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Old 08-02-2017, 06:52 PM
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Dave Harmon
 
Join Date: Jul 2002
Location: Sperry, OK
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Originally Posted by ltc
I have a quick setup question that I'm hoping someone can answer. I've never seen a trimming guide that discusses a full flying stab.

When setting up a conventional wing and tailplane, you normally set the incidence angle on the wing relative to the stab (ignoring thrust/datum line for this discussion). Say 0 deg reference on the stabs and then +0.7 deg positive on the wing.
Based on test flight trimming you then adjust the wing incidence, again relative to the stab, to minimize any elevator trim needed. (I know there is more to it than that, but I'm simplifying for this discussion)

However, on a full flying stab, if you initially set the incidence on the wing relative to the stab, and then have to add trim to the stab, you have adjusted your incidence by default. There is no elevator trim to adjust, since you are adjusting stab/elevator all at once.
Do you just leave it as is?

Am I missing something obvious?

Thanks in advance.
Just use Brian Hebert's Triangle Trimming method but ignore the stab setting.
Use his initial thrust and wing settings....sounds like you are setting up a BJ airplane....if so....use BJ's incidence jigs and start there....note that BJ likes to fly extremely tailheavy so be sure the battery is well fwd.
The Essence/Nuance/Etude should balance a bit fwd from the wing attach bolts....this is a good starting point then move the battery back and forth about 1/4" at a time because this point is right at the teeter point and a little battery movement makes a large change.
Your Prolog was trimmed using TT.......of course it has elevators but the procedure is the same.