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Brainstorm, stop towline recovery chute entanglement.

Postby Bill Cummings » Wed Jun 22, 2016 7:09 pm

Brainstorm, stop towline recovery chute entanglement.
HG pilots are still seen, on line, towing with towline recovery chutes that can blossom and let the pilot overtake the chute and become entangled.
For our training manual we should compile different ways to best mitigate this fixable event.
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Re: Brainstorm, stop towline recovery chute entanglement.

Postby wingspan33 » Wed Jun 22, 2016 7:55 pm

Bill,

I've towed by way of ATOL truck tow system and early aero towing behind a Cosmos trike. I've never caught up with the chute, but that doesn't mean it can't happen.

Considering the described scenario, either the pilot upon release is speeding up seriously, or the person acting to rewind the tow line is hesitating.

Solutions include telling pilots not to speed up a lot after release or tell the rewind person to not hesitate.

Another idea could be to attach a moderate (1+ lb. ?) weight just ahead of the chute that would tend to pull it downward after release.

Third idea - have a chute deployment "bag" attached to the glider end that only deploys the cute when the (thin bungee cord loaded) line stretches out to 20 ft. This should be setup to not snap back toward the pilot. This idea disallows the chute from opening until it's a safe distance ahead of the pilot/glider.


Bill Cummings wrote:Brainstorm, stop towline recovery chute entanglement.
HG pilots are still seen, on line, towing with towline recovery chutes that can blossom and let the pilot overtake the chute and become entangled.
For our training manual we should compile different ways to best mitigate this fixable event.
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Re: Brainstorm, stop towline recovery chute entanglement.

Postby Bill Cummings » Thu Jun 23, 2016 11:03 am

Thank you wingspan33.
Of your suggestions I like # 3 the best.
My description scenario should have been more detailed.
I had, moments before, posted a more detailed scenario on the Training Manual thread concerning static tow.
I'm surprised and disappointed that you couldn't read my mind when I screw up. (My bad!)
I too have never had any trouble with the towline recovery chute while platform towing or aero towing.
Aero towing I've never had a chute on my end of the line but only either a small plastic funnel, a strip of fabric, or nothing at all.
But now that you mention it, while PL towing, I haven't had any trouble with the line chute either.
I've also never caught up to a line chute after release from PL. But I have several times before release.

Your PL response to my post reminds me of something that I discovered in the past. That would be someone offering up advice while they were thinking of one type of tow launching while I'm on a different page thinking of another method of tow launching.
I've caught myself flying of the handle after jumping to a conclusion and thinking to myself, "Now that's a bunch of BS."
Upon reflection I could understand what the person was thinking about and realized the statement was absolutely correct.

For quite some time USHGA was stuck in a paradigm (or inside the box) when they put out their annual questionnaires asking how many flights and of what type each of us had in the past year. They listed tow or foot launch. I'm sure it messed up their results when I wrote in on the questionnaire, and broke it down to: boat tows static, boat tows PL, car or truck land tows (ST or PL), Snow machine tows, aero tows and foot launch.

My thinking was that just listing tow or foot might give someone the idea that they could switch from one style of towing to the other and be safe. Eventually USHGA caught up to the early tow pilots.

(I just now thought of a neat idea for another topic-- make a graph depicting different flight concerns and check which method PL, AT, FL, ST etc. best mitigates each flight concern.)

I'll attempt to stagger back on track --- The weight idea ahead of the line recovery chute, is close to what I've done in the past. [While ST on land, running and not dolly launch.] I've used around thirty feet of three/eighth of and inch (3/8") PolyPro line between the line recovery chute and my tow bridle.
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Re: Brainstorm, stop towline recovery chute entanglement.

Postby SamKellner » Thu Jun 23, 2016 3:30 pm

wingspan33 wrote:Bill,

I've towed by way of ATOL truck tow system and early aero towing behind a Cosmos trike. I've never caught up with the chute, but that doesn't mean it can't happen.

Considering the described scenario, either the pilot upon release is speeding up seriously, or the person acting to rewind the tow line is hesitating.

Solutions include telling pilots not to speed up a lot after release or tell the rewind person to not hesitate.

Another idea could be to attach a moderate (1+ lb. ?) weight just ahead of the chute that would tend to pull it downward after release.

Third idea - have a chute deployment "bag" attached to the glider end that only deploys the cute when the (thin bungee cord loaded) line stretches out to 20 ft. This should be setup to not snap back toward the pilot. This idea disallows the chute from opening until it's a safe distance ahead of the pilot/glider.


Bill Cummings wrote:Brainstorm, stop towline recovery chute entanglement.
HG pilots are still seen, on line, towing with towline recovery chutes that can blossom and let the pilot overtake the chute and become entangled.
For our training manual we should compile different ways to best mitigate this fixable event.


One time at a field near Schertz, Tx, I saw a new pilot hit the chute while releasing from scooter towing to ~ 75ft. Luckily nothing snagged.
The tow line had a section of ~1/2" x 20ft of nylon rope for "weight" ahead of the chute. It didn't do the job.

I think it had to be operator hesitation. Actually there is a operator tendency to tap the break immediately after the pilot releases so that you don't backlash the scooter.
Without a drogue, tapping the break to stop tow force is not a problem. I haven't been using a chute on the scooter. The line falls in a pile.

I'm not opposed to using a drogue. The towtech :D should modify the procedure and keep some force on the line for a bit.

Hopefully we are having some visitors conducting scooter ops here over 4th of July week. I'll see if I can get some other opinions.

:wave:
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Re: Brainstorm, stop towline recovery chute entanglement.

Postby Bill Cummings » Sat Jun 25, 2016 7:20 am

Thank you Scott and Sam,
After reading again this whole thread I think it was Scott that gave me the idea (for another thread --- so why am I bringing it up again here?) -- anyway--- the idea of which method of launching will mitigate different safety concerns.
As Scott and Sam reveal, tension on the line (and speeding up after releasing.), will have an effect on overtaking the line recovery chute. I'm inclined to say that PL presents a far lower possibility of of overtaking the line recovery chute = (LRC), than static towing.
For static towing (ST) launching the LRC is right where the glider will be in a second or two. Platform Launching (PL)
has the LRC and the glider on different course lines from the start. At the very least the LRC and PL glider yields a far shorter time frame in which to converge than when ST.
Depending on the elasticity of a towline, releasing under much tension has proven to be a good way to instantly tie a bow or a knot in the falling towline. For this reason as well as not wanting to release into a climbing hammerhead stall I would always have the tow vehicle reduce (not totally) the line tension before releasing. I reduce tension for releasing while doing ST, (over land or water.) PL (over land or water.)
I'll save Rick some time by admitting that Foot Launch (FL) will totally eliminate any entanglement with a LRC.
Still PL far and away reduces the possibility of a tip stall when launching as compared to FL.
I'm having a heck of a time steering clear of my mitigation flow chart (for a seperate thread,) and sticking with entanglement with a LRC. :roll:
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