My plane "feels" like it's being controlled on the front line,not both,why?

[Skip Chernoff]

I have a  Palmer Thunderbird I that I enjoy sport flying. However I have noticed that when I begin to "stunt" the plane it feels like most of the control tension is coming from the front line. On this plane the front line is the "up" line. None of my other stunters have this feel. They feel like control is equally divided on both lines. What causes this "feel" of flying on one line? Thanks,PhillySkip

[Tim Wescott]

I'm not sure what you're really feeling.  If all the tension were on the up line it'd feel like the plane is trying to force you to give "down" all the time -- is that it?

[Randy Cuberly]

I suspect the airplane is significantly "Nose Heavy" and requires a lot of effort to input enough control to make it maneuver.

Using modeling Clay add weight to the tail and I believe you will see precisely what I mean.  When you arrive at enough to make it maneuver relatively easy take it all off weigh it and substitute lead inside the rear of the fuselage!

Amazing what a properly placed CG will accomplish!

Randy Cuberly

[Tim Wescott]

If you don't have the courage to add tail weight right off, observe what the thing does when the engine cuts (assuming you don't have the motor offset up or down):

If it tends to dive, and seems to speed up, it's nose-heavy.  If it stays pretty level then it's about right.  If it "balloons" and slows down, then it's tail-heavy.

I'd try Randy's suggestion if it does either of the first two.

[Brett Buck]

I have a  Palmer Thunderbird I that I enjoy sport flying. However I have noticed that when I begin to "stunt" the plane it feels like most of the control tension is coming from the front line. On this plane the front line is the "up" line. None of my other stunters have this feel. They feel like control is equally divided on both lines. What causes this "feel" of flying on one line? Thanks,PhillySkip

   I am not sure what you are describing, either. Does it feel heavy on the "up" line for both inside and outside maneuvers? Or heavy on the front line on insides, and heavy on the rear line on outsides?

   If I absolutely had to guess, I would guess like everyone else, that it is nose-heavy. But go very carefully moving the CG back, like almost all classic planes, it is extremely sensitive to CG position and too far aft, even a little bit, can make it almost uncontrollable.

     Brett

[Skip Chernoff]

Fellows, the plane actually flies well(for the oldie that it is) .I have spent much time going thru the trimming process. I can put it thru a respectable  pattern. I know that it is not excessively nose heavy. If anything the CG   might be more towards the tail  side. The plane turns very well  and with engine off glides nicely with slight nose down attitude.
Next time I take her out I'll pay more attention to the handle "feel" when doing outside maneuvers.Thanks for your input......PhillySkip

[Chris McMillin]

Do you fly with your handle straight up and down?
Chris...

[Brett Buck]

Fellows, the plane actually flies well(for the oldie that it is) .I have spent much time going thru the trimming process. I can put it thru a respectable  pattern. I know that it is not excessively nose heavy. If anything the CG   might be more towards the tail  side. The plane turns very well  and with engine off glides nicely with slight nose down attitude.
Next time I take her out I'll pay more attention to the handle "feel" when doing outside maneuvers.Thanks for your input......PhillySkip

      Double check that your lines are centered on your handle. You can create the feel you have by offsetting both lines in the same direction. In this case, I think they would be offset towards the UP side of the handle.

    This is sometimes suggested by people as a trim technique to compensate for airplanes that turn "better" in one direction than the other. It is generally a TERRIBLE idea in more than the smallest amounts. In this case I presume it would be accidental/unintentional, but worth checking.

    Brett

[Skip Chernoff]

Chris I do fly with the handle straight up and down.
Brett , my handle is "neutral" with no bias built in to compensate for uneven outside vs inside loops.

I was thinking that maybe on the day I noticed this phenomena the wind was moving around a bit and maybe I was trying to stunt on a portion of the circle that was not optimal....who knows???

[Brett Buck]

Chris I do fly with the handle straight up and down.
Brett , my handle is "neutral" with no bias built in to compensate for uneven outside vs inside loops.

I was thinking that maybe on the day I noticed this phenomena the wind was moving around a bit and maybe I was trying to stunt on a portion of the circle that was not optimal....who knows???

    Maybe, but then again, the other airplanes work if you are doing it "different"/wrong, it would probably be like that all the time.

    The alternative issue is that there could be some substantial misalignment, causing you to have to apply "up" all the time.

     I think we are all sort of guessing what you are really feeling, because at least it is not a description I have heard before. No harm in that, however, it does make it a bit more difficult to diagnose.

      Brett

[MikeyPratt]

Chris I do fly with the handle straight up and down.
Brett , my handle is "neutral" with no bias built in to compensate for uneven outside vs inside loops.

I was thinking that maybe on the day I noticed this phenomena the wind was moving around a bit and maybe I was trying to stunt on a portion of the circle that was not optimal....who knows???

Skip,
Does it have differential flaps?  Are the lead outs vertical or side by side?  On my old T Bird (no diff flaps)  I had to increase the elevator throw to get the turn I wanted, it always felt hard to turn because the nose was always pulling out of the circle and the rudder was set close to zero.

Mikey

Mike Pratt

[Skip Chernoff]

No differential flaps. Leadouts are horizontal. She turns beautifully. Very little rudder offset. I can't wait to get out to the field again and just concentrate on watching the plane and the feel in the handle.

While I have your attention... is there any advantage or disadvantage to having the up line on the front?    Thanks,Skip

[Tim Wescott]

While I have your attention... is there any advantage or disadvantage to having the up line on the front?

Very slight, and only on some planes.  I'm not sure I could feel the difference, myself.  I wouldn't worry about it until you're good enough to be kicked out of Advanced.

[Skip Chernoff]

Tim, what sort of planes benefit from the up line being forward?  I'm just starting in advanced this year so at my age I'll probably be there the rest of my flying  "career".

[Tim Wescott]

Tim, what sort of planes benefit from the up line being forward?  I'm just starting in advanced this year so at my age I'll probably be there the rest of my flying  "career".

I'm rapidly getting out of my depth, and really hoping that someone who can actually feel the difference will chime in.

With the up line in back, when you pull up you very subtly yaw the plane out.  Visa-versa for up line forward.  I can't remember which direction is which, but gyroscopic precession will make a plane yaw with pitch.  I think that the idea is to counteract that.  I think the idea is that if you're good enough to tell, you try it both ways and use the one that works best (and don't get your leadouts too twisted up in the process).

[Randy Cuberly]

In general, if the leadouts are not much more than an inch or so apart it probably doesn't make much difference which line is the up line.  It does however behoove one to make both lines individually adjustable.  I'm not going to go into the in's and outs of that just suffice it to say that being able to move one and not the other can sometines cure some corner "wiggles" etc.  Again this is fairly subtle stuff and unless the airplane is very well trimmed and you're very much in "tune" with what's going on, it won't be noticeable! 

Randy Cuberly

[MikeyPratt]

Tim, what sort of planes benefit from the up line being forward?  I'm just starting in advanced this year so at my age I'll probably be there the rest of my flying  "career".

Hi Skip,
Very good question.  At one time it worked quit well on most models.  The problem I have with that is, it was used to counteract G/P (or help), but as time goes on we all learn.  Remember we all had off set rudders,  engine side thrust and leadouts were spaced about 1-1/2” apart.  Most of the models I see at contests these days have line spacing about 3/4” to 1” with little to no rudder offset.  Not really sure it's needed much anymore but I have become so used to hooking up the lines that way I'm not sure I could go back to the rear up line lol. 

Later,
Mikey

[Skip Chernoff]

Thanks all for jumping into this thread. From now on I'll pay closer attention to these subtleties.