At 18:11 06 February 2015, kirk.stant wrote:
Our club (in the US) is looking at a Pawnee that has the Tost cable
retractor winch system and we are curious about it's operation.

For example, it appears that the rope requires a Tost weak link
assembly at
the glider end, but none at the towplane end. How are US
operators setting
it up? Tost weak link for glass and a "straw" for Schweizers?

How is the rope deployed on the ground? Does the ground crew
just grab the
rope end at the tail of the towplane and let the towplane taxi
away?

Anyway - any info on club operating procedures with this system
would be
appreciated.

Cheers,

Kirk
66

Kirk, I have done some towing with the Pawnee and the retractable
TOST set up. We did not use the TOST Weak Link set up on the
glider end, we used rope that met the strength requirement for
weak link. There was a Tost weak link on the Towplane side at the
spool.
2.Rope is coiled up on a spool between pilots feet. When on the
ground, ground crew pull the rope out. The spool free wheels.
Generally you taxi to get the rope out. Tow pilot sees when he is
close to the end of the rope limit by looking at the spool.
3. Air loading goes higher on the rope after tow release. An effort to
not overheat the tost motor during recoil is paramount. The rope
can be recoiled a lot easier when flap extension is made and a
slower decent is conducted. Motors are not cheap to replace. The
recoil switch is a momentary push button switch. Push it and it
drives the motor. Release it and the motor stops. Example. If you
were to retract the rope in the air the motor would reel the rope in.
As soon as you released the button the air loading on the rope
would pull the rope back out freely. Once the rope is fully retracted,
there is generally not enough rope exposed to cause the air to pull
the rope out again.
The TOST set up is really nice and I prefer it but it comes at a
higher cost of maintenance if not following strict SOP's. If you have
numerous different tow pilots the costs go way up. You do save on
rope wear though.