Just to be clear - the aspect that interests me
are experimental amateur built designs that attempt to "simplify" aircraft
controls. So the Spratt design is the sort of design I'm interested in
learning about.


We seem to be overlooking the obvious here. Wright Brothers machines
didn't have rudder pedals until at least 1916. Long after either of
the Wrights were designing them. The controllable rudder was designed
and built at Kitty Hawk between Oct 18 and Oct 21, 1902 for the 1902
glider. According to thier notebooks, it was Orville's idea to control
the rudder, but Wilbur's idea to incorportae the mechanism into the
existing roll controls. This was done by means of two wires that were
attached to the rear transverse warping wire on either side of the two
rear center wing struts.

By moving his hips side to side, the pilot slides the hip cradle which
pulls on one of the front wires while slacking the other. The front
wires run out to the wingtips parallel to the leading edge, through
pulleys on the lower front wingtips, and then up to the trailing edges
of the upper wing. As the wire pulls, the lower leading edge and upper
trailing edge are compressed toward each other forcing the biplane
wingtips to become parallelogram wingtips. Now here's the fun part.
The rear wire is passively controlled. It runs from one upper leading
edge wingtip down through a pulley on the lower trailing edge wingtip,
accross the wing parallel to the trailing edge, through another pulley
on the lower trailing edge wingtip, and then up to the the upper
leading edge wingtip. The action of warping the wing into a
parallelogram increases the distance between the upper leading edge
and the lower trailing edge. That pulls on the wire, which compresses
the lower leading edge and upper trailing edge, opposite of the other
wingtip, ergo, roll control. Now with those two rudder wires attached
to that rear warping wire, one gets pulled and the other gets slacked
when the wire slides back and forth. Its actually a VERY simple design
once you see it.

The 1903 and 1904 machines used a similar design, although the actual
placement of the parts was a little different. But by 1905, the
machine had enough power and stability to handle a seated pilot. A new
control system was devised which kept the earlier machines' lever
actuated elevator. But for roll and yaw, a second lever was added. The
top 8" of the lever was designed to hinge sideways, parallel to the
leading edge. Pushing and pulling the new lever fore and aft warped
the wings, while hinging the top of the lever right or up controlled
the rudder. Sounds kinda complex and goofy, but it worked and kept the
pilot's feet free to help hold onto the machine.

Harry "bitchin' hip-cradle bruise" Frey