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Question about Incidence.

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Question about Incidence.

Old 03-10-2014, 11:42 AM
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jbarnes
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Default Question about Incidence.

I've got this AMR 100cc Stick I built last year and have had a couple of dozen flights on. It flies great. But I do have about 3/8" of up trim in the elvator that is annoying me when I sit there and look at in the pits. The stab is fixed and I can't adjust the incidence so I was going to adjust the main wing to compensate for this up trim. I'm having trouble figuring out if I want the front of the wing raised or the back of the wing. I get confused on all this everytime I start messing with incidence. I should write this down somewhere! Jerry.
Old 03-10-2014, 11:49 AM
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speedracerntrixie
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Neither, you will want to set the airplane up on a table and measure everything to see where you are at before making changes. That up trim could simply mean you are nose heavy.
Old 03-10-2014, 12:05 PM
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jbarnes
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Good point. I'm CG'ed at the front of CG recommendation. I've got 2lbs of ballest in the nose. This is why I ask the smart people before I do anything! I'll take half the nose weight out and see how it flies next time I'm out at the field. Thanks.
Old 03-10-2014, 12:43 PM
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AMA 74894
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Originally Posted by jbarnes
Good point. I'm CG'ed at the front of CG recommendation. I've got 2lbs of ballest in the nose. This is why I ask the smart people before I do anything! I'll take half the nose weight out and see how it flies next time I'm out at the field. Thanks.
Hey Jerry...
when you DO fly it, (after having checked the wing, stab and engine thrust as speedreacerntrixie correctly pointed out)
go mid to high throttle, pull to a 45 degree upline, roll inverted and unload (release) the sticks... if the nose still immediately falls, you're still nose heavy.
Old 03-10-2014, 12:49 PM
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Jim is 100% correct there. Most guys, myself included like to have the airplane slowly arc to level inverted in about 5 seconds.
Old 03-10-2014, 01:00 PM
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jbarnes
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I have done that with my other planes to get the CG correct but this Stick seems to have inconsistent results. The plane does fly straight regardless of power setting so I'm thinking the engine thrust line is good. I'll have to do some serious playing with it this next weekend and see what happens. Providing of course it doesn't snow (again)!

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