Using Z.P. canopies with direct bag static line students
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Anyone out there know of any d.z.'s doing this.? Interested in incidence of line twists leading to malfunctions in very lightly loaded z.p. canopies (0.6 - 0.8) . Scenario - D.Z. running both AFF and S/L training. Love to upgrade all student canopies to Z.P. but worried about higher percentage of s/l deployments having line twists leading to higher malfunction rate with z.p. canopies winding up. Or would the much lower wing loading negate this.?
Re: [ptknights] Using Z.P. canopies with direct bag static line students
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Parachute School of Toronto does S/L with their students. I'm not sure if all their student canopies are zero P, but they have Navigators and Solos. Students get tossed either from their 206 or Caravan.
You can contact them, but I've never heard it discussed as "an issue" when I'm there from time to time. One issue is that the guy on the radio needs more patience, as the descent rates are lower, so the students are floating around up there longer.
Re: [ptknights] Using Z.P. canopies with direct bag static line students
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I'm at s/l instructor at my dz and we use Z-po and F-111 canopies. I haven't noticed a difference with either. When I was a student they used direct bag, but for a few years we've been using a static line assist. Not sure if that helps any, but thought I'd type it in case it does
Re: [ptknights] Using Z.P. canopies with direct bag static line students
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When we used direct bag the incidence of line twist was considerably higher under our (non-ZP) Mantas. If it worries you consider pilot chute assist or IAD.
Re: [billvon] Using Z.P. canopies with direct bag static line students
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When we used direct bag the incidence of line twist was considerably higher under our (non-ZP) Mantas. If it worries you consider pilot chute assist or IAD.
Just trying to be clear about the meaning of those statements:
Line twists were more common under traditional Mantas, than under ZP student canopies??
Or more common with direct bag than with IAD?
We know the latter is true; it is the former issue that is being discussed. (As well as the seriousness of line twists, with those ZP student canopies.)
What with main risers snagging on the lower corners of reserve containers and d-bags bouncing off of students' heads, line twists became the "normal" deployment with direct bag. Whether students panic and do foolish things under line twists depends upon how well they were trained in ground school.
I have not noticed a difference (in the occurrence of line twists) between ZP and F-111 canopies loaded the same.
My opinion is based upon 27 years instructing with a variety of S/L sleeve, S/L pilot chute assist, S/L direct bag and IAD, on a bewildering array of student canopies ranging from military-surplus rounds to Para-Commanders to Lasers, to Mantas to Skymasters and most recently Solo 270s.
The only difference between F-111 Mantas and ZP Mantas is that ZP Mantas are better for bigger students because they descend slower. Hanging small students under ZP Mantas is a waste of time.
Re: [mjosparky] Using Z.P. canopies with direct bag static line students
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Why would the canopy material have any effect on line twists? Line twists would have happened before the canopy comes out of the bag.
That hits the nail on the head -- to a large extent, line twists during S/L operations have nothing to do with the canopy.
For static line, it is the tumbling, rolling bag that results in line twists so often, which usually mean nothing except flying straight for 15 seconds until the twists are out.
But another source of line twists is uneven deployments, where the canopy spins itself up as it comes out of the bag, one side starting to fly before the other. So the original poster might be curious whether that characteristic of small, high performance ZP canopies is in any way carried over to large student ZP canopies designed to be docile. Probably not really, but that's a guess, and it would be due to the light wing loading and the generally docile design.
But if a student ZP canopy is any more sensitive and fast reacting to input, particularly in brakes, than a non ZP student canopy, then theoretically it could be more likely to spin up. I personally haven't jumped a ZP student canopy so don't know to what degree they are any faster reacting than old style student canopies.
Re: [pchapman] Using Z.P. canopies with direct bag static line students
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Thanks for the input guys; So a comparison of F111 vs ZP at the same docile wing loading should (in theory) produce no more tendency to "wind up" on opening due to line twists.?
"So the original poster might be curious whether that characteristic of small, high performance ZP canopies is in any way carried over to large student ZP canopies designed to be docile."
Anyone have thoughts on this. One alternative is to beg a test canopy and try it using experienced pilots.
Re: [ptknights] Using Z.P. canopies with direct bag static line students
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I have been using DB S/L since I bought the DZ in '99 and they used it for 2 years as well. Originally the gear was all F-111 Mantas in Telesis 2 containers. I have changed to all Navigators ranging from 200 to 280 and added 3 Vectors. We have also added AFF, so S/L students have declined tremendously, but still have done 1000's. There is absolutely no relevance to the type of material, but there is of course some relevance to the wing loading.
From viewing and analyzing 100's of videos, the real cause of line twist on S/L from DB is this.
DB is so quick at extracting the bag (10 feet, 12 foot S/L and 2 feet in the plane) the student from a hanging position is still upright as the bag is pulled up against and past the reserve container and at the same time it is pulled at an angle towards the airplane. This sideways pull on the dbag and the dbag hitting the reserve container starts the bag spinning as the lines are extended. If you get a student that puts their head down on exit you usually get a cleaner deployment, but the better the arch/exit usually the more line twist (great trade off).
A couple of pointers for DB S/L use.
1) If you mount the radio on the side of the helmet, mount it on the side facing the plane. The outside riser is pulled behind the students head and eventually slides right over and past the outside ear (check students hearing for both ears).
2) Always have a rubber band attached to the container for a good tight stow of the S/L just above the pin going to the S/L end. This really helps controlling the S/L and help in eliminating a short line. My Telesis 2 rigs did not have that when I bought the DZ, we had one short line (thankfully on a training jump, and jumper left immediately), but after I added that absolutely no issue. Also when I sent them in to the manufacturer for inspection they came back with an attachment added (must have been a good idea).
3) Beat it into the students head that they will have line twist not maybe. When it is 100% expected, they handle it fine. I teach it as a nuisance that can be and has to be fixed (same as end cell and stuck slider) not as a malfunction, they are only a malfunction if not cleared by 2500 feet. Then when they don't it's gravy.
Re: [tuffyjensen] Using Z.P. canopies with direct bag static line students
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All good advice.
One other way to reduce line twists - caused by main risers snagging on reserve containers is to do the last two line stows on opposite sides of the d-bag. If you do the last line stow - with the right line group - on the right side of the d-bag and keep it short (less than 18 inches from connector link) then the riser is often lifted out of the main pack tray before it can snag on the bottom corner of the reserve container. Stow the left line group the same way (on the left side of the d-bag) to keep things even.
The Canadian Army used to do similar with static-line rigs, tying the connector links to the corners of the d-bag with 80 pound break cord.
I also stow my (freefall) Stiletto 135 the same way, and rarely suffer line twists.
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