pchapman

I wasn't at PIA 2013 but a friend brought home a few documents including the attached one about two outs by Jim Cowan, a top CRW guy. It looks like a section of a larger document. He gave a talk on "Collisions, Entanglements, and Dual Deployments". The document's value seems to be that it goes into more detail about actually flying two-outs that one usually sees. He also adds the case which is neither biplane or side by side but is "in between", and also adds partial deployment of the 2nd parachute. The document doesn't cover landings.

For better or worse, in Canada the camera rules are less restrictive, so newbie coaches or jumpmasters do get to video their people. Which is a big aid to their work.

(Now I'm just musing since I of course don't have all those years of design experience:) Say that somehow there is an issue with the safety stow getting a little unloaded during the packing process, pulling the grommets towards each other, or everything being compressed into the pack. So then as the bag gets extracted, for whatever reason one bight in the safety stow pops out. Whether it is some inertia thing as you suggest, or some drag of lines scraping in the pack tray, one bight pops out before the bag really starts accelerating away, which will cause the canopy mass to slump down and firmly tension the safety stow. I'm not sure about your scenario but let's assume something like that happens. Then how about going to two safety stows instead of one? Even if that very first bight pops out and unloads the other end of the safety stow, there's a second complete stow that will hold the canopy in the bag. Go to two stows (and a stow pouch) instead of a dozen plus elastics for a full speedbag. That maintains a system close to what the industry is used to but with more protection against accidentally losing that first bight, which with a "safety" stow, then compromises the whole system. (And you avoid riggers cringing when pulling a reserve speedbag across the floor, and have the elastic bands hang up in their little slots, causing 60+ lbs of pressure yank the damn bag off the canopy, squeezing the canopy out of one corner of the bag while the other side remains hung up... Even though your tests all show that at speed, the rapidity of motion causes everything to jiggle free, time after time. I know you keep saying that it always works, and you tested it a million times on main canopies, but it still makes one tend to cringe! I also can't get used to the long stow bights right next to each other on speedbags -- I just think about bights catching each other and causing baglocks. At least on round canopy diapers all those stows next to each other are kept as short as possible. Just saying how I feel, whether or not it reflects any real risks.)

Any comment on the design decisions behind the Infinity's reserve PC, Kelly? For a while it almost seemed that a reduced mesh ratio was seen as something particularly modern, whether on the Vector, Wings, or Infinity. It seemed like a way to start deployment better, by perhaps better catching air if it happened to bounce around in a turbulent burble. But now people are thinking more about the overall drag of pilot chutes, and are wondering if the reduced mesh has now resulted in some pilot chutes that are too "streamlined", with a lower coefficient of drag than they could have. It's easy for skydivers to be critical of manufacturers despite all that the companies accomplish, but respectful discussions on design questions can be interesting. @ John Sherman: At least with the velcro closing the freebag pouch, if one doesn't like the standard solution (and aren't going all the way to a speed bag), one can increase (maybe doubling) the holding effect by folding the velcro over such as on the Wings or Infinity. I think your post also gets into the issue of confusing people by using "line dump" to mean stripping the bag off the canopy as well as dumping the lines, when I think more people now like "line dump" to mean the lines but not full bag strip.

You wondered how to argue things. If one were supporting free interchange of components I would argue it this way about AC 105: (I'm not saying this is the truth, but just that this is a way one would argue it!) a) In the part not quoted above, the FAA says you "should" follow manufacturers' instructions, not "shall". So it is wise to take them to heed, but not mandatory. b) The assembly of a reserve pilot chute can indeed be done according to the manufacturer's instructions (as stated in the quote above): It may not be the type they want, but they may write in their manual, "Assembly: Lark's head the reserve pilot chute to the freebag bridle. Ensure knot is pulled tight." Voila, that's how you assemble a new pilot chute, you've followed their instructions!

How many skydivers' belts do they allow?

As people have noted, every place is different. Plenty of dropzones don't exactly follow some tandem manufacturers' very strict rules, but many follow the spirit of the rules: Unless both the TI and the DZO know that you are a completely competent belly flier / relative work jumper, well past being a newbie, you are unlikely to get to jump with a tandem.

Same PC as a Vector II.

Regarding this case: Well, at least it is an argument not to follow too closely. Seems I've had this sort of little difference in philosophy in another thread lately

Speaking of which, ahem, what is "bridging"? Never heard that term before. Doesn't show up in a search of Gear & Rigging. Hope it is a regional term.

Now this is diverging into BASE packing, but you never pack with the steering lines outside the slider if using the slider (ie, slider up). In this case, it looked like the steering lines went through the slider, in which case, you never pack with the lines outside the guide rings. Unless there's some new or advanced trick I'm unaware of, that's traditional BASE packing rules. It would somewhat defeat the purpose, if one tried to fly with brakes free of the risers, but still constrained by the slider. Unless one also planned to push the toggles up through the slider rings after opening to free them, and be careful not to let go of one while fiddling with the other, in order to get a feel for the canopy as it would be for slider off.... I haven't looked closely enough at the video to try to figure out to what degree the brake might have released due to bad packing, or due to knocking it out with his hand, or some combination thereof. In any case it was still a jump with "high learning potential".

Fair enough on the following gear - people still have to stay safe and within their own skill level given the terrain around. It's sort of glass half empty or half full. I say follow (unless you're afraid of hurting yourself), others might say don't follow (unless you're sure you'll be fine.) Now, I'm actually pretty tolerant of jumpers' decisions as long as everyone makes it down safe. Maybe he just jumped the canopy because it was fun to try something new, and he might not even have packed it himself. But for the purpose of a little internet humor, it does seem funny that Mr Maybe Soon to be Badass BASE Jumper mals the BASE canopy, is sub-optimal in emergency procedures, in over 2 minutes under reserve seems to barely if at all look around to see where the nice vented BASE canopy has drifted (which belongs to his buddy according to the youtube description), and overshoots the target, not exactly demonstrating highly tuned, split-second BASE skills... As for off-landings, hell I've screwed one up when chasing someone's freebag too low, taking a small crossbrace downwind into tall grass and dodging shrubs...

The amusing part is that he's jumping a BASE canopy (in a skydiving rig - a Racer it appears FWIW when it comes to RSL arguments), and on opening one toggle shoots up into the lines, with the brake line not even through the guide ring. And he's jumping slider up. So the brake setting is entirely incorrect. Bad packing, bad position at the cutaway, didn't follow his chopped gear, overshot landing area, fell over on landing. On the plus side, he did have sufficient altitude for his flailing, and kindly wore a GoPro for our benefit. And I bet he learned a whole lot.

Summary: Femur, ankle broken after lost toggle. 1.1 wing loading. Non accelerated landing. 2 fingers in toggle, thumb wrapped. (So it wasn't even an "on top of toggle" grip.) I'd say the lesson is only to not let go. If you can't hold on to a grip that requires holding on, don't do it. Even 4 fingers in the toggle will be the same, if the hand isn't jammed far into the toggle, say just with the first 2 finger segments in the toggle. If you get distracted and relax muscle tension, the hand can fall out. And that's one fairly common way to hold a toggle. The further the toggle is on the hand, the harder it is to slip out. Just the first 2 segments of the fingers, or past the knuckles, or even past the thumb all the way down to the wrist. There are some variations in hand angle that could be relevant too. It would be interesting for newer jumpers to see photos of different techniques...

Looks perfectly fine unless you let go. Takes a little more muscle power perhaps than having all fingers inside the loop, I'll grant you that... Actually, it is a real "toggle grip", as one would have with a wooden toggle on an some old round canopies or some Para Foils.

You are right, I didn't know what cells the brake lines attach to on the Megafly. Just that it uses splits. But I guess that is more for modularity in construction. So here are some concrete examples: For example, in a photo that can be enlarged on this page, http://www.defenseindustrydaily.com/jpads-making-precision-airdrop-a-reality-0678/, the related Gigafly ties the split trailing edge together and has brake lines that attach at points apparently unrelated to the evenly spaced split point. This appears shows something similar on the Megafly http://www.google.com/imgres?hl=en&tbm=isch&tbnid=eqcqDpkZLpjmKM%3A&imgrefurl=https%3A%2F%2Finfo.aiaa.org%2Ftac%2FAASG%2FADSTC%2FPhotos%2520and%2520Images%2FPATCAD%25202009&docid=sMkinCuaBKO8bM&imgurl=https%3A%2F%2Finfo.aiaa.org%2Ftac%2FAASG%2FADSTC%2FPhotos%252520and%252520Images%2FPATCAD%2525202009%2FTwo%252520Megaflies%252520in%252520Flight.JPG&w=1950&h=1601&ei=iFYwU6mlCpTOyAHJhoD4DQ&zoom=1&ved=0CHUQhBwwCw&iact=rc&dur=2766&page=1&start=0&ndsp=43

To follow up on piisfish: - modern huge cargo chute experiment Para-Flite Megafly http://defense-update.com/products/m/megafly.htm - old sport chute Para-Sled http://www.parachutehistory.com/ramair/parasled.html (Hard to see the split at the center of the trailing edge on the photo)

Oops! Hadn't noticed that! Bizarre, I've never seen a list like that before in a manual. Current version is from 2009, so it isn't like it was written before Icons existed. But, as a plus for the manual, at least it says you can check with them if your rig isn't listed...

So we still are left with this idea in our heads: - PD's are fine at high loadings (with some skill and if uninjured). After all, plenty of people were jumping PD-126's by the late 1990s, who weighed over the recommended 176 lb limit even without gear. - The manufacturer of Speed 2000's still absolutely prohibits loading their canopy higher. Without being in a community where the Speed's are used, there's no way of knowing that that prohibition may not have to be taken that seriously. I don't think it is about personal responsibility in this case, given the way the statements in the manual are worded. If one wanted personal responsibility, one could have worded it to allow for some. That's probably enough from me on this matter; I've stated my opinion. In the end, whether a skydiving product sells well in a particular market will depend a lot on having dealers that are reasonably close and other jumpers using the same equipment. Gruesse aus Kanada!

The problem is how the manuals are worded. The PD manual puts it all in a table where you can see, for example, the OP-126 is good to 176 lbs for an 'expert', but the max is '254'. While there are all sorts of warnings, it is clear what the maximum is. In the Speed 2000 manual (at least the one I have), shows similar weights: The Speed 135 is certified to 115 kg (254 lb) and an MSW of 176 lbs. But right above the 176 it says in huge letters "NEVER EXCEED THE LIMITS LISTED BELOW" and that this Maximum Suspended Weight is to "ASSURE SAFE FLIGHT AND LANDING CHARACTERISTICS". Jumpers in North America are familiar with PD equipment, and that they can often be loaded above their recommended level. But for those of us who don't see Speeds used, or read about them on dz.com, all we would have is the manual. And the manual is very clear on never exceeding 176 lb. So that puts the canopy into a category like some ancient, crappy reserve designed in the early 1980s. Maybe it'll be like an overloaded MicroRaven that'll smack you on landing unless you're really careful. That's what I'd think only reading the manual; sounds like a crappy canopy. So their wording could be better.

Note that there isn't just one Terminal Velocity. You are at terminal velocity if in that particular steady body position you are not changing speed. So it might be 120 mph on your belly or 145 mph in sit, plus some increase with altitude due to reduced air density.

No. It’s unfortunate that your ignorance to the natural world impedes your ability to grasp such a concept. I find it amusing that you statement above starts with, intuitively; when clearly we are discussing a counter-intuitive concept. If you have value to add to this conversation please do. Otherwise, I suspect this will be my last engagement with a troll the likes of you. Joellercoaster is correct: No. (I'll emulate his succinct style this time and leave it at that.)

This post digresses from the -1g environment of head down skydiving so isn't relevant except to discuss negative G in general. While I have no professional physiology training, I've been a little bit in touch with aerobatics and acceleration research for many years, so can debate this all day. So excuse me if I go a bit overboard in my response.

Ok, so let's play the guessing game. Vector 3 with those super big tuck tabs?? [edit - yeah, you posted that before I got this post done] And risers packed under them. Bill Booth likes magnets, perhaps partially because he built the rig with the biggest tuck tabs in the industry for many years. So the right riser departs, and since it was said you have a Skyhook, that right riser is trying to pull the reserve pin. But it doesn't, maybe because of luck and that there's a shit load of velcro built into that RSL/Skyhook design. If it had pulled the RSL off the velcro, the Collins lanyard would be cutting you away on the left side. Great idea normally, but useless to you since you had already pulled out the cutaway cable. So the RSL/Skyhook might have been close to dumping your reserve while still connected to the main. Although in the end that's what you had to do anyway. I've done an intentional cutaway where I chopped one side first, and the resultant spin was pretty impressive -- 360 degrees a second even with a 200 sq ft F-111 canopy. You must not have been having fun! (As for your no crying comment, that's better than the character Sandra Bullock played in the movie Gravity. That character got so terribly whiny and screamy every time she thought she was about to die. )

Having blood rush to one's head doesn't make one faint. It might be uncomfortable and distracting but there's no fainting involved, which is normally about lack of blood flow. Adding multiple negative G's is tough, and aerobatic pilots have to acclimatize themselves to it, but negative G on its own doesn't cause fainting. Kids can hang upside down from monkey bars in the playground, and they don't all faint and fall. If one doesn't notice something in freefall it would be because one is really focused on other things -- just like there are times when one hardly notices the wind noise (or one's dirt alert...) in freefall. The 'red head' comment is interesting. Don't know to what degree that applies. Just guessing, but possibly body movement in freefall or tunnel helps promote circulation and reducing blood pooling. And like manseman said, if one is doing a hand stand, especially if not used to doing it a lot, the high muscle tension may cause one to increase pressure in the head too, just when one should be relaxing as much as possible to avoid adding blood pressure at the head.