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RiggerLee last won the day on May 5 2019

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  1. I had not seen that video. I'm surprised he lived through it. I would have expected the decent rate to be higher. I guess he was lucky the canopy was not more asymmetric. The one I remember was back in the day and he died. I wonder what the gs were with double line length? Lee
  2. This idea has come up once or twice. I remember one conversation about the value of dacron lines in mitigating hard openings. We use screamers the folded in half and zigzagged kind in some of our designs. It kind of comes down to the amount of kinetic energy absorbed. Force times distance. The bottom line is that the magnitudes are just to high. You just can't make a meaningful difference in the overall opening. But it can effect some things. Openings are not one smooth curve. The canopy is lifted to line stretch and you can feel a sharp jerk when all that momentum runs out of line. Depending on the snatch force size of pilot chute high speed that can be a painful high but brief spike. It can be the highest peak force in an opening. But it's generally followed by a much larger bell curve of some type. In a square it's mostly determined by the slider and at what speed it loses its dominance over the opening. The area of this second curve is just too large to be affected by a small amount of elongation. So the peak of that first spike is within the realm of something you could effect but the main opening just involves too much kinetic energy. Dacron lines play a different role in creating higher friction to slow the timing and decent of the slider. That is meaningful. More so then their elongation. That and improved staging from the rubber bands having a better grip on them is where their reputation really come from. I've changed my mind over the years. I do think that there is value in risers breaking to control super high peak forces. It's not a common occurrence but I've seen fatalities that I attribute to opening shock. It's not a fun idea but there is something to be said for a fuse in the circuit. Maybe type 6 risers weren't such a crazy idea after all. Lee
  3. Sex swings are more often solid saddles then split saddles. Both exist but split saddles are much harder to climb into and almost guaranty a face plant if you fall forward out of them. So I don't think it would be limited by that otherwise it would push the date up to the 70s. There have been female jumpers forever. At least back to the barn stormers in the 20s. Lee
  4. I know that we have some pretty good historians of the sport here. When did we start using hanging harnesses for training? The question came up today of how long have skydivers been using hanging harnesses for sex. As improvised sex swings. I was guessing around ww1 but I was trying to remember the details of early harness design. Does any one know how far back the practice goes? Lee
  5. Variations of this idea have been in discussion forever. I remember them all the way back to the otter crash at Paris when I was a young jumper. All of them were better then what we are doing now. None of them have gone any where. Do you think any manufacturer wants his harness to officially be part of the restraining system? There are a lot of hurdles in the way of a new idea. Lee
  6. First to be clear. I think what you mean by bi cell is that there are two sections to each cell instead of three. One vertical unloaded rib inbetween the loaded ribs. Like a normal canopy. That would put both diagonal ribs running to the same seam. Well that's kind of over kill to support that seam. This would of course work but it's not very efficient in terms of the bulk of the canopy. Turns out that a 7 cell 3 section is more efficient bulk wise then a 2 section 9 cell. If on the other hand you ment a 5 section cell with 4 diagonal ribs per cell then I can tell you that there is an issue with the vertical rib between the diagonal cells. They build nice long bridges like that all the time but that vertical member has to be able to withstand compression to really work properly. There is kind of an inbetween. There is at least one design out there by... Airborne systems? They make the unloaded rib shorter. So the bow, the support, is all in the bottom skin. The top is smooth, all the top skin seams at the same hiath. The individual skins still inflate and how but no distortion as the unloaded rib shifts upwards. Basically the same thing you get from a crossbarace with out the bulk. PD played with it as well but felt that it didn't give them enough rigidity. But that is some thing that is out there in a "bi" cell. Lee
  7. At normal operating speeds, with full fuel exaustion, the absolute slows it down to about 100, the openings are about average, 3 g. So pretty soft. Early shut down can double the mass of more. So the terminal goes up. You can be dealing with four times the kinetic energy on opening. If it's a flat shot, like a guidance failure, you can be going fast horizontally. If it's high enough it will wait a few seconds to let it slow down before deploying the main. Lee
  8. Strong c1200 cargo canopy. 1200 sqft 15 cells. A,b,c,d,e,f,g lines. grommet spacing can't really be wider then the cell so you wind up with an inner and outer set of grommets to allow three cells to inflate with the slider up. It gives you the area you need to deccelerate the payload before the rest of the canopy opens. You wind up with four grommets front to back in four rows and six on the back edge for break lines. They extend the back edge of the slider and have there own slider stops to increase its area. You actually have eight primary risers that give you inner and outer on each side. They Y near the top front to back to allow the slider to come all the way down, accommodate those four grommets in each row. 16x7 noncascaded 1000 lb lines and 6 primary break lines 2000 lb split to 12 attachment points. So ya, it's a beast, 68 lbs of joy, but I've seen it survive 20,000 lb opening shock. Lee
  9. It astonishes me that some one would ask a question like this here or that we would try to answer it. Don't people go to the dropzone any more? Don't people drink beer any more? This is the sort of question that should be answered standing around the hanger after the last load. People sould just show you or as the very least a green bottle should buy you a full lesson. I'll give you a hint to make a continuity check easier. You don't always have the ability to hang it up where you can easily see the routing. If you are doing it on the floor flat on its side. You can start at the canopy and load the lines of the riser into your fingers separating then on your hand and walk that whole group back to the riser. You can also use a course comb. Load all the lines into it in order at the canopy. Use a second comb from the top to lock them in place. You can even secure them with rubber bands on the ends as you walk it back. It's some thing I learned working with larger more complex canopies. With like 124 lines 60 ft long. 16 risers and 22 grommets in the slider. Try line checking that by your self. Lee
  10. Above reply is probable the best answer is probable the best. I'll bet that it's really not that fun when taken as a whole. Stop and think about the logistics of trying to fly it. You really need a tail gate. The awkwardness of it. The complexity of integrating the wing... Yes they have made some spectacular videos. I'll bet he doesn't go out and make 10 jumps a day with it just for fun with his buds. if you really want to do this don't let any one tell you that it's impossible. In comparison to building a kit plane it's a rather small project. Don't let any one tell you that you need 10,000 jumps to fly it but 500 wing suit jumps probable wouldn't hurt.I You could do this if you really wanted to but if this is your sole goal. I think you will become disenchanted pretty quickly. Skydiving is a broad community that offers a lot and this is about as nitch as you can get. Lee
  11. The comment about Indian woman is kind of an inside joke about Mandy. for a while we seemed to be getting a lot of tandem students from India. She was by far the smallest tandem master so when the Indian family's would show up she would get the small Indian woman. She was absolutely convinced that they could not arch. They always went fetal on her. She was convinced, and she had more empirical evidence then any one I know, that Indian woman were genetically, culturally incapable of arching and would always go fetal on exit. No other group exhibited this phenomenon. Indian woman can not arch. Just ask her. She'll tell you her self. Indian woman are the only cultural/racial group that can not skydive. Lee
  12. Back in the day shipping weight on a tandem rig with harness was 60 lb. I'm curious what the newer smaller rigs are weighing in at now? Mandy looked almost ridicules wearing those big strong rigs. I'm wondering if the smaller rigs would be any more ergonomic, better suited to some one with a shorter mlw, maybe narrower? Or are they still being built on the same long wide patterns? Your also liable to get stuck with all the small Indian woman... And we all know how they are. Lee
  13. They have been working on it for over thirty years. Can't really get around the ratios of the the size of the rings to their guage and the thickness of the webbing. Mini rings are really just too small. There are the aerodine rings which are a substantial improvement. Not quite as good as large rings but so so much better then any mini ring riser. The substantially reduice the internal stresses between the second and third ring. And consequently the load on the loop. I think the reduction in internal stress is the most important part as i have seen risers fail at the tape for the third ring. We've actually pull tested... well everything trying to build 20,000 lb releases. So we've actually pulled all of these peaces of hardware and designs to destruction with load cells. 15,000 lb webbing is exciting when it lets go. Some of the hardware send pieces flying when it snaps. The aerodine rings were some of the best. If you are curious their failure mode is that they bend wrapping around the main ring rather then snapping but you have to build a kevlar riser to have enough strength to make them do it. Lee
  14. It looks like what you have there is just an attached bag. That's normal on there retract pilot chute systems. I'm not seeing a "flag bag" in your pictures, that is also a thing. Flight concepts builds a flag bag on the bottom skin. Flag flies between the canopy and riser. So if it's just the attached deployment bag. This is something they often do with retract, not to be confused with collapsible pilot chutes. The cord bridle runs through rings inside the canopy. When you pack it you pull out the bridle you compress those rings, making sure the fabric is clear. On opening the rings spread retracting the bridle so that the pc is sucked into that grommet and nothing trails behind the canopy. It's a CRW thing. The bag is attached so that the weight of it done not pull the pc and bridle out of the canopy during a wrap when the canopy is collapsed. If it is lose the bag will swing around like a bolo and wrap around things. That's what a lot of companies have gone to tail pockets. To pack it you first need the proper length cord bridle. Attache it to and route it through the internal rings. When you pack it clear the fabric. You had to fold it so that the grommet is at the top. Pull the bag around the canopy and close just like any canopy. Bridles tend to be short. You might want to go to a pullout. But you may need a cord extension because the base of the pc will actually be pulled into the grommet. Call Red, he will walk you through it. Lee
  15. Interesting. I wonder what the speed range is in that thing. It would be interesting to have a wind tunnel in which you could text dynamic control. So instead of just. Changing the angle of a model and measuring forces of pressures to directly test flight control systems... Lee