Jump to image

Builder's notes:

• The major cross piece (unpainted) here is the rear wing spar carry-through structure and serves as the terminal support (through plastic bearing blocks) for the control stick torque tube (the lower of the two aluminum tubes, central and nearly vertical in the pictures, and just showing beneath the elevator push-pull tube).

• The rest of the rectangular structure aft of the rear wing spar (unpainted but well-varnished for protection of the wood) supports the aileron torque tubes and their connection to the universal joints which convert the left-right rotation of the control stick torque tube to the forward-aft rotation of the aileron torque tubes (the slightly gold anodized tubes going to the left and to the right in the pictures) required to pivot the ailerons up and down. The vertical motion of the T-flange terminating the control stick torque tube, measured at the bolt hole center where the top end of the universal joint connects, is 1-7/16th inches, plus-or-minus 1/16th inch. This represents the maximum side-to-side movement of the control stick, and the maximum up and down deflection of the ailerons (about 20 degrees from the chord line of the wings).

• These pictures also show the elevator push-pull tube connection from the control stick to the longer section running back through the tail section, but only the top one showing the bracket pivot structure involved. This mechanism is fairly straight forward where the torque converter is a bit harder to visualize from the plans.

• I added triangular corner blocking to every part of this support structure. It is, in understatement, a critical system of the aircraft, and the plans did not call for much blocking to increase the wetted area of the pieces being epoxied together. This may be overbuilt, but I would never have been comfortable with less than you see here, especially in an area which can only be adequately examined by removing the rear seat shelf.

• You can just make out some white circles underneath the mechanism and support structure. You are looking at the inside of the airframe covering fabric, and these are inspection rings with cloth patches which have not been cut away and replaced with inspection plates. Their purpose is not for inspection which can be done as you see here, from the top, but for possible future access in using tools on the nuts and bolts from below as well as above.

• The three small white circles just forward (above) the rear wing spar carry-through are patches over drain grommets, installed for when water may get into the cockpit. I'd rather it exited here amidships than collect back in the tail section, though there is at least one drain grommet at the very end of the tail section fabric.