tailwheel setup question

how does one decide to use a "cable" versus "spring" for the connection
between rudder horn and tailwheel assembly horn?

how tightly connected and what strength spring, etc?

Thanks
Dick (an evolving tricycle driver G)

On May 15, 2:43 am, "Dick" wrote:
how does one decide to use a "cable" versus "spring" for the connection
between rudder horn and tailwheel assembly horn?

how tightly connected and what strength spring, etc?

Thanks
Dick (an evolving tricycle driver G)

Shouldn't use just cables, as you could lose rudder control if
the tailwheel pivot seized up. Springs are better. Springs also allow
the tailwheel to move up and down on its suspension without having
cables too tight or loose as it travels up and down.
That said, I have seen tailwheels steered with a single push-
pull rod on some homebuilts. I wouldn't be comfortable with that.

The spring takes some experimentation. You need them stiff
enough for good control, but soft enough that you can unlock the
steering easily when you want to (if it has the full-castering
feature). The springs need to allow the wheel to travel beyond normal
rudder travel so that the lock will release.

Dan

On Thu, 15 May 2008 15:59:55 -0700 (PDT),
wrote:

On May 15, 2:43 am, "Dick" wrote:
how does one decide to use a "cable" versus "spring" for the connection
between rudder horn and tailwheel assembly horn?

how tightly connected and what strength spring, etc?

Thanks
Dick (an evolving tricycle driver G)

Shouldn't use just cables, as you could lose rudder control if
the tailwheel pivot seized up. Springs are better. Springs also allow
the tailwheel to move up and down on its suspension without having
cables too tight or loose as it travels up and down.
That said, I have seen tailwheels steered with a single push-
pull rod on some homebuilts. I wouldn't be comfortable with that.

The spring takes some experimentation. You need them stiff
enough for good control, but soft enough that you can unlock the
steering easily when you want to (if it has the full-castering
feature). The springs need to allow the wheel to travel beyond normal
rudder travel so that the lock will release.

Dan

Dan
my tailwind uses a rod setup.
the previous owner tried three setups prior to the rod and each was
almost unflyable judging by the comments previous pilots have made.
they were all spring buffered setups as you describe.

on a really sensitive aircraft the tapered spring and rod setup on
wittman's W8 plans is superb with one caveat.
wittman got the gearing wrong.
I have found that having the bellcrank distance the same as the
tailwheel swivel distance results in a hugely overgeared tailwheel.
making the bellcrank length half of the swivel length has made the
tailwind an absolute pussycat to land and takeoff.
this same setup is used on many pitts specials.

the answer for the original poster is that is a matter of fashion.
pick whichever you like.
if your aircraft is *really* sensitive to land and takeoff you'll
eventually use the rod setup that dan eschews.

make bloody certain that the neutral 'steers straight ahead' point of
the tailwheel coincides with the neutral 'flies straight ahead' point
of the rudder or you will scare yourself. :-)

Stealth Pilot