Tailwheel

While discussing tailwheel weight I wondered why we need a tail dolly?
Why do most modern sailplanes have fixed tailwheels yet SGS gliders
have castering tailwheels. Shouldn't we have a caster instead?

On Wednesday, December 12, 2012 11:05:28 AM UTC-7, soartech wrote:
While discussing tailwheel weight I wondered why we need a tail dolly?

Why do most modern sailplanes have fixed tailwheels yet SGS gliders

have castering tailwheels. Shouldn't we have a caster instead?

Good luck on cross-wind take-offs!

Mike

On Dec 12, 10:05*am, soartech wrote:
While discussing tailwheel weight I wondered why we need a tail dolly?
Why do most modern sailplanes have fixed tailwheels yet SGS gliders
have castering tailwheels. Shouldn't we have a caster instead?

Schweizers are 'nose draggers'. The CG is ahead of the main, so they
tend to follow the rope on the runway. A CG hook tail dragger with a
castering tailwheel would be .... very exciting on the ground, but not
in a good way.

On Wednesday, December 12, 2012 11:05:28 AM UTC-7, soartech wrote:
While discussing tailwheel weight I wondered why we need a tail dolly?

Why do most modern sailplanes have fixed tailwheels yet SGS gliders

have castering tailwheels. Shouldn't we have a caster instead?

Your basic question is valid. Back in the round engine days, some big taildraggers had lockable tail wheels which castered for taxiing and locked straight-ahead for takeoff.

One imagines a variation of this could work with gliders. If the cockpit is empty, weight on the tailwheel would make it caster. With a pilot in the cockpit, the lighter weight on the tailwheel locks it straight ahead. The castering shaft would just have a axial spring pushing the tail wheel down 5mm or so to lock it straight ahead. Basically it would be automatic with no input from the pilot.

On Wednesday, December 12, 2012 1:24:45 PM UTC-5, Bill D wrote:
On Wednesday, December 12, 2012 11:05:28 AM UTC-7, soartech wrote:

While discussing tailwheel weight I wondered why we need a tail dolly?



Why do most modern sailplanes have fixed tailwheels yet SGS gliders



have castering tailwheels. Shouldn't we have a caster instead?



Your basic question is valid. Back in the round engine days, some big taildraggers had lockable tail wheels which castered for taxiing and locked straight-ahead for takeoff.



One imagines a variation of this could work with gliders. If the cockpit is empty, weight on the tailwheel would make it caster. With a pilot in the cockpit, the lighter weight on the tailwheel locks it straight ahead. The castering shaft would just have a axial spring pushing the tail wheel down 5mm or so to lock it straight ahead. Basically it would be automatic with no input from the pilot.

And the first bump it unlocks ?
Complicated and not smart.

Originally Posted by Bill D

On Wednesday, December 12, 2012 11:05:28 AM UTC-7, soartech wrote:
While discussing tailwheel weight I wondered why we need a tail dolly?

Why do most modern sailplanes have fixed tailwheels yet SGS gliders

have castering tailwheels. Shouldn't we have a caster instead?

Your basic question is valid. Back in the round engine days, some big taildraggers had lockable tail wheels which castered for taxiing and locked straight-ahead for takeoff.

One imagines a variation of this could work with gliders. If the cockpit is empty, weight on the tailwheel would make it caster. With a pilot in the cockpit, the lighter weight on the tailwheel locks it straight ahead. The castering shaft would just have a axial spring pushing the tail wheel down 5mm or so to lock it straight ahead. Basically it would be automatic with no input from the pilot.

...and starting with stick full back to keep the glider straight at the beginning of a crosswind take off will unlock the wheel and negate its benefits

Colin

I can't wait till spring....

On Wednesday, December 12, 2012 11:43:25 AM UTC-7, Dave Nadler wrote:
On Wednesday, December 12, 2012 1:24:45 PM UTC-5, Bill D wrote:

On Wednesday, December 12, 2012 11:05:28 AM UTC-7, soartech wrote:



While discussing tailwheel weight I wondered why we need a tail dolly?







Why do most modern sailplanes have fixed tailwheels yet SGS gliders







have castering tailwheels. Shouldn't we have a caster instead?







Your basic question is valid. Back in the round engine days, some big taildraggers had lockable tail wheels which castered for taxiing and locked straight-ahead for takeoff.







One imagines a variation of this could work with gliders. If the cockpit is empty, weight on the tailwheel would make it caster. With a pilot in the cockpit, the lighter weight on the tailwheel locks it straight ahead. The castering shaft would just have a axial spring pushing the tail wheel down 5mm or so to lock it straight ahead. Basically it would be automatic with no input from the pilot.



And the first bump it unlocks ?

Complicated and not smart.

Geez, more negative experts!

A large enough bump might unlock it for a few milliseconds, but it would re-lock instantly. Note that Blanik's are taildraggers and many have permanently castering tail wheels so it can't be a big deal.

It still worries you, a simple latching down-lock which requires manual unlocking for castering is dead simple but almost certainly unnecessary.

Note that it comes with a major safety advantage - taking off with a tail dolly on becomes impossible.

Good luck on cross-wind take-offs!

Mike

Wouldn't it be OK, you just would have to use the rudder more?
Actually I like the automatic locking mechanism idea best so far.
Most of the reported weight and balance numbers showed a 20 lbs or
more
difference with the pilot in place.

On 12/12/2012 12:08 PM, Bill D wrote:

One imagines a variation of this could work with gliders. If the
cockpit is empty, weight on the tailwheel would make it caster.
With a pilot in the cockpit, the lighter weight on the tailwheel
locks it straight ahead. The castering shaft would just have a
axial spring pushing the tail wheel down 5mm or so to lock it
straight ahead. Basically it would be automatic with no input
from the pilot.



And the first bump it unlocks ?

Complicated and not smart.

Geez, more negative experts!

A large enough bump might unlock it for a few milliseconds, but it
would re-lock instantly. Note that Blanik's are taildraggers and
many have permanently castering tail wheels so it can't be a big
deal.

Blaniks have a huge rudder that becomes effective even before the wing
runner lets go. Not so for high performance gliders.

Another likely reason: the tailwheel is large but carefully faired in.
Enabling it to swivel would involve tradeoffs in cost, weight, and drag.

And possibly: people tow the gliders around with vehicles attached to
the tail dolly. Attaching a tow bar to just the might be a problem.

But I agree it would be nice; personally, I'd rather have a steerable
tail wheel. No more directional control problems at low speeds. I love
the one on my ASH 26 E even when I take a tow, and, of course, every
time I land.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)