pchapman

Petejones: Sure, we all learn things over time. But that site is one of those crappy "factoids" sites with short, oversimplified information, some of it erroneous or useless except to a 10 year old. The original post was therefore pretty much spam. So it isn't any good even for those new to the history of skydiving. Google "history of parachuting" and you'll easily get better stuff. I think some of the best info on parachuting history is in books -- I'm not sure what single web site I'd send someone to, if they are new to the subject. What a good web site would be, that's a valid question. And I think your reputation on the forums is becoming one of a newbie who jumps in with their opinion in all sorts of things where it really has very little weight or importance, especially when done in a short sarcastic sounding way. Not all your posts are bad; some are valid critiques of something a previous poster wrote. Act like a know-it-all newbie jumper and you'll get shot down by know-it-all senior jumpers.

Over the past couple decades there's been a tremendous amount of interesting stuff revealed about the Soviet space programs, that wasn't well known or properly understood, or that fills in a lot of technical details. Like the N-1 moon rocket, and their little moon lander. Or the Almaz military space station with guns and a big telescope. Or the Nedelin disaster. Or debunking of some of the rumours of other disasters with 'lost cosmonauts' dead in space.

What did the first officer do? Undo his seatbelt to try to open the cockpit door and fall onto the control column while in the dive? Looks like he was able to neither fly the airplane, nor summon help. Useless.

Sticking to the subject rather than getting into the usual "Racer sucks / Racer rocks" debate: LouDiamond linked to Jump Shack's "speedbag floor test.wmv" video. My interpretation of Jump Shack's point: ====== During ground tests the last elastic may tend to hang up with a little force, so that the canopy easily pulls out of the bag with the one side of the flap hung up. So the idea is that the flap should easily pop open, but if it is even easier for the canopy to extract without the last elastic clearing the flap, then it is perfectly OK. The elastic hangs up only because it flips & twists as the lines are pulled out of it, so it is a little wide. The twisty elastic against the fabric of the flap does cause a little drag. In any actual use, rather than in very slow speed walking-down-the-room situation on the ground, the elastics will pull out of the bag on both sides. ======= So all the above can be debated either way. Compared to what we are used to, it is odd to see an asymmetrical situation when the bag comes off the canopy, and to have elastics hang up on a flap. We're used to bungees (for reserves) or elastics (for mains) through smooth metal grommets. So even having a couple pounds of friction holding a fully fabric flap closed is unexpected. The original post, however, described situations which don't match what Jump Shack expects according to the video. a) The ground example. The question is, what is the "considerable force" needed to open the flap of the one tested on the ground? Jump Shack might argue that even in a zero speed cutaway, the necessary forces to open the flap will be generated without any delay. b) The air example. Despite actual use, the flap opened on one side only. Does the bag come off easily and cleanly enough that the asymmetric nature of it isn't a problem? The situation still would be worrying to skydivers, and not in line with what was expected in the Jump Shack video. Edit: And then there's post #8 about taking 60kgs to open a bag on the ground. Is the flap over the knots at the base of the elastics? What was the force actually being applied to, what is catching or adding friction?

Everyone - not worth clicking through. Just standard well known stuff. (DaVinci, Kittinger, etc)

Nice pics! It's always interesting to see how the Russian design philosophy differed from the US one. E.g., landing retro rockets, and the use of 1 main and a sub sized reserve, rather than a single cluster of 3 canopies. Has anyone landed on the sub sized Soyuz reserve canopy? Landing that could be a bit like being in a car crash. Rough but survivable -- sort of like a high G ballistic return trajectory that occasionally happens if there's a problem, compared to the normally planned entry profile. For more info on descent rates and landing, I looked up the following: European Space Agency on descent rates for Soyuz: A longer description is on this NASA page: http://www.nasa.gov/mission_pages/station/structure/elements/soyuz/landing.html

Um, that's the pressure to PULL OUT the pin. The pressure ON the pin is going to be some multiple higher. Five times? Ten times? Who knows without tests. It doesn't change the arguments about the discs though.

Nice. Not everyone gets to (literally) fly around skyscrapers in Dubai.

Recently a thread was started in General Skydiving Discussions about whether one would cutaway if faced with landing in a place like a city, when flying a fast main but more docile reserve. (http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4005890) It brings up the issue of landing within a city, what ones's choices would be, whether one is under a fast or slow main, or any reserve. Depending where one jumps, it may or may not be much of an issue. I'm only likely to have it happen if at a boogie some where, or on a demo gone wrong. Anyone got good video of landing in an urban area that would be educational for others? Any comments on landing in urban areas? I'm not really invested in this issue, but it is one which I don't really recall seeing threads about. There is a decent video on youtube that I've shown in canopy control classes, showing someone landing on a tight residential street in Deland, beside trees. It looked like wind shear may have been a factor in the rough landing. Just as an example of the risk, over a year ago 'Crash' Moore (who I had known) died when misjudging an off-landing in Deland, even though he had apparently planned to land on a grassy median of a regional road, a relatively wide open area. Similar to what I wrote in the other thread: Some municipal environments will be worse than others, with a lot depending on the design of the neighbourhood. One wants to open high and have a lot of choice of landing area, but that's not always possible. I'd be looking for a municipal park, or a commercial area with larger flat roofs. In purely residential areas, some with above ground hydro will have lines across the streets every 50'. Large backyards may be good, but smaller backyards can also suffer from phone lines and fences every 50'. Peaked roofs of closely spaced homes may be tough to land on and not fall off. So what's left to land on? Medium to large trees I guess. I've done it OK with a slow paraglider, but it would be a little sporty with a fast canopy. If one were over a neighbourhood without wires closely spaced across all the streets, plus large lots and wide suburban streets, that would open up the landing options a lot. The situation is one where one's skill in "putting it down" in tight places may be rewarded.

I'd consider it. The problem is, by the time I figure I can't actually find a spot to land a fast canopy, I'll probably be too low to really want to chop. I'd still consider it though, if the landing choices look really really bad. A bad situation would be too low over an area to find a municipal park, or a commercial area with larger flat roofs. Streets are no good in residential areas served by above ground hydro, where every 50' a wire crosses the street. If every home has a peaked roof, what's left? Backyards can be small and also have phone lines every 50'. About all that's left is decent sized trees. But the actual situation depends so much on the design of the neighbourhood... You know what? I think I'll start a thread in Safety & Training about landings within a city, because otherwise I'll derail this thread. Nothing wrong with asking the question about cutting away, but the more common issue will be dealing with a city landing without a cutaway.

Seems OK to me. But that may be because I've been around canopies which are not built for retractable bridles -- locally I've done up to 8 stacks in recent years, mostly with Cruislites, Ravens, Mavericks, and such 1980s canopies. If you have a canopy where one can be fitted, it makes some sense to use one, particularly if it isn't your regular day to day canopy. I can't argue against it being a more modern and superior way to do CRW.

Seen: - student rigs with big F-111 canopies - 1* side by side, 2* biplane - student rig with big F-111 canopies - reserve stayed in dangling bag for a long time, but when it came out with twists, the main and reserve spiraled around each other rapidly.

Ok, the thread title doesn't describe what happened, but this was a head down freefly dock with a Porter's wingtip in a vertical dive. With the jumper breaking off to make a quick dock with the cameraman before they break off. Quite a bit earlier (1990s?), there were docks, airplane transfers etc with planes using drogues. And the wingsuit plane transfer by DeGayardon I believe it was. And the dock on a Salto aerobatic glider (by Loic?), but it was also using a drogue bigger than its usual landing drogue. I'm not familiar with the latest stunts, so: Is this the first non-drogue dock with an aircraft in a vertical descent, or were others done too? Even with the prop range available on the Porter, the jumpers were really cooking to keep up. Was everything within the authorized parameters for the aircraft? I'm not talking about generic 'no aerobatics' statements, but specific things like prop operating parameters (pitch vs airspeed), and aircraft Vne? For example, for at least some Porters, Vne is 151 KEAS or about 174 mph. Great achievement in any case.

Is that in American civilian skydiving use in some areas? I've never heard it. I don't really know the military, but the use you mentioned doesn't seem to match with the military use either. I could see that if in civilian jumping one dropped multiple groups per pass, and had multiple passes, those who dropped on a particular pass could be called a stick. That would better match military use. Just asking.

Yeah, that's the brochure / manual. (We're getting away from the original thread topic; on the other hand, the original poster will have his answers by now...) The pulling-the-straight-cable arming description they show there is in a section on chest mount reserves, and is also written as if it is a suggested method, rather than a procedure that must be followed. So it is easy to think it doesn't always apply. Interesting topic though. I can see there'd be less wear on the FXC if one pulled with the housing straight, rather than around a curved housing. And to to oppose the pull force, pushing on the main box rather than pushing on the rig or attachment plate. I suppose one could even follow up the 2002 post (#186958) by Alan (Alan Binnebose, Twardo reminds me), since he had provided some very specific info about FXC's, that seemed to go beyond what the factory has provided. Just how much I really care about digging up secrets of the FXC, that the factory doesn't seem to want to share, that I'm not sure of.

That's interesting. I'd like to know more. I've never seen a manual. It's not on FXC's web site, nor on a couple popular rigging manuals sites, nor have I seen one at a DZ with 30 FXC equipped rigs, where I used to do calibration tests on them. I'm sure I asked FXC years back, but they sent what was really a product brochure, with only very abbreviated info on testing. I'll ask them again. The only thing I ever saw that said anything like having the housing straight that was in a post by "alan" on dz.com in 2002. So if they ever had a manual or further instructions, I'd sure like to see them! (Heck, you sure don't disassemble a rig if the FXC is on the main container - with a spring loaded pilot chute-, every time it pops when a student pulls 500' low.)

One additional point: The alternative is to build a chamber big enough to put the whole rig into, to avoid disassembly. Very handy for a DZ that still has a bunch of FXC's.

I made my packing paddles 18" long. They're both easier to use in the role of S-folding a canopy, and as a side benefit they don't pack away into canopies as easily as the one in your photo!

Yeah. As a couple layers I like having a flexible and not bulky windbreaker type jacket (that'll fit under a jumpsuit easily), and a fleece layer with a full zipper. One may need to adjust layers a lot, between a warm lounge to being fairly warm when packing in a cool hangar, to standing outside in a cold wind. How much one wears on the plane depends also on how warm one stays on the ground. If one is toasty warm on the ground then one might survive a cold plane & jump no problem. If one is already toughing it out with cold extremities on the ground, then the plane ride and jump can become much worse.

I had been thinking the same but hadn't gotten around to it, given possible issues with my 2-harness system, different from Wendy's 2 sets of rings on one harness. Someone else locally tried it with 2 harnesses this year, but got choked unconscious by the harnesses pulling in different directions. (From a couple thousand feet up he came down under the downplane, unconscious, and hit the grass runway in easy view of everyone. Quite a show, although it cost him a broken femur and most of the season off jumping. And yes he was hanging vertically between the canopies.)

FXC's seem cheap at first. Who knows, you may be able to get one nearly free. But they are supposed to be factory serviced every 2 years, for about $200 US (haven't checked in the last few years), so in the end they aren't really that cheap other than low acquisition cost.

Part of the issue is the framing of the original question. Originally the question was about it improving a normal landing, making the a flare more efficient. There was skepticism about that. Later the thread turned more to any other ways the flapping might be of use -- to add drag during the flare, not something typically needed, but useful in certain circumstances. And we also had the video that was linked to, which seems not to be about a better flare or a better stop, but just plain having fun!

Some parts of the rodeo might not interest me -- I'm not going to learn from the part of a job that is done quick and sloppy, when I know already how to do it neatly at a moderate pace. But other parts would be interesting, for the parts of the job where I'm always looking for better technique to speed up slow work. Like trying to get a bulging freebag into a tight Wings container with a short closing loop...

... Which explains in detail why having a circular blade (Argus) is a poorer concept than having a single V-blade (the other guys). It's an interesting analysis. To summarize some of what they say: -- A circular cutter blade might at first seem to be better because it in effect has two cutting edges that will contact the loop. But it means the same force now has to cut the closing loop in two places. -- A circular blade tends to be built with thinner edges than a simple V-shaped blade, and thus can have problems with either being too soft, or being too hard and brittle. -- They also mention that the 'anvil' that the cutter hits in the Argus, because of the blade's circular shape, is recessed to the side of the cutter hole, rather than being flush at its edges like on some other designs. This means that if there is a problem cutting all strands of the closing loop, they are more likely to jam, zig zagging into the recessed area. -- Because of the way flaps pull the loop in different directions, the closing loop can be going somewhat diagonally through the hole in the cutter, depending on the rig. Then the blade may tend to cut the nearest part of the loop first, while the loop is under a lot of tension. But then the farthest part of the loop will be under zero tension for a split second but still within the cutter's hole, so the blade still has to sever it. And that's harder to do, when there's just a little bit of closing loop in there, under zero tension. The cutter isn't designed to cut material that is under zero tension. [They aren't really clear that this is a worst case scenario, and depends on the flap arrangement, cutter location, and the direction that the cutter goes, whether arranged top to bottom or left to right in a rig. They don't match that info to either the Poland or Portugal incident, so their scenario is just a worst case one.]

I've long wondered about grabbing risers and giving oneself a 180 twist (to face forward), plus a 360 twist (so the 180 twist doesn't suddenly torque itself out), and landing that way. The risers will be crossed in front of one's face and there's still some untwisting torque that makes using toggles a bit awkward, but one can reach above the twists to use them. Haven't tried it on anything smaller. The only time I landed like that was with a big 200 sq ft canopy. The canopy was attached the right way, but there were twists in the risers that wouldn't come out because a main canopy was wrapped around them. (A little CRW oopsie.) I was able to reach above the crap to get the toggles.