f-111 kill-line pilot chutes deadly?

[wilcox 0]

I received an addition to the PD manual, one of the things was that they strongly recommended not to use f-111 kill line pilot chutes. They even called f-111 kill line pilot chutes deadly.
The short explanation was that f111 kill line pilot chutes lost kill line calibration quickly. And that f111 kill line pilot chutes caused strange openings.

Is it really that bad? Didn't PD recently recommend f111 pilot chutes? Anyone knows the background to this statement or have the same opinion and a more detailed explanation?

[CReWLL 0]

That's a pretty ridiculous thing to say.

[Tonto 1]

Agreed.

I've only ever used F-111 kill line pilot chutes - at least for the past 3700 dives anyway. If they go out of calibration quicker, I have not noticed - and if they do - recalibrate them.

Where's the deadly in that?

t

It's the year of the Pig.

[CReWLL 0]

That's probably why they're called "Kill Line" pilots, anyone that uses one will eventually die. They came out when F-111 was the only fabric they were made from. ZP models should be called "Life Line" pilots.

[tso-d_chris 0]

Sounds bogus.

[davelepka 4]

Was this shipped direct from PD, or through a dealer? If a dealer was involved, maybe they put the information in the box.

A quick look at the PD website didn't turn up anything liek this, and I would guess if they came across a life threatening situaiton, it would be in big flashing text on their site.

Also, I got two canopies from PD in the last month with all the 'use the right rubber bands' and 'freeflying is too fast for your canopy' flyers, but no anti F-111 stuff.

[Danne 0]

I call bullshit!

I checked with PD what kind of PC they recommend for about 3 months ago. They recommended 30" F-111 kill line pilot chutes!

On the other hand,
If you mean F-111 bungy chord kill line pilot chutes, thats totally different. They do loose calibration and are not recommended.

/D

[skybytch 273]

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If you mean F-111 bungy chord kill line pilot chutes, thats totally different. They do loose calibration and are not recommended.

That has nothing to do with the fabric the p/c is made out of - it's the bungee that loses "calibration" not the fabric.

[mr2mk1g 10]

same goes for kill line pc's though surely... ?

[skybytch 273]

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same goes for kill line pc's though surely... ?

A bungee is going to lose calibration (ie wear out) a whole lot faster than a centerline will.

Bungee's have also been known to not allow p/c inflation at subterminal speeds.

[mr2mk1g 10]

Yes I know - but the point is it's still the kill line which looses calibration, not the fabric.

So what difference does it being F111 or ZP make? About the same as on a bungee pc. It's still the retraction method which goes out of whack rather than the fabric itself.

[riggerrob 643]

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Quote

same goes for kill line pc's though surely... ?

A bungee is going to lose calibration (ie wear out) a whole lot faster than a centerline will.

Bungee's have also been known to not allow p/c inflation at subterminal speeds.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Yes, I have suffered one (3 second) pilot chute hesitation during hundreds of hop and pops with bungee pilotchutes.
Hee!
Hee!

The bottom line is: it is going to take 3 seconds. You have the choice of tossing your bungee pilot chute immediately and dragging it for three seconds. ... or you can wait three seconds, toss your pilot chute and get a prompt opening.

[GravityGirl 0]

Show us the documentation you are referring to. If -you can't scan it, please fax it to me at 925-396-6076.

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

[arlo 0]

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I received an addition to the PD manual, one of the things was that they strongly recommended not to use f-111 kill line pilot chutes. They even called f-111 kill line pilot chutes deadly.

no "official" additions/addendums to any PD manuals have been made in the past, oh, year at least. but would you mind emailing a copy of that "addition" you're talking about? my interest is piqued now regarding this. i'm only curious because i do know that the only manuals PD has put out in the past year or so have been military manuals. i happen to know the only technical writer at PD so i'm pretty sure my information is accurate.

thanks and if i were you, i'd seriously consider the source of my information.
hope this clears things up regarding the addition.

[arlo 0]

Okay, several years ago, there was an article about how to prevent hard openings. section 3 of this article (which can be found on PDs website) addresses pilot chutes. the last paragraph apparently is what was read and possibly misinterpreted. i've copied this directly so everyone can be on the same page, so to speak.

it does not say all F-111 pilot chutes are deadly. it says to never use an F-111 shock (bungee) cord collapsing pilot chute can be deadly.

i hope this clears matters up now.

blues,
arlo

(section 3 of article below:)
=========================





3. PILOT CHUTE
The pilot chute has a big effect on canopy deployments. The
size, type of fabric, length of bridle, apex length, mesh size,
and aerodynamic shape all affect the deployment of the
parachute. Some pilot chutes have too much drag at terminal
velocity. This can cause these problems:
1. They slow the bagged canopy down so quickly that the
chance of line dump is increased.
2. When reaching line stretch, the jumper instantly
accelerates the canopy back to his speed, since it is attached
to him by the fully deployed lines. This is the first force the
jumper feels at line stretch. (Moments later, the canopy starts
to fill with air and slows down again. A pilot chute with too
much drag will have slowed the bagged canopy down so
much that the jumper will experience quite a strong force
when the canopy reaches line stretch. The canopy feels this
jolt too, and the pack job will be forcefully spread apart by this
force. This can cause harder openings, since the now
disorganized canopy will inflate more quickly. In extreme
cases, it may even open hard enough to cause structural
damage to the parachute system, bodily injury, or death.
A Pilot chute with more moderate drag will get the canopy to
line stretch with less severe shock to the jumper and the
canopy. The line dump problem is also less likely to occur,
and the pack job is more likely to be released from the bag in
an orderly fashion.
Although a pilot chute with more moderate drag will produce
more consistent openings, a pilot chute can have too little
drag. This could happen if it is too worn out, (high
permeability) too small, malfunctioned, or designed
improperly. The danger here is obvious. The pilot chute must
consistently function correctly. If it does not, a baglock, or a
pilot chute in tow may result.
Most, but not all pilot chutes from container manufacturers are
compatible with Performance Designs canopies. A pilot chute
made from normal F-111 type fabric should be no
more than 32” in diameter. We have found 27 to 30“ to be
adequate for most sport-sized canopies (all measurements are
finished dimensions).
Pilot chutes made of zero porosity fabric are more sensitive to
specific design criteria, and two of similar size may have widely
different drag. They are definitely more sensitive to variations in
design, with factors such as mesh size and hole size at the pilot
chute base making a big difference in the drag produced. The
zero porosity pilot chutes that we have tried that work
adequately are between 25” and 27” (The 25” is preferable with
most sport canopies.) and have relatively fine mesh. These pilot
chutes also seem to be more sensitive to variations in line stow
length and line stow tightness than regular pilot chutes.
This can happen with a ripcord system, a pull out, or a throw
out, if the pilot chute problem is bad enough.
Collapsible 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.

[MB38 0]

Quote

Yes, I have suffered one (3 second) pilot chute hesitation during hundreds of hop and pops with bungee pilotchutes.
Hee!
Hee!

The bottom line is: it is going to take 3 seconds. You have the choice of tossing your bungee pilot chute immediately and dragging it for three seconds. ... or you can wait three seconds, toss your pilot chute and get a prompt opening.

The only situation that comes to mind where I can see this being a problem is during an aircraft emergency where you're getting out low. Then again, if you're that low... use the reserve.

I really don't know what I'm talking about.

[koppel 5]

So what happens to a bungee kill line when it goes out of 'calibration' ? It stretches. Does this impede the opening? Of course not. What happens to a 'Kill-Line' that is worn? It shrinks. Does this impede the opening? Possibly.

If you have a bungee pilot-chute please see your rigger for replacement bungee. People have been known to make them to short causing MASSIVE pilotchute hesitation or no main-pin extraction

I like my canopy...


...it lets me down.

[ChrisClark 0]

Only use a shock cord (bungee) pilot chute that is made with ZP fabric as F111 type fabric will wear out quicker (think F111 canopies against ZP canopies) gradually producing less drag to stretch the bungee cord and eventually not inflating enough.

With a kill line pilot chute made from either ZP or F111 type fabric the problem will be with the kill line shrinking and shortening the centre line, making the pilot chute less efficient. There should be enough slack in the kill line so the centre stretches to its proper length, this should be checked on a regular basis.