On Mon, 1 Feb 2010 09:26:27 -0800 (PST), "
wrote:

On Feb 1, 3:54*am, Stealth Pilot wrote:

I believe that the original poster has a problem but is off on the
wrong track trying to solve the problem.

I may be off on the wrong track, but don't have a problem with
'draggers, in general, or particular.

Just have the desire to tinker and see if I can improve the ground
handling a bit ....... and see if I couldn't stir up a bit of
discussion on the group.

One goal accomplished.

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.

For an analogy consider flying a plane that has it's CG behind the
neutral point and an all flying horizontal stab. This is essentially
what a tail dragger is on the ground.. Move the pivot of the stab
back behind the aerodynamic center and add an anti servo tab linked to
a mass. The whole system will never be stable, but can be self
stabilizing with in a narrow range.
======================
Leon

leon
most successful tailwheels have the pivot axle vertical.
weight and cg position on a taildragger are largely irrelevant to the
tailwheel setup because they dont come into play.
what is important is that you apply full aft stick once the touchdown
has been effected. it is the download from the elevator that gives the
tailwheel its incredible authority on the ground.

be very careful here with your experimentation. this is one area of
aircraft setup that can work well or work absolutely horribly with not
much difference apparent between either state. the rudder shimmy
problem I mentioned before occurred with just one spurious turn of a
1/4 x 28 thread on the link arm.

one of the causes of poor tailwheel performance is the slop in the
attachment of the tailspring to the fuselage. on a lot of aircraft
with poor tailwheel control if you push the wing tip up and down you
can see quite a lot of movement in the tailwheel because the whole
setup is actually quite loose. the spring should be rock solid with
wing wiggle.

I'd make the point as well that people focus on the taildragger as
having groundloop tendencies. if you want to see a real groundloop
just wheelbarrow a trike on on its nosewheel without putting the mains
down. that can be tinsel ball stuff. I know of one commercial pilot
who gave up flying after wheelbarrowing and groundlooping a Cherokee
140.

enjoy the experimenting.
Stealth Pilot