Time to verify that we have our transmitter configured properly to control our servos.

To be honest, you’re best to watch Bob White’s video on how to do this.

  1. Connect the three head servos to the receiver
  2. Make sure there is nothing blocking the servo arms.  When the heli powers up, the servo arms may move slightly.
  3. Power on your transmitter.  Set the throttle to low-stick.
  4. Power the helicopter.

NOTE: the linkage rods from the servo to the swash plate are too long at 19.5mm.  The manual says 19.5mm, however, this pushes the swash plate too high and limits your pitch.  I reduced the length of these linkage rods to ~17mm (6 full turns).  It helped.  It still binds, so I probably could have gone lower, but for now, its good enough.

Step 35 – Get All Three Servos Working in the Same Direction

  1. Get PITCH working first.Push the throttle stick UP
    1. Do all servos go up.  If YES, then they’re all working together.
  2. Get AILERONS working second.
  3. Get ELEVATOR working third.

In order to get all three servos working in the same direction, I had to reverse the following servos on the Futaba transmitter:

  • REVERSE -> CH1 – Aileron (left servo) had to be reversed.

When tilting left or right, the swash plate was tilting in the opposite direction, so I had to adjust the swash plate setting on the radio.

  • SWASH:
    • SWASH -> AIL= -50%
    • SWASH -> ELE= +50%
    • SWASH -> PIT= +50%

Step 36 – Get Servo Arms at 90 degrees.

  1. On the transmitter, ensure all the trims are zeroed.  Do the following:
    1. SUB-TRIM and ensure all channels are at 0:
      1. SUB-TRIM -> AILE = 0
      2. SUB-TRIM -> ELEV = 0
      3. SUB-TRIM -> PITC = 0
    2. PI-CV (N) are at 50% when at mid-stick:
      1. PI-CRV(N) -> P5 = 100%
      2. PI-CRV(N) -> P4 = 75%
      3. PI-CRV(N) -> P3 = 50%
      4. PI-CRV(N) -> P2 = 25%
      5. PI-CRV(N) -> P1 = 0%
    3. The on-screen display shows trims in middle.  If you pushed the faceplate trim buttons away from middle, they beep once.  Upon return to the middle position, they will double-beep.
  2. Set thumb sticks on the transmitter to mid-stick.
  3. Push the servo arms onto the servo motors at 90 degrees.
  4. Use the sub-trim in the radio to position the servo arms to be at 90 degrees.
  5. Here are my SUB-TRIM offsets:
    1. SUB-TRIM -> AILERON:  +31
    2. SUB-TRIM -> ELEVATOR: +44
    3. SUB-TRIM -> PITCH: +30

Step 37 – Swash Plate Leveling

  1. I purchased a swash plate leveling tool.   Refer to this YouTube video:

http://www.youtube.com/watch?v=C2S39oj_iaw

  1. In the video above, he adjusted his sub-trims on the radio transmitter to get the swash plate level.  I did not do that.  Instead,  I adjusted the three linkage rods.  This allowed me to keep the servo arms at a right angle 50%.

Step 38 – Attach Head

  1. Slide the head back down the shaft and attach to the swash plate.
  2. Ensure that at mid-stick the make sure the linkages are all level.  See the black horizontal line below.

Step 39 – Get the Blade Grips to Zero Pitch

  1. Need to get fly-bar at a right angle to the shaft.
  2. Put the throttle at mid-stick.
  3. Ensure the top flat part of the blade grips are level with the top flat part of the head OR use a pitch gauge to ensure the blades are level with the fly-bar cage.
  4. If they are not level, then adjust the shorter linkage rods going to the see-saw, not the longer rods.


Step 40 – Swash Travel Range

When I push the left thumb stick (throttle) to the maximum, it pushes the swash plate up the shaft and it hits the head.  This causes the servos to make a buzzing sound.   So I need to limit the servo’s travel distance using the transmitter.   Go into the SWASH menu and push set the PIT to 10%.  Push the stick all the way forward.  Now rotate the dial and the swash plate will rise towards the head.  Once it hits the top, then back off a bit and that will be your PITCH setting.

The issue is that the linkage rods from the servo to the swash plate are too long at 19.5mm.  The manual says 19.5mm, however, this pushes the swash plate too high and limits your pitch.  I reduced the length of these linkage rods to ~17mm (6 full turns).  It helped.  It still binds, so I probably could have gone lower, but for now, its good enough.

For my Futaba T7C, I use the following swash settings…which are the defaults:

  • SWASH -> AIL = +50 %
  • SWASH -> ELE = +50 %
  • SWASH -> PIT = +50%

If you are still getting binding, the reduce the SWASH->PIT value until the binding stops.