Front Leadout is Up or Front Leadout is Down?

[Kafin Noe’man]

Hi, I just realized that my Cardinal bellcrank setup is in reverse, making the front leadout is up as opposed to the conventional front is down.

How much different will I experience when flying? Will the control and handling be different considering I have always been flying planes with the ‘front is down’ setup?


Best,
Kafin

[Perry Rose]

None for a normal person. Front up on a profile puts the push rod opposite the engine exhaust.

[Dennis Toth]

Kafin,
What are you using for power IC or electric? For IC the reverse setup is the preferred arrangement with the front line up, this gives a very slight outward yaw on down control maneuvers to counter the torque moment of the counterclockwise engine rotation. For electric also ok if running tractor propellers but would want it the opposite for running pushers (clockwise motor rotation). It is a small effect so not really an issue either way, can be trimmed out with a little engine offset and rudder offset.

Best,    DennisT

[john e. holliday]

When you get hundreds or even thousands of flights you can tell us.  My self I try to keep the lead outs within 1 inch between them.  I don't fly enough to tell the different even when flying the planes back to back.  Main thing is get the plane where it and you are happy then try and make the judges happy.  That is the big problem as each set of judges has a different loo on the pattern.

[goozgog]

 Someone here will correct me but
Al Rabe did tests  and decided that
Forward leadout as UP is superior.

 I think it has to do with minimizing yaw
as tension varies between the lead outs
during flight.
  FWIW, that's also why it's a good idea
to keep the leadouts as close together as
possible

  Others have said that the effect is
minimal and if it creates mechanical
difficulties. it might not be worth it.

  I install the bellcrank backwards on the
outboard side so that the "horn"
points back at the pilot.
  I can't remember what Windy used on
the Cardinal but I would go with his design.

   Someone with more knowledge will
show up soon.  :-)

Cheers! - K.

[Istvan Travnik]

This question was worked out and answered very thoroughly, years before:

https://stunthanger.com/smf/building-techniques/bellcrank-normal-or-reverse/msg386941/#msg386941

[Ken Culbertson]

I have always had the up line in front for no other reason than Al told me to, although actually, I have never really cared.  The plane can be trimmed either way, especially if you keep the leadouts close together.  I make my sliders with 3/4 separation, and I let the design and clearances dictate which line is in front.   There is a very slight difference in pressure exerted on the control surface resulting from pulling vs pushing but with CF pushrods it really doesn't matter anymore.  As you reach the top of the skill ladder these things become more noticeable.   If you look at the plans for ships designed "Back in the day" many, if not most, designs had the down line in front and the fixed leadouts about an inch to an inch and a half separation.

Ken