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Building Tips and technical articles. => Building techniques => Topic started by: Wynn Robins on August 04, 2009, 02:38:34 PM
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currently I am building the RSM Mosquito kit - and doing a build article as I go - but....
I have hit a snag with the flap horns in that, as they are on a swept forward trailing edge and have very little space between them, they touch in the middle when full up is applied.
what is the best way to get around this problem?
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Hi Wynn,
On a swept foward trailing edge, a flat should be sanded where the horns. The flat must be 90 degrees perpendicular from the centerline of the aircraft fuselage. If you do that, there will be no binding when up or down is deployed.
Now I'm not sure what you mean by something having very little space between them, and they touch in the middle when full up is applied.
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matt - it is not possible to sand a flat in the trailing edge - the design does not allow for this. also. if I did that, it is not physically possible for the control horns to go into the flaps and have movement both ways without twisting and therefore breaking the flap. even with lucky boxes installed to allow for some movement - the forward sweep is such that the movent in the horizontal plane when the controls are delfected would require a lucky box approximately 2" wide to allow the full range of motion
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What is the forward sweep? I laid up a trailing edge with 15 degree forward sweep, and the lucky box only had to be 1 1/8" wide. If it takes more than that, it's got to be a lot. y1
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Wynn:
Sounds like your only choice is to splay the horns some. In the rear view bend them a couple degrees so they lean apart. (bend them the same amount) That will let them travel a little farther before they touch.
Not elegant but it will work...
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Hi Wynn,
(snip)
Now I'm not sure what you mean by something having very little space between them, and they touch in the middle when full up is applied.
Hi Matt,
On this design (and a lot of older ones) when a swept forward TE was employed, two *half horns* (one for each flap) were used with a split pushrod. Same for some V tails (all, I guess! LOL!!)
Mongo