AH-56 Cheyenne - Tail Mechanics Assembly

The Cheyenne build can be simplified considerably by installing a conventional tail rotor, but for me the compound tail with its variable pitch pusher prop was a big part of the attraction of this project.  There are a few parts that require precision machining, but most of the tail assembly can be completed with fairly basic tools. 

Here's the tail unit for the Align torque tube tail kit which was the key to this project.  You'll need an extra side frame, so a spare tail unit is required.

Here's the simpler version of the pusher prop's journal bearing block.  I later designed a more complex version with anti-rotation lugs, but this version is easier to make and works just fine. 
The rear bevel gear is drilled out, and a spare tail rotor shaft is press fit into place.  The prop shaft is then supported by this bearing block and a 3mm bearing.

Because the tail rotor is moved to the end of the stabilizer, an anti-rotation arm is needed to keep the control slider from flopping around.  I made this from a plastic mixing arm from the junk bin.

Here's the tail unit during the flight testing phase of the project.  Note how the pusher prop shaft is supported by the journal bearing.  The stylish purple standoffs are cut from 4mm knitting needles.  The tail rotor shaft is a 120mm piece of finish ground 3mm stainless drill rod.  Note the nylon thrust collar that keeps the thrust of the tail rotor from driving the bevel gears together.  Note that a new pivot point for the anti-rotation arm must be drilled and tapped to insure that it clears the tail rotor hub.  The mount for the tail control arm is fabricated from carbon fiber or fiberglass plate and clamps onto the 4mm standoffs.  A lot of little details, but none of them very hard.

Here's the custom offset tail control arm that was assembled from K&S brass tubing and I-beam.  Be sure to use silver solder and sufficient flux for strong joints.

Here's another view of the tail unit, this time showing the brass offset bellcrank.  Note again the relocated pivot point for the anti-rotation arm and the thrust collar on the tail rotor shaft.

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