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RiggerLee last won the day on May 5 2019

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  1. RiggerLee


    I had one of those once. Never could get it to sew. Not one stitch. Thread would not pull up around the bodkin case. Never could figure out why. Took it to a shop. They had no luck ether. Remains a mystery to this day. Had such great hopes for it. Not saying that they are bad machines but the one I baught had some mysterious grimlen inside of it. Lee Lee
  2. RiggerLee


    By the way. If you are going to see patches on a sleeve of a jumpsuit. Find a post bed. It's awesome. You'll never want to work on a jumpsuit with with a flat bet again. Sew a patch on an elbow. No problem. Lee
  3. To clarify in the example given we are looking at between 1000 to 2000 lb of snatch force depending on fuel burn off acting on a 65 lb bag. That's why the 80 lb. The locking shows are also made of 1 inch tape. I was thinking more of the bundling of the lines. Tieing them with a light cord at about 12 inch intervals before showing. Since we have eight main risers with a short split to 16 we bundle in 4 groups every 24 inches then then the full bundle in between for a tie every 12 inches. On smaller canopies I've seen them do it in right and left then the full bundle. I was wondering if the larger tandem reserves with non cascaded lines would justify the effort. But I think as things trend small it will be unnessisary. Watching high speed it does make a difference. You can see the bundle deploy. The ties hold through line stretch. The main bundle spreads and you can see the slider splitting the 4 sub bundles as it comes down. Way more orderly then the chaos of a normal deployment. But I have to tell you it sucks. My ass gets sore setting on the floor tieing all those lines. Lee
  4. I haven't looked at the numbers but I've seen friction knots on both. And yes that totally anecdotal. Working with larger canopies we do see some interesting things. I think the first question is the quality of the staging of the line deployment. As canopies get bigger and the bulk and mass of the lines gets larger how they are retained becomes more important to a clean deployment. For example we wound up using 80 lb. Break tie for the line shows. This canopy has 15 cells and 7 non cascaded line groups of 1000 lb line. Which basically adds up to a metric shift ton of line. We also tie the line bundle. Actually we do it twice. Once in four bundles then in one big one. Total pain in the ads but if you look at the really high speed footage of the line deployment it makes a big difference. Some times I wonder if tandem canopies are large enough to justify that effort? I think it's border line but as tandems are trending smaller I think the problem will get better not worse. Lee
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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