RiggerLee

Is the guy that bought Jerry's TSO still building chest mounts? He had TSO's in all four categories. New guy is trying to make a real push to break into the pilot market. You might be able to get a custom rig from him. Lee

It's valid but there is also a point of diminishing returns. I've built PC's like that but I've also jumped for years with out them. Is it worth it? Maybe in base? It's certainly necessary in some of the systems I work on but that's so far out side the skydiving envelope that I question whether it's relevant. Lee

[email protected] Lee

That's also a high load area during opening. When the slider spreads that center cell is the only one open. All the other cells are basically squeezed together to the width of the grommet. So if your whole line set is made of as light a line as possible, bulk/drag, then you may need continuous lines on the center A, B lines. When they started offering light weight HMA lines as an option on some canopies those line sets were non cascaded. I've also seen line sets with special line trims built non cascaded, a competitor was sent a line set to tweek the trim and it was non cascaded. In some ways noncascaded sets are better. It's just a trade off between bulk/drag and the stability of the trim of the airfoil. Cascades... wiggle back and forth depending on the load distribution cord wise on the airfoil. Lee

There used to be a guy on here and on basejumper.com More active as a base jumper, you might have better luck reaching him there. He used to be a navel aviator, I think he flew f-14's. I'm trying to remember his screen name, I think it was flydive. Might be this guy. https://www.dropzone.com/profile/2795-flydive/ http://www.basejumper.com/cgi-bin/forum/gforum.cgi?username=flydive; He could give you some very good input on weather limitations for launching and recovering aircraft. I think they might be able to launch in much worse conditions then they could recover in. I don't it's implausible that a long flight to this location might result in them arriving in worsening weather and unable to land but that is some thing that they would be trying to avoid communicating in route as they pass possible alternates. A pilot would very much not want to box him self in to a forced landing with out fuel to reach an alternate landing site. the worsening weather might make that alternate more difficult to reach. He might now be bucking a head wind. Landing in the water is a scary thing. There is almost no steering with a non modified round. An experienced jumper can try to "slip it" Pulling on two risers, say the two right risers, to try to make it slip right. Limited effectiveness. Landing in the water even a short distance can be life threatening in even mildly cold weather. Yes people die that way. Round canopies can drag you in water just like they do on land. Some parachutes used in the navy have what is called water pockets on them. It's a peace of fabric sewn to every other goar, the triangle slices of the parachute between the lines. It's sewn on three edges leaving the top open like a big pocket. They catch in the water when you are being drug in the water in high winds. The bottom edge of the canopy is held and the air spills out as the canopy rolls out flat onto the water and deflates. So that is very plausible that the most experienced person would be blown into the water, land, be drug, have the canopy collapse, get cut away, barely make it to shore and be in very deep trouble with hypothermia. A dislocated shoulder is exactly the sort of injury that you would expect from a hard landing/dragging event. This could happen even to an experienced jumper and it's the sort of thing that you would expect to happen to some one untrained. Falling out of the plane is not a ridicules idea. Under normal circumstances I would say that that is stupid but in weather, even moderate turbulence, you can literally have any thing not strapped down, ex. people, bouncing off the ceiling. Particularly at the back of the plane away from the CG that tail can move all around. You could find your self bounced off the ceiling, swotted by the far wall and ejected out the door. I've seen pilots do it on purpose. Some one he does not like or wants to fuck with is lounging by the open door, best spot on a hot day. Push on the yoke to unload him, make him weightless, and a hard kick on the rudder and out he goes. Funny as shit especially if he is asleep. It's what passes for humor in skydiving. It's dangerous to fall asleep at the drop zone. With the almost complete lack of control of an unmodified round a tree landing makes perfect sense. Trees look soft and fluffy but they have these hard things hidden in them called branches. You really want to keep your legs together and cover your face with your arms keeping them in tight to protect your neck and arm pits. A basic course... Try to get them to exit with both hands on the silver handle. Count to three, they do this in about half a second, pull down and away to full arm length. Keep feet and legs together. If it were windy I would brief them on how the release worked. squeeze the feet and knees together on landing. Keep them slightly bent, do not lock them straight. Hold on to the risers, it will help to keep the from reaching out for the ground, good way to break or dislocate your arm. Once you hit the ground your whole focus should be on getting that riser lose. Open the cover. Hook that ring and pull. The reality is that they will not exit stable. They will be tumbling ass over teakettle. No point on focusing on any thing but getting that handle pulled and minimizing the parts of the body sticking out for the canopy to wrap around as they tumble. The second they exit they will be blind and disoriented. Rain at that speed is like being sand blasted. Once the canopy gets open every thing gets calm or would normally. You don't feel the wind you are just drifting with it, but wind gust can be violent. The guy in the book was in cloud but describes the violence of the turbulence. It may have been his vertigo but he thinks that at one point the canopy was beneath him. That was actually inside the storm. Normally it's not that bad. It's quiet, peaceful. Until the thunder which can be loud. But when you look down you will see the ground going by under you at an alarming rate. Gust feel like they are pulling the canopy to the side and then letting it go, causing you to swing and oscillate. The canopy osculates. As you land in high winds you're traveling sidewase. This actually helps your landing. It will take your feet out from under you and roll you out sidewase on the ground. I think PLF's are much easier under a round with a little wind. I generally turn sidewase to the wind to help with a nice right or left PLF. But with a canopy like this it's random. Face, ass, side roll the dice. And I like the idea of the one idiot coming away unscathed. That's very real. If you catch the right gust, hit at just the right point on the oscillation, you can almost stand it up. He'll fall over in this wind but there is always one guy like that. How high of winds? I don't think there is really a limit. I would not chose to jump a round in more then 12 mph, I like rounds, strange that way. This is not really recreational. It might be 30 mph now but 50 when the front hits. I think a better question is what wind and sea state can they not land in. It's a crazy plan to begin with, I assume they are being forced into this. Lee

As to the type of parachute. Almost with out exception emergency bail out rigs are round canopies. Recently people have been putting large square canopies in some pilot rigs but this is almost always jump plane pilots at civilian drop zones who are them selves jumpers. Pilots and air crew are rarely jumpers unless it's a hobby for them. I'm not aware of any pilot/aircrew/bail out rigs in the military with square canopies, for good reason, round canopies do not require any input to land so untrained, non jumpers, or unconscious individuals can use them. A square canopy you have to actually unstow the breaks, stear the canopy, and flair it to land with out hurting your self. If you want to see the kinds of containers that might be used look up BA-22 parachute. That is a fairly standard bail out rig that some one might wear moving about in a plane. It's some what heavy and bulky. It can tolerate higher speed deployments. It uses a quarter bag as a kind of diaper holding the bottom half of the canopy closed till the lines are deployed. The canopy is a C-9, One of the toughest canopies ever built, the lines run continuously over the top of the canopy forming a net supporting the canopy. It's some thing you would see in early ejection seats before the parachute was built into the chair. On larger aircraft it allowed them to move around. Bad weather can be scary. We've all been there. In the US there is no wind regulation other then your judgement. We've all tried to get that last jump in before the front rolls in. Every one has at some point landed, even with a square, backing up in forty mph winds. Getting drug is actually very dangerous. It's especially dangerous under a round canopy. There are people that have been drug to death. People have been knocked unconscious on landing or while being drug. They can strike a object like a rock or tree stump and break their neck. Those are real events. The containers generally have releases on the risers. They are primarily there as anti drag devices or to get lose, like to get out of a tree. Look up, capewell parachute release, as an example. You open the cover and that loop of cable pops out where you can grab it. You put your thumb through the loop and pull forwards releasing a lever. As you pull forwards and down the lever moves a slide that locks the bottom of the capwell on the end of the riser into the peace on the harness it flips out ward releasing the hook on the top and that riser goes away. You only need to release one set of risers, on the right or left, to fully collapse the canopy and stop your self from being drug. I've landed, with a square, in 60 mph winds. It's scary. As it happens I did not have any form of release on that rig. I was drug for half a mile across the sea ice before I could get the canopy collapsed. Found it. The quality on You tube does not do it justice. I swear the wind wasn't that bad at the top. It's a weather thing up there where you get an out flow of air through the fiords It can be blowing 50+ at the bottom. At one point you see the corner of my canopy come down level with the horizon. That was not me making a turn. That was when I passed through the wind sheer and found out that I was in trouble. I tried to hide it but inside I was crying like a little girl. There is another even better video from Norway but I have no idea how to find it. It's an out side video of a guy having the same thing happen. Another famous historical event happened when a guy bailed out of a plane over a thunder storm. His parachute opened but he was sucked back up into the thunder storm. You should look it up if you want to know what jumping in a storm is like. I can tell you that rain stings, sleet fucking hurts, I don't know if you could survive hail. https://www.google.com/search?biw=1920&bih=937&tbm=isch&sa=1&ei=JmQ7XdKICsresAXwyb_wCw&q=ba-22+parachute&oq=ba-22+parachute&gs_l=img.3..35i39.10989.12020..12591...0.0..0.62.120.2......0....1..gws-wiz-img.......0i7i30.aiErpGMTluc&ved=0ahUKEwjSs53nt9PjAhVKL6wKHfDkD74Q4dUDCAY&uact=5 https://www.google.com/search?q=capewell+parachute+release&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjD-Kr2vtPjAhVLOKwKHV2JC_cQ_AUIEygD&biw=1920&bih=937 https://loa-shared.s3.amazonaws.com/static/pdf/Rankin_Man_Thunder.pdf Lee

With the way you are flying it, it's probable not an issue yet. Conservative designs will still fly nicely even when noticeable out of trim. Most of the shrinkage is in the outer lines and the break lines. It gets towed down at the corners and the breaks start to get short. I would take a good look at the breaks the next time you jump it. They should bow behind the canopy and not pull the tail down at all in full flight. If it's getting tight I'd replace the middle break line to restore the length and call it good. $20 better then $200. Lee

Little bit of video from the third flight. For the record this is not what it is supposed to do. Let's just say that there was a slight control/guidance issue. It would have made a free flyer proud. It was more then a bit frightening to watch it go into a flat coning spin right above us. That's over 1,500 lb of fuel/lox ready to drop in the middle of us if the cone gets to flat and it stops accelerating upwards. It did get going and the fins finally did provide us with enough stability to clear the area. Appogy was about 13,000 ft. Engine shut down do to IIP, it was about to exceed it's 7 km circle. That translates to about 500 mph over the top. Nose cone fired shortly after that, a bit slower but not by much. Nose tears off. Ballute inflates and whips the rocket around. 10 sec delay till it releases the main. We were only going about 150 mph as it came out so not too bad. Sewing the lines into the risers ala security 150 worked well. I'm pleased with that. And the ballute and cutter system certainly proved them selves that day. One break did not unstow till the very end. But it seemed to be flying it's pattern about 1000 ft low. I think there might be an issue with the terrain soft ware. So it landed as it was turning to base with out flaring. Cracked the boat tail and broke lose one of the actuators for the engine. No biggy. Found the nose cone, broken. Spent three days in the dessert looking for the ballute, no joy. That's a bummer. https://youtu.be/GlgN1bJWO48 https://youtu.be/-cTNevdDCN4 https://youtu.be/2qYF-0SwM94 Remember, you can use the hand to move the view around on the 360 fly cameras. So you can look down or up better the 180 deg. If the guys at Dekunu can figure out how to up load the flight data to their cloud I'll share the flight path as well. We had a couple of their altimeters on there for fun. There little units did good. Lee

We just flew a pair of dekunu altimeters on our rocket. I couldn't be more pleased. They gave us instant access to a great deal of data. this was particularly important as the flight went to shit. We were able to pull key data points out of the unit. We had to kind of hack them to get them to record the flight as we were using them well out side of normal skydiving paramiters. So far I am very excited about these units. Lee

I'm going to disagree. I'm a little out of touch by about a generation in terms of the current designs but in the past certain types of collapse seemed to be a recurring theme. I would not dismiss it as a danger. Other forms of collapse seem to become even more common as canopies improve in performance so I don't think this issue will ever go away completely. The first guy I ever watched die was a leading edge collapse. I didn't fully understand what I was looking at at the time. It was on a Pintale. I'm going to name names here, I don't think there is any way around it, please don't take it as shiting on any manufacturer. It's just history. Later we got a bunch of Conquest, I think that was the name, in from PISA. They had interesting behaviors in front risers. You could watch the dimple roll abound and change as you pulled on the front risers till it reached a point where the top skin would just bedsheet and it would just fall. Later I bought one of the first Extremes in the US from Gyro in Newzeland. Great canopy. Then he came out with his FX. We bought a couple of those. fucking death traps. When you turned one side of the canopy would collapse, it would spin, then the other side would roll under. Quote a ride. Cross flow through the canopy? Leaky seems? There were lots of theories. In the end he backed off on the nose a bit. It was just to close to the edge. Later the first of the Cross fires came out. I remember seeing them at Quincy and I thought, here we go again. Then I watched Mandys Velocity collapse in the middle of a swoop. And then later I watched that VX collapse over that plowed field. OMG I can't believe I forgot about the Novas in all is this but I think that was a slightly different issue. But these are my memories of nose collapses. I also remember people having canopies spin up on them. Like the guy that died when his saber one 210 turned into line twist leaving his body behind. He tried to do a shashay, the canopy unloaded and turned with out him the lines were twisted with the toggle down and he spiraled in. Later I remember a Safire. One side stalled and back spun during a hard turn, cuttaway. I remember when a lot of people were jumping large Triathlons. Then they bought Spectors. Suddenly they couldn't land there canopies at the end of the day. The dynamics of the canopy were different, they surged much worse dropping into that still air. One guy wound up with a severe brain injury from that. Point is that I've seen these things come up time and again. Some of them aren't even design defects. Some of these are a direct result of building a "Better" canopy. And they were fundamentally better. That guy with the saber died because it was a better canopy then he was used to. It made more lift. At that low wing loading you could unload your self easily. Charles almost died because his Spector flew better then his triathlon. I hope we are learning lessons but I don't think that these problems will ever fully go away because they are linked to our desire to build better higher performance canopies. I don't think you are going to covence me that all problems with canopies are behind us. I think as we continue to strive to build better canopies we will continue to bump into the edges of the envelope and will continue to see problems with each new generation. Lee

I might also point out that there is no force spreading, pealing them apart till the slider descends bellow the cascade. By then you are past the worst of the opening shock. All the real force is in straight shear. Lee

All the canopies that I can think of that were made that way were lined with the wide flat dacron. You could really sew the hell out of it. It was also harder to fingertrap with that tighter weave. I doubt it was as strong as a proper fingertrap. I think you would have needed about twice the stitching that they had in it to get to the same percent of strength that you can get with a finger trap, at least with a modern loser weave line. Lee

I think there are factors affecting the perception of this. On the whole I think skydiving has gotten safer over the years that I was involved in it. It seems like accidents and even more so injuries have come in waves. It seems that we go through cycles where some thing new is introduced to the sport and the malfunction, injury, fatality rates spike for a time till we adapt. Having lived through those lessens I would have to say that the equipment and sky diving has gotten safer. But there are other factors that affect the perception of it's safety. It would be interesting to corrolate the attitudes expressed here with the age of the jumpers in the sport. The longer you stay in the sport the more likely you are to bairy a friend. It's a reality check when you watch some one die. I think average time in the sport has gotten shorter. We used to say that the average time was 5 years. A few years ago some one told me that it was down to three before they wondered off and... took up golf. If you stay in the sport long enough statistics catch up with you and you have to attend a funeral. So I think there is a disconnect between lifers and average jumpers in terms of the perception of the dangers in the sport. And I think that difference is growing larger with the lower average time in the sport. So I would say that there is a difference in perspective between older jumpers and the average. It's both from Lifers having lived through times that were actually more dangerous and the average jumper not having been bitch slapped with reality yet primarily do to the lower average time in the sport. I remember when a well liked local jumper died. For a number of that generation it was the first close friend that they had lost and it really affected them. Some of them stopped jumping after that. It was a big reality check. Lee

It will be easy to pack. Canopies that live there do have shorter life spans. The lines need to be replaced more often. But it's only 50 jumps. That's like one good long boogie. If he hasn't gotten it real dusty it wont be bad at all. I wouldn't worry that much about it. Even if you baught a brand new canopy you should make trip to Eloy for the Christmas New Years Eve boogie any way. And then it will have 50 desert jumps on it any way. And then you should take it to South Padre and then it will have beach jumps on it. And then you should do water jumps with it... Lee

Not sure exactly what you are looking for. Depending on what you are looking for you might want to correct it for density altitude to get a corrected air speed. If you just drop it in to exel for instance you'll wind up with true air speed which is relevant in some circumstances but in for some things corrected might give you a better reference across the jump. Lee

Over the years I saw a number of canopies and harnesses damaged on hard openings with larger people. The amount of energy that has to be absorbed goes up with weight but it also goes up with the square of the speed. Falling even just a bit faster makes a big difference. But it's not as simple as that. Fill time of the canopy goes down with faster speeds. That's part of the reason that high altitude openings are so brutal. True air speed and volume fill rate go way up and make a disproportionate change in the opening shock. That's why a preme at a higher altitude is so dangerous especially if you are free flying or sit flying. Snatch force also goes up with airspeed causing more load on bags and canopies. the higher forces combined with heavier canopies are a good set up for line dump and staging problems. It's easier to break rubber bands with the higher load and a heavier canopy to pull against that will resist acceleration longer. Also bags are wider on larger rigs which with older bag designs means more line in between the stows trying to pull them lose. Right now I'm working almost exclusively with recovery systems dealing with 1000-2000 lb loads and the next air frame will be some where north of 7000 lb. All these things become more exaggerated, it's been interesting. You are going to want large canopies. Don't be afraid to go big. Large canopies fly so nice and you have the weight to drive them. You'll make it back from spots that no one can fly from. The opening issues are why I recommend an Optimum. It actually opens a bit slower then other reserves. That sounds like a strange thing to say about a reserve at least in a positive context. With the higher speeds that we are seeing these days I actually see advantages in it. It also seems to be more tolerant of higher speed openings. I know a couple of people that demoed them and made a point of opening them at high speeds from head down dives with no deceleration. I think they have a wider speed envelope then other reserve canopies. You're going to want a slow opening main to begin with but you might also think about having it lined with dacron line. I know it sounds strange, old school, but it does improve the openings. I don't really buy the "line stretch" theory but it's got other things going for it. There is a lot more friction on the slider. It sounds like a small thing but I think it makes a big difference in when the canopy becomes dominant over the slider and starts to push it down and how fast it pushes it down. They also have a lot more bulk and friction on rubber bands so you get better staging on the canopy deployment. That alone can be a life saver, literally. I've seen people killed by hard openings. A slightly larger or domed or flagged slider can be a good idea. Even if you don't seem to need it on normal openings it might save you on the anomalous hard one. But one change I would strongly suggest you make is to consider getting a "Speed Bag" from Jump Shack. Basically every line stow on the bag is a locking stow, they are a bit closer together, less line between them, and there are more of them then on a normal bag. It's about the most line dump resistant design out there. It's a bit harder to pack but you get used to it. Double wrap your bands. You'll break a lot of them but it's worth it. Just buy a big bag of them and keep them in a zip lock. And welcome back. Lee

Technically this is not the wanted section so I'll assume that you're looking for advice. Not sure how long you've been away. I see a frap hat and what look like kroop goggles. You're a big boy but not ridicules. And you're licensed so you get to be a big boy. A student they would be more worried about TSO max weights and liability. Booth and some others actually build sport versions of their tandem rigs for big boys rated for 500 lb loads. In reality I would recomend that you just go with sport gear. Used... tough to find unless you go with a student rig with an adjustable harness. Unless you get really lucky on here you're probable going to have to pony up and pay for a custom rig. PD makes some large reserves. I think the PDr is larger at 281 but I'd recomend that you go with an Optimum. Even though it's a little smaller and rated a bit lower I think they are more tolerant of higher speed deployments. You have your choice of mains up to 260, any of which would be good for you, but over that you're looking at a student canopy like a navigator. No mini risers or mini rings. Only full size risers and rings for you. Lee

Interesting. Taking a wag at the cell width of a 97 I would guess that it was about 21 inches. Allowing about an inch on each side for the inset of the grommets. That still makes the slider about 8 inches wider then the cell. The depth of the stabilizers also factors in. Some canopies have a stabilizer attachment on the B line a good bit lower then the A attachment points. I doubt that it's 4 inches on a 97. So for a 97 the front of the slider is probable setting on the bottom skin but not by that much. The back half of the slider will not be supported on the bottom skin and is probable doing most of the work of holding the canopy closed during the initial part of the opening. Doing more math, by the time you get to a 135 I'm pretty sure that the whole slider is fully engaged. None of it would be sitting on the bottom skin. So I can kind of see where they getaway with a universal slider size and I guess they add just a bit for the larger sizes to help hold the slider up an decelerate the jumper. That also explanes why there is a market for after market slider for their canopies. It leaves a good bit of room increase the width on larger canopies or play with the aspect ratios. Lee

I used to print a t-shirt, "CAN I BE ON YOUR ASH DIVE?" DZ is not a place for thin skinned snow flakes. If words bother you what are you going to do when your friend bounces and you get his gooey stuff all over you? Say what is all that stuff? When I was a student I figured there would be a lot of blood but when peoples bodies break open it's all this clear gooey stuff that dries and looks kind of like thin snot. Any body know what it is? Lee

It won't be that tough to break that record. Current air frame has the performance to take a person over 200,000 ft. So if you don't recover the air frame worst case you're looking at 1.25 mill to fly some one over 200,000 ft. With a recovery system that's another 80 lb's... haven't run the numbers. Not sure you could break 150 but you'd probable still top Eustace's record. That would be about then $400,000 including building the hammer head for the capsule. So not cheep but doable. Yah, that's the same dilldo I talked to at PIA. Nice guy. I squeezed every bit of info I could out of him. My impression is that they have a long way to go. It wasn't that impressive. In his "demo" he had it pressurized up to like 1 psi. Not a real pressure. The "suit" that they have right now is not really functional. They don't seem to have tackled a lot of the real problems yet. All I saw was a really crude mock up with which they were doing a lot of self promotion in hopes of people giving them money. Not saying that I'm not interested. They seem to have a long way to go and they seem to be mostly focused on promotion. Lee

Don't get too hung up on a major or specialization. My experience is that if you are an engineer you are an engineer. What you study in school is just a starting point. You will grow into what ever industry you wind up in. Example, I'm working for a rocket company. We're rocket scientist. The head guy is an electrical engineer. My boss who does the engine development and got put in charge of recovery systems came out of the petroleum industry. I'm not sure about his degree if he has an engineering degree it's probable in mechanical? Another is just a blue collar guy out of the air gas industry. He does all of our cryogenics and most of the construction on the rocket. There is a contractor that is a dynamacist that I'm sure has aerospace degrees. But I think I might be the only person here at the shop that was an AE, aerospace engineering major and I'm the seamstress. Maybe that should tell you some thing about the viability of that degree path... If I was to actually give you advice, I'd tell you to study your math. Maybe even get a minor in it. Regardless of what your paper says, some thing general like mechanical engineering or EE or some thing more specialized like AE, there will be a place for you in what ever industry you presue. But just as an example. I'm working for this company as their parachute rigger. Thinking back on what I've used from school. Alot of my work with pattern sets and design uses a lot of protective geometry and differential geometry. Unrolling sections of surfaces out of 3d space in to 2d to form pattern sets. Reentry models goes back to my AE courses. I cracked an old Thermo text a couple of weeks ago looking at a problem we were having with our pressurization system. Analyzing INU data from drop test. People say that you will never use what you learned in school, I've found the exact opposite. Particularly the math. But more than that I find the things I studied in school just generally inform me of how things will behave. And I never actually finished my degree. Some time I wonder what else I would have learned. It was invaluable but it was also just a starting point and nothing more then a foundation upon which to start building your experience. What you learn afterwards is what your career is built from. Lee

I was going to suggest he cut a hole in the center of his slider with a coffee can but I figured people would give me too much shit in this day in age. Lee

I don't really understand your post. If you want to alter the openings of the canopy your packing technique is by far the easiest thing to change. Is this a new canopy or used? The first thing I would check is the line specs, particularly the break lines. Could it have been built with the wrong break lines? Did some one replace them between relines? Altering the break set depth is the next easiest way to alter the openings. The slider is the third option. How big is it supposed to be? Was it assembled with the wrong slider? Did some one, perhaps of a different weight or tracking habits change it out to slow it down? Changing it's size or it's ratio can alter when the canopy becomes dominant over the slider on opening. Between the three you should be able to get nice openings out of a canopy. Lee

This is a good example of some one off the center of the bell curve where a larger or domed or flag slider could be handy. A better question is are the openings with dome sliders more consistent? That's a different question to whether they can fix a problem under those conditions. Let's say you plotted opening shock for a hundred openings. You get a bell curve. What we want is to avoid the out liers at the top end of the graph, they hurt. Their are a lot of decisions you can make in design, including slider size, that can shift that curve right or left. Keeping in mind that you don't want it to open too slow as well. Are domed sliders better? The question would be if they can tighten that bell curve. Make it narrower. Avoid the out liers at ether end. No more hard openings, no snivils, smaller standard deviation. There is no question that we can shift that curve right and left. That's what we have been doing with these after market sliders for years. We just needed a higher drag slider on some canopies for some jumpers. They will tell every one about how great it is because it fixed they're problem. That is not to say that it's a fundamentally better slider design. A problem we had with the canopies for our system here is that the manufacturer tryed to build the slider too big. It's actually more complicated then that, the damn thing has 22 grommets but the point stands. I built things like this for people for years but what I was doing was shifting the curve. I have no reason to beleve that it actually reduced the spread. So I can't say that a domed slider is fundamentally better then a flat slider. I can just get a bit more drag out of it. Lee

You might check out... https://dekunu.tech/dekunu-one#data They are Australian and no one can pronounce the name of the thing but it's an interesting unit. I was talking to them at PIA and it's a small INU with GPS, accelerometers, gyros, pressure transduicer etc. It's basically a little data logger but what is really interesting is the back end cloud software for analyzing and sharing the jump. Got a student? Let's see what your holding pattern really looked like. Where was every one relitive to that big way CRW formation as it built? How hard was that opening. I literally got mine yesterday so I have not had time to play with it but I cant wait to pull data out of it. You're supposed to be able to get the raw data from it as well. If you go to their web sight and scroll down to a video you can get some since of it. It's edited in with a lot of bull shit video like a toy commercial but there are shots of the interface as well. Looking forward to playing with mine. Lee