Another thought about bellcrank design. Usually, at least in my aircraft, the holes for the bellcrank pivot and the leadout connections are aligned. Some very successful models have the leadout connections slightly further (e.g., 1 cm) towards the leadout guide. This creates a kind of overhang on the bellcrank similar as on the handle. This would provide extra inherent stability to the model itself. These pilots then fly with a handle with minimal overhang. I can understand it, but I prefer the overhang on the handle so I can play with that parameter without having to adjust my model. I have handles with varying degrees of overhang. A lot of overhang in calm conditions. Little overhang in heavy winds.
It's clear that in strong winds with higher speeds, in loopings, a large overhang requires more steering force. You have to twist harder against the centrifugal force. Much less twisting with zero overhang, but still clearly noticeable because the pivoting is not on the handle, but rather on the wrist. I assume a selfcentering bellcrank is not helping here either.
If you follow this line of thinking, namely that strong winds make steering more difficult, why not destabilize the bellcrank by shifting the leadout connections on the bellcrank, towards the other side relative to the pivot? It seems to me that in such a case, the extra centrifugal force from the wind/speed could help you fly the figures with less steering effort. In lighter winds, you could compensate for the instability with a handle with more overhang. I did not find any experiments with this kind of setups on this forum..

Here is the bellcrank from the Granderson Olympic, after its demise. It looks pretty much like a stock J.Roberts crank like the C-25 that Brodak sells. The installation was nicely done. No question that the plane was flying very well in Tim's hands....

Dave

Howard,

You have to remember to teach your new initiates to the JCT not to do combat with the ground! Flying an Oly is stunty stuff...and the ground should not be a tactic, even if they are feeling "contrary"...

The Divot

The last SIG bellcrank introduced was of the self-centering or non-self-centering type, depending on whether it was installed correctly or incorrectly. I believe it was designed by Mike Pratt, who also designed the Primary Force and many other good stunt designs. On the Primary Force plans, the bellcrank is one of those, and it's shown installed "reversed", i.e., de-stablizing. The link shows a picture, now on the Brodak site. I'm not sure if this is the only 4" B.C. that Brodak sells. Steve
https://brodak.com/sig-4-nylon-bellcrank.html 

Just put the holes straight across and go fly.

I have only had an offset (away from the center) one time and I didn't like it.  It was probably not the bellcrank but I still never did it again.  Have we reached any form of answer here?  Which is in theory better?  My stash of 5" printed bellcranks are shaped to be drilled up to 5 degrees either way.

      I want my system to be neutral. But I note that we all used "straight" bellcranks for years that were unstable to various degrees without even realizing. I think Howard is working up to claim that while the bellcrank forces might be unstable but that when you hook it to a control surface, the system as a whole is stable (since while the bellcrank wants to deviate from center, the torque from the control surfaces is in the opposite direction). That would count on the restoring force from the surfaces to require torque faster for a given angle than the bellcrank provides. I don't know if it is true or not.

     Brett

Id found the negitive offset leadouts , definately , when ' it was blowing ' so the handle was ' loaded up ' -
 ;
That , in rounds , the pulled line had way more load , than the other . SO you let the bottom off the handle do the ' fine toonin ' . i.e. de egging .
as it was way more sensitive & lighter . than the one trying to pull you over .      ( Bobs ' top & bottom ' control ! )

This thing had a heavy 3/8 thick wall aluminum pushrod . As a ' damper ' . And Ears on the elevator ends . To balance control loads .
Flying light in clean air , there was alost a ' schnick ' ( as it were ) as you ( with familiarity ) threw on or reversed control .
As in ' 8 ' intersections , etc . more dicernable .

As this one never hit the deck , despite flying in 20 / 25 mph winds , at times . And downdrafts & turbulance from trees . I thought it o.k.
Sort of winds that hold it down & delay vertical turn downwind . WHICH brings up ' Tracking ' & ' Groove ' which it'd do . Even on an aft C G .
( High Point of airfoil / AT bellcrank pivot .

So theres a thing .

Flaps & tail were TOUGH  New Guinea Quater grain , so stiff . Tho I thought the elevator horn coulda been stiffer . Re the ' Hold Down ' mentioned .
This thing atb 70 ounces twanged  7 strand steel 18 thou. lines in lower Sq  turns , when you needed two hands ( and golf shoes on the damp field )
and stretched .016 solids discernably . When the gales off November came early . as it were . was .

BUT . the Bellcrank - gave that ' schnick / schnick ' control precision /in ordinary conditions . When the lines wernt stretching .
On the 16s in gales it gave the elastic rubbery feel , under duress ( working hard manouvreing . Did the full schedule nearly all flights )

SO . Ya gotta watch yer rubbery lines arnt attributeinng to your ' control issues ' . Missdiagnoseing darting dodgeing flight as aircraft . When its actually your control wires .

Pitcher offittr , for the reckoid .