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Collapsible Pilot Chutes - Unnecessary additional risk?

 

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xavenger  (A 1)

Jul 14, 2005, 7:02 AM
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Collapsible Pilot Chutes - Unnecessary additional risk? Can't Post

Hi

Further to a conversation about how to deal with a pilot chute in tow malfunction in the thread entitled "Red or Silver" I got thinking about what the best way would be to eliminate or massively reduce the likelihood of having a pilot chute in tow mal in the first place .. then Bill Booth came along and said:

"if you jump around 1:1, and aren't into "swooping", a non-collapsing pilot chute is just fine. I jump a 190 silhouette with a non-collapser, and I see and feel no distortion."

So yeah, pretty obvious really. A number of PC in tow mals could probably be avoided if we weren't using collapsible PCs in the first place. A significant percentage of the skydiving community probably sees no benefit from them, just additional risk.

If a collapsible pilot chute offers no discernable benefit to the tens of thousands of people flying quite happy at low wing loadings and who are not interested in performance flying - they it would make sense to me that these people could mitigate the risk of a very serious mal simply by changing to a non-collapsible.

I don't mind additional complexity in life, when there is benefit, but I can't see that there is one for a lot of jumpers using collapsible pilot chutes - all I can see is unnecessary risk (ok small) and something else to go wrong.

Am I thinking straight? What are your thoughts?

:-)

James


(This post was edited by xavenger on Jul 14, 2005, 7:03 AM)


riggerrob  (D 14840)

Jul 14, 2005, 7:15 AM
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

By the same logic, bungee-collapsible pilot chutes were fashionable a decade ago. Not even the worst idiot could forget to "cock" a bungeed pilot chute.

For some silly reason bungeed pilot chutes fell out of fashion.
I never understood why.
And I have done dozens of hop-and-pops with bungeed pilot chutes after dropping students.


xavenger  (A 1)

Jul 14, 2005, 7:57 AM
Post #3 of 65 (2588 views)
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Re: [riggerrob] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Can you run this by me again .. what do you mean by a "bungeed pilot chute"? How do you bungee it?


> Not even the worst idiot could
> forget to "cock" a bungeed pilot chute

This idiot doesn't even know what one is! ;-)


hookncrater

Jul 14, 2005, 7:57 AM
Post #4 of 65 (2588 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

If you don't want to use one, don't. No one forces anyone to use a kill-line PC just like no one forces anyone to use mini-risers w/mini-rings.

By the same token, I've seen people who jump lightly loaded canopies still collapse their slider and pull it behind their head. No real benefit there other than not having it flapping.

Also, if I'm not mistaken, companies such as Mirage will substitute a standard non-collapseable PC free of charge when you place your order if you so desire.

How many PC-in-tow mals really happen? If someone's attention to detail is lacking so much that it is dangerous for them to jump a kill-line PC because they can't remember to cock it when they are packing, they probably have other issues as well. Flame away if you like. Wink

My $0.02


larsrulz  (C 34603)

Jul 14, 2005, 8:07 AM
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

The following is an email from John LeBlanc (PD's head canopy designer) to skymedic on here, as has been posted once before on these boards.
_____________________________________________________________________________

It is quite common to not understand the problems associated with an inflated pilot chute on big canopies. What people don't understand is that it is not just the amount of drag produced by the pilot chute. The bigger issue is where that drag is applied: to the top of the canopy in a backwards direction. Having the drag applied here causes several things:

First, it attempts to rotate the canopy back into a flare, thus reducing the amount of flare power remaining.

Second, this "dragging through the air" flight regime makes the canopy bounce around more in light turbulence, making it more difficult to get the canopy to fly a smooth stable approach at a constant airspeed. (A smooth steady state approach is a big help in getting consistent landings.

Third, this extra drag tends to make the canopy flare a bit when making quick heading corrections on final approach. Eventually, that canopy noses over slightly and gains speed again, only to repeat this oscillation a bit more mellow. This makes timing the flare a big challenge, as the best flare from each stage of this oscillation is a bit different! This problem is much more pronounced on bigger canopies, especially those that have a larger section of tail pulled down by each control line, such as PD bigger than 190, Sabres bigger than 190, and all tandem canopies.

Fourth the pilot chute can distort the canopy as the end cells try to out fly the center cell. You can sometimes see this as a bend in the canopy at the center cell, when looking up at it in flight. This causes a change in angle of attack in specific areas of the canopy. It results in more lift being generated in the center cells, but less lift being generated by the end cells. This causes the end cells to be loaded too lightly, making them more prone to folding under from a side gust or downdraft in turbulence. This situation is aggravated by using quick toggle movements to make small heading changes, especially when there is a left, right left sort of thing going on with the toggles. (I know this sounds sounds silly, but watch people on final approach and you'll see this a lot.)

The Collapsible pilot chute will be of benefit to this jumper in a few ways:

First, the canopy will be less susceptible to turbulence.

Second, the canopy will have a more effective flare, particularly when making less than optimum approaches when small corrections are made during the last 10 to 15 seconds. (Its best to plan approaches so that these corrections aren't necessary.)

Third, in the event that the jumper wants to learn about using front risers, the canopy will respond better in this mode, with less riser movement being required, and more potential gained. This is because the adverse affects listed above become more pronounced with added airspeed, so vicious cycle starts to occur: The jumper doesn't get much out of a bit of front risers, so he pulls more riser, which causes more drag on the pilot chute which rotates the canopy back more which gives less effect which causes the jumper to pull more front riser and so on.

Collapsing the pilot chute will produce little extra airspeed at normal full glide, but it will change the handling and effectiveness of the flare. Making sure the brake lines aren't pulling down the tail too much is another. On the Sabre 230, a slight amount of tail pulled down is ok. (Check our web site for trim specs.)

Collapsible pilot chutes are not only for the small high performance canopies, but also help conservative jumpers using conservative canopies to get more out of them. They are particularly important on older F-111 nine cell canopies, such as the PD series. There isn't much excess energy brought to the flare on these old canopies. My recommendation to get rid of the pilot chute has helped many people get better landings on these canopies. The difference in flare power is a bit less noticeable on the Sabres, but it is there.

[Edited for removing specific comments towards specific people]

I would like to point out that these effects are real, and removing the pilot chute will produce more consistent canopy piloting performance. Experienced test jumpers on our staff get far better and more accurate results with a collapsible installed. And if you don't have your equipment set up properly, how will you get the experience needed?

Once you've worked out the steps to create a state of continuing improvements in technique, there is probably no other thing that has a bigger effect than collapsing the pilot chute, other than making sure the brake lines are set with too much tail pulled down at full glide.
_____________________________________________________________________________


xavenger  (A 1)

Jul 14, 2005, 8:07 AM
Post #6 of 65 (2572 views)
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Re: [hookncrater] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

> If you don't want to use one, don't.
> No one forces anyone to use a kill-line
> PC just like no one forces anyone to
> use mini-risers w/mini-rings.

I realise no one is forced to use one .. but I wonder how many newer skydivers (exactly the sort of people who are - or should - be on lower wingloadings) even realise it's an option NOT to have one.


> How many PC-in-tow mals really happen?

I don't know but they clearly happen enough for people to be worried about them and hold a huge conversations as to how to best deal with them. Prevention is the best medicine.


> they can't remember to cock it when
> they are packing, they probably have
> other issues as well

I'm not sure I understand why what other issues someone may or may not have matters at all. No one "deserves" to die for mucking up. If someone has others issues then surely minimizing their risks is a priority and this could be one thing that helps them do that.


xavenger  (A 1)

Jul 14, 2005, 8:10 AM
Post #7 of 65 (2570 views)
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Re: [larsrulz] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Excellent information and exactly the sort of stuff I wanted to read. A very different take to billbooths comment to think about. Thanks.


chuckbrown  (D 19538)

Jul 14, 2005, 8:49 AM
Post #8 of 65 (2524 views)
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Re: [hookncrater] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

In reply to:
By the same token, I've seen people who jump lightly loaded canopies still collapse their slider and pull it behind their head. No real benefit there other than not having it flapping.

Uncollapsed sliders put additional wear on the suspension lines from all the flapping around.


Premier billvon  (D 16479)
Moderator
Jul 14, 2005, 9:19 AM
Post #9 of 65 (2498 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

>I realise no one is forced to use one .. but I wonder how many newer
> skydivers (exactly the sort of people who are - or should - be on
>lower wingloadings) even realise it's an option NOT to have one.

That's something that newer skydivers have to realize. There are a lot of options on rigs:

-pullout/throwout
-ROL/BOC
-big rings/small rings
-type 17/type 8 risers
-collapsible/non collapsible PC
-ringed/nonringed harness
-RSL/collins/none
-B-12's/friction adapters

Some have become so commonplace that the old options are barely mentioned (if offered at all) and newer skydivers often don't notice them. Yet some still make sense - if you have an RW jumper with limited flexibility due to an injury, an ROL PC may make a lot of sense. It is worth asking about.

In general I lean towards everyone getting some sort of collapsible, because everyone seems to want to downsize - and getting a collapsible PC is often like downsizing one size in terms of performance (at least in terms of flare and glide ratio.) And you are a lot safer under a Sabre2 170 with a collapsible than under a Sabre2 150 without one.

>If someone has others issues then surely minimizing their risks is a
> priority and this could be one thing that helps them do that.

Problem is that it's often impossible to make the 'perfect' gear decision. Everything is a tradeoff.


hookncrater

Jul 14, 2005, 9:34 AM
Post #10 of 65 (2478 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Quote:
I realise no one is forced to use one .. but I wonder how many newer skydivers (exactly the sort of people who are - or should - be on lower wingloadings) even realise it's an option NOT to have one.

What Bill said basically sums up my view. A quick perusal of the "options" page of any manufacturer's website will show what can/can't be put on a rig. Plus, just about every student rig I have seen had a std PC.

A lot of things can cause a PC-in-tow, not just a collapsed PC.

I keep waiting for the "what if the kill line breaks?" comments to pop up since some people seem to think that the PC collapses instantaneously if the kill-line goes. Crazy


xavenger  (A 1)

Jul 14, 2005, 9:42 AM
Post #11 of 65 (2465 views)
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Re: [hookncrater] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

> A quick perusal of the "options" page
> of any manufacturers website will show
> what can/can't be put on a rig.

I have hardly ever, ever seen someone come off student status, go to buy their first rig and go through the options like this. Nearly always someone's first rig is recommended to them and even if a new rig a large part of the decision making is done for the newbie by the person at the gear shop. Options are not offered and explained - you're told what you want.

Look what I was trying to ask was is there some mileage in having a non-collapsible pilot shoot if you're on a low wingloading anyway .. if there are no downsides, even the tiniest removal of something else to go wrong it has to be a good idea.

However, another poster had contradicted the notion that there are no down-sides, which is v interesting and likewise billvon who thinks there is a noticable change in canopy characteristics.


(This post was edited by xavenger on Jul 14, 2005, 9:45 AM)


LawnDart21  (D License)

Jul 14, 2005, 12:12 PM
Post #12 of 65 (2395 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Quote:
I got thinking about what the best way would be to eliminate or massively reduce the likelihood of having a pilot chute in tow mal in the first place

I've only been in the sport a short while, but I have yet to ever hear of anyone specifically that had a pc in tow from an uncocked pilot chute. Not saying it doesnt happen, but it happens so infrequenty, I cant see it being a pressing issue that needs to be addressed by going back to non collapsible pilot chutes.


speedy

Jul 14, 2005, 12:44 PM
Post #13 of 65 (2368 views)
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Re: [riggerrob] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

In reply to:
For some silly reason bungeed pilot chutes fell out of fashion.
I never understood why.
And I have done dozens of hop-and-pops with bungeed pilot chutes after dropping students.

Probably because with my canopy/wing loading the damm thing does not stay collapsed Crazy


hookncrater

Jul 14, 2005, 1:01 PM
Post #14 of 65 (2356 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Quote:
I have hardly ever, ever seen someone come off student status, go to buy their first rig and go through the options like this. Nearly always someone's first rig is recommended to them and even if a new rig a large part of the decision making is done for the newbie by the person at the gear shop. Options are not offered and explained - you're told what you want.
Quite simply, those people are sheep. I did my own homework when I was a student, bought a couple of books including Dan Poynter's and Brian Germain's, talked to many instructors, not just mine, and did tons of reading on *gasp* dz.com. Blindly listening to people at the local dz for gear recommendations is probably why you still see people trying to freefly in old Dolphins with ragged out F-111 canopies. Crazy


xavenger  (A 1)

Jul 14, 2005, 1:11 PM
Post #15 of 65 (2345 views)
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Re: [hookncrater] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

> Quite simply, those people are
> sheep. I did my own homework

Good for you that you did your own homework. This doesn't detract from what reality of what I said though - which is practically all new skydivers rely on recommendation from someone else without *really* knowing what they're buying and whether other options might suit them better or even exist. This is pretty much just how it is to the best of my knowledge.

It's the same in most areas of expertise, the expert makes what they believe to be the best recommendation and the newbie goes along with it. Many times the "expert" doesn't even consider a different approach because they're so used to doing something a certain way. Going back to the original topic everyone's so used to collapsible pilot chutes practically no give thinks about or considers the merits of not having one (if any exist that is)


kelpdiver  (B 7)

Jul 14, 2005, 1:50 PM
Post #16 of 65 (2323 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

In reply to:
I have hardly ever, ever seen someone come off student status, go to buy their first rig and go through the options like this. Nearly always someone's first rig is recommended to them and even if a new rig a large part of the decision making is done for the newbie by the person at the gear shop. Options are not offered and explained - you're told what you want.

Good reasons to pick your dealer carefully. I spent a good hour going over the Wings order form because there were a lot more choices then just the ones Bill listed. ZP versus F111 PC, thick or thin chest strap come to mind.


tombuch  (D 8514)

Jul 14, 2005, 2:59 PM
Post #17 of 65 (2281 views)
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Re: [LawnDart21] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

In reply to:
I've only been in the sport a short while, but I have yet to ever hear of anyone specifically that had a pc in tow from an uncocked pilot chute.

Been there, handled that. The rig was packed by a DZ packer rat, and back then collapsible pilot chutes didn't have windows to confirm they were cocked. I got bit. I still see it happen once in a while.
.


bob.dino  (E 2185)

Jul 14, 2005, 4:28 PM
Post #18 of 65 (2247 views)
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Re: [tombuch] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Did you manually pull the pin, go red then silver, or just silver?

/curious


tombuch  (D 8514)

Jul 14, 2005, 4:47 PM
Post #19 of 65 (2235 views)
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Re: [bob.dino] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

In reply to:
Did you manually pull the pin, go red then silver, or just silver?

/curious

My practiced procedure was cutaway then reserve, so that's what I did. It happened on a pick up 60 way with an ugly breakoff, so I wound up throwing at about 1,500 feet, saw the collapsed pilot chute, vented some nasty words in the direction of the packer, and then cutaway and pulled the reserve.
.


veter_

Jul 14, 2005, 7:03 PM
Post #20 of 65 (2205 views)
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Re: [tombuch] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

How about malfunctions when pilot chute gets under the nose of the canopy? Will uncollapsed PC cause a problem?


firstime  (B 28972)

Jul 14, 2005, 7:19 PM
Post #21 of 65 (2197 views)
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Re: [riggerrob] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

 Not even the worst idiot could forget to "cock" a bungeed pilot chute.
Quote:
A gross understatement


Premier billvon  (D 16479)
Moderator
Jul 14, 2005, 8:00 PM
Post #22 of 65 (2182 views)
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Re: [xavenger] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

>I have hardly ever, ever seen someone come off student status,
>go to buy their first rig and go through the options like this. Nearly
> always someone's first rig is recommended to them . . .

That's the way it should be IMO. If a new jumper wants to do the research and they know what they want, great. If not, someone with more experience will make the decisions, and probably make better decisions than the new jumper. I know when I started out, I was thinking things like tertiary rings would be cool and completely overlooking things like harness-ring size.


DancingFlame  (C 177476)

Jul 14, 2005, 11:59 PM
Post #23 of 65 (2144 views)
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Re: [hookncrater] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Quote:
I've seen people who jump lightly loaded canopies still collapse their slider and pull it behind their head. No real benefit there other than not having it flapping.
There is at least one more benefit. Flapping slider causes wear to suspension lines. Collapsed slider causes little-to-no wear. Slider behind the head does not wear lines


billbooth  (D 3546)

Jul 15, 2005, 4:58 AM
Post #24 of 65 (2092 views)
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Re: [DancingFlame] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

Everything humans do to go faster entails risk....whether it's fast cars, fast parachutes, or for that matter, fast women. Highly loaded ZP canopies, micro lines, and collapsible pilot chutes and sliders, all add risk to your skydive. But skydiving itself is risky, and who's to say when the risk becomes "too much". The answer, of course, is "You are". Don't go too far, too fast. You simply don't need all the fast stuff on your first rig. Freefall ought to be enough for a while. I enjoyed the hell out of my few hundred skydives, and my main, a Para-Commander only went 10 MPH.


Premier Remster  (C License)

Jul 15, 2005, 6:01 AM
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Re: [firstime] Collapsible Pilot Chutes - Unnecessary additional risk? [In reply to] Can't Post

In reply to:
Not even the worst idiot could forget to "cock" a bungeed pilot chute.
Quote:
A gross understatement

No its not. Bungee PC dont get cocked.


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