Scorpion Mk 2 build day 4.


Here are some details about the stabilizer setup.

I made a plywood setup rig for this. It will be provided by Ultimate Jets.

Glue the two square blocks on either sides of the setup rig with 5 minute epoxy. The block end should be stopping just at the middle of the stabilizer pivot hole.

Make sure that the plate is vertical during gluing. 




Install the servo on the plate with two screws only.

Slide the stabilizer tube into the plate hole.

It is important to follow the steps below to ensure that no excessive rotation forces are exerted on the pivot tube when installing the aluminium arm.

 Remove both clamping screw from the arm. Insert a slotted screw driver bit for screw size bit so that the flat bit goes into the clamp slot. Squeeze the bit with a long neck pair of pliers to insert it into the slot thus widening the clamp size. The arm should now slide completely freely into the pivot tube.

Leave the drill bit in position till the arm is set on the pivot tube inside the fuselage.





The arm  must be flush with the tube end. The tapped portion of the clamping screws hole should be facing forward. This is extremely important. If the tapped side of the clamp is facing rearwards, no clamping action will be possible when you fasten the socket head screws.

Prepare the control rod. The ball links must be installed so that the bronze crown is facing outwards ( see the picture of the servo ).




Use the M3 socket head screws and lock nut. The head  must be installed on the inner side or the arm. Do not tighten yet as you will need to adjust the length of the pushrod later.

Place the stabilizer so that the trailing edge is 5 cm above the work bench surface at the tip, with the setup rig sitting flat.

Place the aluminium clamping arm vertical. Drill a 3 mm hole in the servo arm at 7 mm from the rotation axis. Insert a M3 socket head screw in the arm, head facing inwards, to the servo. Place the front ball link so that the bronze crown faces outwards. Fasten with a lock nut.



The assembly should look like this.



Plug the servo into your receiver with the trim at zero. Adjust the position of the servo arm on the spline so that it is vertical. Verify the position of the stabilizer on the work bench. Verify that the aluminium clamping arm is vertical. Place a drop of thread lock liquid and turn the ball links to adjust the length of the pushrod accordingly. When everything is setup square, fasten the servo spline screw and verify that the ball link lock nuts are tight.




Remove the whole assembly from the setup rig and position in the fuselage. Fasten the servo to the mounting plate with 4 screws. Plug the servo to the receiver and pull the elevator stick full nose up. Move the stabilizer trailing edge so that the root is set 45 mm above the trailing edge of the fuselage. Remove the slotted #6 bit and fasten the tow clamping screws on the aluminium arm using two drops of locking fluid.




Using the slotted bit is very important to get the clamp wide enough so that it slides into the elevator tube without having to exercise any torsion effort on it.