>Would you please outline how you transmit the movement to the tailwheel
>and where the springs are located relative to the idler arm and the
>tailwheel. It should be relatively easy to obtain a new arm for you.
>Regards,
>Ken Whiteley
It is a bit awkward to describe without a drawing, but perhaps you can follow
the description below and make a drawing from it.
The idler plate is 3" long by 4.5" wide by 0.19 thick steel. It has a collar
around the tailwheel shaft to allow the idler plate free rotation. The aft
edge is a duplicate of the original tailwheel arm so the rudder limits are
imposed by the original tailwheel stops. It has a stud welded into a hole
located exactly above the original rudder drive bolt hole. The idler plate
sits on top of and in contact with the tailwheel arm, which is held down by
the collar; grease is used between the plate and the arm to allow free
movement.
Eyebolts will be cut off and welded flush to the tailwheel arm in the holes
originally intended for cables. The eyes will protrude from the bottom of the
arm and will be oriented so the eye opening is tangent to the circle centered
at the tailwheel shaft.
Eyebolts are also used in the idler plate, located forward of the tailwheel
arm and at the same radius as the original cable holes. Spacers are used below
the plate so the eye is at the same distance below the tailwheel arm as the
eyes on the tailwheel arm. These eyebolts/spacers are located so that they
will contact the tailwheel arm when rotated about 15 degrees, thus limiting
the spring driven steering to +/- 15 degrees, after which these stops provide
direct drive to the tailwheel as in the original design. Changing the spacer
diameter will allow changing the differential movement limits slightly if
necessary.
6-32 (8-32?) bolts connect through the eyes on the tailwheel arm and the
idler plate, one on the port side another on starboard. A compression spring
will be located on each bolt, forward of the idler plate eye; pre-tension will
be adjusted by tightening this spring against the eyebolt. Port and starboard
6-32 bolts must be adjusted commensurately. Rotating the idler plate further
compresses the spring on the forward moving side, pressuring the tailwheel to
follow.
Drive to the idler plate is via cables from the pedals to the top of the
eyebolts where another (smaller) spacer is placed above the idler plate, held
in place with washers and a nut. Since the rudder is driven directly from the
idler plate, it leads the tailwheel when a pedal is depressed.
While light and simple in concept, there are quite a number of small parts
needed; fortunately, most are inexpensive. Cost so far is under $25, plus the
extra tailwheel arm whose cost is presently unknown. If all else fails, $5
worth of steel and a LOT of filing should make a second tailwheel arm. Once
the design is proven, one won't need a second arm, but I need the original
setup as a standard for comparison until I'm satisfied with yaw handling on
the ground.
Anyone want to sell their excess tailwheel arm?
Comments?
Regards,
John A044 Newtown, CT USA
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