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<DIV><FONT face=Arial size=2><SPAN class=393020416-10022005>What he is saying is
this: As the servo arm rotates from 90 degrees, the effective length of
the servo arm gets shorter, meaning that for each incremental degree of
rotation of the servo arm from 90 degrees, you get less incremental movement of
the pushrod. Therefore the control is inherently more sensitive around
neutral than it is at the ends of the servo throw, assuming linearity in the
rest of the system. Expo can be used to counter this natural
tendency.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=393020416-10022005></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=393020416-10022005>HOWEVER, the
effective length of the surface control horn also gets shorter as the surface
moves from neutral, increasing movement with each incremental movement of the
pushrod. So it is a race between decreasing effectiveness of
the servo output arm vs. increasing effectiveness of the control horn.
Then you get into non-linearity of the aerodynamic surface effectiveness itself
as it moves from neutral, and you can get confused real quick. You are
dealing with several areas of non-linearity, and trying to compromise between
them all.</SPAN></FONT></DIV>
<DIV><SPAN lang=en-us><FONT face=Arial size=2></FONT></SPAN> </DIV>
<DIV><SPAN lang=en-us><FONT face=Arial size=2>Jon Lowe</FONT></SPAN> <BR></DIV>
<P>
<DIV></DIV><FONT face=Tahoma size=2><FONT face=Arial></FONT>-----Original
Message-----<BR><B>From:</B> discussion-request@nsrca.org
[mailto:discussion-request@nsrca.org] <B>On Behalf Of </B>Tim
Taylor<BR><B>Sent:</B> Thursday, February 10, 2005 8:28 AM<BR><B>To:</B>
discussion@nsrca.org<BR><B>Subject:</B> Re: [SPAM] Re: Notes to Self
3<BR><BR></FONT></P>
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<DIV><FONT face=Arial size=2>Troy let me get this straight in my mind, You
said</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>"The reason is the servo wheel is round and its Y
axis distance changes for each degree of travel as the servo rotates around
the back side."</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Now It took me a few readings and some pondering
to understand what you said. It doesn't matter what type arm you use,correct
so far? What I take this to mean is as the servo arm moves the point at which
the servo is connected to the driving rod and the center arm screw is at it's
farthest point at 90 degrees to the servo case (assuming the servo case is 90
degrees to the hinge line) as it moves forward or backwards the
distance between the pivot points decreases with each degree of rotation.
Correct?</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=troy_newman@msn.com href="mailto:troy_newman@msn.com">Troy A.
Newman</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, February 11, 2005 11:05
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [SPAM] Re: Notes to Self
3</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>8103, 9303 and 10X expo are the same Positive
is softer and Negative is harder feel. I'm writing an article for the KF
right now that talks about Expo and how to use it. When to use it. And the
effects of it. Sometimes a reverse expo (faster response) at center can be
of benefit. We have played with this in snaps and found that it has some
promise...Lots of regular expo on the ailerons and rudder and reverse expo
on the elevator...The result is the model will pitch harder on entry before
the rotations.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Another thing depending on the radio it takes
20-30% expo just to get the output to be linear. The reason is the servo
wheel is round and its Y axis distance changes for each degree of travel as
the servo rotates around the back side.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>This is March KF stuff so I won't elaborate
here but I have some data to back up my words. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Troy</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></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=tncbrown@charter.net href="mailto:tncbrown@charter.net">T&C
Brown</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, February 09, 2005
8:42 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Notes to Self 3</DIV>
<DIV><BR></DIV>
<DIV><FONT size=2>That is odd Tim. I wonder why JR decided after all
these years to change from a pos. setting to a neg. for a "softer
feel". I'm a firm believer in "If it ain't broke, don't fix
it" </FONT></DIV>
<DIV><FONT size=2>I made the same mistake a few years back when I switched
from a Futaba 7UAP to a JR 8103 and inadvertently put neg. expo in the
8103. Talk about pucker factor for a few minutes.</FONT><FONT size=2> </FONT></DIV>
<DIV><FONT size=2>Maybe Fu-tuh-boo-boo is rubbing off on JR!
(BG)</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV><FONT size=2>T-Bone</FONT></DIV>
<DIV><FONT size=2></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=twtaylor@ftc-i.net href="mailto:twtaylor@ftc-i.net">Tim
Taylor</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, February 09, 2005
12:18 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Notes to Self 3</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>That's the whole point in the story Ron, I
ASSUMED I was right and didn't NEED to RTFB and could have screwed up
big time. I've been flying JR radios for years but always a PCM10 of
some sort, this 9303 is a new radio for me. What I did was get in a
hurry, I wanted to fly and trim this airplane and didn't do what I
should have done first. I hope my not so comical errors will help
someone else from making the same mistake I did.</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=vanputte@cox.net href="mailto:vanputte@cox.net">Ron Van
Putte</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, February 09,
2005 12:01 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Notes to Self
3</DIV>
<DIV><BR></DIV><BR>On Feb 9, 2005, at 8:28 AM, Tim Taylor
wrote:<BR><BR>
<BLOCKQUOTE><?fontfamily><?param Arial><?smaller>As our Continuing
story unfolds........<?/smaller><?/fontfamily><BR> <BR><?fontfamily><?param Arial><?smaller>Timmy
T is looking out of the shop door and sees that the weather is just
perfect for some trim flights<?/smaller><?/fontfamily><BR> <BR><?fontfamily><?param Arial><?smaller>So
we pack up the trailer and go for some trim flights. Recalling
the last flights all control throws too sensitive so
I dial in less rates on low and put high rates to what low was
before. Ok time to dial in some Expo on all surfaces, pop up the
screen on the 9303 and dial in 30%. Ok time to fly. Airplane seems
pretty stable now but the controls feel a bit "Twitchy" hmmm no
problem continue the flight land and have a look. Ok maybe I didn't
get enough expo dialed in so add some more. Next flight about the
same but the controls seem a bit more "twicthy" hmmm something's not
right here. Ok times up for flying for today pack up and head home.
On the way home I get to thinking about the last flight and how the
airplane changed the "feel" after I added the expo. Ok I get to
wondering where the heck did I put the book for this new radio, Ok
lets review the book on page A20 is the expo directions, it states
"NOTE: Use only positive percentages unless there is a distinct need
to do otherwise". Hmmmmmm that don't sound right! Turn the
transmitter on and look at the expo I've got dialed into the radio,
*&%^$*&#)(#&%^%)@(_*&_(^# Everything is done
to the NEGATIVE !!!!!! No damn wonder! So "Note to self" today's
lesson is READ THE FRIGGIN BOOK
!!!!!!!!!<?/smaller><?/fontfamily><BR> <BR><?fontfamily><?param Arial><?smaller>Ok
while I'm at it lets program a little down elevator trim at
low idle, I wonder what page that is on in the
book.................. "Fade to Black as Timmy T reaches for the
book."<?/smaller><?/fontfamily><BR></BLOCKQUOTE><BR>My guess is that
he's using a JR radio, because negative exponential is what you want
on a Futaba transmitter to soften the control response. That's why
well-meaning people at the field need to find out what brand of
transmitter the guy being counseled has before telling him how to
change the expo. <BR><BR>I had a similar situation when I was helping
a novice trim out his airplane. After I flew a trim flight for him, I
told him he needed 50 - 60% exponential on elevator and aileron. I
asked him if he knew how to do that and he said that he did. The
airplane was a handful on the subsequent flight, because he put in the
wrong expo!<BR><BR>Ron Van
Putte<BR></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>