pchapman

I have collected a big pile of old USPA Parachutist mags back into the 60s, with the help of Beatnik who has a much more complete collection (but isn't on this site much these days I think). But I'm not actively collecting; too much to skim through already and using up basement space! The thing is, some organizations finally got their archives all digitized. Which is amazing; a huge job. To refresh my own memory too: The US "Skydiving" recently went online, back to their start in 1979. (https://skydivingmagazine.org/browse-issues/ ) The Brits have had their issues online for some time, right back to 1964 ("Sport Parachutist", "Skydive the Mag") (https://britishskydiving.org/magazine-archive/ ) Lesser collections: In Canada ("Canpara") we only have the newly created digital issues, so from 2015+. (https://www.cspa.ca/en/digital-issues ) For the USPA "Parachutist" I only know of an unofficial archive of covers. (and occasionally indexes and some other lesser known old skydive mag covers) (http://manifestmaster.com/skydiver/index.html ) A very few old time "Parachutist" magazines have been uploaded in the Facebook Oldschool Skydiving forum, along with some other interesting odds & ends documents from the old days. For those who have joined that private group: (https://www.facebook.com/groups/28649069239/files/ ) Anything I'm missing?

Report back if you find out anything more interesting... I can understand the dilemma. Brake line adjustment could be a quickie fix. For a bigger canopy, being a bit out of spec on lines isn't necessarily black death dangerous. Plenty of people have flown big canopies that were out of trim a long time before anyone ever noticed or a rigger ever checked it. Still there can be a difference between a particular jumper choosing to jump an old officially-out-of-trim canopy, and having it as a club canopy where the assumption of risk & liability situation may be a bit murkier or uncomfortable. Since the canopy otherwise sounds like it is in good condition, maybe that new line set is a good solution. If you or another rigger can build one efficiently, still a relatively cheap way for the club to have a decent canopy, compared to looking for another used canopy.

The safe answer is indeed a new line set. On the other hand, it that worth it for a little-produced, little-known canopy from way back, from a company that doesn't exist any more? (Correct? Flight Concepts became Parachutes Direct which is also gone now?) Otherwise if one wants to test pilot a bit, one could start fiddling with brake settings to affect the opening. Do the brakes need to be set deeper to try to catch air more, like pulling on rears? Although if the lines out of spec are "all over", then it isn't a very consistent situation. (How far is "out of spec" for that company? Is it something that was in the manuals?) I don't like providing simplistic answers, but I kind of think providing your customer with links to facebook and dropzone gear classifieds pages may be appropriate, to find a new used main parachute at an affordable price....

Huh. Just a cheap shot but I'd say: " At Aerodyne, we value tradition and heritage. With the Pilot Classic, we've brought back one of the most memorable features of our former Tempo reserve, and added it to one of our most popular canopies. Straight -- or nearly straight -- through the sewing machine, to our customers!"

I also emailed PD to ask about the discrepancy with manuals vs. data panels, without mentioning any names, just that "some skydivers are talking about this". .... No response in over a week and a half. So they ignore ordinary jumpers too, not just Eric Fradet who is more of a pain in the ass for them! :-)

Those pics Gowler posted were either of a slider pocket that was already to be on a canopy of mine, or a slider pocket I made. (Thanks. I'm not looking up my old slider pocket posts; the question has come up a few times over the years.) The pockets shown are a bit unusual in that they just happen to be 'sewn down' across part of their width, to adjust the 'scoop' and canopy opening. Started with a big pocket; sewed down more as needed to speed up the opening again. The one on my Sabre 1 135, I don't think that one is sewn down at all! Riggerrob makes a good point about a simpler method. Or doing both front and back sails. Doing a 'proper' pocket with binding tape and ZP fabric is a bit of a pain without a proper binder setup. Since I didn't have that at times, sometimes I just sewed the binding tape to one side of the fabric as a faster option compared to actually folding it over the edge. Cruder but faster. The pocket is cut with the folded over part angling wider, when cut on the table (rather than just a big rectangle), so that when folded over it bulges to catch air better. Hope that makes sense to interpret.

Sounds like they don't want to answer except through lawyers in an actual court case! Good luck.

The data panel photo's resolution is too poor to read well. But it looks like there are multiple discrepancies / errors / typos? There's the 220 maximum (vs. 254 in the manual). I would guess the manual is correct because that's been consistent over the years, as has the web site. (I used archive.org to check the website & manual for April 2008, the date of manufacture for that canopy.) And the kg equivalent says 000? Or can't I read that right? And one of the other suggested weight levels don't match either the current manual or the one from April 2008 - the label I think says 149 lbs for Experts, while the 2008 and current manuals both say 169 lb. And the April 2008 website said 159. Of course, those are just recommendations, and not certification limits -- but still it shows some sloppiness in typing numbers in! Shrug. Give PD a call and ask what's the real value. Wonder if they'll have some original TSO paperwork they would actually share, to prove which value is correct for actual certification, 220 or 254. It would be interesting to see what a newer OP-113 says on its data panel... Lawyers like to get picky about all this kind of stuff, even if it is all in the territory of "a heavily loaded reserve and the jumper chose to use either way".

Spare parts availability for Parachute Systems? Someone said spare parts are available from a "ParaCo" in I guess South Africa. This is an image posted recently on one of the facebook rigging sites:

I can only offer this ancient chart, from 2007, from a Vortex dealer back then. (Ranch Pro Shop in NY) It isn't really helpful that the main canopies listed are only out of date canopies from Parachute Systems like the ZP.exe or Hurricane. Something newer must exist... Vortex container sizing.htm

Thanks IJskonijn for the correction. Vigil in the early days did "recommend" yearly pressure checks on the Vigil II's in early manuals but seems to have removed it from the manuals somewhere along the way (for the II, 2+, and Cuatro) as far as I can see in a quick check this morning. So to correct my previous statements: The Vigil does not require any annual pressure comparisons to an altimeter. (Used to, but not for quite some time) (But yeah it sounds like a good idea to do occasionally since it gives a pressure readout) The M2 does require an annual inspection of the entire unit (which logically would be rigger performed) and annual pressure comparison to an altimeter. Technically that inspection also includes checking that the 'altitude lock release' occurs at the appropriate altitude during climb (e.g., 1475 ft) (i.e., center line between the arrows disappears). Which pretty means having the rig in a climbing airplane with someone watching the M2 control unit. Not sure who is doing that regularly! And by altimeter, they mean something like an aviation altimeter with high accuracy. Good luck for the average skydiver being able to figure out how to actually get a reference hPa reading to compare with what the M2 says. The long version of that: There are hPa to mmHg conversions to do here in North America, plus aviation altimeters show the equivalent ISA pressure at sea level and not the current level at airport elevation. But you could set the alti to 29.92 mmHg and get pressure altitude and use an ISA atmosphere chart or formula off the web to convert to actual pressure. (I have seen web sites with Station Pressure for weather stations but then one better be at that weather station, again unless one is great at using ISA tables.) It all gets kind of messy and even as a private pilot I'd have to puzzle through it. Or am I missing some shortcut? Also, in recent years M2 had changed their lifetime from 15 years (their traditional life), to 15.5 years (probably to match Cypres). Just one more thing I noticed. All good with all that? There's always something that changes in manuals....

Yet lets face it, skipping the maintenance - and increasing total lifetime- is what may be saving Cypres. Otherwise, everyone was buying Vigils or M2's. Cypres' 12.5 years and 2 servicings sucked compared to Vigil's 20 years & 1 servicing, or M2's 15 and 0. Cypres' new 15.5 and 0 is competitive, as have been the prices of all 3 models in recent years. 12.5 and 2 servicings made sense when it was the pioneering electronic AAD and everyone was cautious about AAD's, but the market didn't want that king of careful, cautious, expensive approach once there were decent competitors. (And we also had to get past the era in the 2000's & 2010's when everyone was having recalls & service bulletins, Vigil by far the most of all. The real AAD-war era! Cypres was known for its arrogance in denying problems early on; while Vigil had so many service bulletins, they changed their numbering system so you'd forget how many they previously had.) I know there's stuff in Vigil & M2 manuals about mandatory yearly comparisons to aircraft altimeters to confirm accuracy of at least the pressure sensor.... That very few ever talk about.... But what percentage of jumpers actually do those yearly checks? 1%? 5% (Maybe there are some high end full-service rigging shops that'll do it for you? If those exist, good for them.) I still figure Cypres has the edge on quality of algorithms, and that's what I buy, but most rigs out there nowadays in my area have Vigils. Maybe Cypres' are making a come back, I dunno, but I'd expect them to.

Stirring the pot, eh Jerry? Like many sayings, the one about "the simpler, the better" holds true only in some situations. But you know that too, since you know all the tradeoffs that come with things that are engineered. While all the modern add-ons can make rigging more complex, I'm not sure many jumpers would want to keep things simple and ditch AAD's (complex electronics and cutter design!) or even MARDs (despite all their slightly confusing variety and some valid concerns about certain rare situations). Added safety balanced against reliability and of course money. Super strong Navy Conical? Yeah it'll work, but most of us would these days like the tradeoffs that come with complexity. Like ram-air steering since not all DZs are out in big farm fields any more. Or somewhat reduced weight & bulk would be appreciated -- Doesn't have to be quite as bulletproof (or nylon burn proof...) if a diaper keeps opening sequences less messy. And ram-air reserves have kind of proven themselves (even if the spectre of a bag-lock has never been entirely removed). You sure you'd be OK with a terminal Navy Conical opening? We're not all 20 anymore y'know!

Getting aerodynamic principles just right, and explaining them correctly, is quite tricky. There are plenty of ways to explain something that are "sorta kinda right in some circumstances, for the example being given, but not sufficiently correct to really explain most of the possible situations". And this particular discussion has been messed up by one participant not having really good command of the English language. Not his fault, but makes explanations and interpretations even more confusing & sketchy & vague. I'll certainly disagree with Veis on a lot of his aerodynamics. Although I do agree that the Kutta condition or Kutta-Joukowski don't imply that neighbouring air molecules, one going over and one going under an airfoil, need to meet up again at the trailing edge. That just isn't true. So, billvon, I don't think that is a useful part of how to describe lift. I'll wimp out from wading too far into this, as writing a good textbook explanation of lift is hard. But I'd say: 1. Lift comes from pushing air down. [Circulation in other words, if doing Kutta-Joukowski integration around the whole airfoil stuff] Edit: That's simple Newton's laws stuff, or force diagrams. Pushing air down means you have pushed up on the wing. 2. You can do that with a flat plate, the so-called barn door, at some angle of attack, catching the air. No curved airfoil needed. But, it is a very inefficient way to make lift, as there's a ton of drag for the lift being produced. (At the sizes and speeds we are talking about. Things are different at the sizes & speeds of paper airplanes and insects. [Small Reynolds numbers ]) 3. Airfoils happen to be a shape that can make lift, while still being really low drag. Very efficient, that's why we use them. 4. There is some pressure pushing up on the bottom of airfoils if at enough angle of attack. [This gets complex and depends on exact shape & angle] 4. But most of the lift comes from the top: The way air works is that it speeds up and lowers pressure when moving around a gently curved surface. That's where the Bernoulli stuff come into play. That provides most of the lift of an airfoil. 5. But the air can't turn too sudden of a corner. So at too high an angle of attack, the air starts to separate from the surface of the wing and turns into a swirling chaotic mess of waves and vortexes. The airfoil has stalled. Lift starts to decrease* but drag is massively up, so you no longer have an efficient airfoil and your airplane or parachute is probably going to start dropping suddenly (assuming we are talking about roughly horizontal flight), leading to even higher angle of attack and even lousier flying. *[Edit: Duh somehow I said it was still increasing. Which isn't true for a regular airfoil after the stall. What I should have said is that one can have very low aspect ratio aircraft, or aircraft with strakes, or a wingsuit, or something, where there isn't a simple clean stall. Parts of the wing may not be working efficiently, and there's increasing drag, but lift from say vortexes can keep on rising past say 15 degrees to say 40 degrees angle of attack. The concept of "the stall" isn't as clear cut any more.]

Yeah, I don't know all the in's and out's of Kevlar abrasion resistance, in particular how old Kevlar lines got a poor reputation for degrading so quickly. Was it because of Kevlar on Kevlar between lines? Or a lot of flexing with say coarser weave lines? Or the formulation of Kevlar at the time? Certainly Kevlar doesn't tend to get for example the same 'line burns' that spectra or nylon might, being more resistant to heat and that kind of abrasion. (E.g., in Kevlar reinforcement on some kill line bridles.) Kevlar is better in that way.