pchapman

(@ anyone reading, not just the OP:) Nice, he gets 2 swoops in, in opposite directions more or less, before turning around yet again for a respectable final swoop and landing. Skydiving has pretty much the only aerial activity where increasing speed as much as possible before landing, for fun, was the object. It has been a little bizarre in that way. But there are exceptions. I guess hang gliders got into the game some years ago, maybe a decade back, playing with swoops and also doing 'speed gliding' racing runs low to the ground on slopes. Mind you, they'll still have their fatalities, like Chris Mueller, who caught his bar on the ground during a flat land competition of sorts. Not that I'm very in tune at all with what's going on in the HG world nowadays. A small subset of glider pilots (aka sailplane pilots) play the swoop game, the ones returning to the finish line at the end of a major competition. As with the HG video, they may do a swoop at high speed just feet off the ground, downwind, starting a farm field back from the airfield, cross the airfield, then have the energy to pull up, do a teardrop 180 degree turn, and land back upwind normally at the airfield.

Anyone have experience using the wind tunnel as an optional part of a static line or IAD progression system (known as the "gradual" progression programs here in Canada)? A local DZ is looking at the issue because a tunnel will be opening this season 1 1/2 hrs from the DZ, when in the past the closest tunnel was 6 hours away. Everyone talks about tunnel use for the AFF or PFF programs. But then why not offer some way for gradual progression students take advantage of the tunnel too, in a manner integrated with the DZ's system? Someone suggested looking at what points it would be best to have tunnel training, such as at one or more of the following points: - before the first static line jump - before the first 5 sec freefall - before the 15 sec freefall This shouldn't be about whether a tunnel is needed or useful, but how to make it fit with static line and similar systems -- ones where students are normally left on their own to figure out stability.

There was a thread somewhere a while back where some of the issues came up. For example, the FAA allows "parachutists" to fly without being in seats. Then the problem is that an observer is strictly speaking not a parachutist planning to jump, and so wouldn't qualify to sit on the floor... even if observers and others have been seated on the floor in C-182 jump planes from the beginning of time. I don't recall every seeing any statement from the FAA about how far the definition could be stretched for others involved in parachuting related operations, if at all.

If anyone gets the Benny, go for the upgraded liner, just $10 extra I think. Gives one a cloth covering over all the foam rather than just exposed foam that wears relatively quickly. [edited: directed to newbies in general, not the OP who already got his helmet]

Never heard that term around where I am. It appears to be what I've seen called a "flip through" on your 3-rings.

On many canopies at many wing loadings, it isn't that easy to stall it on landing if you have reasonable experience for that type of canopy. We don't have people breaking ankles all the time from folding up their canopy. Landing problems are more likely to occur from not flaring enough, flaring unevenly, or too high or low. I've stalled out accuracy canopies, seen heavily loaded Stilettos fold at the end of the flare, and more. But it isn't a common occurrence, even if jumpers need to learn about the stall point on their canopy. People tend to be saved from stalls during the flare, because normally one is planed out very close to the ground anyway, so an error at the end of the flare has a less bad effect. But if you fully stall out an overloaded Micro Raven or even an accuracy canopy at 10 feet (and miss the tuffet), you might be in trouble. If you are going to stall a canopy on landing, the best time to do so is no earlier than when your feet are 3 inches off the ground and you have already slowed to no more than jogging speed. If someone flared too high, often they end up mushing down to the ground rather than fully stalling the canopy. The canopy may be out of energy to plane out and fly level, and has to start dropping, but often is not actually stalled. Still, that is one time one really doesn't want to stall the canopy. You mentioned the issue of someone being told "to flare all the way down". There may be an issue of language and interpretation involved, as the phrase may in effect have the caveat "...but of course only 'all the way' to the point where the canopy stalls, and not past where it stalls, as anyone educated in canopy flight should know." It's those kind of caveats that sometimes get missed, either by the person speaking or the person listening. A good student training program will include some work on stall practice. The goal may not be to actually stall the student canopy while up high, since that's tough to do, but will at least get the student used to slow canopy flight, signs of a stall, and introduce them to the concept of testing their canopy for the stall point. Whether they can remember that and apply it properly in the future when they start to downsize, that's the next issue...

That would be it. Looks like that's close to the only paper they have available online. I had remembered incorrectly; there are no live links for the papers listed for each AIAA Decelerator Systems conference, recent or not.

The closest I have in digital format is "Ram Air Parachute Design" by Lingard in 1995, at the AIAA Aerodynamic Decelerator Systems Technology Conference. The website for that conference had (when I looked a few years back) a very few of the older conference papers available free, and it included that one. He gave a presentation at some PIA symposium around 1990, based on his 1980s work, so some paper copies of that may exist. Not sure where my copy is at the moment.

It did make it to Incidents already http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4574506;sb=post_latest_reply;so=ASC;forum_view=forum_view_collapsed;;page=unread#unread

Fair enough. But given that you've talked with Karel, is the rule about changing the battery at every repack total B.S.? Or is is the electronics design so crappy that its going to drain the battery in 180 days and fail to power up or fire? That rule was added in near the end of the time where the AAD was fully supported, and it wasn't clear to me whether it really was a problem with the Argus, or it was something that Karel did while flailing around trying to save the situation after all the bad press about cutters. After all, the rule is worded so that even if a jumper has a cutaway the day after a repack, he has to have new batteries again put in the Argus. Sounds like a rule made by a man who wasn't thinking. It really leaves open only 2 possible answers: a) the electronics are terrible for this day and age, or b) it is a useless rule imposed on users by a desperate company, a rule that continues to cost jumpers using the Argus AAD. I do wonder whether that rule is really needed or not. But with that rule being there, I do follow it for my rigging customers. P.M. me if you'd like me to start a new thread to address that issue, if there's a lot you can say about it.

I see lots of people with T-shirts, ball caps, and other clothing that have logos on them, maybe for a company like Nike or a sports team. Maybe ask them how much they get paid for displaying the logo? They give that clothing out free, right?

Dirtbox has a point about someone who jumps a lot -- they likely do it because they are highly immersed in skydiving and like to learn more and do more. He is in effect (in my mind) defending high jump number per year people against the feeling that some are just in it for the jump numbers or are just automatons. Sure, there is always the guy who wants to do 200 Lodi hop and pops to finish qualifying for his tandem rating, or the tandem instructor who does a million tandems but nothing else, and gets bored and takes shortcuts. But they're not all like that. For every example, there can be a counter example. So for the valid case of "500 jumps can take the same number of days at the DZ, whether in 1 or 3 years", one can contrast it to a different example: One guy jumps at a US turbine DZ and puts in 10 jumps a day; another pays 25% more per jump at a Canadian C-182 DZ for 30% less working time in freefall and only 5 jumps a day. Both come out to the DZ just as often, and both feel they are dedicated to the sport and learning all they can. Will the guy with 10 jumps a day be a more skilled skydiver? Sure, most likely. But it is hard to tell how much more 'current' that makes him. Both have spent the same number of days at the DZ. The guy with fewer jumps will resent if he's told he's half as current as the other guy, as if he's half as good or half as dedicated. Even where there are real skill differences, these equity issues can get people riled up when too much is made of differences in currency. So there's one extreme, where number of jumps per year (or just number of jumps) is used as a direct scale for currency. Another extreme is the one where once one is considered current, one is current, and fine distinctions don't matter. The truth not surprisingly is somewhere in between. But I don't have the answer to exactly where.

I don't have answers for your interesting question. But I am curious, are the E-rigs an earlier bailout rig? Current production at Spekon seems to be the RE-5 and SE-5, and are supposed to have a TSO & ETSO (based on C23d). Although earlier versions of their bailout rigs may have a JTSO based on C23b, or even earlier ones may have only German approval. It all looks a bit messy to an outsider. Just curious what rigs are out there, as one doesn't see many European emergency parachutes here in North America, although perhaps some more in the sailplane community. The issue of needle woven vs. traditional shuttle woven webbing is an interesting one. A recent book on fall arrest equipment says, The numbering itself is revealing, as the traditional shuttle woven material is class 1 (i.e. "good"), while the needle woven material that was traditionally not allowed for milspec webbing was class 2 (i.e. "bad"). Bally Ribbon Mills notes that class 1A is ok but still not as good as class 1: DZ.com member "RIGGER" (a rather experienced and technically minded rigger) mentioned in 2008 that (post=3059812) Nevertheless, Bally still says that shuttle woven class 1 has: So in the end: 1. some needle woven webbing is acceptable for military and life saving use, in particular class 1A 2. it sounds like it is still not as resistant to strength loss from abrasion. 3. none of this helps you determine what the standards should be for fraying on the gear in your shop

Lee isn't suggesting using an orphaned non processor controlled AAD with no maintenance, expired pyro, and no approval. He's talking about the design concept of a pin puller mounted right at the pin, like the old Sentinel Micro Puller. I had posted the photo because I also thought that if anyone does question cutters, then at-the-pin pin-pullers ought to be given consideration. A pretty neat little device from Snyder's workshop that I don't think a lot of jumpers ever saw. [Edit: Later I realize that your "how does this fit into it" list of FAA rules wasn't supposed to be countering what Lee wrote about the Micro Puller, as your reply to him first suggested. Instead, you were changing topic to that of the FAA AAD rules for tandems being more specific than for other AADs. Excuse me.]

I sure don't know what the coach was thinking or whether his own fall rate was messed up. Bu one bad jump with one AFF-I and they are all useless? But the way you presented the issue, had the coach been curly haired and Jewish, you might have warned us that one should never jump with curly haired Jewish coaches because those people always screw things up...

Re: fruitloops A slightly more complex prank, which I don't know the name for, goes like in the image below. In words: It starts with the pranker dropping knees and dropping down as for a fruitloop, but instead of going into a stand, continues swinging their leg back up until they straddle the other jumper, and then lets go with their hands. Now the pranker is rodeoing the other jumper from below. Keeping his momentum going, and arching back, the pranker can now continue rotating, flipping the other jumper 180 degrees right on their back. [inline superfruitloop-small.jpg] That prank involves contact with more than normal grip locations and so is in a higher risk range, but still acceptable for anyone who does sit-trains or rodeos. It really does give the pranked jumper a good surprise. (While I like it, between the time I first saw it on video, and actually found the perfect situation to do it to someone, was about 15 years. So I'm not out doing this all the time to novice jumpers.) One more situation to consider with pranks is where the prank is not un-announced, but still not discussed in detail. I've seen a couple cases where coaches did the above prank or a plain fruitloop, to a junior jumper, and the jumper was told to expect some fun stuff later in the dive if learning objectives on the dive are already completed. The pranked jumper may love the prank, but as usual for pranks in this thread, if something goes wrong there would be a lot of finger pointing. In these coach plus novice situations, the pranks have some learning objective (even if one might argue that the justification is weak). The idea is both to break up the monotony of whatever drills they've been working on, and accustom the novice to an unexpected body position. After all, the novice should be at the stage where recoveries from instability are no problem as long as they have a little spare altitude. It would of course be safer to fully pre-announce and fully describe the prank, making it a formal part of the jump. That way if the novice screws it up -- like the example earlier in the thread where a guy tumbled for quite a few seconds before regaining stability -- nobody can say the maneuver wasn't briefed.

It seems not terribly worse than going to a new drop zone where all the ground features are unfamiliar. In the end, you evaluate your altitude and look at your position relative to the 'runway' area you'll be landing on. Having a good horizon and visual cues away from the LZ must be useful but aren't essential. I'll leave it to the professional swoopers to discuss where they are pointing their eyes at all times during a swoop approach. Certainly one might 'back off', when one has to put extra mental effort into the general setup, focusing less (or not at all) on hitting the gate. (I've pretty much only done 180 degree turn swoops when it was dark with cars or lamps illuminating the LZ, and wasn't trying to hit gates.) It may take hundreds of jumps to get the sight picture for the perfect competition swoop, but we're just talking about a swoop, not trying to break the distance world record on your first night swoop.

Well it has been a great thread, a topic not much discussed, with lots for people to think about. Parachutes are finicky than in the 80s, which changes risks on opening. And there are serious issues about what the assumption of risk is on any given jump. If something does go very bad, even when the prank was low risk, the bad thing that happened could be a) blamed on the prank (because it wasn't in 'the plan'), or b) could be considered just an accident (because the prank was within some normal boundaries of risk and playing in the sky with your buddies). Indeed, the jump might be of lower risk than some alternative fully-consensual jump, like some freefly or tracking jump with way too many people of too low a skill. An example of the dilemma is seen in another thread I came across from years back where a participant in this thread told a story of where someone died after a prank. (Since he chose not to bring it up himself here, I won't link to his old post.) A guy was fruit-looped, and had his cutaway handle pulled right out. Fruit-looping isn't that high a risk relative work activity, isn't particularly likely to catch a handle (probably less so than common sit-train exits that are considered acceptable), and cutaway handles get pulled in other ways. Still, it happened, and the jumper (with 1000+ jumps) didn't notice, nor did he catch on what the problem was in time when he pulled. He went in without getting the reserve out.

I'd like to mention that Kotscha's new website location is Freefallsuits.com. The old one at Freefalljump.com is basically the same thing but some of the pages are broken. That site he told me was supposed to have been taken down but somehow was still live. I just talked to him today -- He was still in Toronto after dealing with those couple customer relations issues that had gotten out of hand, bad enough that he felt he had to solve them in person, whatever the cost. I understand that Chris won't push the wingsuits as much for the near future, while he focuses attention on setting up the Eloy-area production facility and perhaps then refine the designs. But he's still very enthused about wingsuiting.

Just curious what people are finding when doing tensile tests on low bulk fabric, which in particular would be PD Optimum reserves. Does one actually find less apparent strain or separation of the fabric weave with the new 'softer' material? The PD reserve manual is common to the Optimum & regular reserve, so there would be no change in tests done. Initial gut reaction is to be wary of 'lighter' fabric but of course the strength is supposed to be similar to regular fabric. Not that they publish specs, unlike for paraglider fabrics. I've only had to do a couple and was wondering what others were seeing.

Since people are talking about how to pull reserve pins, that reminds one of the old Sentinel Micro Puller... so I put up a post in History & Trivia on that. (http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view&post=4573133)

Since there's some interest lately in the idea that pulling the pin might be an option for AADs, I thought I'd mention the old SSE Sentinel. In particular, the "Micro Puller" they had in the last years. (The current thread on the pulling issue is titled "Cutting the loop or pulling the pin?" in Rigging) Traditionally the Sentinel was a cigarette package sized box (containing an aneroid capsule & electronics & adjustment controls) mounted outside the rig, and had had a very large puller assembly. Initially they were attached to a belly mount reserve. The first ones I saw had the puller mounted on the top reserve flap of 2 pin piggyback reserves, where they could interface with the ripcord. The electronics box was typically mounted near the hip on the rig. I can't quite recall how the pullers worked, but I think an electrically actuated pyrotechnic charge forced a piston to move inside a cylinder, with a metal arm sticking out. That arm caught on a cylindrical piece that went over the ripcord, between the two pins was it? Thus it could push on the "V" between one pin and the cable to the next pin? One must have had about 4" of tubes and brackets involved - quite bulky. Later on they had a pin puller assembly with two closed tubes that would fit in the reserve tray, and had a pulling cable much like that on an FXC -- a metal loop on the end would grab the ripcord pin, with a cable going into an armored flexible housing leading inside the pack. Finally in SSE's last years they had the Micro Puller: It didn't appear in the '90 Para-Gear manual, but did in the '93, for example. The Micro Puller was actually pretty neat and nothing like the unwieldy and clunky earlier pullers. No rig modifications were now needed for the puller, although the electronics box still had to be put somewhere. What disadvantages might the Micro Puller have? One PIA publication noted that the Micro Puller wasn't compatible with certain RSL systems, in particular the Vector II style "eye on ripcord & figure 9 RSL pin". Somewhere else there was some bulletin about making sure the pull distance would be sufficient with some ripcord. But it would work with normal ripcords. One might look into any possible friction issues between the puller's moving parts and the lip of the reserve top flap grommet, if it were poorly positioned. But overall I heard no complaints about the system, which was rare overall. Yet a DZ where I jumped, Sentinels with Micro Pullers were somewhat popular in the mid 1990s. The puller was advertised as having a 100 lb pull force, which was achieved with just a very slim firing cylinder in the puller, one much slimmer than the cutters for Cypres' etc. The problem with pullers in general is that if the ripcord is being pulled, they have to push off of something with the same high force, and that has often meant some metal hardware that's bolted to the reserve top flap for rigidity. The Micro Puller instead pushed off of the closing loop itself, so no rig mods were needed for the puller. While I'm happy with loop cutters (when well designed), the Micro Puller was a pretty neat little gadget. Anyone have a better photo of the Micro Puller? I just can't find anything out there.

Best for History & Trivia! The video includes stuff like: - one of the early airplane recovery parachute attempts (something that never took off until decades later) - various barnstorming stunts not involving parachutes - wing walkers wouldn't be wearing them - quite a bit of video of British paratrooper training 'drag off' jumps, deploying from platforms out on the wings of a large Handley Page bomber biplane - some jumps off an aircraft where the jumpers climb down rope ladders (as a stunt I guess), before dropping off and pulling immediately, while unstable

The thing that we're trying to make clear is that if the object (canopy & skydiver) is in equilibrium with the surrounding fluid (the air), there is no "pushing" involved. Just as when one is flying back to the DZ with a tailwind, there is no pushing on the back of the canopy. Like a balloon that's been flying, or a boat in the river current (ignoring air drag from the part above water), there's no push needed because there's no drag. The object and the surrounding fluid are moving together with no pushing and pulling involved. As others point out, when there's a change in the fluid flow, it takes time for the object to adapt to the fluid's flow. A dandelion seed dropped from a bridge will almost instantly conform to the movement of a 10 mph wind, while a base jumper (if there were altitude) would take many seconds to have the wind accelerate the jumper to pretty much the same horizontal speed as the wind. The same applies to a skydiver exiting at 90 mph horizontally in an air mass. Even when there is a sudden change in the fluid flow, like a wind gust, one has to consider the direction in airflow as a whole, using vectors to figure out the actual direction. Say a skydiver is flying 30 mph forwards, and hits a gust that's 10 mph from the side. Maybe it just happened, or maybe he was flying between the tall buildings in Dubai, was in wind shadow behind one, and then came out in the open. The canopy wouldn't feel a 10 mph push from the side. It would feel the vector sum of 30 mph forwards and 10 from the side -- so the wind the canopy feels would be from 18.4 degrees away from straight ahead (if I did the trig right). (For simplicity, we're ignoring descent angle here. Also, gusts usually aren't perfectly 'instant', so there may be some transition time from the one situation to the next.) Only once one understands basics like that, THEN one can get into the questions about how wind from different angles actually affects the flight of a canopy -- such as how easily a gust from the side might tend to roll a wingtip under, or what the directional stability of the canopy is and so how quickly it would tend to turn into the direction of the wind, etc.

Yes, finding aviation weather observations (METARs) and forecasts (TAFs) is the way to go. Cloud heights are also a big part of it. Non aviation general forecasts don't distinguish between 100% cloud at 1000' versus 100% at 15000'. The forecast may unfortunately be for some larger airport nowhere close to where the DZ is, and forecasts can't be perfectly accurate. A particular layer of broken cloud won't necessarily be at all locations in a 100 mile wide area for the entire afternoon, and might dissipate in spots or completely fill in at others. While hanging out at the DZ has its benefits, and one can't jump if one isn't at the DZ, some fore-knowledge of the weather is useful in planning one's visits.