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
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
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