RE: Hangar 9 30cc P-47 Build Thread
It is now time to fit the servos to actuate the gear doors. I used a square piece of balsa that was 3/8 of an inch thick as the base to mount the servo to. I sanded a slight contour to the side of the balsa that matches the airfoil. Servo is mounted using a servo tape. The arm is a standard JR arm using the longer side of the arm and the outer hole. The balsa block is the same size as the servo case and butts up against the spar and inner rib. It places the servo to about the perfect location for the door operation. The pushrod is 2-56 threaded rod and uses (2) Hayes Clevis's for actuation. Any clevis can be used; I just grabbed some out of my box.
I adjusted the servo linkage to where I was driving the servo at 140 - 150% of travel for total travel. I also used the DX18 gear door sequencer to sequence the gear door operation to the main retracts. This makes it easy and you do not require any additional radio accessories to complete the system. Also you will need to position the servo for the left wheel well door as shown in these photos. The servo for the right wheel door is positions forward of this door with the arm swinging over the back side of the servo. By setting the servos up this way I did not need to use separate channels for each door servo.
Pics #1, #2, and #3 show the servo installed and door pushrod position.
The control horn shown on the gear door is made from 1/16 inch plywood. The hole is 3 of an inch from the bottom and the horn is positioned to set the hole at 1/2 of an inch from the inner edge. Doors are actuated from the aft side of the door.