On Feb 1, 10:26 am, "
wrote:

Those that think a "negative caster" tail wheel would just flop
sideways, or even swap ends if not restrained are forgetting about
choosing a pivot angle to match. With the proper pivot angle and
weight on the tail the system can be stable up to a point.

The only "stable" arrangement is tire/surface contact behind the pivot
axis/surface intersection point, with the pivot vertical or angled top-
back a little. And that stable arrangement applies to both trike and
tailwheels. If you photograph a trike from the side, as I have done,
and draw a line through the nose strut axis, as I have done, you will
see that the pivot axis, being angled, intersects the surface ahead of
the center of the tread area. It's the same principle found on a
bicycle. Anytime you try to put the tread contact ahead of the pivot
you are creating an unstable arrangement that simply won't work.

Furthermore, neither arrangement will offer any stability if the tail
is off the ground. A taildragger is still a taildragger even when it's
moving with the tail up a bit, and the pilot MUST control it with his
feet. Every so often someone tries to tame the taildragger by
proposing complex solutions, and it could be done with computers and
servos and a whole lot of stuff, but it would be about as much fun and
take about the same skill as driving a kiddy car.

Dan