0
Gary73

BOC pouch extraction forces?

Recommended Posts

How tight should a BOC pouch be? That is, what are safe minimum and maximum forces for pilot chute extraction? I think I know it when I feel it, but are there any objective standards? I'd like to be able to give my customers more than just an opinion.
Thanks

"Extraordinary claims require extraordinary evidence." - Carl Sagan

Share this post


Link to post
Share on other sites
Thanks, Gary. How timely your post is for me.
I hope there are actually specs/recommendations on that.

I bought a new (old) rig and put 3 jumps on it.

1. Hard Pull training kicked in and I got it out on the second attempt.
2. Thinking it may have been the way the pilot chute was folded and stuffed by the packer, I folded and stuffed it myself...still hard, but I was ready for it and got it out.
3. Tried different folding and stuffing and it was still hard to get out.

So, after all that indication that the BOC pouch was too tight, I grounded the rig until my rigger can look at it and loosen it up some.

Good question on just HOW much to loosen it.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

Share this post


Link to post
Share on other sites

I'm not sure it's possible to get a pocket too tight. But it IS possible to pack the PC in such a way that it bunches at the mouth and can't be extracted. Using the word 'stuffing' indicates the wrong mind set. The PC should be folded and PLACED in the pouch. not stuffed. And it may be that your earlier pouchs were TOO LOOSE and you got used to it.B|

BTW the standard for reserves could be applied. Not more than 22 lbs. But the last think I'd like to do is try to lift 22 lbs off the floor pulling in the angle of a BOC extraction.:S

When I sew on simple spandex and elastic pouchs they are sewn on flat against the bottom flap. The give of the flap and spandex are plenty. If I but any slack in it at all I wouldn't trust it to hold a zp pilot chute. Now if the FLAP at the mouth is narrower than the pocket, i.e. the flap pulls the pocket TIGHTER when it's packed, then it might be too tight.

I still try out different PC packing techniques. Every body likes their own. But the critical issue is to not pack it so that one part pulls past another.

There have been several methods referenced on here. I know Brian Germain has one, I think on his web site. All though I don't use it it looked fine.

And do have a rigger look at it if your not satisfied. But not just any rigger. A rigger right out of a course, while rated, may not have the experience with multiple pocket types, gear and pilot chutes to give you the best advice. For this kind of thing please find a rigger that has experience but also is open to new ideas. The oldest rigger around might still be jumping a ripcord. This advice applies to all kinds of container/gear questions beyond normal inspection and repack. Not trying to dis any rigger or get work for myself, it's just that I know how LITTLE I knew after I got my rating.


--------------------------------------------------------------------------------

Terry Urban
D-8631
S&TA ME, FAA Master rigger

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

Share this post


Link to post
Share on other sites
I am not sure what TSO C23D says about main pull forces, but it is probably similar to reserve pull force "minimum 5 pounds and maximum 22 pounds."
Also remember that a BOC puts your arm at a "weak" angle, so the lower end of the scale (ten-ish pounds) is better.
Anything over 22 pounds would be dangerous.

Share this post


Link to post
Share on other sites
I use Brian's way of folding the PC. Have had no problems on either my old Talon or new Infinity. But it tends to make the PC short and fat. This can make it a hard pull on a BOC with a tight opening.
50 donations so far. Give it a try.

You know you want to spank it
Jump an Infinity

Share this post


Link to post
Share on other sites
Quote

I am not sure what TSO C23D says about main pull forces, but it is probably similar to reserve pull force "minimum 5 pounds and maximum 22 pounds."
Also remember that a BOC puts your arm at a "weak" angle, so the lower end of the scale (ten-ish pounds) is better.
Anything over 22 pounds would be dangerous.



I think you nail it. The pull you can get with you arm at that angle (pulling the PC is much much less than the angle you have on the reserve handle. I like Brian Germains fold and pack instruction for the PC. It makes a pointed wedge of the PC. This type of folding will not bunch creating a ball that is hard to pull, and it locks (as best one can) the bridal into the folds trying to eliminate a horse shoe. Well thougt out IMO.
"America will never be destroyed from the outside,
if we falter and lose our freedoms,
it will be because we destroyed ourselves."
Abraham Lincoln

Share this post


Link to post
Share on other sites
Quote

I like Brian Germains fold and pack instruction for the PC. It makes a pointed wedge of the PC.



Another advantage of this method is that you would notice an uncocked pilot (don't ask me why one would forget to cock).
"We call on the common man to rise up in revolt against this evil of typographical ignorance."
http://bancomicsans.com

Share this post


Link to post
Share on other sites
You're absolutely correct..."stuffing" is not a good mind set...a bad choice of words on my part. I hope any students reading this thread do not embrace that idea and adopt the "placing" mind set instead.

Thanks for the knock on the head.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

Share this post


Link to post
Share on other sites
Quote

Quote

I like Brian Germains fold and pack instruction for the PC. It makes a pointed wedge of the PC.



Another advantage of this method is that you would notice an uncocked pilot (don't ask me why one would forget to cock).


:$You know, I never really thought of that but it would be easier to notice:)
"America will never be destroyed from the outside,
if we falter and lose our freedoms,
it will be because we destroyed ourselves."
Abraham Lincoln

Share this post


Link to post
Share on other sites
Quote

Quote



Another advantage of this method is that you would notice an uncocked pilot (don't ask me why one would forget to cock).



:$You know, I never really thought of that but it would be easier to notice:)



That is one of the reasons I use it. It has worked this way once. Got interrupted in the middle of my pack job and when I finally came back to it, was in a hurry to get on a load and forgot to cock the PC. It was that last step of folding the PC that alerted me to it. So Brian's method not only greatly reduces the risk of a horseshoe, but has the side benefit of one more check that you cocked your PC.
50 donations so far. Give it a try.

You know you want to spank it
Jump an Infinity

Share this post


Link to post
Share on other sites
Quote

That is one of the reasons I use it. It has worked this way once. Got interrupted in the middle of my pack job and when I finally came back to it, was in a hurry to get on a load and forgot to cock the PC. It was that last step of folding the PC that alerted me to it. So Brian's method not only greatly reduces the risk of a horseshoe, but has the side benefit of one more check that you cocked your PC.


You must have some problem with your packing procedures.

I cock my PC after I set my brakes.
I check or cock my PC before bagging canopy.
I check or recock my PC when I put the D-bag to the pack tray.
I check the PC when I insert my pin.

Share this post


Link to post
Share on other sites

Hmm now that I look at it again I don't like it. It's the last step, fold in half I don't like. That means that you have to pull the fold past the rest of the PC. I don't like any method that you fold in half last. Now Brian's goal was to keep it in. And I'm sure works fine for smaller zp pc's.

I can't find a diagram of my method anywhere. I lay it out fabric down, mesh up as a full circle. I fold one point on the circumference to the middle, the opposite point to the center under the bridle, s fold the bridle on the mesh and then one side to the other so it's a rectangle 1/4 the diameter from handle to bridle exit and 1 diameter wide. I fold the handle side corner down to the lower edge flag style then back up to the handle flag style. Repeat on other side and fold in thirds or roll to the center.

Hmmm, seems like the only one I like is mine.;):PB| I take photos if anybody cares.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

Share this post


Link to post
Share on other sites
Quote

Hmm now that I look at it again I don't like it. It's the last step, fold in half I don't like. That means that you have to pull the fold past the rest of the PC. I don't like any method that you fold in half last. Now Brian's goal was to keep it in. And I'm sure works fine for smaller zp pc's.

I can't find a diagram of my method anywhere. I lay it out fabric down, mesh up as a full circle. I fold one point on the circumference to the middle, the opposite point to the center under the bridle, s fold the bridle on the mesh and then one side to the other so it's a rectangle 1/4 the diameter from handle to bridle exit and 1 diameter wide. I fold the handle side corner down to the lower edge flag style then back up to the handle flag style. Repeat on other side and fold in thirds or roll to the center.

Hmmm, seems like the only one I like is mine.;):PB| I take photos if anybody cares.



I would like to see. I do have hundreds of jumps on Brians method. Don't think I will change but you never know.
"America will never be destroyed from the outside,
if we falter and lose our freedoms,
it will be because we destroyed ourselves."
Abraham Lincoln

Share this post


Link to post
Share on other sites
Quote


You must have some problem with your packing procedures.



I admit, I was in a hurry and got out of sequence in my normal steps, but I caught it. That's why I do my PC that way, just one more opportunity to check that the PC is cocked.

If all of our packing procedures were so perfect, we wouldn't need to make any more checks after cocking the PC correctly the first time.

Quote


I cock my PC after I set my brakes.
I check or cock my PC before bagging canopy.
I check or recock my PC when I put the D-bag to the pack tray.
I check the PC when I insert my pin.





Hmmmmm. Thanks for your insightful critique of my packing.

Share this post


Link to post
Share on other sites
Quote

Hmm now that I look at it again I don't like it. It's the last step, fold in half I don't like. That means that you have to pull the fold past the rest of the PC. I don't like any method that you fold in half last. Now Brian's goal was to keep it in. And I'm sure works fine for smaller zp pc's.

I can't find a diagram of my method anywhere. I lay it out fabric down, mesh up as a full circle. I fold one point on the circumference to the middle, the opposite point to the center under the bridle, s fold the bridle on the mesh and then one side to the other so it's a rectangle 1/4 the diameter from handle to bridle exit and 1 diameter wide. I fold the handle side corner down to the lower edge flag style then back up to the handle flag style. Repeat on other side and fold in thirds or roll to the center.

Hmmm, seems like the only one I like is mine.;):PB| I take photos if anybody cares.




I agree, I don't like it.

I fold my pilot chute the same way you do with a small twist....

I DO NOT fold the bridle into the pilot chute. I think it is best to keep the bridle and pilot chute seperate.

I fold the pilot chute and then s-fold the bridle into the pouch. The PC is last.

When you extract the PC to full arm extention the remainder of the bridle is extracted when the PC inflates.

I have watched alot of slow- mo video and I am convinced this is the best way.

If you fold all that excess bridle into the PC then it is immediately exposed to the realtive wind as soon as you pull the handle out of the pouch.

Everything should be in sequence.... first the PC, THEN the bridle, and THEN the pin!

IMNSHO!


Share this post


Link to post
Share on other sites
I don't know that I've seen numbers or an objective evaluation of pull force on a throw out. I would agree that you could start within the reserve limits (5# min, 22# max). I also agree that you need to consider the location and angle of the BOC as not optimum, so inline force of 22# may be excessive for you.

PC packing, as demonstrated by this thread, is a whole other can of worms. When I teach a new packer, I reiterate that there is one purpose for all the folds and rolls of a PC pack job. That is to be able to get the PC out of the pouch. Once you've got the PC out of the pouch, all those folds are gone. I tell them that there are probably as many ways to fold a PC as there are jumpers.

Of course then I show them the PC pack that I use. The one I learned from a BASE jumper and I haven't had any problems with. (Can't describe it in words. I'll just have to show you some time.)

I still watch other people fold there PCs and watch for a new technique. I have yet to be overly impressed with any given technique that I'll change mine.

One technique for a tight pouch, before you put the PC in the pouch, give the bottom of the container a couple good pounds with a fist. This can give the container enough concave shape that there is room for the PC in the pouch.

I also stand the packed container so that the weight is on the BOC as I close the riser covers (last step, not part of my putting the D-bag in the main pack tray). This helps flatten the packed PC in hopes that it slides out more easily.

[Caution read the entire post before trying this.]
The Spandex pouch will expand over time. Unless you feel it is dangerous for you to jump, I'm not sure I would speed up that stretching process. I have seen some packers use a packing paddle to assist with getting a PC in a tight pouch. After you have the PC folded into the final shape you want it in, set a packing paddle on the side that will touch the Spandex. Put the end of it even with the edge of the PC that will be deepest into the pouch. Holding them together as a single unit, feed both into the pouch. Then pull out the paddle.

The paddle will help keep the PC from rubbing on the Spandex, which is working against you getting the PC in the pouch. It also provides some rigidity so you don't feel like you're pushing rope or stuffing it in there.

Recognize that you helped get a PC in a place it didn't want to be. Do the practice pulls before jumping this technique. It is a lot easier to re-pack a PC than it is to repack a reserve after you have a total from a hard pull. And cheaper than the Cypres fire when you play with it for too long.

Remember when you were learning to use a throw out? Your instructor had you do practice touches on the ground. Then they had you throw the PC. They repacked it and you did it again. They repacked it and you did it again. I see nothing wrong with pulling a PC out three times before a jump if you are going to use a packing paddle to assist with getting the PC in the pouch.
Packin' Jack
42nd Lost Prairie: The Ultimate Answer to Life, the Universe, and Skydiving
25 Jul - 3 Aug 2009
2007 photos: http://www.skydive.com/prairie/pages/prairie.htm

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

0