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General control line discussion => Open Forum => Topic started by: sleepy gomez on June 06, 2013, 10:09:32 PM
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What is the flight effect, other than appearance, of having leadouts under or over on the outside of the wing as opposed to internal leadouts?
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Hi Sleepy. In a very fine technical sense having exposed leadouts adds slightly more drag to the inboard wing panel but its so slight as to really not matter, given the short lengths of wire. If the wire were stuck down tight on the wing surface it could have a turbulator effect but again not a measurable thing. It's mostly cosmetics. Here's a shot of the trainer I built recently having exposed controls. I did this so that prospective trainees could see how the controls work and because I put the wing very low in the fuselage. Sure this is just a trainer but it is obvious the exposed controls have no discernible effect.
Dave
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The flight characteristics will usually be effected with exposed L.O.'s. The plane may fly O.B. Wing high or low depending if L.O.'S mounted on top of wing or below. This I believe is related to the plane's VERTICAL Ctr. Gr. The weight of the landing gear hanging below the VCG coupled with the external controls will usually cause the wing to ride out of level. It helps to keep the struts and wheels as small and light as possible. If you hold the L.O.'S with the O.B. wing hanging down vertical you will probably see the O.B. wing canted if the L.O.'S ARE EXTERNAL. The ext. L.O.'S along with the weight of the Landing gear contribute to this effect. In flight, this is amplified by centrifugal force. I asked similar questions about this about a year ago on this forum when a friend and I were trying to build a better U-KEY type plane to learn to fly the pattern. One that we could build quick and tear up and repair easy. We have almost succeeded, especially in the tear up department!
If you could go back into the past threads on this Sleepy you will find their comments. I believe Phil Cartier and others made some great comments about this. They can explain much better than me. Joe Gilbert and the late great Mike Donavan were a big help in Brent Rogillio and I overcoming some of the short comings of external controls. Also Brett Buck, Ted Fancher, and some others have answered some threads dealing with VCG ISSUES which were very, very good information.
Doug
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If the leadout guide is at the level of the vertical CG, I don't see much effect from outside of wing leadouts. I have them on both high wing and low wing airplanes.
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That's "if".
Doug