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Control horn position

Old 10-01-2008, 06:52 PM
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Default Control horn position

I am nearly ready to install the control horn on my scratch built ME109 and I need to ask where the control horn would be best mounted in relationship to the center of the wing. would more foreword be preferable, perhaps on the CG or near it? Thank You for all the help this has been fun . Jeffie
Old 10-01-2008, 07:11 PM
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Default RE: Control horn position

Well, I'm no expert, but I think you mean "Bell crank position." And my estimation is that it needs to be on the CG or very slightly behind the CG so that any inertial yaw is toward the outside of the circle. All of my planes, hung by the leadouts, hang just slightly nose down.
Old 10-01-2008, 08:46 PM
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Default RE: Control horn position

Bell crank!! DOH!!![:@]
Yea that thing.
Thank You.
Old 10-01-2008, 08:55 PM
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Default RE: Control horn position

Actually the bell crank can go in any position you like but ideally should be slightly forward of the CG. The only reason for this is that there's always a slightly rearward rake to the lines coming through the leadouts (whether adjustable or not) so the aim is to have as straight a run as possible from the lead out guide to the bellcrank which cuts down on a little friction at the guide. That's an ideal world and it's far from critical so in practise just put the bellcrank roughly around the CG but in a place it can have strong support.
Old 10-01-2008, 09:08 PM
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Default RE: Control horn position

Not critical. That works for me. So foreword of the centerline of the wing should work.
Old 10-01-2008, 10:01 PM
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Default RE: Control horn position

I must throw my two cents and say that the pivot point of the belcrank fall behind the CG but not very far behind. Here is one example and if you check plans of other C/L planes you will find the same set up. This is to help keep the nose pointed to the outside of the circle for line tension. Also right side engine thust and right offset rudder for same reason.

Also consider a small weight on the outboard wing tip to help compensate the control line weight supported by the inboard wing panel.


Note the CG on this plane and the location of the belcrank in this view. Trust me on this one.

Robert
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Old 10-02-2008, 07:42 AM
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Default RE: Control horn position

Great. Yea I can do that. thanks all.
Old 10-03-2008, 03:01 PM
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Default RE: Control horn position

Jeffie,

Bellcrank position is not important, except for one thing: wear on the leadout guide near the inboard tip.

Wherever the bellcrank is, line pull will aim at the CG through the leadout guides, so for least friction that means the bellcrank would mount where the pull points through the leadouts at the CG at the fuselage center, or where the bellcrank pivot bolt is, anyway. Figure about 5° angled back from the CG to place the leadout guides (or, rather, the middle between the two of them.)

Even this isn't really critical, but gives you a good start...

Luck!


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