pchapman

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Everything posted by pchapman

  1. Thanks. Yeah I was kind of thinking Adobe Flash Player has been disappearing from most browsers. Even Adobe wants its use stopped after Dec 31. Not sure why dropzone.com is still trying to use it, especially with an mp4 file that seems to contain actual MPEG-4 content, unless I'm missing something.
  2. Huh, audio only on Firefox, Chrome, or Edge, on my Windows PC. Not sure what I'm missing. But I could inspect the contents of the web page, copy the .mp4's actual location on the dropzone site, load that into a browser on its own (still fails to play video), and 'download page' to download the mp4. Worked fine once the mp4 was on my drive. This is the direct link to the file: https://www.dropzone.com/uploads/monthly_2020_11/1205120192_Firstsolojumpcopy2.mp4.eb8b4129e1060b5ec8b18df5798165ed.mp4
  3. My analogy to this situation (where wording was surely deliberately chosen to be misleading): White House releases Pearl Harbour accomplishments Highlights include: - Ending World War II We have taken decisive action to understand, engage, and defeat the enemy. - .... etc
  4. I noticed that the USPA SIM does have a detailed description of a PLF. It isn't perfect, but at least does put a lot of detail into the roll. It doesn't however get into differences between low and high horizontal speed for example. It just mentions leaning into the direction of the landing (whatever direction that may be - not necessarily forward or straight down). So the legs would always be slightly 'back' of vertical, with no rules about how to deal with cases with more speed -- where people might have legs out in 'front'. E.g. - if one is going forward, and about to hit at a 45 degree angle from the vertical, then: a) the classic PLF instructions would have you trail legs slightly BEHIND you. Giving you very little support going into the PLF! -- You would pretty much catch the feet on the ground and then body slam the ground. Ok, that's exaggerating somewhat. Classic PLF may still work as that angle is similar to round canopy jumps with a lot of wind. But as the horizontal speed increases and the angle of arrival is closer towards the horizon, this situation (a) becomes more true. b) But it would also be bad to have legs out 45 degrees in front relative to your center of mass, as that would pile drive you into the ground when moving at that 45 degree descent. Impact point with feet are directly in line with your motion and center of mass. c) So you would want legs out in front a little, to absorb some impact and slow down a bit, but with the center of mass then going 'over' your legs to enter a roll. d) It would be overdoing things to have legs up higher than 45 degrees from center of mass, as that would tend to make you slide but also pitch butt down, and smack pelvis & spine into the ground. So on the one hand the SIM does go into more detail than the 'classic 1960s round canopy' sort of diagram (that you show), but it doesn't get into all the modern issues (that you were concerned about when starting the thread). This kind of stuff is good for making one's own thoughts on a subject clearer and better organized! My sketch could be clearer but shows a few of the points above:
  5. PLF still makes sense at the novice level, and that's the level that is normally taught in skydiving for nearly everything. At a more advanced level, that's where in skydiving we have generally had to learn much more on our own. And people now are taking more and more canopy control classes, whether enforced at the intermediate level (depending on jurisdiction), or for learning swooping a little further down the road. I don't know what other coaches have done, but when I've taught canopy classes for those just getting into faster canopies, all those other variations on landing do come up: All the stuff about how if you aren't going to run out a landing, you can slide, but there are all sorts of things to be aware of relating to protecting the spine, foot position, roughness of the ground, and so on. I can't recall exactly what they do in judo or parkour, but I think one sees rolls that are a little more of a 'forward roll', although still twisted to the side. That might work if one is flexible with no gear on, and with certain softer surfaces and with certain moderate speeds. Worth looking at but I doubt anything is going to greatly change skydiving landing rolls. As an example of a situation where both sliding and PLF can work together: A low slide, one butt cheek on the ground, can be good for scrubbing off speed if the ground is smooth. But if you might hit an obstacle, say a rock, dirt ridge, or stump in some higher grass, then it would be better to slide with the feet but keeping one's torso off the ground, and the center of gravity higher, so that if one hits something, one can at least get thrown forward into some sort of roll, instead of piling straight into the obstacle. PLF is still great for vertical speed, sliding is great for horizontal speed if the surface is smooth, and for everything in between, it gets a little more complicated, but the PLF is still the first thing you want to have in your toolbag. I think this PLF topic falls less into the category of "what's wrong with the PLF", than "how do we keep educating skydivers on more advanced knowledge, after they are licensed and are no longer students".
  6. Skydive Niagara in Ontario Canada has been operating one for many years now. Have been there but don't know anything about how well it is working out for them. http://www.niagaraskydive.com/ Go Skydive in Quebec by Ottawa used to run 1 or 2 Navajos, but has now transitioned to Caravans as their big planes -- So they might be a good place to ask, both because of language and because they can give a more unbiased opinion if they no longer use a Navajo! goskydive.ca
  7. Unfortunately I don't have the link, but somewhere I recently saw a video where some jumpers (speaking Spanish?) were testing hook knives on tandem bridles, tensioned somewhat with one person at each side pulling the bridle. While the cheapest plastic knife had issues, any of the decent knives (Jack, Benchmade I think) cut the tandem bridles with no problem, with one easy slice. Impressive.
  8. Since nobody more qualified has answered yet: Check how much stitching goes through the shoulder pad area to see how difficult it would be to access the area. On some really old rigs (eg Vector II) it was easy for me to add some padding between the fabric layers, because almost no stitching had to be taken out to get access, to slide new padding in from the back, sliding it between the actual harness webbing inside the container layers, and the layer next to one's shoulder. Which is where the original old and maybe worn out foam is. But as rigs got more complex, there's more likely to me more stitching through the shoulder area -- e.g., for a Vector RSL or Skyhook RSL, there are long stretches of velcro sewn on in the the right shoulder pad area, with the sewing through more than just the top layer of fabric, and sewn through the existing foam layer I think. Things change again when there is spacer foam added to the backpad (on newer rigs), but that tends not to have sewing through it. So I don't know for sure what it would be like on your older Vector 3, but anyway, a rigger could make a good guess at it if they see the rig. (Since I'm a rigger and not in a TSO-required area, to fix an older rig of mine with too much sewing in the shoulder pad area, I just sewed some backpack straps under the shoulder straps, almost like an RI Curve's Bio Yoke... Probably not an option for you, although one might argue that a hand tacked version would not be a permanent modification to the rig itself. )
  9. The 2nd part of that quote is the key caveat to the first part. As you say, in CRW the canopies are well matched. I think much of the issue is not "does one steer with toggles?", it is whether one releases the toggles in the first place in order to steer! I don't see as much risk in just steering with toggles if they are already released. Toggles or risers, use whatever works for you. But releasing them can make things worse if the main and reserve canopies are not well matched.
  10. OK, if one is really tall and also outweighing the instructors by a fair bit, yes it does become harder for the instructors to wrangle the student if things aren't going really well. The 'different instructor every time' is a problem at many DZs. Sometimes a DZ might be able to focus more on an individual student's progression, if they can make it out during the week rather than the weekend. Having done the tunnel time should have helped a lot too. There should be ways to get through the issues, but it is hard to diagnose the details at a distance (especially without the video that Riggerrob mentioned). And SoCal is one of the places on the planet where you should be able to access different DZ's and experienced instructors much better than elsewhere...
  11. to the OP: I'm not sure that there's much different for a taller vs shorter student (or instructor) in terms of how to fly?! But I'm saying this as only a moderately experienced AFF style instructor. The basics are the same even if individuals with different bodies will have to emphasize particular things a little more or less. (Eg., someone less flexible may have to work harder at arching, or someone tall might have more issues with getting a good enough exit position in a smaller doorway.) Tall or short, one has to keep arms and legs in the right positions, not too stiff, but not to floppy either. Every student has to get that right, to keep from chipping, flipping, spinning, sliding away, etc. It almost sounds more like there's a bit of a disconnect between the instructor and student in terms of teaching or learning styles and techniques? It happens. Instructors aren't all perfect either. Have you run out of other instructors to try learning from?
  12. So the two sources are the same for biplanes, except for the SIM allowing the option of unstowing the brakes on the front canopy and steering with them. I don't think there is one standard procedure in the world that everyone agrees on because it isn't as if it gets tested a lot. Nevertheless, I get the feeling that over time, the tendency has become to recommend a more 'conservative' approach, not unstowing the front brakes in a biplane. From a 2013 post of mine: The APF also used toggled stowed -- And it says it is based largely on the PIA report, but with updates based on more recent field tests. I also have a note about the USPA SIM, although I didn't note the year. Perhaps also 2013 or so? Has this explanatory text been removed since then? I haven't checked. Anyway, here's the SIM note: As you can see, historically much of the input on the subject in the past 20+ years is basically the PIA dual square report, with modification later based on Jim Cowan's tests.
  13. Gary unfortunately passed away last year (https://www.dropzone.com/forums/topic/266644-gary-peek/ ) but the Parks College group have done a lot of study of canopy openings, both from the practical in-flight side and on the theoretical side - eg published conference papers on the subject.
  14. I had been thinking of a similiar post to Deimian's, so with him breaking the ice here goes: One does seem to hear of more damaging openings from larger canopies, but it isn't always so. Confounding variables may be that older jumpers traditionally have sometimes been under big canopies, and maybe are more susceptible to injury. Or that heavier jumpers are also more likely to be on bigger canopies, and thus tend to start deployment at higher freefall speeds. As an example of a bad small canopy opening, although with a non-standard slider: I know someone about 160 lbs, a DZ packer and thus with experience, who broke some neck vertebrae recently on a Crossfire 2 109 with a 'slightly smaller' than normal slider. Someone else thought it was acceptable to put that particular removable slider on in place of the regular one. Worked fine for 40 odd jumps but one time it didn't. I certainly can't go against Performance Designs, but want to mention one factor among many competing ones in how canopies open. Fill time certainly is longer for larger canopies which have larger internal volume (rising faster than the size increases, due to volume cubing when area is squared). But what about plain old bottom surface inflation before filling? If a 20 ft wide canopy can snap open and create as much drag as it does, then a 30 ft wide canopy might be able to snap open 20 ft wide in nearly the same time (with just a little more mass to push around)... and then continue to open fully to 30 ft, creating even more drag than the 20 ft canopy. This only applies if the canopy expansion is very fast, so that the jumper hasn't been gradually slowing down. With more time involved, the 30 ft wide canopy won't add more pounds of drag because the jumper will be slowing rapidly before the canopy area gets too big. So that's a scenario where I'd rather have an explosive opening on a smaller rather than a larger canopy. As for the Para-Flite experience, I wonder if the trends in zero-p canopies are different than in F111 style ones. We never had openings quite as explosive back when the fabric would let more air through. And just for fun and maybe just a little education, a few pics of hard openings I've seen as a PFF (~AFF) instructor with students -- where they had a largely open canopy while only a short distance away from me in freefall. Shows 5 different opening in series of 1 or more pics. [Edited to change description, as file names not shown in-line] Some were sore but no long term injuries. A blown brake line in pic #1. The last series shows how a canopy can start inflating a lot in the middle even when the slider is at the slider stops on the stabilizers -- I haven't quite thought through the geometry issues contributing to that. (These students were on Aerodyne Solo canopies, full ZP versions. They later shipped larger sliders that helped somewhat.) Some filling of the cells is happening, especially in the center cell in some photos, that may be driving some openings, but there's a lot of 'squished flat' bottom surface inflation happening in many photos too. When your student is still within 50 feet of you and slider down, you're glad not to be them!
  15. Yes, it can be a problem with AFF or the similar PFF, that a lot of minor stuff gets a bit missed along the way. Dropzones are busy, instructors are busy, instructors aren't paid a ton, so the emphasis is on the big stuff: Your freefall maneuvers, your pull, flying the canopy to landing, your flare. All sorts of other stuff should be gradually introduced during the process -- Getting you started to being more independent in checking all the components of your gear and donning it, starting to learn how to spot that your exit point is correct, learning to evaluate the dropzone weather and winds situation, etc. Each jump you should be taking on a little more responsibility, doing a little bit more yourself. But things get rushed and it is quicker for the instructor to deal with all the details, vital as they are. So there's plenty of learning to go. If you are in the USPA AFF system, I don't know the details of how it works, but you're not truly solo yet, you're not licenced and on your own. There's still supervision. You may indeed need to ask instructors more questions and have them slow down. A slow or rainy day at the DZ may be useful in case you do need to catch up. Take the time to go over gear checks some more. Similar to what ghost47 has said, go through the jump in your mind from beginning to end, and ask yourself whether you know what you have to do. Find specific things to address. Do I want to skydive at all? If yes, continue. Do I know how to select the right gear? Do I know how to inspect it? Do I know how to evaluate the weather? Do I know how to plan the circuit pattern myself? And so on. You'll get some idea if there are specific things that you know well (and don't need to have excess fear about), or if there are specific things that worry you because you're unsure about how to do those tasks. In which case, get more training on those things. Overcoming fear is part of the process of becoming a skydiver. That's part of the fun of hurling yourself at a planet. Some fears are entirely rational, some need to be overcome.
  16. Hmm, interesting task, although sounds almost like a circular issue. Since there are no worldwide skydiving laws or ones handed down on scrolls since the ancient Greeks, what is defensible may be whatever the USPA puts in its current manual. Canada's CSPA rules are a little looser, with 60 days for a checkout jump for a student, and I don't think any formal limit on retaking the FJC -- although I've seen a DZ use 1 year as a standard. But while that may be of interest to skydivers discussing how things are done across the world, it isn't gonna matter a bit to a jury in the US of A. Vague rule or ones with worlds like "should" or "recommendation" can sometimes be useful. Harder to pin someone down on them...
  17. Sounds something like that, having the alti on standard above-sea-level figures. (Another possibility for having the issue in general, although not in your particular case, is zeroing the alti wrong, missing that it is set at -1000 feet instead of 0 feet. That's for altis in feet where one full revolution of the big hand = 1000 feet.) Since it is vital for pilots to report to air traffic control the proper way, above MSL, I've seen jump planes with a skydiving alti stuck to the instrument panel so that can be zeroed on the ground and the pilot doesn't have to do the mental math all the time either for ATC or skydivers. I had the same problem once when dropping static line students years ago. I couldn't convince the pilot he was wrong, so I just asked him for an extra thousand feet of altitude for these particular students. Which he gave me, no problem, putting us slightly above our desired altitude instead of at an altitude below what's allowed...
  18. Thanks Councilman. All my old bookmarks say ukskydiver.co.uk -- so they changed their address slightly to uk-skydiver.co.uk. As for the library, there is the Linda Hall library in Kansas City. Can't recall if there are any others. "This digital collection is a portion of a more extensive Parachute History Collection, and was developed as a collaborative venture between the Linda Hall Library and the Aerodynamic Deceleration Systems Technical Committee of the American Institute of Aeronautics and Astronautics." The old parachuting books are fascinating and contain stuff not in our 'standard' histories of parachuting -- since they were military, or stunt jumper, or 'foreign', or just didn't happen to make it into the sources that everyone then copies. Found a few of the old books to at least photocopy from university libraries.
  19. In Canada I've seen us respect the concept of the UPT rules -- only EXPERIENCED RW folks need apply!! -- while ignoring some of the details. Eg, if someone has plenty of experience, and is generally current, we don't worry about having to have a tandem or AFF style rating 100 RW jumps in the last year. That totally shuts out a lot of jumpers, even super current ones, if they are jumping in different disciplines. The UPT rules are so dumb that many who do tandem videos on weekends wouldn't be allowed to follow a tandem out the door... if they were not wearing a video camera. So screw you UPT. Which calls the whole list into question, even though the concept is very important, as tandem students are held to a higher safety standard. (Plenty of cases out there where tandem RW went wrong, including stuff like where the RW jumper's mom gets killed as a tandem passenger, due to bad RW.) But up across the border we can be more dismissive of USPA / UPT rules and any associated lawyers.
  20. Does any museum care about such stuff? Especially if it isn't military or maybe smoke jumper related. Kind of thinking out loud here. There are always the collectors of old gear out there of course. Some things get bought and sold on ebay, although some of that wheeling & dealing is more about making a buck than preserving history. Others try to keep gear airworthy or at least preserved for history. As you likely know, 'Beatnik' might have the biggest collection of vintage parachute gear in Canada. I keep my personal collection of vintage gear & magazines fairly small, but still have issues with how much basement space is taken up... Then there's the idea of putting something online, like scanning old manuals in to rigging manual sites. BUT: Ugh, do any even exist now? Parachutemanuals.com and the ukskydiver.co.uk sites are both gone. A lot of lost history, although someone in the know could find that stuff on archive.org hopefully. Or there's someone like Andrew Hilton with a big Flickr site with photos of his vintage gear and accessories, so that at least shares something with other enthusiasts. So, you got anything interesting? :-)
  21. Hmm. I guess one would have to look at each countries' training system, or indeed what particular DZs teach. Certainly new jumpers are taught about airspace, weather, equipment technical info, etc, and there are lists of such things in training manuals, so that each phase of a jump is considered. Skydiving doesn't have as much money involved like in say commercial or military aviation, so the progression systems are more casual (after the initial licence) and more dependent on the jumper learning the skills themselves, and they and their buddies evaluating their own skills to do a particular jump. (The UK is more stringent than the US & Canada, with some sort of more formal allowances to do RW or freefly or swooping, something that would be handled more at the local DZ level on the left side of the pond.) I'm not sure whether 'airmanship' is just something that's there when none of the individual pieces are neglected, or whether it is some separate concept. Certainly, it is often used to apply to things "beyond the letter of the law", beyond the basics of the rules, to include a more nuanced appreciation of all the factors including how to interact with others in the air. Perhaps a little more Human Factors stuff can be introduced. For example, one thing I'd like to see pushed a little more in some places, is the idea of a self-evaluation of the risks, potential risks, and challenges on any particular jump. Go over all of that and see whether the jump still makes sense, or whether something about it should be changed.
  22. "On all other tandem container systems, the main container closing and the drogue attachment are two separate systems, at two different locations." Ah thanks, I mistakenly thought the question on the test would relate to potential dangers of Sigmas in a test for Sigma instructors on how to jump Sigmas. That answer about system design was "too obvious" to me, given that I rigged the DZ's first Sigmas 18 years ago... Still, if they ask for "primary causes", I'd like to see a list of all tandem accidents say in the last 10 years and have causes listed by frequency....
  23. Non-US DZ but US registered Caravan: Skydive Burnaby, Ontario Canada. N806JA. (Yes it is a short Caravan, not a Grand Caravan.)
  24. 96- List the primary causes of tandem incidents that resulted in a fatality That last one has always thrown me. The Sigma manual (at least the last I checked) has nothing listed under "incident", "accident", or "fatality" that is in any way relevant. So "read the manual" seems not to help?? I always came up with some B.S. generic answer that seemed to pass. Duh, 'not following proper procedures' for example. Luckily the DZ I'm at took that question out of the tandem exam in recent years. We have customized versions of the exam that are still really long, but cut out some of the less useful stuff, and add in DZ specific stuff. (We're in Canada, so we don't care as much about US lawyers. We still try to adhere to industry best practices.)
  25. Looks like a run of the mill raft dive. Plenty of those done over the years. Not suited to most DZ aircraft but there are tailgate planes out there too.