Dave Mackintosh wrote: ↑24 Mar 2021, 21:29
I have also prepped the fin to receive the elevator servo. I can see this will be a pain to rig at the field, so I will either leave the stab in position, Or....................... any ideas chaps? Maybe some quick release clevis? Your thoughts folks.
Thanks.
Dave, FWIW, I'm mounting the elevator servo in the top of the fin with mounting access through the tailplane seat.
The pushrod is horizontal (parallel to the tailplane) and exits through a small hole in the fin post just below the elevator.
On the end of the pushrod is a ball link (see image).
The corresponding sized pin to suit the inside of the ball, drops perpendicular from the elevator.
Connection is just a case of aligning/guiding the pin into the ball, seating the tailplane and then fastening the tailplane bolts.
The height and size of the hole in the fin post determines the amount of "float" in the pushrod so
once the pin is in and tailplane bolts are tightened, the pin can't come out of the ball.
On a scratch built 25% Pilatus B4, the pushrod was vertical, parallel to the fin post.
All I had there was a 90 degree bend at the end of the wire (parallel to the elevator hinge line), with the termination about 10-12mm long.
In the elevator, set back from the hinge line about 20mm, was a control horn with the corresponding sized hole for the wire.
Connection was a matter of sliding the horn (read as 'the tailplane') sideways onto the wire completely to the bend.
At that point, the tailplane bolts aligned with the bolt holes in the top of the fin.
The sideways "float" of the pushrod is limited to the size of the pushrod exit.
Limit the sideways float of the pushrod such that it is impossible for the wire to come out of the control horn without removing the tailplane.
I flew that model hard. Slope aerobatics, winch launches etc at no point was I ever concerned about the elevator connection.