSRCA-discussion] Trimming question.</DIV> <DIV><BR></DIV> <DIV>I noticed recently that I need to add a bit of down trim as the air temperature drops....maybe as much as 4 beebs going from 30+ days to 15C. That upsets the knife edge trim on the aircraft. </DIV> <DIV> </DIV> <DIV>Is that normal, or do I have something set a bit marginally, like CG or wing incidence?</DIV> <DIV> </DIV> <DIV>Do you guys typically have a "cold weather set-up" ?</DIV> <DIV> </DIV> <DIV>Colin.</DIV> <DIV> <HR SIZE=1> <A title=http://us.rd.yahoo.com/evt=40705/*http://mrd.mail.yahoo.com/try_beta?.intl=ca href="http://us.rd.yahoo.com/evt=40705/*http://mrd.mail.yahoo.com/try_beta?.intl=ca"><B>All new Yahoo! Mail - </B></A> <HR SIZE=1> Get a sneak peak at messages with a handy reading pane. <DIV> <HR> <DIV></DIV>_______________________________________________<BR>NSRCA-discussion mailing
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