I'm still searching for some answers, and I just keep coming up with more questions. The basic problem is this:

 

When I lower flaps on my 360, there is not enough pitch trim to take out the nose up stick force required to keep my pitch attitude.

Scotty,

 

In general, more information is required - CG, airspeed, flap deflection angle, trim tab size, etc.

 

But first, some observations and comments.

 

If I remember correctly, the flap range is -7* to +45* as measured from faired in to the TE fuselage fillet being -7*.  You can check this range on the ground by using a digital level.  I am sure you have noticed the tremendous pitch change (nose down) as the flaps are deployed.  I think there should be some old e-mails around where I affixed a digital level to the longeron and checked aircraft angles at several speeds and flap angles and the aircraft pitch angle change was as much as 6*.  I am also sure that you noticed the pitch change from slowing down to, say, 100 KIAS while the flaps are in full reflex (-7*), resulting in a strong nose up AOA.  So, one can consider that the flap position also contributes to aircraft trim at certain airspeeds.  Just as wheels down also introduces drag, pitch down and CG moved slightly forward (nose gear). 

 

I am sure that you have read here that some almost never go beyond about 30-35* flap extension when landing.  This can affect how much nose up trim would be required.

 

If you don't have a flap position indicator, you can position the flaps to various positions on the ground and, using a marking pen, mark the flap position against the wing TE out by an aileron (unless the builder cut off most of the flap leading edge).

 

As to your specific question, another question: At what flap deployment position do you lose the ability to trim for a specific attitude?  Please note that some of us could argue that maintaining a fixed descent rate (fixed attitude) and airspeed at say, 100 KIAS with flaps at about +10* (+ 17* from faired in)  is very difficult.  A little pitch change yields a speed change yields a pitch change........ and the same is true for a speed variation.  If you have an AOA indicator and are trying to maintain a steady indication, good luck!  Darn persnickety wing if you ask me. 

 

If your problem is only at full flap deployment (final approach to landing), don't fully deploy them.  Frankly, I can't find a steady state trim position during that flight stage and prefer some feedback to my hand anyway.  Of course, that may be because I am using the Reichel trim wheel spring system for the elevator which results in a "dead band" of low force/hi sensitivity - perhaps unlike a tab which has more constant air forces positioning the elevator.  Hmmmmm, I guess that speed changes would change the effectiveness of the tab at certain set positions.

 

BTW, is your elevator arm 3" or 4" - this is the length of the bellcrank arm extending down from the elevator to the rearmost elevator pushrod rod end.

 

Oh, how much force is required to overcome the lack of trim?  1#, 2#s...?

 

Anyway,

 

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