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.