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anti-servo tab

Scot Dahlgren wrote,

"I was considering adding an anti-servo tab to my small tail. can anyone tell
me;

-the dimensions of the servo tab on the bigger tail (lxw)
-the gearing (how many degrees servo tab up for 10 degrees tail up)
-the dimensions of the big tail."

to Scott and others:- in Australia people are using anti-servo tabs initially to please our aviation authority, who require the back pressure on the elevator control to be increased and for reasons that have been subject to test and discussion for some years.  Generally these anti-servo's consist of a linkage which causes the trim tab to increase in angle as the elevator is moved in the same direction thus increasing the returning force.
We measured the net angular effect of one of the trim tab linkages used here on a machine that is flying and the owner is pleased with the feel and response and we are incorporating the same angles on the larger Mk11 tail, the measurements are as follows:-

(a) If the elevaor and trim tab is initially in the in line with the tail plane ie, the centered position to begin with, then moving the elevator to its maximum up position(+26 degrees) will cause the trim tab to move (rotate) +22 degrees up and  if the elevator is moved to its maximum down position (-11 degrees) then the trim tab will move (rotate) -10 degrees.
(b) If the trim tab is already up the maximum amount (+30 degrees) when the elevator is centered in line with the tailplane then moving the elevator to the maximum up postion (+26 degrees) will cause the trim tab to move from +30 degrees to +54 degrees and moving the elevator to its maximum down position (-11 degrees) will cause the trim tab to move from +30 degrees to +18 degrees.
(c) If the trim tab is already down the maximum amount (-30 degrees) when the elevator is in line with the tailplane then moving the elevator to the maximum down position (-11 degrees)  will move the trim tab from -30 degrees to -42 degrees and moving the elevator to the maximum up position will cause the trim tab to move from -30 degrees to -2 degrees.

Scott or others if you are interested we have a drawing done by one of the partners in our project showing how we very simply moved the ESCO trim actuator to achieve the desired result.  If anyone is interested please email me and I will and I will send it as a pdf file or fax it to you if there isn't many.  Please bear in mind our plane is nearing completion but has yet to be flown and tested.

Chris Moore