Pawnee with Tost internal tow rope system

Thanks for the input, Fred.

There is some built in redundancy with a tow reel, one can always leave the rope trailing behind if the retract mechanism fails. In the event of some sort of other failure that would have a the rope partially retracted or hopelessly tangled, planning ahead with a new rope at the ready and with a length of heavy weed whacker line taped to the tug end as a "fish tape", a temporary fix should take just a few minutes.

1) If the partial rope or broken rope is hanging out the back of the tug, pull it clear of the guillotine and conduit (the fairlead tube running from the guillotine to the tail fitting.

2) Push the nylon "fish tape" from the back to the front. Then, if the reel is inop and half full of rope (a condition I have not experienced), tie the new rope around the reel using a bowline (easy to undo later) and use as a normal drag behind tow rope. Or, if the reel is operable, replace as normal.

As Fred says, all the reel installations I've seen have a guillotine. I did not make the guillotines used with my tow reels on the SoaringNV ships. Those were sourced from Rex, as he had some extras made - - a good design too..

Tost makes some tow reels that use a frangible mount for the reel behind the pilot seat. There is a slug clamped on the line and that stops the rope payout when is should and places the towing loads on the tail post cluster (unlike the forward mount reels, we are talking about, that put the load on the landing gear and fuselage main cluster where the spray tank would go. I don't like the Tost design as much, though have never flown with it. Seems in the event of some sort of tangle or other problem that locked up the reel before the towing slug reached the tail, the frangible mount could break loose and see the reel go bouncing down the fuselage towards the tail - with attendant collateral damage.

I recall reading about just that issue here on ras, but it's been a few years back.

Bumper reminds me of one thing I did come up with at SoaringNV when we had a rope break and had trouble fishing the new rope through the tube. I started carrying in the towplane a 15 or 20' length (long enough to pass through the tube) length of the white plastic tubing used to plumb in refrigerator ice makers. It is rigid enough to push through the tube from either end and flexible enough to go around any bends and pass any joints you might have. Put some kind of hook in the end to pull the tow rope with and you're back in business pretty quickly. F

Originally Posted by

I've towed with the TOST reel on the Skyline Soaring Club's Pawnee, the Rex Mayes reel on a tow plane I bought when SoaringNV opened, and Bumper's proprietary reel on another SoaringNV tow plane. All had guillotines: I never used that feature. I liked having the spool between my feet so I could see it spooling out and would be reminded to reel it in after glider release.

The best reel was Bumper's, but as he says, he has zero interest in building more. I don't blame him: he spent a whole lot of time on the installations he made for SoaringNV as he trouble-shooted (?) little features of the design.

One thing to remember about reel systems with guillotines is that if you use the guillotine you lose the rope and the weak link. At least with a hook on the tow plane tail you can drop the line and hope the glider pilot is sharp enough to remember to bring it back to the field so you can re-use it.

I liked using a reel mainly so I didn't have to approach high over fences, power lines, trees, etc. This is particularly important if you have a short towplane runway.

One thing to keep in mind with a reel is that if you break a rope, have it jump off the reel as it is reeling in, or have to guillotine it, you are probably out of service for about 30 minutes, maybe more. With a tail hook you just clip another rope on and start up again.

Correct me if I'm wrong but wouldn't the rope still be attached to the glider along with the weak link after the rope is guillotined at the tug end unless of course you are towing off a belly hook with a back realease

:-) Colin

On Monday, February 9, 2015 at 7:43:05 PM UTC-6, Ventus_a wrote:
;896658 Wrote:
I've towed with the TOST reel on the Skyline Soaring Club's Pawnee, the
Rex Mayes reel on a tow plane I bought when SoaringNV opened, and
Bumper's proprietary reel on another SoaringNV tow plane. All had
guillotines: I never used that feature. I liked having the spool
between my feet so I could see it spooling out and would be reminded to
reel it in after glider release.

The best reel was Bumper's, but as he says, he has zero interest in
building more. I don't blame him: he spent a whole lot of time on the
installations he made for SoaringNV as he trouble-shooted (?) little
features of the design.

One thing to remember about reel systems with guillotines is that if you
use the guillotine you lose the rope and the weak link. At least with a
hook on the tow plane tail you can drop the line and hope the glider
pilot is sharp enough to remember to bring it back to the field so you
can re-use it.

I liked using a reel mainly so I didn't have to approach high over
fences, power lines, trees, etc. This is particularly important if you
have a short towplane runway.

One thing to keep in mind with a reel is that if you break a rope, have
it jump off the reel as it is reeling in, or have to guillotine it, you
are probably out of service for about 30 minutes, maybe more. With a
tail hook you just clip another rope on and start up again.


Correct me if I'm wrong but wouldn't the rope still be attached to the
glider along with the weak link after the rope is guillotined at the tug
end unless of course you are towing off a belly hook with a back
realease

:-) Colin




--
Ventus_a

Yes Colin, and that's why you have a radio to hear the tow pilot tell you that he/she cut the cord. You can then drop the towline over the glider field so the valuable Tost rings can be retrieved (at least that's what I would do).

On Tuesday, February 10, 2015 at 9:56:17 AM UTC-5, wrote:


Correct me if I'm wrong but wouldn't the rope still be attached to the
glider along with the weak link after the rope is guillotined at the tug
end unless of course you are towing off a belly hook with a back
realease

:-) Colin




--
Ventus_a

Yes Colin, and that's why you have a radio to hear the tow pilot tell you that he/she cut the cord. You can then drop the towline over the glider field so the valuable Tost rings can be retrieved (at least that's what I would do).

I doubt most pilots will need to be told that the rope just got cut.
Depending upon how it falls back, it is fairly likely to back release.
We should assume it didn't and do as Herb says by operating the release where it would fall safely and possibly be retieved.
UH

On Friday, February 6, 2015 at 10:12:01 AM UTC-8, 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



On Friday, February 6, 2015 at 10:12:01 AM UTC-8, 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

I'm building up 10 Wakerly-Walls winches. They are for PA 25 only. It is installed in front of pilots feet. Been used for over 50 years with NO PROBLEMS and no accidents. They will be FAA approved shortly and for sale then. ha12Aatt.net

On Saturday, December 9, 2017 at 4:26:53 PM UTC-5, wrote:
On Friday, February 6, 2015 at 10:12:01 AM UTC-8, 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



On Friday, February 6, 2015 at 10:12:01 AM UTC-8, 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

I'm building up 10 Wakerly-Walls winches. They are for PA 25 only. It is installed in front of pilots feet. Been used for over 50 years with NO PROBLEMS and no accidents. They will be FAA approved shortly and for sale then. ha12Aatt.net

Approximate cost?
Uli
'AS'

On Saturday, December 9, 2017 at 1:26:53 PM UTC-8, wrote:

I'm building up 10 Wakerly-Walls winches. They are for PA 25 only. It is installed in front of pilots feet. Been used for over 50 years with NO PROBLEMS and no accidents. They will be FAA approved shortly and for sale then. ha12Aatt.net

I made three front mounted tow reels for SoaringNV's PA-25's. I used the basic design from the reels made by Jim Indrebo, followed by Rex Mayes. Their reels uses a 1/4 urethane tube for the drive belt and Hall effect sensor for reel keep-run and auto-off.

I further refined the design by using a stronger mount to spread the load better at the gear cluster, a chain drive to eliminate slippage, a much more powerful motor so rewind would be fast and efficient at any speed (with the belt drive one would have to slow to pattern speed to retract - redline?, no problem with mine. In fact I tested it by towing my golf cart toward the chocked Pawnee!

I made the electronics box modular, so you could swap or replace the electronics box (2 screws in nut plates and two plugs) for service or troubleshooting. No need to remove the whole unit.

The tail fitting was more robust, and used a brass sleeve slide fitting on the stinger to allow for tailspring movement. And rather than a Delrin funnel (which the rope wore grooves in, I made the funnel of anodized aluminum that could rotate on the stinger for even wear.

The motor was shorted with an approx. 2 ohm resistor dynamic braking of rope pay-out, so the line person had a small amount of resistance to prevent overrun. This also keeps the rope from paying back out after retract in flight.

The Hall sensors allow for one button "start and forget" retract. A relay prevents "bounce back on" if a reel magnet should happen to line up with the hall sensor on full retract.

I did not build or design the guillotine. Rex had a few extra and we purchased those from Williams Soaring. The motors were sealed, purchase from Surplus Supply, and were from a robotics over run of some sort - they were excellent. The rig hauled in 200 feet of line in little more than 20 seconds IIRC.

As with most everything I've ever made or designed, there's always improvements I think of only after MKI. Guess that's why there was a MKIV yaw string (now owned by Wings and Wheels who's doing a great job BTW!). There was a new, easie to make MKV yaw string a couple of years back that few people know about - an abject failure . . . so it may stay with just a few people knowing about it :c)

Fred was right about my lack of desire to make more of the reels. I built one, then two more at the same time, not much mass production time savings. Each took about 80 hours I think. Could be done faster with plans, and if Piper built their frames exactly alike . . I didn't design the mount to be adjustable, so they were fitted to each ship.

On Friday, February 6, 2015 at 10:12:01 AM UTC-8, 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