pchapman

You might have been thinking of a specific situation. Like a C-182 with the door closed. Or another jump plane where the jumpers closed the door before the plane descended. It's only particularly hazardous with an open door and jumpers nearby. Whether it is dangerous or not depends completely on the situation.

Interesting how things differ in different places. I had never ever heard anyone talk about cleaning housings routinely, in over 20 years either with local riggers or the occasional rigger instructor. Didn't see any pipe cleaner listed in Para Gear's big rigging kit (tho' it might be a bit outdated), nor in some DZ.com thread about what tools a new rigger needs. Sure there's the old idea of gravel getting in the reserve housing if you are submerging yourself in the pea pit when downwinding your ParaCommander, and that during a repack one wants to make sure that cables slide in cleanly without obstruction, but I had never heard of cleaning the housings being on any rigging to do list.

I would think someone would still have the DVD available. But a couple torrents are also available on popular sites.

I was surprised that anyone actually bothers to follow the supposed ideal of once a month that Bill Booth puts in his instructions! After all, people are used to seeing manuals with all sorts of cover-their-ass statements about frequent inspections, that nobody does. There isn't much incentive with 3-rings and cutaway cables as there's so little evidence that it matters, 1 month vs. 6 month. One just doesn't hear people say, "Gee that was a tough cutaway... but I kind of expected that, it's been 3 months since the repack when I last had the cables lubed." But I'm not saying it doesn't matter. There have been tests where lubed cables have lower forces than dry ones, which become more significant under high G. But I haven't seen studies on friction vs. time in the field for rigs, to what degree the friction goes up after 1 month or the old 120 days or 180 days for repacks in the US. As for stiff 3 rings, mini risers do sometimes seem to get pretty stiff. But likely doesn't usually matter unless one has a super low drag bag lock with a collapsed pilot chute or something like that? Again, I can't rule out possible problems but we don't see good data or anecdotal evidence on forces to pull the risers away. (Although there was one case of a problem riser release mentioned earlier in this thread.) Oh, and good spotting mxk -- a lot of manuals just parrot Bill Booth's instructions from 30+ years back. So unless one has some particular 1980s big type 8 risers, even he says there is no reason to exercise the 3-rings / bottom of the risers!

See "All roads have wires" thread, also in S&T.

Hmm, haven't bothered with this thread before. Well, here goes: A lady goes to her doctor and complains about her poor sex life and her husband's low libido; that she's tried everything and nothing gets him excited about her any more. The doctor ponders and then goes to a locked drawer, pulls out a pill, and hands it to the lady. "I can't officially give you this, but try it out. Slip it into his drink." The lady goes away, and a week later comes back to the doctor. "Did the pill work?", the doctor asks. "Oh it was great! We had the most amazing and passionate sex of our lives. He grabbed me and we did it right there on the table!" She continued, a little bashful, "I don't think we'll go back to that restaurant."

RiggerLee pointed out the idea of stalling one side of the canopy. That's possible, but I'd say more common if one already has the canopy really slowed down. Otherwise putting on a lot of brake will just cause a sudden turn & dive. Now the line tension thing Joellercoaster mentioned is important. That's the traditional way people would get themselves into line twists back in the 1990s when canopies got faster. (E.g., one Canadian jumper with 4000 jumps died in the mid 1990s when she put herself into diving line twists while maneuvering around too quickly, and she was too low to chop or didn't chop in time.) Anyway, with some canopies if you snap into a diving turn too quickly with a toggle, you lose line tension as the canopy dives for the horizon and you get suddenly yanked towards it. (Rather than smoothly being pulled along in a turn more gradually entered.) It is worse if you snap into the turn and let up quickly too, say making a 90 degree turn, rather than trying to keep the G's up in a continuous spiral.. All this is why canopy drills that suggest doing quick turns back and forth, are there for you to get a feel for the natural timing of the turns, so you can sashay left and right in a rhythm with your canopy that keeps the canopy and lines loaded up. Going back to the example of a sudden turn, once the tension is gone or reduced for a moment, the resistance of the lines to twisting is similarly gone or reduced, and with your momentum in turning, your body rolls along the long axis and you twist up under your canopy. Once that first half twist is in the lines, there's almost no resistance to twisting so you keep winding up until the momentum is gone. So it isn't the canopy twisting on you; you twist up under the canopy.

Doesn't look like he was trying to swoop between the trees. More likely scenario is that for the outlanding, he turned over the end of the field to land 'back into the wind', and finds that with his setup, and perhaps winds having died down at dusk, he has a really flat glide ratio and is overshooting into the gap. It doesn't seem like the 'swooped' in the sense of having any extra speed going into the gap or initial intention to go through it. He just set up too close in for a full speed landing into a limited landing area. At least that's my guess. What could he have done? Once he was deep on final and might have realized he was overshooting, I don't see a lot of good choices. Get deep in brakes -- which wouldn't kill the glide ratio tremendously in zero wind and a typical modern canopy -- and get ready to roll it out. Or turn and flare it into a tree crown. The options of course get a little better the further back he is when he realizes the mistake. Easier to turn away or S-turn or flare-turn or something, and still land on something flat-ish. (Edit: I've chosen to swoop under wires on a road during an outlanding at dusk... but only because I knew that road and the wire location already!)

A few years back a found a file sharing site that had many old Playboy magazines digitized. It was interesting to check out some of the early editions -- from the '50s through the '60s-- so incredibly mild compared to today's standards. A few breasts, a little nudity with legs discretely crossed, that sort of thing. Far more cheesy cartoons than girls. Some articles could be pretty long, like a 15+ page interview in the late '60s with an author of a book on the Kennedy assassination. The magazines were also fun to skim through for the advertisements -- the hard liquor, the aftershave, the cigarettes, hi-fi's & records etc. Interesting to compare the legend to what the magazines actually looked like back in another era.

Correcting for Rob's phone: "or Aidan Walters" (Of Eden North, Alberta) At least, I assume that's right.

And anyone know what they bought it for, if it sold for 1.1M? Wonder if it was a big drain on Perris in the end or did they get something out of it for all the dollars they must have put into getting it back into revenue service?

Well played Calvin. I applaud with halved coconuts, imported by African swallows. Nice touch about the density gradient under acceleration, even if minor. For the thread, that does remind me that for the skydiver under a parachute, the full mass is important for dynamic calculations, while for static forces -- for the forces on the lines -- one should technically subtract the weight of the air the skydiver displaces. We're buoyant in air, although just a tiny bit. Someone online calculated that a typical person's weight on a scale is about 0.2 lbs lighter than their actual mass. (Without getting into gravity variations on earth, an even smaller factor.) Cool about those new single surface paragliders. The closest I've flown are single surface Paradactyl canopies, and their lift to drag ratios are so low that they are pretty sluggish dynamically anyway, even if they entrain no air within. (CORRECTION TO MY EARLIER POST: D'oh, I used 2.25 in my calculation for air density kg per cubic meter when it should be 1.25. It's been a while since I engineered this stuff. So the air masses inside a parachute are lower than the original numbers -- but they can still be a few pounds.)

One could have up to 10 lbs of air in a big student canopy, and something like 2 lbs in a small canopy, very roughly. (About 2.25 kg mass per cubic meter for air near sea level). Might actually be useful to include if one were modelling dynamic maneuvering. To reinforce what Calvin said, the air mass only matters for maneuvering and not steady state flight since the air is neutrally buoyant in the air. But lets not make this too complex Calvin, or else we'll soon be talking about what happens if the 747 taking off has a treadmill in it facing backwards, with a bunch of pigeons on it, that suddenly flap upward, while holding helium balloons in their beaks.

A quickly written opinion on all this: ======= Edited to add short version Ultimately, all the weight matters for the wing loading. That's the total load the aerial vehicle has to support. Stitches and all. But people can define different types of payload if it is useful to them. And at an engineering level, yes one can vary what one includes --eg the lines don't have to carry the weight of the stitches and fabric that's above them. But that's minimal. =========== Long version Well you can always define various types of loads added to an aircraft. In an airplane you can have just the weight of the passengers & baggage as payload, or also include the fuel, or also include crew and removable equipment weights. Stuff like that; one can have a bunch of different defined weights. But ultimately, it is the total weight of the whole airplane and everything in it, just like the whole parachute system and jumper, that are the load that has to be sustained by the aerodynamic surfaces. (Calculating the wing area to use for the wing loading on a plane is an area where one can get use different definitions and standards. Eg, assuming the fuselage does not contribute to lift other than extending the wing through the fuselage to calculate the nominal area. But issues of definition apply to parachutes too. Constructed area, bottom skin or PIA area, inflated area, inflated projected area? As long as everyone is clear on the definition used.) If someone wanted, they could define some sort of parachute payload weight that includes only the jumper, or only from the 3 rings down, or only the links down, not including the main parachute. No problem with that as long as there's some purpose to it and everyone is on the same page. Now if you want to get into the engineering of the whole system, then will have to look at where the weight is. Yeah, lines don't have to take the weight of the fabric above the, just everything below, although it isn't a big difference from the total system weight. On an airplane, it all matters more for the stress calculations -- Having a lot of fuel in the wings (rather than in the fuselage) or a lot of wing weight spreads the load out across the wings, decreases the bending moment and stresses at the root of the wing from the fuselage. As for rig weights, my first instructor years back, Bob Wright, built a couple rigs for himself, in about the late 1980s, that were as light as 11 lbs. Reserve was hand deployed over the shoulder, slip-in 1" wide leg straps with no adjustments, that sort of thing. Impressive.

Some Canadians must manage to get things sorted out legally for long term work in the US. Not sure how they do it, although as with other types of work, if a company can show they need a specific foreigner when locals aren't really available to do the job, they may be able to get someone in fully legally. So I don't know how it has worked for some of the Canadians who have infiltrated the USA?? There's TK running Skydive City, Jay Mo has been jumping for PD, G. Dutrisac works for PD. "Crash" used to work for years as a rigger around DeLand. Riggerrob worked for RI years back. Many of these are 'real jobs' too, where it isn't just a cash business. I've heard of others too, in more regular skydiving jobs, who worked in the US for years before returning home, or for multiple jump seasons without me ever understanding just what their status was. Who knows, things may have tightened up over the years -- DZ's in the US (as in Canada) may be more strict about paperwork than they were 10 or 20 years ago. If someone wants to make a little cash on the packing mat, sometimes a Canadian will go down on holiday to meet other Canadians and pack for them -- sort of a team packer. I don't know packing mat politics, but that's more acceptable to the local packing mat staff. One isn't then just trying to steal their business in general, but working only for one's own group.

And its out on p2p now too, well seeded, almost instantly after the BluRay DVD was out. Didn't necessarily expect that for a niche documentary.

I found it again easily by googling 'eric fradet rigging manual' and picking the first frenchy result. Which happens to be http://www.ffp.asso.fr/materiel/manuel-du-materiel/ Half a dozen pdfs are available there. (He even took some stuff off dropzone.com!)

Skipping non-essential gear info at the start is normal. The problem at some dz's is that after that, there may not be any particular points to teach you those additional details. I've seen it (outside the USA) where instructors just add tidbits of additional information over subsequent jumps, if they happen to have time, but without having any structure or checklist to follow. One does sometimes have to be active and ask for additional help. Some aspects of the gear (parts but not procedures) may also get explained more once you start taking packing lessons. Which may be a formal course, or informally done at a smaller DZ over time.

Ooh, neat, how does that work? To start with, she has a Katana 107 and massive competition booties :P Who knows, maybe it does work. [cynical] Especially if you stretch one leg out as you turn the bootie, pressing that thigh down and leaning on that side of the harness... [/cynical]

Check rigging documents sites? People (including myself) have uploaded manuals for some old canopies there. parachutemanuals.com http://www.ukskydiver.co.uk/cms/index.php?/files/ Poyters vol 1 is another obvious source for brief info on canopies. Of course there's always more to what a canopy is like than what is in the manual....

Could it be the recently departed Ted Mayfield, well known for both being a big supporter of skydiving and being a little on the lax side with students? I can't vouch for the details but the below quote from an online article is inline with what I've heard before. (Of course the 'parachutes failed to open' thing will have been more complex in reality.) Who knows, the IRM seems a bit alarmist perhaps because it may deal with only a highly unusual extreme.

Another option is for a local rigger to sew something up. Just add an inch or two long riser tab with a ring, to create that a small 'third riser' as some called it. I didn't like the simpler version of putting the 2nd ring within the slink, as the brake line would in certain flight conditions rub against the slink, at least on my canopy. A really simple version that has worked great for me: [inline "PChapman_mini_3rd_riser__swoop riser__brake_line_guide(mini).jpg"] (One can't see it in the photo but the brake line does go in and out of the locking ring from the top, so the line does pop free of that lower ring.)

Maybe you can even bring down that apparent 379:1 post to jump ratio!

The Mountain News site -- linked earlier in the thread -- said an Air Coupe. Which I think technically would be an Aircoupe or Ercoupe depending on the model. Pretty low power like skybill suggested.

As another data point, I saw a 2005 thread where Bill Booth said a good silicone lube like ACE's is what they use. I don't know if opinions changed or whether which choice one makes it isn't set in stone at UPT. (I haven't mined the threads for more recent info.)