Flexible pins

[Yuri]

Yo !

While jumping in Moscow at New Years i came across a couple of BASE rigs that use flexible pins. This is an old idea and there's been some discussion recently about flexible pins applied to BASE, but those rigs are the first i have seen actually used in the field. I was very impressed with the rig and would jump those containers any day. There is probably a couple dozen jumps made on this design so far, most at low/very low altitude. It seems to combine a security of pin rigs with foolproofness of velcro design.

I understand the main problem in a way of flexible pins is a pin's material. The rigs i've seen used a doubled-up yellow cable. This may not be ideal but it looked adequate. There may be a better material that nobody thought about yet - i see a huge potential in reviving this idea...

Does anybody care to comment ?

bsbd!

Yuri.

http://base416.com

[guest]

Hi Yuri..ive had my skydiving rig like that for some time and with the help of my rigger we decided that the yellow cables(as used in cutaway systems) are the best option...the chances of accidental container opening are reduced as is pull poundage on the pins.

Its a common mod among the freeflyers here in the UK and should have benefits for wingsuit flyers and aerialists as well...IMHO

The only downside weve found is that it wears closure loops faster than normal.

I hope this helps...

Sean

[guest]

Hi Yuri!
There is one thing I have not understood: in which way a flexible pin is/would be safer than a stainless steel pin? Once anyway you have got to close the loop, isn't the flexible pin more likely to jam between grommet and loop? Or the advantage of having less friction makes the flexible pin anyway better than the s.s. pin?
Could you please explain better this point?
Blue Skies
Andrea

[guest]

stainless steel pins will move when pushed because they are stiff,flexible pins are less likely to move when pushed..instead they will just bend.

True if you only use one length of cable the flexible pin will/may jam against the grommet but using two stops this happening by giving an optimum surface area which reduces pin pressure against the loop and pin pressure against the grommet...I believe this is why most static line systems used in skydiving employ this method as do some tandem rigs..

Any comments from riggers out there?

Anyone el

[Yuri]

Yo !

The force required to extract steel pins used today on most rigs will vary a lot depending on the pull direction. If a pin is inserted all the way in and a bridle pulls inwards the force to extract that pin will be much higher than pull from any other directions. Flexible pins make the pull force very constant. In fact, changing the shape of a hard pin a bit (bend the ring so there's no corner on the outside curve) would address the same problem equally well. So far nobody considers this serious enough to invest into manufacturing new pins and/or using flexible pins.

bsbd!

Yuri.

[guest]

Manufacturers..any comments?

[guest]

I had a friend who used a flexible plastic covered steel cable pin several years ago on all his BASE jumps. He was using a skydiving container but with a base canopy in it. It worked great since it was several inches long. We didn't have to work about it popping out while he was climbing around on towers. I talked to the manufacturers about this when the pin rigs came out and they claimed the plastic on these
pins would 1.) easily get damaged and form a bur on the plastic 2.) was brittle when in the very cold weather. Now if it formed a bur, that involves many problems, such as damaging the closing loop or possible snagging on the closing loop. Longer curved metal pins seem like they might be a better solution.

[guest]

True the burrs are a problem...they will occur if the pins arent covered or looked after..As far as cold weather goes..this particular type of cable is used in skydiving rigs which operate in all temperatures...(low in England most of the time)..but looking at Yuris original post you wont get many places colder than Russia this time of year!!So maybe these guys are doing the ideal field test..

sean out

[space]

The pros are as stated, the cons are;
Because the pin is flexible and longer, it´s quite easy to pack a PC in tow when one does not leave enough slack in the bridle on the canopy side of the pin, outside the container.
The second con is the possibility of burning a groove in the teflon coated plastic upon a fast extraction of the pull up cord.
3rd, Grommet condition and orientation must be correct.
4th, the cables must be kept in good condition and ascertained more often than metal pins.

[guest]

I got round the bag lock situation on my skydiving rig by removing the velcro from the bridle..this ensures you have a "snatch" by literally not being able to stow the spare bridle underneath flap 4..thats with a four inch flexible pin...if you reduced the pin length to say two inches the slack in the bridle between bottom and top pins should provide the "snatch" needed to remove the top pin..this is all "possibles" of course because I am applying the stuff used on my Javelin..

[guest]

There are Pros and Cons to using flexible pins. Many of both have been stated in this thread so I won't go into them in detail.

The one-word-issue with flixible pins is: Maintainance. They require more frequent inspection, will almost certainly require periodic replacement and are susceptible to a much larger range of potential problems than a small SS curved pin.

From a design safety standpoint, if there is a possibility that it can go wrong, there is a virtual certainty that once in circulation, someone will turn the possibility into a probability :-)



Adam Filippino
CR Home Page http://www.crmojo.com

[guest]

I agree with Adams comments.

We used flexible pins in Australia many years ago when we used to use modified skydiving gear. We had to be fairly careful in priming the pin prior to exit, the flexi pin material would occasionally get nicks/cuts/bends in it (due mainly to the way people used them and how tight the closing loop was). This increased the likelihood of pin extraction hesitations which is definitely no good for lower jumps. ;) Although we didn't do long freefalls then, I could see major problems with bridle/pin entanglement with disturbed airflow at greater airspeed too.

Regarding use of doubled up metal cable pins, there are still problems with extraction repeatability/reliability which is a life threatening situation for lower altitude jumps.

Although it is easier to pop a curved pin (just be careful), they are also less likely to get damaged and are a darn site easier to extract than flexi pins on low airspeed deployments.

Stay Safe
Have Fun
Good Luck

Tom B

[obi]

Hi,

I have a flexible pin on my tandem-rig (an Atom from PdF) and have made about 500 jumps with it. It is a coated steel-cable (kind of the yellow cutaway-cables, but stiffer) that is folded at the fixing point and so you have 2 pins. It works fine and I never had a problem with it, but I'm taking care of my material pretty well. You defintifely have to check it for damage and even when it's in perfect condition, you have to replace the closing loop quite often because there's a lot more friction applied to it during the opening due to the length of the pins (about 4 inches). I check my loop and the pins on every pack-job (takes 1 sec. each). I also use special tandem-loop-material which is a lot stronger. Once I ran out of tandem-loops and used 3 normal loops on 1 day.
I never had a premature opening on a pin-rig, but since I had one on a pretty new velcro-rig not too long ago, this is something I'm thinking about these days... :-) I like the idea of the long flexi-pins and I already have some ideas to play with as soon as my new pin-rig arrives. But as you can see from all the postings, there are many things to consider.

hummmmmmmmmmmmm