pchapman

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.

To humbly expand a bit on Mark's statement: The wear & abrasion (to itself) issue was the big problem that people talked about. It was all a bit before my time, but Kevlar didn't work out on main canopies, while it was used on a few early ram air reserves, where the frequency of packing was less. (As the OP may know, but I'm just giving a bit of history.) It also was used for a while for high strength reinforcements -- Like reinforcement circumferential bands on lightweight National Phantom round reserves, or being used as reinforcement tapes in ram-air reserves, or being used as the reserve closing loop for the then-popular Racer rigs. I guess it was the first 'extra strength' material out there in use! Kevlar is "an HMA", a high modulus aramid, but must be formulated & woven in a different manner than our current HMA lines which last better. (Although clearly they have their wear issues too, if made really skinny...) So Kevlar had a real wear problem. While for the other things Mark mentions, it was more a case of "being ahead of its time" rather than being inherently deficient -- We didn't all have stainless grommets to resist abrasion, and canopy designs & packing techniques weren't ready either. Just like the early days of Microline / Spectra, where there were more problems with instant openings, broken risers, too small sliders, etc. Thus part of the whole problem was the changes in rigging technique & design needed, for the new material. Here's an example from a 1980 [Edit: corrected. Not '85] CSPA rigger's bulletin, where they quote GQ Security (which produced the Unit ram-air canopy, some of which had Kevlar lines) on some of the pitfalls for riggers to watch for:

Of all the copied media out there, I don't think this is very high on the list for tracking down those sharing it. But it does beg the question: (which might be answered in some other Lone Star thread somewhere) Who is behind Parakit Inc., of Georgetown Texas, who copyrighted the Lone Star manual in 1985? Are they still around? Or are relatives still selling the manual or hanging on to it to sell for millions down the road? I'm guessing not. Reference - link from a friend - it's on the Internet Archive! -- https://archive.org/details/lone-star-parachute-assembly-kit-scanned-manual Sure has some good practical detail on building a canopy, even if an old fashioned one.

Here's what I have, data from about 30 years back when I was new to the sport and a bit obsessed with collecting data and understanding the sport. 1. Two pages from I guess the Italian skydiving magazine in 1992 listing the early tandem fatalities in order. (Apparently there was also one on a European Galaxy rig sometime in that era, that isn't in those stats.) First tandem fatality is shown as the one with one snap not done up, TI spent entire jump trying to hook it up, without deploying anything (even the drogue). 2. An html file from UPT listing tandem fatalities and causes in order (but with no dates). From 2008, back when they listed that on their web site. 3. Scribbled pencil notes of mine from the early 1990s, where I listed a bit of the evolution of tandems (eg the date when Strong & Booth got their FAA exemptions to allow tandems), plus all the early fatalities and dates. I think most of the data on dates comes from an article in Parachutist,July 1989. (Which I can't find at the moment.) That list puts that first tandem fatality -- with the snap not done up -- as Oct 19, 1986. Back in those days people were wondering what the heck was going on with Vector tandems, as in the first dozen fatal accidents, there were 10 on Vectors, and 1 on a Galaxy, before there was 1 was a Strong Dual Hawk. There sure were a lot of different causes of accidents -- Stupid stuff we're not allowed to do with tandems now, main bags that much more easily came out of the container early, plus a lot more casual training and attitudes towards tandems. Which brought in the idea that 'it isn't just another skydive'. It also took a while to come up with the first tandem CYPRES, and eventually the idea of making one mandatory for tandems. (Wish I had the dates for those.) RWS tandem fatality list as of Feb08.htm

I had a look at the manuals to familiarize myself with them. Basically in line with what Jerry is saying, - the earlier Peregrine Glide has a semi-exposed RPC - the newer Peregrine Falkyn had a covered RPC

Here's all mine. (Did you get yourself a 'dactyl?) Paradactyl Manual (slightly expanded version).pdf Paradactyl - shorter Guardian manual [P Chapman scan from M Stevens copy].pdf Paradactyl manual (DactylManual)[M Stevens scan].pdf

A tip -- If you can turn off Javascript and refresh, most WaPo articles can be viewed. (Depending on the browser & operating system, that can be very longwinded to do, or easy to do with some browser extension.)

From BasicOne's posts, I get the idea that the M2 cutters are like this: a) The old ones had the "flat plate plunger" design that shears the loop at both cutter holes. Something not at all known to the public before, I think. Quite a different design. b) Then I guess after Airtec/CYPRES' patent expired on single blade cutters, newer cutters use a single blade like a Cypres. That the kind BasicOne did tests on, using 2019+ M2 cutters, and was concerned with the amount of damage to the cutting edge after firing.

Boy this brings back memories of the AAD wars from a decade or more ago! As far as I recall, this is how I'd put this into context compared to the other AAD companies: Cypres always had the hardest, best cutting cutters. Vigil has the circular cutters (effectively 2 blades), that they tout as being a good concept, but have come under some criticism, even though they generally do the job. (eg, one serious critique in "What's going on with AAD's" by Kirk Smith, 2011) Argus had serious cutter issues. They also used circular cutters. (I got the impression that was due more to a Cypres patent in the early days?) Most issues were actually with their older style cutters, before upgrades in hardness & manufacture, but in any case the tide turned against the company and their AAD's are pretty much irrelevant now. Mars M2.... don't recall hearing of cutter issues before (for actual cutting), but never saw any engineering data on their cutter hardness. (There was one accident relating to their very old MPAAD design, not the M2.) Someone should ask Mars about their M2 cutter hardness. That's just one measure of goodness, but a decent one. I would still have to dig up info on other designs, to see what metal hardness values were found for other companies. .......Hmm, here's something I had on the Argus vs. others: (My interpretations of the Polish report on the fatality there in 2009 that involved the Argus.) So, I wonder what an M2 cutter is like. Great testing by the original poster, BasicOne, thanks, but I'd like to see independent confirmation too! [Edit:] After all, the M2 has been reasonably popular in recent years too, and surely cutting loops successfully, even if not out there in number like Vigils and Cypres'.

Sorry, can't be true. I don't know anything about what may have gone on in the background, but the canopies are very different. Excalibur wasn't tapered -- Adding taper was a huge change in canopy design complexity! Excalibur had different nose inlet shapes. Different standard sizes. The Precision built FX's were of course licenced from Icarus in NZ. Maybe that's what you were thinking of? (I still fly an FX but don't know all the history from back then!)

Space X uses Pioneer drogue parachutes for the return of their Dragon spacecraft. (But Airborne Systems provides their main parachutes.) High speed parachute design is a specialized thing, so even Space X didn't do it in house. Still got my Pioneer Titan canopy, though it has been a decade since I used it at Bridge Day... Will be interesting to see what happens to Strong.

Interesting. How much of an issue is this in practice? I don't know, but I see the EG18X smoke grenade is on the list as no longer exempted. Its baby brother -- with less smoke volume -- is the EG18, isn't mentioned, so that one is still OK without the extra regulations. I have used the EG18X on demos. A pretty decent grenade for that use, at a reasonable price. Some years back they seemed to be the best I would see available. But in recent years there are pricier grenades out there with higher performance. So I don't know what high end, well sponsored teams use. But for smaller demos, the EG18X's were nice to have. So it kind of looks like the higher end, better stuff, is getting more regulation.

Since this 2018 thread was revived: It is interesting to consider the "two ways to double stow" issue that sundevil777 brought up after Westerly's observations. To recap, there's the "wrap around twice like wrapping it with tape" , and there's "make a single stow, stretch the elastic, make a half twist to create a new 2nd loop, and put that over the line bight". One sees the first method, for example, in one PD tips youtube video. I confirmed that both methods are equivalent topologically in the sense that the final result can be changed from one to the other while the elastic is in place on the lines. If you try it, you can look down at the line bight in its double stow, and move one loop of the elastic over a little and be back to the first instead of the 2nd configuration. Like sundevil said, there's technically no actual knot created. But the 'twist 180' method does seem a more secure or little more grabby, as there's more rubber band overlapping other parts of the rubber band. Whether there's any significant effect on line deployment in practice, who knows. So far I'm not worried about which method I use. I also tend to do the twist 180 method. Which one does will depend on what one is used to , but perhaps also likely on how tight the elastics are when trying to wrap the bights. The simple wrapping method works better for me if there's a lot of stretch in the elastic relative to the position of the lines needing to be stowed. As for Westerly's elastic breakage issue: I may not be imagining correctly what Westerly did. I'm not sure if he meant putting in the 180 twist, or even adding another 180 on top of that, which does change things and make it impossible to simply slide the elastics around once in place on the line bight, to change to the other configurations. That might in effect be 'tighter' and put more stress on the elastic when the bight gets yanked out of it.

Lines out of trim. (If they are the kind that go out of trim. Any Spectra in there,as main lines or brake lines?)

Still F-111 if I recall correctly. An invention a little ahead of its time, just waiting for ZP to arrive...