Pilot Chutes....

[funks 1]

After reading a couple of posts recently (the fight one, and one in incidents) it got me thinking...is the reduction in drag really worth having a collapsable pilot chute? And is there really that much of a reduction in drag by collapsing the pilot chute to make it worth it? Besides the chute just wearing out over time, it seems like going with a non-collapsable pc could remove one very serious mal (pc in tow, due to uncocked pc) from the skydiving equation....

My thoughts are that (at least) I wouldnt even notice the difference under canopy if my pc didnt collapse, perhaps a crazy ass swooper would, but i dont think i would....

thoughts???

[piisfish 140]

no need to be a crazy ass swooper...
when there is wind I'm always happy to have a collapsed PC.
moreover speed (up to a certain extent) is your friend for landing. Horizontal speed means lift...

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[diablopilot 2]

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After reading a couple of posts recently (the fight one, and one in incidents) it got me thinking...is the reduction in drag really worth having a collapsable pilot chute?

Yes. Especialy as your airspeed increases, such as when you load a canopy heavier. A no colapsable P/C produces a huge amount of drag at even 30 mph. that drad will slow the canopy reducing lift, AND distort the top skin of the canopy also reducing lift and stability.

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You're not as good as you think you are. Seriously.

[lopullterri 0]

Even a large canopy is affected by the drag of a p/c. It distorts the topskin of your canopy and is affecting the flight and landing. In turbulance or moderate winds, it affects it even more. The best way to answer your question is to spend some time watching canopies land with non-collapsing p/c's.

~"I am not afraid. I was born to do this"~

[Liemberg 0]

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I wouldnt even notice the difference under canopy if my pc didnt collapse, perhaps a crazy ass swooper would, but i dont think i would....

I dont know how you load that Sabre of yours but I can asure you that when it is loaded 1 or higher, you'll notice the difference. You can feel the pilot dancing up and down if it is non collapsable.

There is no reason other than plain stupidity to forget to cock a PC. It is fairly simple to build in a procedure to asure that it is cocked (takes one extra second to check when you fold your PC - much smarter than making a dumbass of yourself 'looking for a green light' on jumprun...)

Anyone who skips that deserves what is coming...

"Whoever in discussion adduces authority uses not intellect but memory." - Leonardo da Vinci
A thousand words...

[larsrulz 0]

John LeBlanc (chief designer at PD) sent the following email to a fellow jumper at my DZ; he had asked about the benefit of a collapsable pilot chute on a Sabre 230:

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.

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.

I got a strong urge to fly, but I got no where to fly to. -PF

[towerrat 0]

here's a little experiment.
Get a regular (non-collapsible) pilot chute.
have a friend drive while you hold it out of the window. I'll bet you have a hard time holding on to it at 25 or 30 mph.

Play stupid games, win stupid prizes!

[jeffmullins 0]

Yes a collapsible pilot chute makes a large difference in canopy performance, especially when you are jumping small high performance canopies. Also, a coolapsed pilot chute will still have enough drag to deploy your main in most circumstances.

[Sandro29 0]

I recently changed my PC on my Sabre 150 to a collapsable one. I only have 100 jumps experience, but I can feel a difference on landing and on windy days.

My PC is also a little smaller than the original PC...I though it might help soften the opening somewhat...it feels a little smother since I changed.

I noticed the bridle on my new PC is a little shorter and was wondering what the minimum length should be on a Sabre 150...and if the lenght of the bridle plays a part in the somewhat softer openings.

If at first you don't succeed....then Skydiving is not for you!

[diablopilot 2]

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and if the lenght of the bridle plays a part in the somewhat softer openings.

Not really.

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I noticed the bridle on my new PC is a little shorter and was wondering what the minimum length should be on a Sabre 150...

Won't make a difference for the canopy. It's a good idea to make sure it's compadible with your container and deployment system.

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You're not as good as you think you are. Seriously.

[Sandro29 0]

I checked with my rigger before I installed it....but never realy asked about the bridle length.

The collapsable PC does make a difference during flight though....even with my little experience I can feel the difference.

My original PC was 33" F111 non-collapsable...and I always had cracker openings. My new PC is 24" ZP collapsable and the openings are not as hard. I'm assuming its the size that doesn't seem to have quite as much snatch force compared to the larger one...even though the materials are different.

If at first you don't succeed....then Skydiving is not for you!

[eeva 0]

yes, having a collapsible pilot does make a lot of difference. I've recently replaced mine with a collapsible one, and even on my Merit 190, I've noticed much improvement in making turns, flying in turbulent winds and especially when flaring.

Grtz,
eva

I live not in dreams, but in contemplation of a reality that is perhaps the future - R.M.Rilke

[diablopilot 2]

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I'm assuming its the size that doesn't seem to have quite as much snatch force compared to the larger one...even though the materials are different.

I think the difference you're noticing is more because of the "kill-line" rather than the size or material.

A standard P/C will impart a pulling force on the top skin through out the deployment, "striping" the center cell and presenting the center nose cell to the air faster causing a more rapid inflation that you might encounter with a collapsible which is "killed" as soon as the bag comes off the pack job.

The size of a collapsible P/C has less to do with the opening after the canopy is out of the bag than pack job and slider placement. With a properly functioning "kill-line" P/C the difference in size (24", 28", 30", etc.) is mainly confined to how quickly the bag gets to line stretch. This is called "snatch force" A P/C can create an opening with a large snatch force, and it will pull you upright quickly, but then you may have a canopy/pack job combination that produces a soft opening.

What portion of the opening seems hard or fast to you with your current gear? What is your main canopy type?

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You're not as good as you think you are. Seriously.

[Sandro29 0]

I currently jump a Sabre 150 with a wing load of 1:3.
I pretty careful as to how neet the packjob is (I try not to disturb the lines during the packing) and I pull the slider, out towards the nose as much as I can. This slider position has definately slowed/softened the opening somewhat.

Once the lines have reached full stretch, the canopy seems and looks like it just fully inflates all at once. openings are usually right on heading. I'm in the saddle in about 500' consistantly....from pull-time to fully opened canopy.

I can't say that I dislike the openings because I personally would rather have a canopy that OPEN than one that snivels for close to 700'.

If I could just soften the opening just a little..it be perfect.

By the way....I've also increased the size of the slider slightly..it helps a litltle as well.

Thanks for yor replies.....

If at first you don't succeed....then Skydiving is not for you!

[diablopilot 2]

If it's an original Sabre have you tired any of the following?:

1) Rolling the nose (4 left and 4 right) inward 3 or 4 times?

2) Rolling the tail a bight tighter?

3) Making sure the slider is up against the stops throughout the entire pack job?

4) Making sure that in addition to pulling the slider out front to back it is equaly distributed right to left?

I have found an overly large amount of neatness can sometimes have a detimental effect. Making knive edge iorn like folds when flaking between A's and B's and B's and C's looks nice but how much does it help? Ensuring your break lines an D lines are clear of material and centered with the other linegroups seems to work just as well and for whatever reason produces nice openings.

Something else to look at if you can not solve the problem by pack job alone:

Deployment speed. Make sure you are slowing down sufficiently prior to deployment, 5 mph makes a big difference.

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By the way....I've also increased the size of the slider slightly..it helps a litltle as well.

Careful that you're using a manufacturer approved slider size. A larger slider can sometimes make a canopy open HARDER if it alows the botom skin to inflate too rapidly. Sounds like you dont have this problem. You can make a slider effect larger than ti's actula length and width dimensions in some easily modified ways.

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You're not as good as you think you are. Seriously.

[Sandro29 0]

Its an original Sabre....the ones thast are known for their hard openings....lol


1. I've tried splitting the nose (as you mentioned) as well as rolling it in either direction, and that also helps to slow it down somewhat. Although I do not feel any difference if I simply roll the nose to the left , right, or split it.

2. I pro pack, and always make sure the slider is up against the stops

3. The slider seems to be properly balanced left to right, although I have found a difference if its pulled more towards the nose, rather than balance it from front to back.

The slider I put in is the same sixe in width, but 3/4" longer in lenght....that also seems to help slightly.

I think I've pretty much tried every little trick that I've heard off.....guess I'll just have to live with it....or maybe take up a more docile sport, like golf. What am I saying...I play golf already!!

Thanks for all the replies....they are much appreciated. If you happen to know or hear of any other tricks to slow down an opening....I'll definately listen.

If at first you don't succeed....then Skydiving is not for you!

[Squeak 17]

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here's a little experiment.
Get a regular (non-collapsible) pilot chute.
have a friend drive while you hold it out of the window. I'll bet you have a hard time holding on to it at 25 or 30 mph.

Yeah DON'T do this people have had their arms broken trying this from a moving vehicle

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[mikeat10500 12]

Don't try this either...but if you cut your bridle short enough. The PC will lay in the dead air at the trailing edge of the canopy(on top). My PC is only visible in this "side on" photo 'cause the top skin is distorted.
Non-collapsible, non-retractable, non-complicated.
P.S.
Not-approved by anyone.

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Mike Wheadon B-3715,HEMP#1
Higher Expectations for Modern Parachutists.

[JohnMitchell 16]

A shorter bridle might end up giving you problems with pilot chute hesitations. Are you also sure your hidden pilot chute is not inflating some, or some of the time, like when swooping? I couldn't really tell from the picture.

[mjosparky 4]

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here's a little experiment.
Get a regular (non-collapsible) pilot chute.
have a friend drive while you hold it out of the window. I'll bet you have a hard time holding on to it at 25 or 30 mph.

Yeah DON'T do this people have had their arms broken trying this from a moving vehicle

Who would be dumb enough to hang on to the PC until their arm broke? Think about it.
Sparky

My idea of a fair fight is clubbing baby seals

[diablopilot 2]

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Who would be dumb enough to hang on to the PC until their arm broke?

Haven't been hanging around the new breed of skydiver after hours much have you?


Ok, I thought it was funny.

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You're not as good as you think you are. Seriously.

[Squeak 17]

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here's a little experiment.
Get a regular (non-collapsible) pilot chute.
have a friend drive while you hold it out of the window. I'll bet you have a hard time holding on to it at 25 or 30 mph.

Yeah DON'T do this people have had their arms broken trying this from a moving vehicle

Who would be dumb enough to hang on to the PC until their arm broke? Think about it.
Sparky

Can you say SNATCH FORCE

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

[mikeat10500 12]

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A shorter bridle might end up giving you problems with pilot chute hesitations.

Yes..100% correct.

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Are you also sure your hidden pilot chute is not inflating some, or some of the time, like when swooping? I couldn't really tell from the picture.

90% deflated 90% of the time...saw video from above. Partial inflation in turns...never fully inflates after canopy opens. I used it on a Hornet 135 I was jumping, but only 3 times. I'm no swooper...yet.

-----------------------------------
Mike Wheadon B-3715,HEMP#1
Higher Expectations for Modern Parachutists.

[mjosparky 4]

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Can you say SNATCH FORCE

I can not only say it, I'll go you one better, I know what it means. I have tested PC many times in the last 20 years, usually from the bed of a truck using a strain gauge. Not once have I broke my arm. But then again, I am just dumb rigger.
Like I said "Who would be dumb enough to hang on to the PC until their arm broke? Think about it. "

My idea of a fair fight is clubbing baby seals

[Squeak 17]

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Can you say SNATCH FORCE

I can not only say it, I'll go you one better, I know what it means. I have tested PC many times in the last 20 years, usually from the bed of a truck using a strain gauge. Not once have I broke my arm. But then again,

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I am just dumb rigger.

Hmm if I agree is that a personal attack

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Like I said "Who would be dumb enough to hang on to the PC until their arm broke? "

Not me

You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?