Collapsible Pilot Chutes - Unnecessary additional risk?

[tdog 0]

HYJACK ALERT:

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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.

I jump 1.15 to 1. In a canopy class I was strongly urged to collapse my slider, pull it down, and loosen the chest strap. I had always collapsed it and just left it up there, thinking no reason to pull it down.

The second I loosened the chest strap a few inches the canopy changed it's glide slope so much that it felt like I raised my brakes a few inches if not more. My heart missed a beat, I was not expecting something so drastic. Now I always do it (after I am 100% sure I have time, sometimes I am flying in traffic the whole way down and have to live with a flapping slider up there) because my canopy does fly and land better, just as my canopy instructor promised. And, that is at low wingloading.

[nicknitro71 0]

It does come down to the canopy and WL.

On my BASE canopy ( ACE 240 @ 70) I can barely tell the difference between a 32" and a 46" PC and the increase in drag beween the two is over 50%.

Memento Audere Semper

903

[tso-d_chris 0]

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The second I loosened the chest strap a few inches the canopy changed it's glide slope so much that it felt like I raised my brakes a few inches if not more. My heart missed a beat, I was not expecting something so drastic.

When you loosen your chest strap, you allow your canopy to flatten out a bit, by allowing your risers to spread apart. This increases the amount of effective lift producing surface area of the canopy. Even better is that it does so without increasing your drag with respect to forward motion. The result is a canopy that is able to produce more lift. This extra lift can be the difference between an off field landing and landing in the peas on a long spot.

Collapsable pilot chutes and sliders serve the same purpose. They make your canopy fly more efficiently by reducing air resistance with respect to forward motion. Sure, this is important if you swoop, but it is also important if you have a long spot.

I can think of few situations where a superior glide ratio (all else being equal) is not better.

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[tdog 0]

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I can think of few situations where a superior glide ratio (all else being equal) is not better.

And those are????

[tso-d_chris 0]

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And those are????

The first to come to mind is that a steeper gliding seven cell is often more stable when it is necessary to sink a canopy into an extremely tight landing area.

That is not a good reason to get a steeper gliding canopy, IMO.

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[tbrown 26]

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

I've had one or two of those back in the seventies on an old model seven cell (a Pioneer Viking Superlite). My p/c wrapped around the front right lines and dragged like an anchor. I elected to keep the canopy, but as I got closer to the ground, the exertion of holding the canopy in a straight line of flight turned my right arm to jelly. By the time I landed, my arm simply would not obey when it was time to flare and I made a nice left turn into the fresh plowed dirt of the big student zone at Perris. I got up and walked away from that one, but I'm not so sure I would've if I'd done that with one of today's canopies. I might've broken some serious face. It's a fact that a pilot chute CAN take a dive underneath your canopy, or around a line group. Can't say for sure, but it stands to reason that a collapsed p/c would be a lot easier to handle.

I might also add that there were plenty of p/c in tow malfunctions before collapsables ever came along, and they're not about to go away. I like kill line collapsables, even if I'm jumping a 210 ft canopy. They're safe, you just gotta learn how to use them and maintain them - just like the rest of your rig.

Your humble servant.....Professor Gravity !

[skymedic 0]

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then Bill Booth came along and said:

Just remember...He maybe Bill Boothe but he is not the only opinion out there. I tend to lean towards John Leblanc on this one...

Marc
otherwise known as Mr.Fallinwoman....

[VectorBoy 0]

When I bought my own rig that had a non-collapsable everyone told me that at 1:1 I shouldn't waste money on a new PC. This advice was almost universal 100% from everybody, instructors, coaches, riggers and even the vendors that could of had a vested interest in selling me a new PC.

I somehow new there was room for improvement. Well after going against all of the advice and installing a new collapsable on my 1:1 I found a dramatic improvment. More so than any other thing that had been done to my gear or technique.

Which made me wonder if I was so much more "in tune" with my gear than all that gave the advice ( most probably not! ) or it had just been soo many years and jumps ago since that large and experienced group had struggled at the meager wingloading of 1:1 ( much more likely)

Try It! I would look up at my spectre and see it dragging along the inflated PC, bowing the plane form and curling up the topskin. A collapsable PC doesn't suck.

[divenfly03 0]

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HYJACK ALERT:

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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.

I jump 1.15 to 1. In a canopy class I was strongly urged to collapse my slider, pull it down, and loosen the chest strap. I had always collapsed it and just left it up there, thinking no reason to pull it down.

The second I loosened the chest strap a few inches the canopy changed it's glide slope so much that it felt like I raised my brakes a few inches if not more. My heart missed a beat, I was not expecting something so drastic. Now I always do it (after I am 100% sure I have time, sometimes I am flying in traffic the whole way down and have to live with a flapping slider up there) because my canopy does fly and land better, just as my canopy instructor promised. And, that is at low wingloading.

Out of curiosity, and apologies for the continued hijack, must the slider be collapsed to gain the improved performance you noted when the chest strap was loosened? Have you evaluated the effect of just loosening the chest strap?

[tdog 0]

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Out of curiosity, and apologies for the continued hijack, must the slider be collapsed to gain the improved performance you noted when the chest strap was loosened? Have you evaluated the effect of just loosening the chest strap?

Umm.... Pulling it down past the Slinks and toggles, with MY slider is required, otherwise the width of the slider is narrower than the width of the loosened chest strap - and the slider becomes the narrowest common denominator.... The one time I pulled it down not collapsed I realized the error of my ways, all of a sudden I had a huge piece of fabric behind my head that obscured ALL my vision back there. Collapsing it and wrapping it up I can still see...

So... It is a chain effect. To widen the canopy attachment the slider has to be lower, to see the slider has to be collapsed. At least on MY rig.

[billbooth 10]

It's all very natural...The canopy manufacturer (John LeBlanc) simply wants his open canopy to perform as well as possible. (All those deployment devices, pilot chutes, bags and sliders, are just a necessary nuisance to him.) While the rig manufacturer (Bill Booth) simply wants the canopy to simply deploy as reliably as possible. So, he hates to see those devices made more complicated than necessary, because he knows that that will lead to an increase in deployment malfunctions. (There is simply no doubt that you cannot forget to cock a non-collapsible pilot chute or slider, and therefore they are more reliable.) And remember, a very good percentage of malfunctions are caused by, you got it, human error. It is simply a matter of maximum reliability vs. maximum speed. Choose one...you cannot have both.

I have over 5,000 (non-tandem) jumps without a collapsible pilot chute, and I have never had a pilot chute in tow, nor have I ever been injured by my fully inflated 36" pilot chute "dragging" behind my fully inflated canopy. But remember, I don't jump much greater than a 1:1 wing loading. It's a simple rule I live by...I always want a little more canopy over my head than absolutely necessary, for those off-DZ, or broken-line, or last minute avoidance situations. Call me old fashioned, but I still walk without a limp after 35 years of skydiving.

So, unless swooping is your thing, don't over-complicate your deployment devices, and don't jump a tiny canopy just to be cool. The tiny canopy injury rate now far exceeds even that of the old flat circular rounds. We cetainly have come a long way...of have we. In my book, a entire class of canopies that hurts a lot of people cannot be called "successful", and certainly isn't "progress". This is clearly NOT the fault of the canopy manufacturers. Canopies do not crash themselves. I believe it is the fault of a DZ culture, which pushes inexperienced jumpers into gear they simply cannot handle. And pushes nearly everybody toward less reliable deployment devices, just to get that last few percentage points of performance out of their canopy. In my oinion, it just isn't worth the risk.

[tso-d_chris 0]

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I always want a little more canopy over my head than absolutely necessary, for those off-DZ, or broken-line, or last minute avoidance situations. Call me old fashioned, but I still walk without a limp after 35 years of skydiving.

It seems anti-intuitive to not take measures to maximize the performance of the square footage you do have. Why handicap the canopy at all? Is cocking a pilot chute such a complicated process that the obvious benefits be sacrificed? Maximum glide and lift on flare are not just beneficial to swoopers.

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I believe it is the fault of a DZ culture, which pushes inexperienced jumpers into gear they simply cannot handle. And pushes nearly everybody toward less reliable deployment devices, just to get that last few percentage points of performance out of their canopy. In my oinion, it just isn't worth the risk.

Last time I checked, these "less reliable deployment devices" are provided by the container manufacturers. In fact, The Relative Workshop builds what is arguably the most imitated container on the market. If kill lines are such a huge danger as you are implying, why do you build them? Don't the manufacturers help define the DZ culture?

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In my oinion, it just isn't worth the risk.

Except during front riser flight, full flight, braked flight, turning and landing, I can't think of a single scenario when a collapsable pilot chute would be beneficial, pushing the odds just a little further in favor of the jumper.

[kelpdiver 2]

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Out of curiosity, and apologies for the continued hijack, must the slider be collapsed to gain the improved performance you noted when the chest strap was loosened? Have you evaluated the effect of just loosening the chest strap?

That's all I do thanks to the fat connectors.

There is still a gain, just not a huge one. It also seems to make light turbulence a bit more interesting as my body weight can shift more in the harness.

[billbooth 10]

Why all the hostility, Chris? I'm just offering my opinion.

I would imagine that failure to cock the pilot chute is one of the most common packing errors, often leading to one of the scariest malfunction I can think of....Your pin is pulled...your container is open...but your pilot chute doesn't have enough drag to lift out the bag. What do you do? Nothing will happen if you breakaway, and the moment you pull your reserve, your main bag is going to go...and, as I have noted before, simultaneous deployments are rarely much fun. For me, NOTHING is worth increasing the risk of that malfunction. For this reason, I DID refuse to make collapsible pilot chutes for many, many years. I finally gave up, and started to make them just a few years ago, because of the often poorly constructed collapsibles I was apparently "forcing" my customers to buy after-market.

I have measured forward speed of the same 1:1 loaded canopy, with and without a collapsible, and found absolutely no difference. Extra risk...no measurable added performance... WHY?

As I've said above, I will admit that for highly loaded canopies, collapsibles do make a quite a difference. They just are not necessary for everybody, and I think students should be advised of that fact.

[tso-d_chris 0]

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Why all the hostility, Chris? I'm just offering my opinion.

Was not intended to be hostile; I apologize if that is how you interpreted it. I just fail to see the consistancy of your argument.

A pilot chute in tow is a malfunction that is nearly always preventable.

Personally, I like to cock my PC twice during each pack job. That way, should I fail to do it at either time, I have a built in backup. It only adds a few seconds at most to a pack job. Plus, there is a lot to be said for pin checks.

Besides, I'm not convinced skydiving gear should be idiot proof. The less jumpers have to think about their gear, the less jumpers will think about their gear.

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I have measured forward speed of the same 1:1 loaded canopy, with and without a collapsible, and found absolutely no difference.

Gotta call BS here, Bill. Absolutely no difference? How did you reach that conclusion? Where, exactly, is the critical wingloading where a collapsable PC makes a difference? There is none. All canopies benefit from a collapsed pilot chute. Admittedly, the benefit is greater on smaller canopies, but the detrimental effects of an inflated PC is noticeable at even low loadings.

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They just are not necessary for everybody, and I think students should be advised of that fact.

I don't remember reading anything about collpsable PCs being necessary. For that matter, neither are helmets, goggles, altimeters, shoes, etc. They all put the odds just a little more in the jumper's favor, though. Even collapsables on lightly loaded canopies.

[sundevil777 94]

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You said yourself that you have had 5000 collapsable PC jumps without a PC in tow.

Actually, he said they were non-collapsible without a PC in tow.

Bill, what do you think of the old method of letting a light weight bag go back over the PC?

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[skymedic 0]

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I have measured forward speed of the same 1:1 loaded canopy, with and without a collapsible, and found absolutely no difference. Extra risk...no measurable added performance... WHY?

Why do you collapse the drogue on your tandem canopies after deployment? wouldn't avoiding that reduce a chance of forgetting to cock it beforehand resulting in a drogue in tow....although I understand your sigmas will cock themselves in freefall even if you forget...

Marc
otherwise known as Mr.Fallinwoman....

[mjosparky 3]

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Gotta call BS here, Bill. Absolutely no difference? How did you reach that conclusion? Where, exactly, is the critical wingloading where a collapsable PC makes a difference? There is none. All canopies benefit from a collapsed pilot chute. Admittedly, the benefit is greater on smaller canopies, but the detrimental effects of an inflated PC is noticeable at even low loadings.

Several years ago I made jumps on 11 different canopies over a 3 day period. They ranged in size for 189 sq. ft. to almost 300 sq. ft. The first jump on each canopy was with a 32" F-111 no-collapsible PC. The second was with a 28" ZP center line collapsible PC. On each jump the forward speed was measured with a hand held radar gun with the canopy flying head on. The largest speed differential was less then 2 mph with the average less the 1 mph.

I would have to agree with you that all canopies will benefit for a collapsed pilot chute but very few jumpers have access the equipment necessary to measure the difference. And very few jumps have the ability to use the difference.

Sparky

My idea of a fair fight is clubbing baby seals

[tso-d_chris 0]

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Actually, he said they were non-collapsible without a PC in tow.

You are correct. Oops. I edited the post. Thanks.

[tso-d_chris 0]

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Several years ago I made jumps on 11 different canopies over a 3 day period. They ranged in size for 189 sq. ft. to almost 300 sq. ft. The first jump on each canopy was with a 32" F-111 no-collapsible PC. The second was with a 28" ZP center line collapsible PC. On each jump the forward speed was measured with a hand held radar gun with the canopy flying head on. The largest speed differential was less then 2 mph with the average less the 1 mph.

That sounds interesting. I have heard 10% reduction in forward speed with an uncollapsed PC, which sounds a little bit high. I'm curious, were the canopies being swooped, or were they straight in approaches? Was the angle of descent measured? I always miss out on all the cool science experiments.

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And very few jumps have the ability to use the difference.

I agree. Most jumpers don't know how to utilize the extra bit when they need it. Better canopy training is helping to remedy this. The need for that bit of extra performance doesn't arise every jump, either. Lack of spotting education is helping to change this.

If I had to recommend a new jumper get a collapsable pilot or canopy coaching, I'll likely recommend the coaching. But if they are trying to decide between a kill line PC and a non-collapseable PC, I'm gonna advise for worse case, just as I would for a reserve, and recommend the kill line.

Someone once said that its nice to be good, but its better to be lucky. There is some truth to that. Someone else said that we make our own luck. There is also some truth to that. Skydiving is inherently dangerous, and you never know when the sport is going to present its next No Shit There I Was, Thought I Was Gonna Die T-shirt Moment (TM). I personally don't want to handicap my canopy to simplify my packing. I can take my time packing.

[GravityGirl 0]

My bottom line when I discuss this option with my customers is this.

People/skydivers are creatures of habits. Mostly every skydiver these days will downsize in the future. They'll downsize to a canopy that will most definately benfit from a collapsable slider.

If you are on the boarder of standard or collapsable, please consider that you will be learning to pack and ingraining into your mucsle memory NOT collapsing a pilot chute. If/when you get to the point where a collapsable PC would be beneficial, you'll be more prone to forgetting to cock your PC than someone who has always cocked it, because that is what they were taught and that is what they've done for the last 500 jumps.

I rarely see anyone forgetting to walk their slider up or stow their lines. If cocking a pilot chute is and always has been part of the packing proceedure, then the odds of that step being forgotten are slim.

On the other hand if you pack 500 parachutes without cocking a PC, then you downsize and get one... well, you can see how the odds for forgetting would be much higher.

Just my opinion. Worth what you paid for it.

~~~~~~~~~~~~~~~~~
Peace and Blue Skies!
Bonnie ==>Gravity Gear!

[billvon 2,406]

>>I have measured forward speed of the same 1:1 loaded canopy,
>> with and without a collapsible, and found absolutely no difference.

>Gotta call BS here, Bill. Absolutely no difference? How did you reach
>that conclusion? Where, exactly, is the critical wingloading where a
> collapsable PC makes a difference? . . .
> All canopies benefit from a collapsed pilot chute.

I think you may be confusing two different things. "Benefit" is not the same as "forward speed." You can quantify forward speed; benefit is a lot harder to quantify. If a canopy that will land you in a very tight area is your goal, a non-collapsible PC will give you a significant benefit; it will shorten your runout. If your goal is swooping, a non-collapsible PC will be to your detriment.

IIRC, non-collapsible PC's generally do not affect forward speed, but do affect L/D (which means a steeper glide.)

>I don't remember reading anything about collpsable PCs being
> necessary. For that matter, neither are helmets, goggles,
> altimeters, shoes, etc. They all put the odds just a little more in the
> jumper's favor, though. Even collapsables on lightly loaded
> canopies.

On a very lightly loaded canopy, a collapsible PC doesn't help much and can cause problems for newer jumpers (who are the sort that generally jump very large canopies.) It's up to each jumper to decide if the risk (i.e. forgetting to cock the PC) is worth the benefit (i.e. a better planeout once they downsize a few times.)

[xavenger 0]

Gravitygirl. I think your comments - on reinforcing the appropriate habits from day one are very valid. Whilst not having a non-collapsible pilot chute to start with may be sensible, if there is a strong likelihood of a jumper moving on to a system with a collapsible a later date it may be difficult for someone to change routine.

James

[mjosparky 3]

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I'm curious, were the canopies being swooped, or were they straight in approaches? Was the angle of descent measured? I always miss out on all the cool science experiments.

All the canopies were flown straight in at full flight for speed measurements. No adjustment was made for angle of attack or descent rate of the different canopies. I would not call it a "scientific experiment." Test parameters, data points and other controls usually present for a test program were weak at best.

Sparky

My idea of a fair fight is clubbing baby seals

[tso-d_chris 0]

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I think you may be confusing two different things. "Benefit" is not the same as "forward speed." You can quantify forward speed; benefit is a lot harder to quantify.

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Faster forward speed equals more lift produced by the canopy. Usually, more lift is beneficial, but as you pointed out, sometimes a steeper glide can be beneficial as well.

non-collapsible PC's generally do not affect forward speed, but do affect L/D (which means a steeper glide.)

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Wouldn't steeper glide plus unchanged forward speed equal increased overall speed? I don't understand how that is possible with the increased drag of a non collapsed PC.

On a very lightly loaded canopy, a collapsible PC doesn't help much and can cause problems for newer jumpers (who are the sort that generally jump very large canopies.) It's up to each jumper to decide if the risk (i.e. forgetting to cock the PC) is worth the benefit (i.e. a better planeout once they downsize a few times.) ***

True, lightly loaded canopies benefit the least. I think it is better to learn to use a kill-line as early as possible. As GravityGirl pointed out earlier, there is more risk associated with introducing it later, after habits have already been developed. You view it as something extra because you (probably) didn't start with one. But if it were there from the beginning, cocking the kill line would be an integral part of the pack job.

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