Winter project, tow out gear - wing wheel

bildan wrote:

I've watched people try to perfectly align non-castering wing wheels
for years. The slightest mis-alignment will get worse the further the
glider moves until they have to stop and re-align it. With a flapped
glider, this has to put unnecessary force on the flap hinges.

My non-castering wing wheel cuffs the right aileron which is free to
move. But a snug fitting cuff will *not* move if on straight. I
achieve a perfect and snug fit by molding the cuff in place on the wing
with Great Stuff insulation foam spray. Again, one quickly learns how
to put the cuff on straight first try. It's no problem, really.


The tow out bar itself will need some careful re-design. The
accidents I have seen and read about all seem to involve a failure of
some kind with the tow out bar. Mostly this is the glider tailwheel
jumping off the bar leading to a jackknife-type accident. I like a
tow-out bar that lets the glider roll on the tail dolly wheel. Maybe
this means vertical-only compliance so the bar remains straight aft
eliminating the possibility of a jack-knife.

Some have expressed concern over the diameter of the wing wheel. Any
concerns over the diameter of the tail dolly wheel?

I have built a tow-out bar for a LAK-12 and have no concern about things
coming loose such as the tailwheel jumping off the bar. Not exceeding 5
mph is part of that lack of concern.

One thing I'm not in love with, regarding the conventional tow-out bar,
is the torque applied to the fuselage between the tail dolly mounting
location and the tailwheel location. This torque is a function of the
weight of the empty glider at the tail and the lever distance between
the tail dolly cuff and the tail wheel. Your idea of allowing the
fuselage to ride on the tail dolly wheel eliminates this torque. I've
thought about this before but haven't tried anything.

Regards,

-Doug