pchapman

One old thread on it is at http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=2414079;. Another (with a long list of Vigil gripes in 2006) is at http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=2404920;page=1;mh=-1;;sb=post_latest_reply;so=ASC. But the actual announcement by AAD/Vigil isn't shown in the threads, nor is it on their web site, even though a bunch of their other old announcements are still there. Anyone still have that 'sunlight' announcement downloaded? Probably doesn't apply now to Vigil 2's but, yes, it would be nice to know how the problem was resolved.

Ok, I just read the long thread through Google Translate but that's still a mess to understand. Some of the thread is from 2005-2009 on AADs & pressurization in general. Then the last half of the thread deals with the Aug 2010 incident. While we're likely to hear more eventually, this is the uncertain impression I have: An-26. In military use I guess. Climbs, pilot decides to turn on pressurization & air conditioning packs at 600m (2000'). Plane later descends to near or below 300m (1000'), and opens ramp to drop cargo (planning to climb later to drop jumpers). Basically the Cypres' saw a climb from 0' past arming height (1500'), and then a sudden drop from 2000' to firing height as the ramp opened. Pop. This interpretation assumes that however the An-26 pressurization system was set up, there wasn't enough venting to let the interior pressure increase as the aircraft descended. (Keep in mind that the AAD is looking for something over 1000' pressure altitude, to correspond to 750' belly to earth & AAD in the burble.) There was no mention of other AAD brands on the flight. (Well, some mechanical PPK-U's, but that's another issue.) Sounds like it would be a case that would fool other AAD's too. So there's no point to be scored for Vigil, just a reminder that when playing around with pressurization, any AAD can be fooled. This time, the pressure changes were "more realistic", so we don't get into the argument of what AAD's should do if the pilot pressurizes on the ground to well below ground reference level.

For those thinking of clicking through, that's a long & detailed article on the kid, within the Life magazine on Google Books.

Ah, a template -- easier to do things, easier to screw things up... (And to be fair, I've seen UPT mess up an SB & reissue it with minor changes but not even a name or version change.)

And also: The Aviacom/Argus bulletin came out showing that the cutters had to be replaced before the next jump. Within a few hours, a new version came out giving much longer (such as at next repack) to get the change made. (That's not even visible in the original bulletin thread, as some posts were removed by moderators to clean up the thread.) Although everyone makes mistakes, this was a major bulletin from the company, so one expects care to be taken. It makes it look as if they are a little confused and uncertain of what to do with this whole messy cutter situation.

"Slots" There is a thread somewhere on it. Someone in the UK had developed a number of single surface canopies with unusual shapes, back in the '80s, including a few versions of the Slots canopy with rows of curved single surface panels with large lateral gaps between them. He also did a canopy in the shape of the Olympic rings.

www.pprune.org - more professional pilot oriented site. Started in the UK I think but very broadly used by English speaking pilots I hear. (For Canadians, a similar one is http://www.avcanada.ca/forums2/) Useful thread!

Sarcasm: Maybe the mom or her lawyer have an idea how to build an AAD for the same price, with multiple redundant sensors and processors, and the appropriate software logic to handle it all.

So I'm still not seeing what is to be made of the really evil (by today's morality) & vengeful God in the Old Testament. You know, things like the Lord saying to Jesus that the man gathering firewood on the sabbath is to be stoned to death. Does anything in the New Testament explain these behaviours?

At my DZ (in Ontario Canada) the DZO has all the Sigma tandems flat packed. But he's a flat packing fan (eg, all student canopies must be flat packed). He believes flat packing tandems will reduce the malfunction rate, and cites a couple US DZ's who apparently found that to be true. But that may be from 2002 or so when the DZ first went to Sigmas. Most at the DZ are not convinced. Maybe it reduces line overs from poor pro packing, but that can be a training and supervision issue. I don't know if we've had any line over mals over the years with flat packing, but it certainly hasn't come up as an issue among the tandem instructors. Most tandem mals over the years have been tension knots, I think especially as the Dacron Sigma lines get closer to replacement time. I don't see that pro packing would have much advantage in that regard.

I'm trying to figure out the proper terminology for types of soft link covers. PD has the black "slink hats" that they officially call Slink Riser Covers (SRC's). They have the tabs to the sides that keep the slider at the hats instread of going down the risers. But there there are also the narrower, typically white covers that pass through the hole in the middle of the assembled slink, and go upward. They protect the bottom of the lines from wear, where they connect to the slinks. I'm not even sure where factory built ones are available. What are they properly called?

Hmm! Which in turn reminds me of the lazy jumper who had his reserve repacked, went jumping for the weekend, then saw his rigger and asked about the bill for the repack. The rigger (Steve West) replied that he had left the bill under the reserve pin cover. And that was in the days before "bomb proof" pin protection.

Good question. I don't know how they work. Yes. Just like maintaining different civil law in Quebec vs. other provinces, due to different origins. (Napoleonic code vs. Brit civil law, or something like that) Two systems with appropriate domains and interfaces are fine, if that's what people want. If one system is seen as essentially undesirable or incompatible with the other though... No problem with your devil's advocate questions.

Just a comment: There is the issue of whether consent is really consent. Sharia law was rejected where I am (province of Ontario) a few years back, and allowed no official standing, for various reasons. Naturally it was more about family law matters, that sort of thing, not stonings and chopping body parts off. A major argument against sharia was the concept of two systems of justice. Another was the idea that someone might not really be consenting, and be subject to community pressure to use the sharia law. Yet then the decisions of a sharia court would have some weight in the eyes of the law, much as if one decided to go to arbitration, or signed a business contract. So you are right that one SHOULD still have recourse to civil court, but in practice, that layer of justice might be harder to exercise if sharia law courts have any official standing.

It has become common for rigs to be sized and bought that way, especially when the main canopy is already quite large, to keep the bulk of the rig down. While there are good arguments for keeping your reserve size large, people often want to have the smallest reserve size they think they can get away with. While there are counter arguments, there is some logic to it: You very rarely need to land your reserve, so having a little faster landing than normal is no big deal.

A few random ideas, although none are "must do's": --Observation decks on the CN Tower (900' & 1400' up). They do charge a lot, like they're the only 1800' foot tower in town... which they are. The whole thing is maybe not as big deal to a skydiver. --The city is known for having quite a few theatrical productions including big name ones. -- Take the old ferries from the waterfront over to Toronto Island. Big parkland. Cool breezes; better if it is still a hot summer's day. They always used to have bike rentals if one wanted to explore the whole length of the island. -- Until Labour Day (sept 6), the Canadian National Exhibition is on. A variety of stuff going on there, even if it isn't in its heyday like before the internet. -- Royal Ontario Museum - Various antiquities, dinosaurs. There are some nice neighbourhoods to wander around in, off the downtown business core, but that gets more complex to describe.

Consult the Pope? Alan Pope's classic tunnel testing textbooks, that is. (Not that I've looked at one in ages.) Like others, I'd guess that the usual issue is to get turbulence levels down in a tunnel. Only for very smooth shapes like airfoils would I think it would matter much, what the fine tuning of the turbulence level would be. There must be ways of characterizing turbulence levels. As for skydiver wind tunnels, I think only the really early ones (or simple amusement park style ones) blew from below. Other non-circulating ones have the fans above, and some sort of smoothed bell or cone intakes below. A modern tunnel that is recirculating has vanes to get the airflow around the corners, but no flow straightening grid or whatever you'd call it, as found in aeronautical tunnels to reduce turbulence. Others with more tunnel experience than me would know more. So I'd guess: Just get some sort of flow straightener in there, avoid too much blockage by having the tunnel large enough, and worry more about the issues of getting measurements for non "hard" objects. It is one thing to get the drag of a specific airfoil, another to get the drag of some complex biological object that can be oriented in many different ways.

There's no duty importing US-made skydiving stuff into Canada. But there are taxes on the purchase. And if sent by courier one can get caught up with unexpected brokerage fees if one doesn't plan ahead. Most skydiving equipment bought from the US is made there. I'm not sure whether there would be duties on anything made elsewhere (e.g., something from Parasport Italia, or PD goods manufactured in Honduras), but I never heard it discussed. What the value of an imported package is, can be hard to tell, and to customs it depends on what is stated on the customs declaration on the package. Of course, a low value looks more reasonable if it is used gear, not brand new gear in plastic bags with manuals and possibly with an invoice in the box. What the shipper writes on the box, depends. A private individual selling gear might be more flexible than an established company in that regard. Sometimes a package might be labelled stating that the contents are being returned to the owner after inspection & repair, which probably didn't cost that much. Canadians often go on skydiving vacations to the States, or may do a shopping trip to a border town (and stop off to pick something send to them at a UPS store or similar). When the car is full of sports equipment, it can be hard to tell if there is more coming back than going out. Disclaimer: Not advocating anything. Just sayin'... PS - Confusing title to the thread. Makes it seem like the gear is going Canada to the US.

Hi Hackish, Somehow we talked past each other. I do see that you're posting it to get a discussion going. (And that you aren't the one who sewed this up!) I was just trying to understand whether the chest strap was simply added on to a stub of the old strap -- I think a closer look at the photos does show this to be the case. Looks like harness stitching? Still, the orientation is frowned on. The slipperiness issue is interesting, and we don't have easy to find standards on that as far as I know. A complete replacement of the original chest strap in its original configuration gets complex, as on that rig the stitching through the original chest strap at the MLW is also part of the main 3 ring / harness junction stitching.

Yeah the term squidding refers to when the canopy is staying still stretched out with little air in it. If the deployment airspeed is above that critical airspeed for squidding, the canopy won't open at that time. If there's enough drag from the uninflated canopy (relative to the mass of the system with payload), then it will slow down, eventually drop below the critical speed, and then open. There's a bit on it in the Irvin Recovery Systems Design Guide, free online. Erdnarob also described the pulsating of an open canopy, which doesn't technically fall under the squidding term, although I can see how it might be described that way. Jellyfishing perhaps? A largely unvented canopy tends to spill air in an uneven manner so it can get into those pulsating cycles or oscillate from side to side, although I'm not sure of the relationship between those two behaviours. As I understand it, the post-inflation rebound (or whatever it is best called?) is mainly due to wake recontact. So it isn't so much the mass of the top of the canopy, as the mass of the air being dragged behind the opening canopy, that hits it from above when the canopy "comes to a sudden stop".

Hey John, It is one thing to discuss bar tacks vs. cross stitch patterns (diamond or W patterns). That's an interesting enough question, considering that bar tacks are often used for somewhat load bearing applications -- like line attachments tapes (other than ParaFlite), or climbing harnesses. But in this case, we're not even talking about bar tacks, but multiple rows of straight stitches. Poynter didn't explain much relevant about the theory of stitch patterns other than to say , "Never sew a straight line back and forth in an attempt to duplicate a bar tack. This just perforates the material." So the stitching in that chest strap may be doubted more than your words suggested... (To clarify the photos: I assume they are showing that new chest strap is just sewn onto the stub of the old strap?)

Compared to learning to fly, we don't really have "ground school". Yes we get 1/2 a day before the first jump typically, but that's it. In flying, you show up at the airport in they day, brief with the instructor, go fly, and debrief. Same with skydiving. But in flying you also pay separately for a series of evening classes once or twice a week, a few hours of classroom time to learn all the theory. We don't have that in skydiving. All we have is some home study from the SIM (in the US) or PIMs (in Canada where I am). Which of course works best for the types who like to study printed material. Aerodynamics seem pretty limited in the SIM, and perhaps a little less so in the PIMs. So, yes, the emphasis is more on practical considerations rather than the background theory. One can always argue about how much theory is needed for applying to actual jumping.

I've seen it done to do a pull test on the main, like on the reserve, in particular on that center aft top skin that takes a beating. But the impression I got was to test it only to 20 lbs, to find a nice balance in this situation. (I did rip an old Stiletto doing a 30 lb test as requested. That got a bit awkward as it was someone's pre-purchase inspection.) It's up to the owner to decide whether to wait for a cell to blow out or not, much like the situation when dealing with relining a canopy.

I wouldn't have even realized that there's been any change in policy, as I've jumped at that DZ a lot, and don't recall the issue coming up. Maybe it just did recently, so the DZO is clarifying things. I'm talking about the specific case where someone on the load decides they had better not jump, while others do. It is a more common event to climb, get caught by clouds, have to jump from a lower altitude, and pay for the highest one went. I've had times there where the whole load I was on came down because we couldn't get minimum altitude -- and we haven't been charged -- but only in special circumstances. That would have been with the 182's (not Caravan) when we had an informal agreement about the load, where we were not on the hook if we came down. Normally, if the jumpers are really anxious to go up for a hop and pop but the weather still sucks, we're on the hook if we choose take the plane up. But sometimes the DZO is also eager to get things going, get S/L students back up in the air or whatever, so then a C-182 ceiling check load is informally agreed on where the jumper's aren't on the hook if we can't make 2500'. But that's an exception to the normal rules.

Yet more perspectives on the aviators / medical / welding oxygen issue: (This is not about the original poster's N. Zealand issue.) 1) http://www.avweb.com/news/pelican/182079-1.html Although 11 years old, this article by a high time pilot also concludes that it's all the same stuff, and that non-aviation oxygen should be legal at least to the FAA. Oxygen specs can be confusing because you get percentages that may be volume per volume, or mole per mole, or weight per volume, or don't have an explanation what "%" means. 2) Next, there's a technical discussion of the different oxygen grades (eg, grades A through E and beyond) at http://www-personal.umich.edu/~lpt/oxlabel.htm That source gets into a lot of detail and suggests that there can be differences. Industrial oxygen would get refilled without a vacuum purge that is used for medical or aviation oxygen for long term safety. Also, what is called the aviation oxygen grade (E) is stricter than the minimum US grade for human use (A) for water content. (Yet the previous article mentions an older document that specifies only grade A for aviation.) Still, that doesn't clarify actual supply quality vs. just the specifications. 3) From Mountain High, a well known designer of aviation oxygen equipment: http://www.mountainhighoxygen.com/index.phtml?nav_id=25&article_id=18 Part of what they say is: