billbooth

Bill: Pyrotechnic reefing line cutters hooked to barometric speed and altitude sensors are what make zero/zero ejection seats possible. These parachute systems are expected to function from zero altitude/zero airspeed (with ballistic deployment and skirt-spreader guns), all the way up to Mach 1. However, the initial cost and subsequent maintenance of such systems would break the budget of any skydiver I know. I'm not saying that this is an impossible problem to solve. But to do it cheaply, with no reduction in deployment reliability, is a hard nut to crack. But believe me, it is being worked on at this very moment. Any ideas from any readers will be listened to and appreciated. I believe that tying the slider to the canopy, and releasing it with pyrotechnic cutter adds too much cost and complexity to be truly safe. A simpler method must be found. For instance, our tandem reserve canopies are reefed so that only the center cell opens immediately, forming a large drogue, but the slider will not start down the lines, nor any other cells open, until the tandem pair decelerates to around 90 mph, even if initial deployment velocity is 170 mph. We accomplished this through the relationship of slider size vs cell size, and a unique cross-porting system. Sport reserves could be set up like this, but they would not pass the 3 second test at low speed. This is one of the reasons I made tandem opening altitudes higher.

16 years ago Bill Coe and I figured out how to make Vector tandem reserves open soft enough at tandem terminal (170 mph) to avoid injuring even the proverbial 87 year old grandmother. So why can't you buy a sport reserve that opens softly at head down speeds? Simple, because of current TSO rules, no one call sell a reserve that won't open completely within 3 seconds after a breakaway. Without complicated reefing devices like pyrotechnic cutters, no canopy can open in 3 seconds at 30 mph and not "kill" you at 170 mph. It's simply a case of the rules being way behind the state of the art. What to do: Change the rules like we did for tandem reserves. Bill Coe and I are on the committee that is revising the current TSO, and Bill is championing, over some opposition, a rule change that will allow longer opening times on a special class of reserves specifically made for the higher speed disciplines. However, if you jump one of these reserves in the future, you are going to have to up your pull altitudes by a factor of 2, get a tandem Cypres, and really hope that you never have a canopy collision that requires a low/slow breakaway.

I have read this entire thread and must say that the pros and cons of this subject have been very well covered. However, perhaps I can add some insight. As the patent holder on both the pull out and throw out pilot chute systems, I have listened to customers jump stories about both for the past 25 years. Hand deploy pilot chutes had a lot of problems in the early days. But these problems have mostly disappeared as the result of design improvements like the Spandex pouch, the bottom of container (BOC) location (borrowed from the pull out), and covered bridle paths. However, the same old problems with the pullout, such as lost handles and no-pulls due to improper packing still remain. Plus, while the throw out allows you to actually throw the pilot chute into the clean air outside the burble, the pull out forces you to release the pilot chute inside the burble. To get hesitation free deployments, pull out jumpers have to momentarily alter their body position to break up the burble. On small, highly loaded ellipticals, this can cause line twists, which can become malfunctions. Perhaps this is why a good 95% of my customers, including me, jump throwouts. I would say that the jumping public has already settled this debate. Both systems work when correctly maintained, packed, and deployed. However, people just seem to have fewer problems with today's manifestation of the throw out.

AM I was talking about housings on the rig, especially the long one. Should you have hard housings in your risers jumping a stiletto at 1.5? Absolutely. But please make sure these short riser housings are plugged at the top end. If even a half an inch of yellow cable protrudes beyond the top edge of either of these riser housings, even a minor riser twist will jam the protruding end against the open upper end of the housing, and give you an impossible cutaway. An uncapped housing could also slide down the cable, through the riser closing loop, and also give you a no release situation. This should be obvious, but I have actually seen some risers with uncapped housings on them. (The fact that these riser housings are up against the top of a tape channel does not count as a capped housing.) There is a downside to these riser housings. (There is always a downside to every new thing you put on a rig. The trick has always been finding it before you sell too many rigs.) The riser housings increase the bulk under the riser covers, and on some rigs this can mean riser covers coming open in freefall. If you jump a rig without secondary riser covers, and do a lot of head down, this can be a consideration. Bill

A complete list of what will or will not harm Nylon is available in The Parachute Manual. WD-40 will cause no harm as long as you wipe most of it off. However, most oils actually attract dust and get a little tacky at low temperatures. There are also Teflon sprays, but they are really a very fine power which doesn't "stick" around for very long. This is why we now use a silicone LUBRICANT spray ( be careful here, there are also silicon adhesives) which stays with the cable longer, and remains slippery down to 50 below zero. I have easily broken away my main during a high wind landing at the North Pole, so I know this stuff works under any condition. Simply spray the silicone on a paper towel, and then wipe down the yellow cutaway cables. If your cables are covered with a sticky black stain, be sure to remove it all. You are cleaning as well as lubricating. The black stain is a combination of machine oils and metal dust left over from the manufacturing process. We wash the housings washed before installation, but some residue is still left behind, and your housings make new metal dust every time you flex them. If you jump in the desert, fine sand can also find its way into your housings. If you want the lowest friction possible, (and believe me you do if you jump mini rings and a small elliptical which might generate 6 "G" spinning malfunctions), I recommend you also occasionally clean your housings with a small bore gun cleaning rod, with a small cloth soaked in silicon spray. This cleaning is important because dirty housings can multiply your breakaway force by a factor of up to TEN! One more hint: If you have been living in Tibet and are still jumping a rig with soft housings, get them converted to metal housings, NOW. It would take me several paragraphs to tell you everything that is wrong with soft housings, and I'm out of time tonight.

First, the yellow coating I use on my breakaway handles is Lolon F (an "alloy" of nylon, not Teflon), coating a 7x7 steel cable. It is the best choice for breakaway cables for several reasons. It is very tough, reasonably slippery, flexible, easy to form ends with, and won't get brittle until -60C. I have never heard of it cracking or coming off the cable in the 20 years I have been using it. (Jump shack IS using Teflon, which they color code red. We do not use it for too many reasons to go into here.) The black coating we use for student ripcords is another form of nylon. We do not use it for 3 ring cable because it is too stiff, not as slippery, and cracks far easier than Lolon F. However, Its stiffness is a good feature for a spring loaded pilot chute main container system, and because main systems are packed before each jump, a crack should be easily spotted. I offer a third kind of nylon, with no color coding, for main container flex pins on my older Tandem systems. It is a thicker coating on a thicker steel cable. Each coating and cable size is carefully chosen for its application after a lot of testing. Here are the positives and negatives of flex pins on solo system main containers. Positives: 1. If your container is too big for your canopy and/or your closing loop is too long, and you jump a rig without adequate bridle protection, and your entire bridle comes out of the pilot chute pouch (without the pilot chute) while doing head down, then the flex-pin is less likely to be prematurely removed by the wind drag on the horseshoed bridle, which by the way, is well under one pound.. Negatives: 1. Because the flex-pin is longer than a curved pin, you must be very careful to leave enough pilot chute bridle, between the pin and bag, slack AND exposed, to allow the pin to leave the loop. If you carefully tuck all bridle between the pin and the bag safely inside your container, you will have a pilot chute in tow malfunction. 2. Because the flex-pin is longer and has more surface friction than a stainless curved pin, it damages your closing loop ten times faster. Also, you cannot put your pull-up cord under a flex-pin before removing it as you would with a stainless curved pin, because the pull-up cord would then cut grooves in the nylon coating of the flex-pin causing a possible total on your next jump. This causes you to further damage your closing loop each time you remove your pull-up cord. And the heat damage the flex-pin and pull-up cord do to your closing loop is nearly invisible. This sets you up for a broken loop, out -of-sequence horseshoe malfunction. Do you pack your own rig every time? Are you sure the packers understand the above limitations of your flex-pin system? Then you have to worry about which type of nylon coating your flex-pin has (will it crack, or splinter, or come off the steel cable core?), and whether the nicopress swage which holds the whole thing together was properly applied. Standards for the above items are simply not published. 3. Curved pins cannot be "pushed" out, they simply rotate in place. Try it. When a curved pin comes out prematurely, it was most likely pulled out by a bridle snag. And anything which snags your bridle will probably not stop pulling after only one inch. So flex-pins offer no protection from bridle snag induced premature openings. This is just the short list. If flex-pins were better for most solo rig applications, we would offer them. We don't. Bill Booth (Bill is the owner of the Relative Workshop, and inventor of the hand deployed pilot chute and three ring release.)