pchapman

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Everything posted by pchapman

  1. I don't think this is a big deal in the long run. The USPA would like to get decent feedback from the field. I still think it is kind of stupid to put it into the BSR's as filling out paperwork doesn't seem to be a fundamental part of actually making a safe skydive. So I laugh at the USPA's actions, even while understanding that they probably thought, "But nobody's gonna fill this stuff out unless we really, really try to force them by making it sound super important." But taking the time to look at the SIM, the BSR info actually makes it sound like data collection would fit the mandate. It has stuff like: Maybe a little more feedback communication is OK for the organization to have. Anyway, not my problem really. I'm in the CSPA where we have long had Accident/Incident/Malfunction forms we're supposed to send in for all sort of stuff. (The info does get anonymized and originals shredded.) Any AAD fire would likely qualify, not just on instructional jumps. Yes it is a battle to get people to send them in, and some DZ's are better than others at getting people to submit them. Incident reports are great for annual safety reviews too, internally on a DZ. I'm ready to just move along on this.
  2. Sounds like a Cypres. ;-) (A new one, that is.)
  3. One needs some context there. 1. The bar tack failures, that situation was fixed about 19 years ago, and only applied to certain models. (Mind you, a fixed one is probably not as good as one that didn't need the fix.) 2. The blowing up stuff, that happened at freefly speeds to particularly heavy jumpers. Ok, I don't recall if the weights were above the certified level or just the recommended level. Nobody will argue that a Raven is as strong as a PD, nor do Ravens have the spanwise reinforcements. Still, it isn't something that happens generally. I wouldn't pick a Raven for a high use freefly rig, but wouldn't have any issue with one being in a general purpose rig, as long as it isn't too heavily loaded.
  4. This is largely ancient history stuff, but this reply is based on what I see in my notes from the Argus war era: There were 5 incidents or accidents that I have records of. All but one of which involved the early cutter design. All those cutters should have been removed from service by a service bulletin. The only new cutter involved in an incident was the San Marcos, Texas one, where the investigation found a steel ball such as from a shot bag within the cutter, and with a damaged cutter. The conclusion was that it was the foreign object that prevented the cutter from fully cutting the loop. So the new style cutter with a harder cutting edge never seems to have had any issue cutting the loop (when no steel foreign object was involved). It just seems like nobody trusted the Argus folks any more by that point, so many rig companies (and the occasional DZ) didn't want to give them a chance any more, new cutter or not. It didn't seem to based on any evidence from the track record of the new cutter. Who knows what would have happened had Argus' remained in more common use. It is up for debate whether a device should be banned without evidence of issues with the new system, while at the same time there is a lack of trust of the company as a whole. As for "letting go on climbout and taking down the whole airplane", I'm not sure why the Argus would be likely to activate unexpectedly on the way up. The chance of something going bad on climbout is in my opinion much much higher from other things -- multi-way climbouts, poorly packed BOC's, newbies in general, whatever. I wouldn't be much concerned about some Argus inexplicably deciding to pop while in the plane, and then have the new style cutter for the first time ever hold the rig closed until climbout...
  5. I say no big deal, color the attachments if you want. Yes there is some concern about acidity of markers. At least get a brand name like Sharpie. But I've never heard of canopies falling apart or fatalities from this. Maybe it's an issue if you're trying to get 3000 jumps out of your canopy rather than just 2500, who knows. It's just not high on the list on concerns in skydiving. Although I already had thousands of jumps and was an active rigger, I coloured the attachments on one canopy of mine, as it made packing just a little faster.
  6. And to be clear, discussion of the BSR rule itself seems to be going on at https://www.dropzone.com/forums/topic/265231-uspa-board-meeting/
  7. I looked up what seems to be the topic of discussion, for anyone (like me) who isn't closely watching USPA board meetings: Ref: https://uspa.org/Information/News/uspa-board-meets-in-dallas Edit for sarcastic comment: Although the rule hardly seems to be a BASIC safety requirement at all. Seems to be an administrative / data collection / reporting / paperwork requirement. Fair enough if the USPA is curious about the stats. (Is it just put into the BSR's because few bother with doing other incident reports? Are incident reports supposed to be mandatory in the USPA?) 'Before your jump, make sure to have some reporting forms stuffed in your jumpsuit, to make sure you have a safe jump! '
  8. The original poster may have better luck with some of the WWII recreation groups out there (or whatever they prefer to be called). Liberty team etc. Or someone who supplies them, like NPTC at Dunnellon Florida. Pretty silly 25 year rule though that the Daks over Normandy group have, whether it is their own or some European country's regs.
  9. The DZ I'm at had it happen once, about 15 years ago to one of their C-182's, late 1960's vintage I believe, while taxiing out. Bent the wing and horizontal tail but was fixed up. At the time the DZ was rocking as many as 6 182's . After that the DZO did start cycling airplanes through maintenance to have the flat-bar gear legs removed and inspected. I vaguely recall x-ray inspections were planned, but on the other hand I helped with stripping paint so some Magnaflux style test must have been on the agenda. So I don't know if it was one or both or what makes sense. In any case, repetitive jump ops on grass at near max gross weights must use up a lot of fatigue life, and you never know if there's a hidden nick or scratch somewhere. I know the break point was near the fuselage, but I don't recall if it was hidden within the heavy gear 'box' structure that holds the gear leg as it goes into the fuselage. Those gear boxes get a beating too and I guess can be partially inspected when the floor boards are unscrewed or unriveted? Not sure. I'm saying all this just as a jumper, not as anyone with 182 maintenance experience.
  10. Aha, I see I'm thinking about the Vector III and you're testing on an Icon. One difference is how the RSL is attached over the shoulder: The Vector has velcro over a long distance. (Like 8" or so on a tiny Vector I'm repacking, including the Collins leg.) The Icon just has the RSL in a fold-over channel, with no or minimal velcro? You can clarify on that point. So yes, you may find it a lot easier to back-load the L side cutaway cable with an Icon than Vector. That's one place the 2 rigs differ, despite Aerodyne having Skyhook tech bought from UPT. (Aerodyne and UPT have dealt with other minor aspects of staging loop rigging slightly differently too.) I should also note that you are testing the harness without anyone in it, allowing the shoulder to flex. Wearing the rig would reduce that flex. (In the air under canopy it gets messier: Although there's tension on the harness, the shoulder straps can also sit somewhat above the jumper's shoulders.) Although the flex might not matter that much either way with the the Icon where the RSL pulled free relatively easily. So far unless I see better evidence, I'll still trust that the split RSL/Collins lanyard, combined with the velcro'd RSL, will do a the job UPT intends it to do, keeping a backloaded Skyhook/RSL/Collins lanyard from pulling out the L cutaway cable. But I'm also somewhat more concerned with Icon's design. Yet in some cases all the velcro can be detrimental, such as on a Sigma with a baglocked main and collapsed drogue, where the drag may not always pull the RSL completely free. Tradeoffs. @ skytribe: Thanks for those documents. I had a similar informal statement from UPT from years earlier, but it's nice to have a printed document stating their position, more recently (2016).
  11. Photo link not working. And not much force to remove the staging loop? Sorry, I lost your point. If the pilot chute pulls the bridle at the staging loop, it releases easily as it should (on a normal deployment). If the RSL/Skyhook system pulls the bridle at the staging loop, it releases easily as it should (on a Skyhook assisted deployment). Meanwhile the bag is in the container and can't fall out and "back load" the RSL system or pull the Collins lanyard. Or are you suggesting freebags should be much harder to pull out of the container, with much stronger staging restraints? (The rigger's seal thread on the Skyhook does a bit of that, when the deployment is started by the pilot chute. Takes some pounds of force to break it.) ----------- Back to your test: Were you able to pull the L side cutaway cable far, when pulling the bridle, with the RSL velcro still attached all across the shoulder, when pulling down and back (relative to someone wearing a rig standing up)? That would be the direction the freebag would tumble out in the rare cases where that could happen. That test seems interesting.
  12. I'm just playing at this, but from the logic of the bulletin it sounds like the there's no problem. "All systems that had their last functional check-up carried out over 4 years + 3 months are considered not airworthy and should not be installed in any parachute system." And then it lists those that aren't airworthy. Although technically not stated, it is clearly is supposed to mean at that point in time (13 June 2014), and because of the reason just mentioned. Not grounded forever and ever into the future for no stated reason. If it was on the list but its LAST checkup is now within 4 years + 3 mo (despite whatever lack of maintenance in the past), then it is OK. I vaguely recall there was a time when the 'check every 4 years' requirement was specified only very vaguely or in different ways in different publications. Every 4 years on the dot? 4 calendar years? I think this bulletin helped clarify that. So something serviced in '16 will be fine for any US repack coming up soon. Subject to the normal requirements to replace the battery every repack.
  13. Seems these days that half the newbie questions are about putting big canopies into a hot little rig. Fitting 10 pounds of shit into a 5 pound bag, so to speak. The term "full fitting" comes up more than it should.... (No offence to the OP. Finding, choosing, and putting together gear is one of the tougher parts of becoming a skydiver.)
  14. It works. But Jump Shack / John Sherman never liked that design though. It's a matter of different design priorities. They don't like the heavy pilot chute cap, that affects how well the pilot chute launches, and making it top heavy, trying to invert the pilot chute at low speed. (Teardrop uses aluminum I recall, and the Flightline Reflex used fibreglass - maybe lighter, I'm not sure off hand.) I think Sherman also had a thing about ripcord forces, that when tightening down an external pilot chute a bunch (which is has to be, with no other flaps to cover it), it is easier to get too high a pull force with a single pin pop-pop than a two-pin. Or something like that; I don't recall his exact argument. That could also be debated, as any pop top tends to need to be tightened way up. Teardrops and Reflexes work. Although from the few Racers and Reflexes and Teardrops I've seen around over the years, certainly some needed better tightening, and the one pin ones look worse if the pack settles or the rig flexes over time.
  15. They're not separate and unrelated, but all connected together unless pulled in a particular way to disconnect the MARD. It's messy without diagrams but until someone has a more elegant description: The reserve bag falls out, which pulls on the MARD device on the bridle, which stays connected to the RSL because the RSL is supposed to pull on the bag without disconnecting... and thus it stays connected when pulled from the other end. (Assuming the pilot chute didn't grab enough air to disconnect the MARD first.) That RSL lanyard from the MARD part pulls on the rest of the RSL system, which includes the Collins lanyard. (It's a very very rare situation, but can lead to an unwanted one sided cutaway, while the reserve bag is falling down and possibly spinning around wrapping itself in the bridle.) One then asks, will the Collins lanyard pull the cutaway cable too much, before the whole RSL system to the main riser is stretched taut? And how is the RSL held in place and with how much resistance, where it goes over the shoulder? Some rigs have the RSL sitting within a folded channel. UPT has it velcroed down. The Velcro damages stuff around it, but does hold the RSL more tightly in place, especially when pulled in shear (lengthwise instead of peeling). UPT also have the loop of the Collins lanyard (that goes around the cutaway cable) on a separate 'leg' of the RSL system -- which in effect gives more slack in the system: Pulling the MARD lanyard 6" won't therefore pull the Collins lanyard 6". Originally UPT didn't have that separate leg, but since one of the accidents they changed the design.
  16. You seem to be lacking information about the Collins lanyard. I understand it is patented and only on modern UPT rigs or those that licensed it (eg Aerodyne), or is in some place far away not selling to the US market. The lanyard only started to show up in conjunction with the Skyhook MARD. If you had some rig without a Collins lanyard, it would be difficult for the average rigger to retrofit one. One would have to buy new shorter cutaway housings to provide a break between them, and generally redesign things. When many modern rigs (and their RSL setup) were first designed, the Collins lanyard didn't exist. RSL's existed long before the Collins lanyard started to be seen. So there are tons of rigs out there that were never built or designed for a Collins lanyard. So for the accident you mentioned, one should ask, "Why wasn't the cutaway housing tacked or clamped down properly?", rather than, "Why did the rig fail to have a Collins lanyard?".
  17. Here's some stuff on the Nova. Just a scattershot of opinions & observations from people across the years, all taken from dropzone.com. From a file I have of interesting stuff seen on DZ. So nothing is definitive, but without a lot of searching the archives, this might help. First off, I get the impression that they were light on the front risers. Which means that it is easier to get the nose to tuck under if one front risers too aggressively. Good canopies can be fine with light fronts, but if there are issues, then the combination can be bad. =================== Billvon said it wasn't just trim: Right after the first few collapses happened, Glide Path claimed it was line trim, and sent out new line trim kits. There were collapses even with the new line sets, though. ============== Dan Preston on Novas: novas were investigated by greg yarbonet (invented the slider). he found the airfoil to be less than ideal and the design was made worse by any sewing inaccuracies. he also was involved in testing the ill fated crossfire and told us both had very similar problems. ============ Riggerrob wrote : Some Novas flew great and others were scary. I know several freefall videographers who did hondreds of jumps on Novas in the violently turbulent desert air of Southern California and never had any problems. (Dan Preston said the same in another post.) ========= Cobaltdan 2001: one of our top factory pilots, caven warren has over 1600 jumps on the smallest nova made before switching to alpha's and then cobalts. i looked into nova's after 'red' owner of flight concepts called me and asked if we were interested in resurecting the nova design. what i concluded from speaking with caven and other past nova pilots, accident reports and talking with howard adams (rigger from glide path), is that i am guessing there must have been construction flaws. what i mean by this is that the airfoil used in the nova seems to be very sensitive to particular construction tollerances. i believe this fact was not realized during construction and many nova were effectively out of required spec. there were many accidents and fatalities where a nova simply collapsed on a turn. then there were particular nova's that were flown to the limit for 1600+ jumps ie. caven warren 540 king, without incident. overall my sugestion would be to avoid an old nova, as you never know...? ============ Winsor Naugler about Nova canopy and pressurization and angle of attack June 2016 re canopy collapse fatality Germany Most canopies use a high-lift airfoil, which is generally quite stable. The NOVA used a semi-symmetric airfoil, which is more efficient but less stable. In particular, the NOVA was/is susceptible to stagnation point migration to the upper leading edge under conditions of rapid rate of change of angle of attack. Put another way, when you hit turbulence, it tends to fold up. This was most likely when setting up to land and encountering either thermals or rotors on short final. Glide Path recommended a minimum wing loading on the NOVA of 1.3 psf IIRC, to reduce the likelihood of canopy collapse on short final. Unfortunately, it did not completely eliminate this characteristic. I jumped a 170 NOVA with an exit weight of about 190#, and made the mistake of testing front riser control. I pulled down to my chin when the canopy instantly folded up and I swung forward and above it. I missed the slack lines as I dropped past the canopy, which reinflated in time for me to land uneventfully. I started about 500 feet, and was back under a good canopy at about 100 feet. I expect things to happen faster on a smaller canopy, but it was quite abrupt on the big one. ============================================
  18. They have a flash video splash page! Pretty awesome if it is 1999 or something,but not now when most browsers are trying to avoid running it at all....
  19. That's fine. Your goal is to be stable. Having an arch just makes it a lot easier to achieve, especially as a novice. The more experience a jumper has, the more they can manage to stay stable despite less stable or unstable body positions. Having the ability to arch more also helps when jumping with others to adjust fall rate. While that can be more of a limitation later, that isn't really much of a concern now. One can adjust fall rate with arms and legs to some degree too. (I didn't check the video though, for any fine tuning of comments.)
  20. Nice post. A few more comments from me on similar subjects, although I have said some of it before: - MARDs: Racers could use one. Almost every company has a MARD now. It has been a slow process since UPT first introduced them in skydiving but soon most jumpers will expect one. -Riggers uncomfortable with adjustable loops: I personally think the worry is overdone. But for those who are concerned: Maybe take a digital photo of the pilot chute cap with the adjustment ends of the reserve closing loop visible, and a ruler? Or record measurements in your own log. Although it isn't absolute proof, one can say, "Well this is where the reserve loop was adjusted after I did the pull force test." How many people bounce with reserve no-pulls (and thus hard pulls) these days anyway? "Jeez, happens to all the other riggers, I don't want to be blamed whenever my Racer customers bounce." And jumpers can screw up other things on a rig you pack, like RSL or Collins lanyard routing. So there's always potential for questions about your work if your customer bounces. Hell, on some rigs if you packed with the closing loop as short as stated in the manual (which some dumb ass lawyer could point to in court), you would have 30+ pound reserve pulls all the time! At least in the old days there were more Reflexes and Teardrops around, also with field-adjustable loops, so any worry by riggers was diluted and not all directed at Jump Shack. - 2 cutters: Unlike HPC I'm not worried about doubling the failure rate. Regular AAD's are pretty reliable so doubling a practically zero number isn't a problem. It's like airplane or rocket engines: Yes, the more engines you add, the more the risk of having an engine blow up. But they put 9 engines on a Falcon 9 first stage because they think they are reliable enough. So this issue depends on whether you trust cutters or not. The loop-not-through-cutter issue shouldn't be a problem on a Racer, as the jumper can inspect that on every pin check. Unlike with most other rigs. - Reserve speedbags: Yeah they seem to work but the market would be way happier with the option for a normal bag. Parachute Labs used to offer either, but don't any more. One thing I don't like is the big loops of line they use when stowing lines on the reserve speedbag. (Photo: https://www.facebook.com/ParachuteLabs/photos/a.275708273406/10154224082248407/?type=3&theater) That has a purpose in that it balances the weight of the lines for when the speedbag is accelerated away from the rig. But big loops of line next to each other just seem to remind me of all the main bag locks that have happened over the years. At least reserves are packed neatly. - Reserve loop replacement They really need a design where one can swap loops out quickly, which includes popping the reserve PC cap off and on. Not spending an hour with needle and tacking cord pretending to be a military rigger from the '60s. - Size of company Indeed a concern. Will anyone step up and take over when John and Nancy retire? I feel they need some entrepreneur who is willing to make a lot of changes, in design, marketing, and general optics, if the brand is to survive in the long term.
  21. Man, what a busy body you are. The thread is about the holding area. You move it down to the pattern. Then you talk about stuff at 300-100 feet. Then you talk about people coming out of their hooks, which could be 50-5 feet. Would you like to divert the discussion to talk about turbulence in the stratosphere too? Winds on Mars? You just spout random stuff about turbulence, thermals, wind shear, whatever. It's more dangerous during a turn! No, it's more dangerous when you come out of a turn! It's all dangerous! Won't somebody think of the children! (Yes there is some sensible stuff hidden in there within the confusing stuff but it's all rather mixed up together and out of any reasonable context.)
  22. The NeXgen actually started to be produced July 1, 2013. (A relevant document was labelled "AERODYNE_NEWSLETTER02_nxgn". I haven't checked whether this is now up on the web at their site.)
  23. I'll expand on what Rob mentioned: Nobody should get hung up on a particular number. Various ones get bandied about. For a typical low speed cambered airfoil in skydiving, at moderately high angle of attack as in typical flight, it might be 80%, but that's just a guess. Based on having done undergrad aero engineering, but not having actually calculated anything for a particular situation & airfoil. (Who knows, maybe 60% is better for an airplane at cruise, which is typically at a fairly low angle of attack, as airplanes tend to cruise much faster than their stall speed, so the wings doesn't have to work as hard to provide enough lift to keep the plane up. Less 'bite' into the air needed.) It may be best just to say "most of the lift comes from the front, upper part of the airfoil", than quoting one number. Since attachments can no longer be uploaded, I'll have to resort to links: https://www.mh-aerotools.de/airfoils/images/velo6.gif A reasonable example would be the airfoil in that link, which is at a moderate angle of attack. The graph shows velocity ratios from front to back on the airfoil, top and bottom, but that basically translates into pressure ratios. That is whether the pressures are higher or lower than the ambient pressure. The difference between the upper and lower lines is the lift. The bottom surface has low speed, higher pressure air, so it does get a 'push' upwards. The top surface has higher speed, low pressure air, especially towards the front. Most of the area between the lines is above the value of v/V=1, so that's the contribution from the upper surface. If the angle of attack goes even higher, then that front upper surface line is even peakier, spiking upwards more. The front of the airfoil is working especially hard, up closer to the stall. All that lift at the front top of the airfoil is why we use airfoils and not just flat surfaces. You can fly a barn door, but there's not nearly as much lift, and there's a ton of drag. Airfoils are the magical way to get a lot of lift for not much drag. (Things are a big different at small scale and low speed, so don't dump on insects for having simple flat wings. Viscosity & Reynolds numbers and all that.) As an example of comparing angles of attack, see: https://i.stack.imgur.com/f7wHm.png It's a bit messy, but shows pressures on top and bottom for three different angles of attack. At low angle of attack the wing isn't 'working hard' so the upper surface isn't providing much lift anyway. As the angle of attack increases, there's some more upward push on the bottom, but a lot of lift is added at the front of the upper surface.
  24. Wings Boost has a metal pin. So which one were you thinking of? (Quite a few variations out there to keep track of...)
  25. That sounds like what I expected. It's hard to know what forces might be set up in the system without a lot of testing. Indeed the red lanyard for the Skyhook system was set up to be a weak link in the chain -- strong enough to work as the MARD almost all of the time but break in case of some weird high force situation. I wonder what the strength of the bungee is. The ultimate strength would likely be largely from the sheath. But there isn't just a particular Mil Spec style bungee out there? If I were building the thing, I'd want careful control of the bungee loop source and material and stitching, so that a bungee good for 200 lbs (or whatever it actually is) didn't get replaced by a low quality one that's good for 100 to 150 lb depending on batch. It does look like the bungee is sewn into the RSL, and not a loose part, so it isn't something a rigger would easily mess up by trying to replace. Mxk's suggested tests sound good to try 'just in case' although I see that you would argue that those situations shouldn't happen: The 'pulling 180 degrees' opposite test would be interesting, although it shouldn't happen unless the MARD somehow hung up on something. Once the rig opens the MARD should be free (or only lightly restrained to a rig flap as many are), so that if one tries to pull the PC end of the bridle back 'against' the MARD, the MARD will just rotate as needed so the folded bridle acting as the pin will always pull straight out of the cloth loops. The 'fold the MARD in half' case is also interesting to test. If the MARD can still disconnect without much force in that situation, then it isn't a problem. Even if disconnect forces went up, some could argue whether a disconnect is needed at all when the RSL is pulling super hard. Normally people expect MARDs to disconnect if there's any light force from the PC end. Yet they also don't want it to disconnect when chopping from some weird vertical-axis spinning mal (ie, helicopter style, not a smooth spiral canopy-on-horizon) just because the PC bounced around while the RSL & main were starting to extract the reserve bag just fine. Is a MARD supposed to disconnect at 0 lbs, or 5 lbs, or is a higher value allowed in cases where it is far less than the RSL end's force? Still, the 'folding MARD' thing could be tested. Even on the ground with a car coming to the end of a long slack rope. Maybe the MARD is light enough that even in the case of an explosive main opening just as a cutaway is performed, giving say a 20g or whatever acceleration to the MARD, it will either not fold the material, or is one of the extreme cases that will break the bungee as the deliberate weak link. I'm just winging it here; thinking through all the possible failure cases of MARDs is tricky.