Is Your Hand Deploy Pilot Chute Correctly Made?

[billbooth 10]

Jon;
Each "no-stretch" line, Kevlar, Spectra, and Vectran has advantages and disadvantages. Because the melting point of Spectra is 100 degrees lower than Nylon, it seems to sacrifice itself, without doing any damage to the Nylon bridle we use. And is much easier to replace the kill line than the whole bridle. And, (I hate to admit this) Spectra costs less. We put a little slack in a new kill line, so that when it shrinks, it doesn't matter that much.
Bill

[MrHixxx 0]

Thank you for the response Bill. Concerning the bridle, I guess that is why the mfg. of my bridle uses kevlar tape on the inside against the kill line and covers the outside with nylon. Am I correct in assuming that kevlar tape is not going wear with a Kevlar kill line? So, all in all it is a cost issue with materials?
In addition, I would think Vectran is a terrible choice since it is so sensitive to friction?
-Jon
"Sous ma tub, Dr. Suess ma tub"

[Kinaa 0]

Man, i wish i read all this stuf before i ordered my rig...
I ordered 24" p/c because the main matufacturer recomend that size, but now i would defenetly go for 28" and some large rings istead of minirings
Blue ones
Igor

[billbooth 10]

Igor;
As long as your 24" pilot chute is correctly made, and your main isn't over 200 square feet, your deployments, while not perfect, will probably be OK. But if the apex is below any part part of your pilot chute's skirt, expect problems. Bill

[crazymel 0]

Okay - another dumb newbie question from me!! I just received my new rig, and it has a collapsable pc (have never jumped with one before). I did your check, and it seemed okay, but it doesn't wanna inflate "fully". So, after I've pulled the kill line tight, the "blue" appears in the window at the pin (which means the pc is cocked, right?), but as soon as I've packed the pc, it goes back to white... I will obviously check with the JM first before I jump it for the first time, but at the moment our dz is closed, and I'm curious. What am I doing wrong?
Life is for the LIVING!!!!!

[billbooth 10]

Crazymel;
Pilot chutes are not rocket science. As long as your pilot chute passes the tests I gave you, it should be OK. It is normal for a "fully cocked" pilot chute to slightly "uncock" during the rig closing process. The blue mark on the kill line it there so that you can quickly "pin check" your rig without having to unpack the pilot chute. It seems that your blue mark is just slightly in the wrong place or simply not long enough. The easiest thing for you to do is take out a blue marker, and make it a little longer. Or, you could pay a rigger $40 an hour to do it for you. (Just kidding) Bill

[Kinaa 0]

Thanx Bill, ill try to change the order. Eaven if the 24" p/c is made correctly and is recomended by manufacturer ill play on safe Blue sky

[Craig 0]

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Well I just checked the pilot chute of my Mirage G3, bought in August of 2000, and guess what, according to Bill's aritcle up top, they put the support tape on the mesh on wrong (that is, not on the "bias")

Just FYI my Mirage, built in Oct. 2001 is made to the specs. Bill suggested above....the tapes are on the bias.

[kallend 1,623]

Bill - thanks for the interesting thread.
Can you explain the "collapse" sequence in more detail? How do the tension and friction forces in the bridle and kill line change during the deployment so that the PC doesn't collapse too soon, yet collapses at the "correct" time? What is the correct time for the PC to collapse anyway?
John K.

[KellyF 16]

The collapse sequence is controlled by the geometry between the canopy, bag, and center (kill) line. The pilot chute, bridle, and bag have a fixed geometry, that is, nothing changes significantly during the deplyment process. The "magic" comes from the kill line that is attached to the apex (center) of the pilot chute and the bridle attachment at the top of the parachute. When the parachute is packed and the pilot chute cocked, the bag and bridle (with the bottom of the pilot chute attached) is essentially moved closer to the parachute. During deployment, when the bag comes off, the outer edge (skirt) of the pilot chute tries to keep separating from the parachute, taking the bag with it (like the freebag on a reserve), however, the apex of the pilot chute is attached to the parachute. So while the bag, bridle, and skirt of the pilot chute are moving away from the parachute, the apex is staying the same distance, so the pilotchute collapses, and only after the bag comes off of the parachute and the pilot chute has done it's job. The catch line (the second one inside the bag) is not really necessary for this process to take place, it's job is to allow the bag and bridle to only move far enough for the pilot chute to collapse fully, thereby reducing wear on the rest of the components in the system.
I hope all this jibberish helps :)

[billvon 2,395]

Results of an impromptu survey at the DZ this weekend:
23 PC's correctly made, 2 (1 Mirage original and 1 Reflex aftermarket) made incorrectly. Neither jumper noticed any problems with the incorrectly manufactured PC's.
-bill von

[billbooth 10]

Bill;
Thanks for doing the survey. I look at people's pilot chutes (when they're not looking) all the time, and I also find about 15% incorrectly made in the US. At some dropzones in Europe, I have found as many as half bad. As I said above, it's a combination of pilot chute size, vs weight of canopy, vs how much the apex is pulled, vs how much stretch a particular mesh has on the bias, vs deployment speed, vs how tightly the lines are stowed, that determines how well any particular pilot chute will work. Then there's any particular jumper's definition of "works" to be considered. Pilot chutes don't have to be perfect to "work", but separation velocities ouside the desirable range yield partial malfunctions that very few people ever blame on the pilot chute.
But again, as I've said above, everytime someone brought my attention to a pilot chute that was hesitating, two factors were ALWAYS there. The mesh was sewn on the bias, and the apex was pulled all the way down to the skirt. And as people go to smaller and smaller pilot chutes, the tolerence for poor construction gets less and less.

[rapper4mpi 0]

I did an informal survey at my DZ. I looked at about 8 pilotchutes, 2 had the apex above the skirt, probably from age (shrunken kill-line). But about hlf had the support tape sewn incorrectly not on the bias. Very interesting.
-Rap

[Iflyme 0]

Quote

By the way, I love your screen name "Iflyme". I wish I had thought of it.

Being the honest type of skydiver I am -- I can honestly say (sadly) that I didn't think of it myself ... I saw it on a list of skydiving licence plates ...
Anyway, Bill, it's great to have you here ... you and all the others who share their knowledge with the rest of us!
"There's nothing new under the sun"

[Krishan 0]

Well Mirage recieved my pilot chute today and I called Bill Hallet about it. He didnt seem to think that the support tape not being on the bias made much of a difference.
He did think that my 26" zp pc was too small though. I started jumping a 170 sq ft canopy and now jump a 150. Always had a delay.
They are going to make me a 28"zp or 30" f1-11 pc and will make sure the support tapes are sewn on the bias as is normally they standard.
Overall, I'm happy with the response from Mirage.

[SkydiveMonkey 0]

Hi BIll,
I looked at my p/c and it's just within spec. My question is: is a 28 inch F111 p/c ok for a hornet 170? Also, how many jumps will it last as it's F111?
boobies - the cause of, and solution to, all of lifes problems

[base283 0]

Hi Bill,
I am a DZO in Norway at the established BASE DZ at Kjerag for some weeks in the summer. Block constructed PC´s have been a problem there due to unknowing constructors, also in Italy I have seen this problem, Most of the time when I see this problem, It has been a wall strike or consecutive off heading openings that clues me in on the PC.
But the question I wish to ask you is about orbiting PC´s whether due to construction or attachment to the bridle (most BASE PC´s are bridleless manufactured and attached by the jumper). How important do you think that a stable PC (non orbiting PC) is for the opening sequence? It has been difficult for me to disseminate info relating to PC construction and performance in the BASE scene even though I have ground crewed for over 7000 jumps. I hope that an authority on PC´s such as you can respond as maybe they will listen to you. Thank you so much in advance.
I look forward to your reply.
Tracy walker,
BASE Instructor examiner.
base283

[Greig 0]

Bill,
Is the weight of the canopy the only consideration in PC size? Can you post a list of which size of PC (assuming its ZP) works best with which range of canopy sizes?

[billbooth 10]

Greig;
I recommend a 28" - 30" ZP pilot chute for canopies from 100 to 220 sq.ft., and a 24" ZP for canopies below 100 sq. ft. We also make a 34" F-111 pilot chute for canopies 200 sq. ft. and larger. We don't make a separate size pilot chute for each canopy size, because there is a pretty large acceptable range for separation velocity (see above posts). Obviously, if you only do base jumps or hop-n-pops, you might choose a larger pilot chute. If you do a lot of head down, and often open above 120 mph, then maybe a smaller pilot chute would be a better choice.

[billbooth 10]

base283;
Some pilot chute designs orbit more than others. Like you, I imagine an orbiting PC could cause off heading openings and line twists. The more carefully and symmetrically made a pilot chute is, the less it will spin or orbit. We make our pilot chutes to very tight tolerances to try to avoid this problem. I understand a lot of base pilot chutes are "homemade", so that could be a problem. I have made only one base jump (El Cap) so I am no expert on very low speed pilot chute design. However, I imagine body position, and container and bag design, are far more important for a clean deployment than pilot chute design. In most videos of line twists I've seen, the bag left the container spinning. It did not start to spin after it left the container.
Bill

[billbooth 10]

Skydivemonkey;
Your 28" "F-111" PC is probably just fine for a 170 sq. ft. canopy. I only say probable because there are many fabrics labled F-111 these days, and some keep their "porosity" much longer than others. If your pilot chute deploys your canopy, from container opening to line stretch, in about a half, to three quarters of a second, then it is doing its job correctly.
Bill

[kallend 1,623]

Well, what do you know? Last week a very experienced load organizer was grumbling about long delays after tossing his PC before anything happened. I asked to look at it and, lo and behold, the reinforcing tapes were parallel to the mesh.
He bought a new PC right then, and the problem went away.

[Remster 24]

I guess that Bill Booth guy knows what he's talking about! lol....
thx for all the posts Bill !
Remster
Muff 914

[billbooth 10]

Kallend;

You know, if I had told that guy directly that his pilot chute was improperly made, he probably would have thought I was just trying to sell him something, and ignored me. I've been "blown off" so many times, that when I see bad gear nowadays, I usually don't even bother to point it out. Am I getting cynical in my old age? Thanks for your good deed. You just might have saved that guy's life, because his pilot chute was just going to get worse and worse until on one jump, it wouldn't have worked at all.
Bill

[Krishan 0]

Well I got my pilot chute back from Mirage today. Or I should say I got a brand spankin new pilot chute back with only my old hackey handle, everything else brand new, free of charge. It is a little bigger 28" zp i think and the tape is sown correctly on the mesh, to prevent stretching.
I got kick ass customer service from Mirage. They rock.