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Trying to trim out k/e coupling

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Trying to trim out k/e coupling

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Old 01-31-2005 | 07:16 AM
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Default Trying to trim out k/e coupling

The plane is a GP Cap 232 with OS 50 sx engine. I have programmed the rudder ele and rudder aileron mixes and have achieved succeess in ironing out a lot of the coupling. It seems very hard to get it just right as it seems that at different power and rudder settings the coupling varies. I have yet to find a mix % that will allow me to give full power and do a k/e loop, for instance. Anyone have any tricks or tips or can refer me to a thread/articl/site for some more info.
Old 01-31-2005 | 10:30 PM
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Default RE: Trying to trim out k/e coupling

A couple of topics previous to this one on the "IMAC" forum I found some good info located at the Aircraft Proving Grounds website:

http://www.geistware.com/rcmodeling/...tics/setup.htm

I am sure there are more articles out there, but this should get you started in fine tuning. Specifically reguarding multi-point mixing. Checkout set-up #2 as well.

Wheels up!
Old 02-01-2005 | 08:49 PM
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Default RE: Trying to trim out k/e coupling

I have really good mixing for nice stright knife edge, but I still have to work the elevator a LOT in a knife edge loop. As wind conditions change you are going to have to learn to fly through it. Typically even on a perfectly calm day, when I come over the top and through the 3rd quarter of the loop coming downward I have to really hold a ton of down elevator to keep my distance out consistant. Once I level out in knife edge at the bottom its hands off everything but rudder again.

I also find that in extremely high alpha low speed knife edge it changes again, theres just no way to mix for every condition. You should just mix it out for staright and level knife edge flight straight into the wind and then just learn to fly it through everything else.

Mike
Old 02-01-2005 | 11:31 PM
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Default RE: Trying to trim out k/e coupling

Spoiler-I set low rate rudder to be just enough to hold knife edge and do that maneuver and four- and eight-point rolls at full throttle. You may notice that left and right knife edge require slightly different amounts of rudder and ail and ele coupling because of P-factor/torque. If you can't hold the nose up with a little rudder move the CG back; check by needing only a small amount of down to hold inverted. Jim
Old 02-03-2005 | 05:41 AM
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Default RE: Trying to trim out k/e coupling

Thanks guys, will keep on tweaking and flying!
Old 02-03-2005 | 10:13 AM
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Default RE: Trying to trim out k/e coupling

Also remember that Rud>Ele mix is not liniear. The mix is speed senasitive. the fast you fly the less rudder required the slower you fly more rudder is needed. As you increase rudder the mixing percentage changes. Some people do this mix on a curve mix so they can compensate for the amount of rudder used. Others use a linear mix and try to fly at the same speed.

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