mathrick

The PD reserve manual linked earlier in the thread specifically addresses this question: if there are any unknowns in the canopy's history or reasons to suspect it has incomplete history, you must do complete permeability testing (ie. send it to PD for factory inspection). This is because visual testing is not sufficient to establish the critical parameters of the fabric, without which the reserve is unsafe. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Oh man, that sure is some hardcore taildragging action there. Taxiing this thing must've been an interesting experience. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Because it can result in tension knots, which can give you anything from a spinner on opening, to a sudden blocked toggle during flare, turning it into a low hook turn. It also shortens the brake lines, effectively putting them out of trim. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

I bought a packboy very early when I was learning to pack, and used it, then around the time I had 30-40 packjobs, I stopped and went back to pull-up cords. I found packboys much easier to lose (mostly because there aren't a million of them always strewn around the packing floor), I can't stuff it in my leg strap like I can with a cord, and I actually find it easier to use a cord than to thread the metal rod through the grommets without letting the spectra loop slip; it just seems to require more careful concentration to get it through successfully. But I imagine I'd judge the balance differently if I had to pack all day; I only pack for myself and occasionally some student canopies, so a "heavy pack day" is maybe 15 jobs for me. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

What is the cost of having them, other than the monetary cost when ordering a new rig? @Ken: you always have to cut the existing rings, unless detachable ones were factory installed, but I don't think that has ever been the case on any rig? That was also the true of RW-6; installation instructions had much more on cutting the old rings than installing the new ones. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Altitude in ft, descent rate in mph. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

This is very impressive level of customer service, but wouldn't manufacturing detachable rings like UPT did with RW-6 be a cheaper and ultimately less painful option for everyone involved? "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

The elongation problem has led to at least one impossible cutaway followed by main-reserve entanglement. I don't see how that is "not catastrophic" or better than it breaking. The affected part has completely failed to perform its critical function. That is a catastrophic failure if you ask me. What new things exactly does hardware breaking under load introduce that weren't present before in manufacturing and testing? Sure it's a new *instance* that hasn't been seen precisely in that form before, but it is of the same class as previous ones. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Because generally gluing things down with a resin-type substance makes it hard to rotate them? I don't quite see how you'd work around that. I'm not familiar with the specific Contour mount you're referring to, so I have no idea how it managed to make the camera able to rotate around an axis while having gaps pluggable by polymorph. The only way I see is to have an internal point-attached mount covered externally by an enclosed fairing, but that's way more complex even than my idea. The mounting plate doesn't rotate with with the visor when it goes up and down, but it is adjustable if you loosen the hex bolt in the middle. That's how the helmet is constructed, and the washer is specifically intended as an attachment point; the other side doesn't have mounting holes drilled (though you can swap them freely). "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Have you actually looked at the helmet? It's not possible if I use the mounting washer plate; all the moving parts are right there and there's simply no way to make it sit flush. I could make a permanent fairing if I mounted it on the audible cover sitting below. In that case, I'd have to add 2-3cm of spacing between the shell and the camera to reduce the amount of visor caught in the FOV to acceptable levels, but that opens me to riser strikes and I don't know enough to know if I should be worried about those. It'd also make the whole thing fixed and not removable ever, and make angle adjustments difficult to impossible. All things you can live with, I suppose; people have jumped with cameras 3x the size side-mounted, but I just don't know that it's obviously a better solution than dicking around with a breakaway mount. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Not possible because of how Rev2 is shaped and operates and the fact it's a side mount. The camera also has to be offset forward a bit from the mounting plate to avoid having a large portion of the FOV obscured by the visor, which presents extra snag and pinch points. A fairing is possible to prevent lines flying back to front (as seen by the helmet) from catching onto things, but front to back, as well as bottom to top (think PC catching onto your wrist and releasing just as your hand is close to your face) will always have a chance of getting jammed between the visor and the camera. Making the camera sit completely flush with the shell is impossible due to the fact the whole front hinges up and down. If you take a look at Rev2's product page, you can see the mounting plate -- it's the round washer with three mounting holes. It doesn't rotate together with the visor, so it always stays in the same orientation. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Heh, I only have experience with Lodi's Otter(s), so very limited, but I was shocked at how loud it was. It's every bit as bad as the Skyvan, except it holds for the whole plane, and not just the section near the cockpit. I'm absolutely going to invest in hearing protection now, I just need to figure out what brand blocks out enough engine noise without also making other people and my dytter inaudible. As for jumprun speed, I've heard much about how good Otters are because you can feather the left propeller during exit, but for the few jumps I've on it, that didn't seem to be the case, so it had rather noticeable blast. And horribly, horribly windy during boarding, I've never had to pull down my visor for that before Otter. Skyvans seem to vary hugely between individual units, depending on what they're fitted with. They're never not loud, but they seem to go anywhere from "loud" to "please make it stop". Ditto climbing speed, some are slow, other can get to altitude in little over 10 min. Definitely lots of fun exiting, as long as you're not in the floater position :) Their substantial jumprun speed and sudden onset of the relative wind seem to make it rather tricky to do a good floater without at least some tumbling for jumpers who don't jump Skyvans regularly enough to learn their quirks. My hop'n'pops were always a gamble with a Skyvan. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Indeed, my earlier attempts at a design had that, and the helmet has a built-in cutaway too. But manual release systems require composure, mental power, time, and not having a snapped neck to activate; all precious commodities when you're busy entangling with your last remaining canopy. So I'm trying to make it release on its own, since I cannot completely prevent snags, given the shape of the camera and the helmet. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

G3 is G2 with redesigned mouth grill to reduce fogging. Everything else is, AFAIK, not related to the model, but rather to the particular unit's DOM. Early G2's and G3's came in carbon fibre, later ones switched to moulded ABS, without the model designation changing. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

That was a Navajo. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Aye, doing it with plastic latches is another idea I've considered since. I'm not targetting any helmets other than my own, so I will make it extremely specific to the Rev2 attachment point and shell shape. It won't be cast plastic (I'm not doing big runs, just my own individual fabrication), but I have access to 3D printing which will hopefully be repeatable enough. @Andreas, Terry: thanks, will give it a look. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

In pretty much all the non-student rigs I've seen, the reserve is smaller until you hit about 100sqft. For student rigs, it's 50/50, depending on how big the main is (our student rigs all have 240 reserves, whilst main is either 260 or 240). You generally want it slightly smaller, for two-out handling(*). My own (second-hand) rig is 170/147, and it was completed for me by an instructor and a master rigger. 190/160 sounds like it should be about the same ratio, though you will obviously still want to run it through a competent adult before committing to anything. (*) Based on PD's tests, it's really a function of line length, rather than area as such. Smaller wings tend to have shorter lines, though it's not impossible to find a combination of main/reserve where the smaller reserve will have longer lines. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

I know some happy 120 WS users, at least one is Spectre (along with a 135 Sabre 2, of all things, although I believe Spectre was bought as the WS-specific replacement for Sabre 2). Also a Storm (though that one might be 135, I can't recall now). As for the Optimum, PD have many demo reserves to be hooked up as mains that they ship out regularly, so it's not exactly an unknown for them. I can't imagine they'd have many qualms about selling you one, at least if you satisfied them that you're going to be wingsuiting seriously. Otherwise I can see how they'd want to avoid potential hassle down the line when someone complains about durability. But there's already a WS-specific F111 7-cell (Squirrel Epicene), so WS folk are already willing to make sacrifices to get more reliable openings. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

I'm sorry, I didn't mean to suggest that this was not planned and prepared ahead of time. I'm sure it works 9 times out of 10, probably also 99 out 100. The "blind luck" isn't in reference to "these people randomly jumped out of a plane and it just so happened that they did the most impressive CF". Of course it's all thanks to their immense skill and massive amounts of practice that they got back to earth in one piece and after doing everything they set out to do. The "blind luck" is in reference to the fact that it appears to be planned for the best case, rather than the worst case. Most of the time the best scenario is what happens and everything is well, but if anything doesn't go as planned (and it doesn't, it's skydiving after all), it's pretty much guaranteed to turn even the smallest emergency into a feedback loop rapidly leading to the worst possible outcome. A wrap in a 16-way CF is a scary enough proposition in even the most straightforward configuration, but by making sure you have the experience and skill to handle the jump itself, and by having a plan for every imaginable scenario and minimising the risks taken, you can deal with almost all malfunctions and come out unscathed. Even then it might just not be your lucky day, which is why CF is considered more dangerous than regular skydiving, which is more dangerous than not jumping out of planes at all, but by anticipating the malfunctions and planning for them you can manage the risk and bring it down to acceptable levels. Now, how do you plan to deal with a 3-person spinning wrap, 2 of whom have industrial-strength sparklers attached? What's your EP for being covered in melting nylon? How about the bottom jumper getting into a spin and sending exploding fire rockets all over the place into the middle of the formation? How do you react to your harness being cut through with burning magnesium? Try going through the most trivial, expected types of CF malfunctions and counting the ones that don't end up as likely multiple fatalities on this jump. A similar kind of thing, this time with a less happy outcome, was this funeral service demo jump injury (@ 13m33s). Does that mean these demo jumpers are not very qualified, hard-practicing jumpers? Nothing of the sort. Do I think this was an entirely preventable injury which had nothing to do with a random fluke and everything with indefensible, poor planning which could and should have foreseen this happening? Absolutely. And, as much as a single data point is not statistics and the plural of anecdote is not data, I don't think it's entirely coincidental that it happened during the funeral service for a Golden Knight killed during a demo jump a week earlier. Unfortunately, Denmark has pretty much no CF happening at all, and I haven't found a DZ to call home yet in the US, so I have never been and it won't be very soon I am at a CF briefing. So maybe there are very good plans for the situations I mentioned and they're all amply prepared to deal with those and more. In that case, I'll be very happy to stand corrected. But I think of CF as of any other kind of skydiving, just more complicated with more to go wrong, and the basic rule of surviving in the skydiving I've been taught is that you assume, for every single jump, that everything that can possibly go wrong will, and plan for that. And from this perspective and my knowledge of the gear involved, I see a jump with no kind of plan other than "we'll just hope it won't go wrong". And no matter how badass you are, if you do that, sooner or later you will lose big time. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Holy crap, that's insane. This is the kind of shit that looks super cool when it goes right, and turns into a massive, spiralling out of control clusterfuck with multiple fatalities when anything doesn't go exactly as planned. Blind luck that it worked out; I don't think it should've been attempted and I don't think the person(s) who planned and agreed to doing it have acted responsibly. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Right, the things you learn after you make a public post on the 'tubes. It also has the property of getting stronger with higher humidity, which is rather less than optimal. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

@Jerry: the MIL-T-5661 is specifically specced to have both minimum and maximum breaking strength at 80lbs with very close tolerances. It's used for static line applications, where you need to ensure that the attachment point will hold and lift your D-bag, but will break once under load. @peter: yeah, those are the considerations. I wanted a to-spec cord precisely because you never really know otherwise. It's also a problem with the nylon bolts, because almost none of the ones I've seen in retail are rated for specific forces and what you get is essentially a crapshot, with much higher shear strengths than people imagine to begin with, even for rated components. But yeah, nylon screws are another angle I'm approaching it from. The mount is meant to be a side-mount for a small sony cam on my Rev2. The idea I'm sitting with at the moment is a pair of slightly concave (exaggerated in the drawings) circular pads, bound together in the middle with the break cord (red line). [inline camera-front.jpg][inline camera-side.jpg] The hope is that such a configuration would create mostly uniform leverage regardless of the direction of the pull. The lighter coloured gray bumps in side view are for locking together the pads without twisting and sliding. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

I'm looking for ways to create a self-detaching camera mount that will be stable and secure in normal conditions, yet will reliably be ripped off should it ever entangle with any part of the deployment system. One of the ideas I'm considering is based on the use of break cords, as they're designed to do exactly that. It might be a total dud, which I won't know without some testing, however I've run into an unexpected difficulty when trying to get some for playing with. The only type I can find anywhere is the 80lbs MIL-T-5661, as sold and used for BASE static line attachments. But going by the ballpark figure of the PC pull force of 75lbs (there's a huge variability in reported and calculated values for different PCs and freefall times, so I might just as well pick Bill's guideline value of 75lbs), it won't be strong enough to break the cord, and even if I were to go by the much larger figures of 160+lbs at terminal speeds, it would definitely lead to significant delays on slow deployments (ie. cutaway and reserve extraction). The value that would seem more reasonable is in the 30-50lbs range. But it's not just that I have difficulty locating retailers, I can't even find any references to any grade of break cord other than the 80lbs ever existing. Am I just blind and can't search? Are they called something else than break cord/tape when not sold by BASE stores? Are there any other similar materials with close tolerances for their breaking strength that could be used? "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

Somewhat tangential, but I've heard that ZP is not commonly chosen for PCs because it tends to be significantly less forgiving of inexact PC geometry. Is that (still?) true? "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."

How though? It's not obvious, and you asserting so doesn't make it any more obvious to people who didn't get it before. "Skydivers are highly emotional people. They get all excited about their magical black box full of mysterious life saving forces."