billbooth

I was, of course, very interested in this rumor, because if Sunpath did put out a tandem rig, it would very likely be a good one. So I called Pat and Derek Thomas, who own Sunpath (and whom I am partners with in our military sales company, CPS), and asked. IT'S NEWS TO THEM. As a matter of fact, Pat asked me to quash the rumor by making this post. All of us would like to know who started this...anyone ideas?

You're right. I've eliminated the incorrect calculation. Bear in mind that the 1.5 seconds represents the freebag separating from the canopy, not reserve inflation. In other words, the 100 feet reserve deployment is still not an accurate claim. Nope. The 1.5 seconds represents the time from breakaway to a "fully open" reserve canopy. 0.5 seconds is the time from breakaway to reserve canopy out of the bag. It's kind of amazing the first time you do a Skyhook breakaway. By the time you finish pulling your breakaway pillow to arms length, your reserve is at line stretch. I can see some people thinking they're fully open in 50 feet, even though it isn't true.

I wasn't referring to the claims made by the original poster. I was referring to claims made by the manufacturer's advertisements. As I have said before, it is difficult to record the exact moment in a canopy opening when the jumper's vertical velocity becomes life saving. (I know...I've tried many times.) The opening shock, and the rapid swing under the deploying canopy really throws the instruments off. However, I can determine, by looking at video, when the canopy seems to be "fully open". On reserves in the 120 square foot range, this time averages about one and a half seconds from breakaway. A simple trip to the freefall tables (found in many log books) says than you fall 62 feet in the first two seconds. So, if we assume an initial vertical velocity of 20 feet per second under the malfunction, and a two second reserve opening time, the distance fallen between breakaway and reserve opening is 20+20+ 62, which equals 102 feet. (If I got that wrong, some math student please correct me.) Since Skyhook openings almost always take less than 2 seconds, I believe that the 100 foot reserve opening number can easily be defended. (In fact, if you plug in 20 fps initial vertical rate, with a one and a half second opening, you get under 75 feet.) HOWEVER, 1. Most skydiving altimeters exhibit errors in excess of 100 feet. 2. Many malfunctions have MUCH higher rates of descent. 3. It can often take more than 100 feet just to look at your altimeter. 4. It can easily take another 100 feet just to locate and pull your breakaway handle. Therefore, I never have, and never will, advocate breaking away at 100 feet. All that can be said of the Skyhook for sure, is that it is the fastest, and "cleanest" way to get a reserve over your head after a breakaway. I apologize if some of you found some of our advertising misleading.

I imagine they must have tried two pins in one loop first...it IS simpler. However, it must not have worked for some reason. My guess is that sometimes one pin leaving took the other pin with it...or the pins ended up stacked on top of each other, and made too big a bump. Someone from PDF, who knows, please tell me the reason. You've got my curiosity up.

kligeme (Mark) must have been having a "bad hair day". (Sorry Mark)

Bill is only a senior rigger. Are you sure his advice is solid? But the rumor is that when he grows up he wants to be a Master rigger.

If I had chosen a D-ring handle for the 3-ring release, it never would have caught on. In fact, coming up with a suitable handle for the 3-ring was harder than coming up with the device itself. When your ripcord handle comes out of the pocket it floats, but the pressure from the reserve pilot chute spring keeps the ripcord pin in place. Not so for a 3-ring. If the handle is knocked loose in freefall, the whole device will likely come apart. Also, low altitude accidental release of your reserve is not as serious as accidental release of your main. I have written here before on this subject, and why the soft handle is more suitable for a 3-ring than for a reserve ripcord.

Bill -- I'm seeking clarification, since that statement conflicts with the manual for my canopy (Pilot). The manual states to leave 24-28 inches unstowed to prevent line twists. Does your statement reflect a belief that the risk of a snagged line takes priority over the risk of line twists (makes sense) or that you disagree that more unstowed line reduces the risk of line twists? Thanks for your time. Doug Yes, and yes. As I said above, I remain unconvinced that leaving a lot of line unstowed makes line twists less likely. However, I do know that leaving a lot of line unstowed allows line/flap entanglements. However, I have not jumped every canopy, out of every rig. If you get line twists all the time by "short stowing" your lines, I'd try leaving a little more unstowed until the line twists went away. "As short as possible" is the key phrase.

I, too, sort of like the idea of just dropping the bag straight into the container without rotation...and a lot of people use this method already, to at least some degree. However, this is only possible with certain ratios of pack tray length vs height, and does not work very well on all rig sizes. There is also the problem of "pocketed" bottom corners, that might cause deployment problems on some rigs. Let's face it, the way we do things right now works very well (as long as we don't leave too much line unstowed). Any widespread change just might make things worse, not better. I am trying several different things right now in an effort to improve main deployments, but I don't know yet if anything I try will really make things any better.

Double locking stows may or may not cause a baglock. As usual, it depends. 1. Size of rubberbands...2. Size of line...3. Type of line (Spectra has a lot less friction than Vectran)...4. Size, material, and construction details of pilot chute...5. Speed at deployment. It's simply a question of release force of the lines vs. the drag of the pilot chute. Since a correctly designed pilot chute should pull near 100 pounds at terminal, and it should take no less than 5, nor more than 10 pounds to unstow a line group off a sport bag (7 - 15 lbs. on a large military or tandem bag), there is rarely a problem...unless something gets tangled up.

I threw this together quickly last night and will append/edit if anyone provides feedback. Jim Very clear pictures. Thank you. I believe this is the best way to stow lines so far. However. the important point, no matter how you stow, is to leave as little unstowed line as possible.

The belly band (strap) keeps the horizontal back strap (bottom of your rig) tight against your back, lessening the chance you might fall out of the "hole" between the back strap and your leg straps, which is often "exaggerated" when sit flying.

I once invented a parachute that took only 3 seconds to pack...trouble was, that it took 10 minutes to open.

We have been test jumping this line stow method for a while now. I really like it. It leaves the absolute minimum of line unstowed, and still allows both risers to be stowed down the sides of the container. Speaking of risers...their main purpose is to keep "things" from entangling with the deploying suspension lines. Ideally, they should be long enough to reach the BOTTOM of the container...like they still do in reserve containers. Main risers, however, have gotten much shorter so that pocket rocket drivers can reach up and either collapse or pull down the slider. This shortening of the main risers has had, as usual, unintended consequences. 1. With risers this short, the main turn toggles are no longer in, or at least very close to in, the main container where they should be. This makes it possible for the toggles to get free without the main container being open. This has killed several people. My answer to this new problem was secondary riser covers. 2. The shorter the risers, the longer the unstowed suspension line has to be, thus increasing the chance of entanglement. I don't yet know what my answer to this problem will be, but I am working on it. As to why line twists happen, I suspect that unstowed line length has very little to do with it. My two leading suspects (other than body position and the old reliable "shit happens") are: 1. Too small or improperly made pilot chutes. (The longer the time to line stretch, the longer the rather unsymetrical bag is exposed to the slipstream, and therefore, the more likely it will spin) 2. The often very different forces that are required to open the left and right tuck tab riser covers. If one cover releases just a split second later than the other, it simply can't help things very much, can it? Velcro riser covers didn't suffer from this problem, but alas, they are no longer cool. Some people also think (Bill Coe included) that uneven riser cover release is a main contributing factor to hard openings. This is another problem I am working on.

In the past few years, I have heard of 5 cases of main suspension lines entangling with container flaps. Three of these were on Vectors. While this malfunction is quite rare (well under one in a million jumps) it is nonetheless quite serious. While we might debate several causes for this problem, let me suggest the one I believe is most likely. I am rather sure that this is the main cause, because I have seen it cause line/flap entanglements before...and the solution that worked way back then will probably work just as well again now. A little history lesson is indicated. For a brief time in the 70's, "free-packing" mains (no deployment bag...just coil all of the lines in the packtray, and fold the canopy on top) was popular. Some jumpers even did away with the pilot chute and bridle, and just attached a pull-out handle directly to the canopy. Aside from the hard openings, one other problem reared its ugly head. Suspension line kept getting entangled with the main flaps. The reason was obvious. Just after the main flaps were pushed apart by the canopy leaving, they hit the air flowing around the jumper, and "dove" right back into the pack tray, and all those looped lines. It was a miracle they didn't entangle every time! This problem was quickly solved, of course, by putting the main canopy back in its deployment bag and stowing the lines so that everything left at once, there was little or nothing for the flaps to entangle with when they were thrown back into the packtray following bag extraction. So, what has this got to do with now...we all use bags, don't we? Yes, but do we still stow ALL of the suspension line to that bag? The answer is NO. I went over to the DZ, and did an informal poll. What I found out shocked me. Almost all of the packers left over (sometimes WAY over) 36" (the "minimum" amount of unstowed line required to allow this problem) of line unstowed, and worse yet, COILED in the pack tray under the bag. I should get out more. I had no idea this very dangerous practice had crept back into the sport. Because I had remembered the past problem, on page 39, paragraph 2 of our Vector III packing manual it states:" Leave no more than 15" of lines unstowed between the bag and the connector links." This is something I thought everybody already knew, but I put it in just to be sure. Apparently it didn't do a lot of good, did it? The point here: Read your owners manual, and do what it says. There are good reasons for every word in there, although those reasons are not always given. Otherwise, we are all condemned to re-live the mistakes of the past...again and again.

So? You, personally, are also responsible for a negligible percentage of worldwide emissions. Does that mean you shouldn't care? Jumpalot asked about a way of measuring the damage that he, personally, is doing to the environment, so he can work on offsetting it. No, it simply means that we often spend too much time worrying about things that don't really matter, when our time could be far better spent.

General aviation carbon emissions are less than negligible, simply because there is so little activity...and skydiving makes up just a tiny portion of that. If you do some research, I think that you will find that sheep farts are a far greater problem. I understand they are the single greatest source of pollution in New Zealand anyway. Why don't you direct your efforts in that direction. Let me know what you come up with.

Tandem rigs are more complicated, the canopies are much bigger, and therefore have a lot more line to tangle up with itself. They are also harder to pack neatly because of their size. So, unless you are careful, you will have more malfunctions than on smaller, simpler systems. However, I know of several drop zones that go thousands of jumps between tandem malfunctions. The only difference is that they flat pack, and do so very carefully.

On page 29 of our Vector 3 Owner's Manual it states: "Fully compress the spring to see how much loop can be pulled through the top of the pilot chute. If you can pull more than 1/2 to 3/4 inches (1.3 - 1.9 cm) through, the loop is too long." My riggers tell me that this works out to a total, pre-tensioned loop length of no more than 5 inches (13 cm), on every rig we make, from the smallest to the largest. These numbers are especially critical when using an AAD.

Everyone's asking my opinion on this, so here goes. I am assuming the tandem passenger in this photo is a whuffo. If everybody involved was a very experience jumper, I might modify my opinion a bit. No, I don't think it is "safe" to do hybrids with tandem. Two main reasons...1. To get into that position, the hybrid jumper has to "crawl around" on the students harness. Depending on where the main release handle is placed, this greatly increases the chance of accidental drogue release...and as we all know, drogue release during tandem relative work can, and has been fatal. 2. You should never get either directly over or under a tandem. A tandem master under drogue cannot get out of the way if you accidentally deploy underneath, and the tandem student might pull the drogue release at any moment at ANY altitude. And always remember, a tandem jump is for the student's education, not for your amusement.

We've been doing quite a lot of testing with direct bag static line ram air systems for the military lately...many of these tests are done at over 120 mph. In this case, the "super pilot chute" is the aircraft, which I will guarantee you pulls a lot harder than any main parachute could. While opening shocks are often a bit harder than a normal terminal freefall deployment (due mainly to the angle at which the relative wind first hits the canopy), we are not killing people or tearing up canopies.

2. The super pilotchute theory. On this one I appear to be the only concerned person in the skydiving world. Let's hope I'm wrong. I share your concern. That's my job. When I started the Skyhook project, I was also worried about the main pulling too hard in certain situations. However, the more video I watched, the more confident I became. Believe me, before I put a new system on the market, most of the worrying has already been done. To make extra sure on the Skyhook project, before I sold the first one, I showed it to every expert I could find at the last PIA Symposium . I asked each of them to tell me what was wrong with it. What did I miss? What am I forgetting? I waited another full month while doing more testing. Nobody came up with any serious concerns that couldn't be answered. Only then did I release it for sale. As I have said many times before...No device is perfect. The best we can hope for is a device that is more reliable than the humans jumping it. Luckily, that is pretty easy to accomplish.

When I finally got to look at the Guam rig, the RSL lanyard was was simply lying across its velcro bridle path...the velcro cover was open. I agree with you that some low drag malfunctions will not generate enough force to even open tuck tab riser covers. So I was somewhat surprised to see that this one had indeed opened the riser covers and the velcro bridle path. I suspect that the TM help this process while trying to untangle himself from the mess. This could also explain how all the locking stows (except the bag-lock-stow) came loose. In every other bag lock I've seen, the locking stows were always more or less intact. You are right, pilot chute size can affect opening shock...mostly on mains where it remains connected, but also on free-bagged reserves. But as I said above, every Skyhook breakaway, from every malfunction we have recorded, takes the same 1/2 second to line stretch. From this I must deduce that exactly the same force is being applied by all malfunctions. One test jumper, spinning on a tiny main, recorded a VERTICAL velocity of 84 mph just before breakaway...with a normal (quick, but not hard) reserve opening. His body's actual airspeed around the outside of the spin-arc (which is what the canopy would "see" during deployment) must have been well over 100. His canopy, though spinning was "fully open". Yet no bag strip, higher than usual snatch force, or hard opening was noted...and this guy was one of my original Skyhook test jumpers with dozens of Skyhook cutaways...so he knows what "normal" feels like. As I said above, this is somewhat of a mystery, but that is how it seems to work. No device is perfect, so I cannot promise that a Skyhook will function "perfectly" in every conceivable scenario. However, with 3 years, hundreds of test jumps, and about 2,000 actual rigs in the field...so far so good.

RWS's response was very poor to problems raised concerning the tandem fatalities in Guam and Tokyo where the skyhook was suspected of failing to clear the velcro running down to the RSL when bag locks were cutaway. These situations ended with main reserve entanglements. ______________________________________________________ First off, the Tandem rig in Guam DID NOT even have a Skyhook on it. Secondly, in the Japan fatality, the reserve was pulled without ever releasing the drogue, much less cutting away. So obviously, the Skyhook was NOT a factor in either of these fatalities. I investigated both fatalities, and have reported everything I know about both. Here it is again: In Japan, the reserve pilot chute entangled with the drogue bridle, an extremely rare occurrence. There was nothing wrong with either drogue release handle or the drogue release mechanism itself. The handles simply weren't pulled. The Guam incident started with a main baglock about 18" from the ends of the risers. The tandem pair then seemed to tumble into the mess. The reserve was pulled before breakaway, then sometime later, the breakaway handle was pulled. The main canopy somehow got completely out of the bag. Every stow but the first (baglock causing) stow eventually released. The reserve never even got out of the bag. This is my best guess about both incidents, because there was no video nor eyewitness accounts from either. I didn't even get to look at the Guam rig for several months after the incident. We have always released any information that might be of help in preventing future fatalities..and we always will. About the Skyhook: When we breakaway from a fast spinner (say a stiletto 97), it is a breakaway from a "fully open" canopy at "high speed". Guess what? The reserve deployment speed (to line-stretch) is exactly the same (1/2 a second) as when we break away from a large stable main (or for that matter from a bag lock at terminal). It really seems like that spinner would put a lot more load on the Skyhook lanyard, but it doesn't. I don't fully understand why, but I think it is because the canopy "breathes" (un-loads) for split second after breakaway, and before it can re-inflate and start pulling hard again, the Skyhook has the reserve out of the bag. Also remember, the Skyhook is only connected to one side of the canopy, and the Skyhook lanyard is designed to break if you put too much load on it. I hope this answers your question. If not, give me a call me at Relative Workshop, and I'll tell you everything I know about either situation. I talk much better than I type.

I've been working on the Skyhook concept (Main Assisted Reserve Deployment) for over 20 years now. Check out the Skyhook video for a test from the early '80's. In the course of getting to the actual final product, I tried several different designs, including some similar to Eric's and Mark's, but was never completely happy with any of them. When I finally solved all the problems, finished the design, and applied for the Skyhook patent, I of course included information on the Sorcerer rig, Eric Fradet's method, and several other ways to accomplish the same thing in the application. The Skyhook patent has been allowed, and I will license it sometime in the future. The same thing happened with the 3-ring. Before and (mostly) after I introduced it, many competing designs were offered. The 3-ring survives simply because it worked better than the others. I believe (well, at least hope) that the Skyhook will share a similar future.