Kill - Line Pilot Chute Rethink

[Poczynek 0]

Hi All,
yet another incident (failure to cock Pilot chute) over the weekend at my DZ that resulted in a reserve ride. I suspect that this happening more then we all know. I personnaly am beginning to believe that the majority of skydivers - who are not hard core swoopers - are better off not uutilizing the kill-line. The performance trade off for non-swoopers is not significant verses the potential for trouble.

David

phat, dumb & happy

[riddler 0]

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The performance ...

The performance is more significant on smaller canopies, I believe. You would feel less of an improvement on your 170 than someone on a 66.

I've heard that a lot of un-cocked pilot chutes will still pull the pin, if given more time to snivel. Is this true?

[Poczynek 0]

Riddler,
From what I have seen it is running at about 50/50, half the time the non-inflated pilot chute can pull the pin, the other times it doesn't. I suspect that there are several factors - how much drag size & material, how tight the main closing pin, and perhaps others. And your point is about canopy size is well taken, the impact (performance) on my 170 is probabably minimal when compared to significantly smaller canopys.

phat, dumb & happy

[ernokaikkonen 0]

>I've heard that a lot of un-cocked pilot chutes will still pull the pin,
>if given more time to snivel. Is this true?

In many, but not all cases, yes. When kill-line PCs were a newer thing, a jumper on my DZ jumped a few dozen jumps with his new gear, complaining about slow openings, until someone asked:
-"Did you cock the PC?"
-"Did I what?"


Poczynek: I think you're underestimating the effect an uncollapsed PC has on canopy flight. I'd estimate modern canopies sized 150 sqft or less wont fly too well with a non-collapsible... that's just a guess though.

I've jumped my TurboZX145 with a non-collapsible and with a kill-line pc, and the difference is very noticeable. The non-collapsible was bigger than the kill-line though.


Parachutes de France sold a kill-line pc with a retractable pin a few years ago, but not anymore. It was good idea IMO: You simply couldn't close the container without cocking the PC. Does anyone know why they were discontinued?

[nacmacfeegle 0]

I would challenge that the effect of the PC drag is dependent upon the acreage of nylon above you. I think its probably more dependent on the canopy's flight characteristics, wing loading, and style of pilot input.

"Parachutes de France sold a kill-line pc with a retractable pin a few years ago, but not anymore."

I have a similarly designed Precision kill line PC that came with my old Monarch (now retired to service as a play mat), I keep it as a spare as its fitted with a pipe handle, I don't really like it.

The pin is attached to the kill line, when cocked the pin is contained within the same chanel as the kill line. As you cock it, the pin is quided out of a gap in the bridle by some bar tacks. When its cocked the pin sticks out, with the 'eye' still within the bridle.

As you say, its impossible to pack an uncocked PC of this design, well possible, but you have to leave a pull up or packing tool in the closing loop.

The Precision PC is called a "LifeLine Pilot Chute", no details on their site though. Google failed as well.

The reason I don't like it is because the bridle / pin assembly seems quite stiff. On a conventional design PC, the pin is attached via a small piece of tape, which gives the bridle a fair amount of flexibility, and room to "wiggle" without unseating the pin. If the main cover were to get knocked during a funnel , or some other chaotic event , there is a slightly higher probability that the pin could be knocked out of the closing loop. This would lead to an open container and its associated drama.

Apart from those misgivings, I think it was step in the right direction to defeating Darwin.

--------------------

He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. Thomas Jefferson

[Hooknswoop 19]

Gear education and gear checks. I have never owned a rig without a kill line PC and I have never had a reserve ride because of it or forgot to cock it.

Hook

[Unutsch 0]

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Gear education and gear checks. Hook

amen to that, bro'!!!

Check out the site of the Fallen Angels FreeflY Organisation:
http://www.padliangeli.org

[Poczynek 0]

I am all for gear checks and don't mean to downplay their importance - I always intend to get one, but have gotten my self in situations where they have been skipped - and I don't think I am alone - but what I am trying to get at is the performance factor of a collapsible pilot chute over a non collapsible so that one can make an informed decision regarding using one or not. For instance on my 170 Spectre - am I getting 1.5 knot increase in forward airspeed or 4? Are there any published charts / data that provides this information. If for instance the performance factor is so low - why add the additional possibility of equipment / operator malfunction?

phat, dumb & happy

[ernokaikkonen 0]

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I would challenge that the effect of the PC drag is dependent upon the acreage of nylon above you. I think its probably more dependent on the canopy's flight characteristics, wing loading, and style of pilot input.

I'm not going to get into an argument with an engineer about forces that affect a flying parachute ... but still:

Attached to a faster flying(=smaller) parachute, a PC would exert more force on the system, than it would if it was attached to a larger parachute, right?

Because if you hold a PC out of a car window, it will pull harder when you're going faster. Therefore a non-collapsible PC would have a larger effect on the flight of a smaller parachute? I'm sure one of the physicists on the forums will correct me if I'm wrong...

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The reason I don't like it is because the bridle / pin assembly seems quite stiff. On a conventional design PC, the pin is attached via a small piece of tape, which gives the bridle a fair amount of flexibility, and room to "wiggle" without unseating the pin.

I hadn't thought about that, but on the (PdeF)rigs I've seen the system, it hasn't really seemed like a problem to me. Is there anyone out there who has the facts on why these aren't on the market anymore?

[floormonkey 0]

I am all for gear checks and don't mean to downplay their importance - I always intend to get one, but have gotten my self in situations where they have been skipped - and I don't think I am alone - ***

This is not a flame...but there is absolutly NO EXCUSE for not getting a gear check if you want one. If you are in too much of a hurry, you need to slow down. If you are too cool to get one, you need your ego deflated. If there is no one to do it, do it yourself. If folks at your DZ don't know how, teach them. If you don't want one, that's fine. Skipping a gear check if you want one is not much different then not putting on a helmet. If you want it, it's there.

[skycat 0]

Check your own gear before you put it on if you used a packer or better yet pack for yourself, and make sure you cock it. There are DZs that start students out on collapsible PCs they have never known anything else, and to them cocking it is part of packing.

non-collapsing pilot chutes can cause issues such as when you have a pilot chute over the nose. The pilot chute is still open filled with air, pulling the bridle tight around the nose. This can cause the canopy to have a built in turn and the worst case would be to have it collapse depending how many lines it wrapped around. (I had 4 of these in a row as a student) With a pilot chute that is collapsed I've never seen it be more than an annoyance if the jumper even noticed it.

Fly it like you stole it!

[nightjumps 1]

OK. Bigun's got to get on his soapbox about this one. Two things - 1) I've paid packers and done a gear check myself and not seen the color in the window, so I take it back to them and have them re-cock the pilot chute and I'm almost always met with "I cocked it." It just must be shrinking or just cause the color isn't in the window doesn't mean its not cocked. My second peeve is, I can't tell you how many folks I see pull the hackey a little and then start milking the bridle down to the color and calling it cocked - that is a false cock and doesn't mean the pilot chute is at its maximum operating capacity. If you are cocking the pilot chute and can't get color, reach into the bottom of the pilot chute and pull the kill line away from the bag (not milk towards it). If you still can't see color, then by all means get a rigger to check it, it might have shrunk to the point of needing it replaced. Using a magic marker to re-color the kill line is a no no. If you're doing that, you need it replaced. Bigun steps down off the soap box - Next!

[Jimbo 0]

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Attached to a faster flying(=smaller) parachute,

It's not necessarily size that effects the parachutes speed, more importantly I think is loading. If we assume two like canopies then it is fair to say that my 170 with 600 lbs underneath it is likely going to be faster and more 'high performance' than your 99 with 99lbs under it. Make sense?

-
Jim

"Like" - The modern day comma
Good bye, my friends. You are missed.

[Kris 0]

Good points.

Another thing to look for to be absolutely sure: Check the kill-line slack in the PC compared to the tapes. You can do this by looking through the mesh while holding the PC inverted by the bridle. If the tapes are slack and the kill-line is taut, it isn't cocked. It should be the opposite with the tapes taut and the kill-line having slack.

I check this every time I cock my PC.

Kris

Sky, Muff Bro, Rodriguez Bro, and
Bastion of Purity and Innocence!™

[tlshealy 0]

I really don't understand why bungie collapsibles are not used more, especially on larger or lower performance canopies, the ones I've jumped collapsed at about 40~50 mph so unless your doing a base jump exit speed or hop and pops are not a factor, and if they do get worn out or fail, they just don't collapse. I think they would be ideal for student canopies, or lower wing loadings. But I have a kill-line and agree that with correct gear checks and inspections you should never have a problem with one.
Blue Skies
Tad

[nightjumps 1]

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Good points.

Another thing to look for to be absolutely sure: Check the kill-line slack in the PC compared to the tapes. You can do this by looking through the mesh while holding the PC inverted by the bridle. If the tapes are slack and the kill-line is taut, it isn't cocked. It should be the opposite with the tapes taut and the kill-line having slack. I check this every time I cock my PC.

Kris

Yep Kris, Forgot about including that. Thanks for the post.

[floormonkey 0]

Bungee PC's aren't around as much because of ellipitical canopies. According to a manufacturer, (either PD or Atair, I'll see if I can find it) bungee PC's cause funky openings, esp. on ellipticals and highly loaded canopies.

[floormonkey 0]

from the PD warning addendum "Solving opening problems"

"Collapisible pilot chutes can affect deployments too. The shock cord method of collapsing the pilot chute is tricky to design so that it works consistently. It must be properly designed and use only zero porosity fabric to maintain its calibration. Never use an F-111 shock cord collapsing pilot chute! It can be deadly, because the calibration speed changes rapidly as the fabric changes its porosity. We have seen many F-111 shock cord collapsing pilot chutes cause deployment problems due to inconsistency or outright failure to inflate."

[Watcher 0]

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It's not necessarily size that effects the parachutes speed, more importantly I think is loading.

Ok I think this is a wrong conclusion. You need to consider parasitic drag, and a Uncollapsed PC is the biggest source of parasitic drag that can be reduced. That being said, a 99 has a hell of a lot less physical fabric and line bulk to create drag while a 170 has a lot more drag with ussually significantly bigger openings on the nose, larger cells etc. Because of this even a lightly loaded 99 is going to be more affected by a 32 in noncollapsible PC.

Now in reply to the whole thread. A non collapsed PC pulls significantly on the center cell of the canopy which in turns pulls it back letting the 2 sides push forward drastically changing the shape of the canopy. The perforamance of the canopy is greatly decreased with said drogue deployed behind you. Last year I had the kill line break away from the attachement point on the PC, so i had a fully deployed PC behind me, the performance degregation on the canopy was extremely drastic.

Anything below a 260 be a good canidate for a Kill-line.

And cocking a PC is really not difficult even if you have packers, when you lay down the canopy with brakes SET, walk and cock your pilot chute then leave, 5 seconds then can ussually remedy any problems.

Jonathan Bartlett
D-24876
AFF-I

[JYorkster 0]

Same here. Always had a kill-line...never had a reserve ride.

Learn how to pack! Check your gear! Reserve rides due to not cocking a pilot chute show a clear problem of complacency. I am continually amazed about how little people understand about their own gear.

Rock

[listo 0]

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Gear education and gear checks.

OMG, who forgot to cock their pilot chute That is like forgetting to stow your brakes. Do it once and I bet you won't ever forget it again.

Most Kill-line pilot chutes have a window somewhere on the bridle that indicates whether or not it is cocked. Obviously this person didn't get a "pin check" or proper "gear check" before getting on the plane. Otherwise, it would have been noticed. I personally check my PC while I am doing my pin checks before I ever put my rig on.

I have never had a problem like that.

Listo

Live today as tomorrow may not come

[listo 0]

dont forget to mention that the bungee cord collapsibles are also dangerous because they can re-inflate during canopy flight, especially on higher loaded canopies with faster forward speeds.

Those things are just bad Ju Ju waiting to happen. Modern gear is always a plus, after all, the gear is getting more and more safe and reliable everyday. Why not stay up to date?

Listo

Live today as tomorrow may not come

[nacmacfeegle 0]

I don't really like doing low hop'n pops with a bungee PC either......

--------------------

He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. Thomas Jefferson

[Nick 0]

Personnaly when I use packers I will always set the brakes and cock the pilotchute myself, and I'll always check my gear immediatly after packing and the normal gear check (in the UK remember) on the flight line.

Nick
Gravity- It's not just a good idea, it's the LAW!

[billvon 2,400]

A few points:

1. If you have a non-collapsible PC on your 170 sq ft whatever and you want a bit more performance, a collapsible is a much, much better way to get that performance than by downsizing. Always 'streamline' your gear for performance before sacrificing square footage - it will help keep you alive while still giving you better performance.

2. Bungees work but must be maintained meticulously. Someone who occasionally forgets to check their kill line will, I suspect, not be checking their bungee PC often enough to keep the system safe.

3. Bungee collapsible affect your bailout procedures, so consider that change carefully.

4. Making a routine is key. Leaving your slider at the links and jumping will likely destroy your canopy and could kill you; most people have a routine that prevents them from forgetting to do that. You can build in the same routine to keep you from forgetting that PC-cocking step.