pchapman

It was brought to my attention that the Vigil II manual now states: Do not open the door of the plane during the flight in the activation zone to avoid a possible pressure variation, which could result in an unexpected activation. There was no fanfare about this change that I'm aware of. This is in the current manual that was published some time in June 2010, v II.0.3. Earlier versions didn't have that. (At least not II.0.1 which had been around a while -- I guess the "II" refers to the Vigil II, not revision 2, so this new manual is in essence v 0.3) The "activation zone" would I suppose be at least the range from 150 ft (arming) to 840 ft + 260 ft = 1100 ft to include the belly vs. non-belly pressure adjustment. In Student mode, 1040+260= 1300 ft max. If Tandems are on board, no door open until 2040 + 260 = 2300 ft max. Technically this new rule could prohibit, say, sliding open an Otter door after seat belts are off when students or tandems are on board. In practice though, I figure it is more a precaution for C-182's and the like, with a smaller cabin volume and doors that can go from well-sealed to popped open very quickly. Perhaps 'cracking' the door open for a moment while holding the handle might be better than just letting the door fly right up. For intentional door openings, the altitude range is of most concern if there's a tandem on board, and one were thinking of throwing a wind drift indicator or dropping a hop & pop. For unintentional door openings, there are obviously still concerns about rare but not impossible AAD firings.

... and fuel was cheaper. 600 hp to take up ONE student? So, was this serious or a joke?

I probably shouldn't stick my nose into an area I know little about, but my naive question is, how does one know that a 1500' pull is wrong? (Or is it in the FAR's? I can't recall.) Somewhere I read Lodi isn't USPA, and I don't know if pull altitudes are printed on the back of Lodi's famous little waiver tickets. So where does one learn the special Lodi rules? I checked their web site, and can't find any rules for experienced jumpers. Nothing about pull altitudes, wingsuits, hook turns, or whatever. Presumably there is a board in a hangar somewhere with some rules. But can they cover an equivalent for every USPA rule, on who can jump a camera, how many jumps before jumping a wing suit, etc.? Or is everything "wide open" unless the owner specifically chooses to ban something? Just trying to understand "how the system works."

I doubt "international waters" is an issue. In general, nobody could enforce blockades if it had to be enforced within 12nm or whatever of a coast and port. (Although laws have changed and the situation different, I don't recall that the blockades of Germany & the UK in the world wars took place only within 12 miles of shore...) The UN HRC report suggests that a blockade can be made on the high seas. (And leaving aside what "national" waters might mean to the Gaza.) The problem with laws around war these days is that everything can be considered a crime because the rules are so vague. I'm not sure much can be done about that. Two examples: The UN HRC report does look at the issue of the legality of the blockade. One may or may not agree with the conclusions but it is interesting to see the legal arguments. One issue is that a blockade is not allowed to continue if it causes "disproportionate damage on the civilian population". The report seems to say, Palestinians are short of food etc., therefore the blockade is disproportionate, and NOT legal. Yet I suppose Israel can say, "No it isn't disproportionate, as long as both the terrorists AND civilians are starving to death in equal proportion." So then the UN HRC report goes on to suggest that when legal blockade doesn't exist, a boat can only be stopped for certain military purposes, such as if it "was making an effective contribution to the opposing forces’ war effort". The report goes on to conclude that even Israel didn't think it was a big or immediate military threat, but the report thinks Israel was worried about the propaganda effect of the blockade runner. Thus the report concludes that, again, Israel didn't have the right to board the boat. Yet Israel could easily say that a propaganda victory IS an effective contribution to the other sides war effort. Willpower and support are an important part of warfare. Whether or not the force used at a tactical level was way too high, examples like this show how international laws that could make something a crime, don't automatically make them so, based on one interpretation.

PM'ed

On the weekend I got around to jumping my UT-15 rig & canopy -- the name applies to both the Para Commander style round canopy and the fore-and-aft rig. Some in the East considered the UT-15 better than the Para Commander. I guess a few UT-15 canopies made it to the west during the Cold War? The rig, though, having parts incompatible with American rigs, and not being TSO'd, would be quite rare on this side of the Atlantic. Well, Beatnik has one, but that's no surprise to any regulars here. His uses the "upside down" 3-ring mechanism, with 2 rings on the harness, one on the riser -- there's some sound logic to that. Some noteworthy things about the UT-15 system: OSK canopy releases My rig, built in 1983, a "series 5" model, uses the previous generation of releases, the OSK. While the mechanism is different, it would be in the Capewell class: Big hunks of metal at each shoulder, intricate mechanisms, operated by one hand on each. Their operation is seen in the photo sequence attached. I've heard of a couple different ways to place one's hand on the mechanism, but the way I practiced was to get ready to squeeze the knurled plates on either side of the OSK, with the index finger on the tab that sticks out in front of the OSK. Pressing down on a rocker button on the tab allows the tab to rotate down, removing the safety for the mechanism. Then one sqeezes the plates on the sides, pulling downwards on the mechanism to rotate that part of it down. This allows two other hinged bar pieces to move, releasing the bar that is attached to the riser. I was told not to use any oil on the OSK's, but to clean them with vodka. One source said the OSK's are good, while another guy told me (just before I jumped) he had one lock up so I'd better take a big hook knife along. I'm still trying to learn more about the OSK's. Harness The harness has the usual eastern look, with webbing having a loose weave and stitching using different patterns than normal over here. Hardware tends to look lightweight compared to US military hardware. The harness is of the continuous sling type, rather than separated leg straps. Reserve The reserve for the rig was a Rogallo PZ-81 canopy. Although it has a good reputation, the one I have seems to have some wear from use as a main, so I instead hooked on a Z-5 round reserve. It has no pilot chute, which here would not be used with a rig where one cuts away. However, it has large pockets around the top of the canopy that effectively act as a pilot chute to drag it all out. The reserve attaches in the usual Russian way, not with a snap onto a ring, but with a heavy pin slid through the loop on the end of the risers. A spring clip inserts into the mounts for the pin, to prevent the pin, which pushes and turns to unlock, from coming out. Main deployment handle The slack in the ripcord very neatly feeds into the rounded handle, so that there is no slack hanging out. A hole in the handle allows for inspection of the hidden part. Canopy sleeve In North America, one normally had a cotton sleeve, often quite heavy, for a round sport canopy. Nylon wasn't normally used, to avoid burns. Yet the UT-15 has long used a thin nylon sleeve -- a very different design philosophy. Line stowage is conventional for anyone used to Para Commander sleeves. One minor change is that bungees are used instead of elastics. Another is that the cover over the lines slides down over that area and has an elastic mouth, instead of being a velcro closed flap. The top of the sleeve has a couple pockets that catch air, presumably to help lift the sleeve. Two pilot chutes are used. One doesn't try to close the 3-pin rig with all flaps shutting over the two pilot chutes. That would be a bit of a struggle. Instead there's a sequence where a pin is put in, and a pilot chute is compressed and slid in underneath the partially closed flaps. The opening at the top of the sleeve is closed with a drawstring that one ties off. As for flying the UT-15, it is essentially like a Para Commander, but beyond that I can't tell based on my limited experience with the canopy. The after landing photo is just for fun, to show I hit the tuffet on a light wind downwind approach, the canopy settling in front.

Here's a couple photos of an acquaintance's FAI certificate (license) from National Parachute Jumper-Riggers, Inc. He's Canadian but his club in Canada associated themselves the NPJR as he and others hadn't yet started to create a national organization. I like the statement in the booklet that says: "The Civil, Naval, and Military Authorities, including the Police, are respectfully requested to aid and assist the holder of this Certificate."

On the subject of Advanced vs Expert ranges, that mchamp brought up: Yes, DocPop is right if mchamp claims that the canopy he flies determines his skill level. Although it did sound that way from mchamp's post, I think he meant what he wrote only as a hypothetical situation. So let's look at mchamp's example again. Say there is a jumper who we can call "Advanced" in canopy skills, who when geared up is 144 lbs. At that skill level, PD's table suggests that it is Ok to fly a Sabre2 150, but not a 135 (WL

So who owned the 'dactyls at Couch Freaks?

In Canada, the bat-wing ban existed by 1958. Without knowing the true answer to the original question, this suggests the ban might well have existed in the US that early as well. I get the impression that when a national Canadian parachuting organization got started, when they were trying to come up with a formal list of rules, they relied heavily on prior experience, and thus on rules from the USA. (This was actually from talking to a founder of the organization today!) I've got a reprint of the 1958 rules of the Parachute Club of Canada (PCC), which was later renamed the Canadian Sport Parachuting Association. The PCC was first formed in 1956. The relevant BSR stated: "13. Parachute descents shall not be made with the use of bat-wings or similar devices."

Pilot chute hesitations are well known, so now you know what one is like. I did like that you knew enough about your gear & were heads up enough to check the yellow cables going through the 3-ring loops. It got dangerous there, with an emergency handle that was partially pulled (even if at the time it only seemed like it had moved no more than just out of the velcro keeper). One wouldn't want an inadvertent cutaway when low.

Yes, RC shop / hobby shop. I've occasionally seen it at a crafts store too. For the record, you must have meant to type .025 I can't recall exactly what sizes I've found best, but .025 seems good for Cypres material, and acceptable for everything else. If one is making a fid only for heavier lines, a slightly thicker wire is easier to push through. You described quite an elegant handle with the grommets & leather washers. I just wrap the wire ends through & around a piece of wooden dowel. Sharp wire ends can tuck into a hole in the wood or just be wrapped with tape.

I can't prove anything, but get the impression that in practice, longer lines give lower g forces. Basically, the canopy has a lot further to fly around a wide spiral than a tight one. Say a small canopy with 10' can fly 60 mph easily enough in a diving spiral. A lot of its speed will be in a downwards component, and some will be in a horizontal component, circling around that 20 ft plus diameter cylinder. (Of course line length doesn't actually equal radius of the helix or spiral. This isn't quite a baseball on a string. The jumper at the center is getting pulled away from the center by the canopy, so the jumper isn't just purely spinning, and the radius of the spiral is greater than the 10'.) To make the example easy to picture in one's mind, now put 100' long lines on the canopy. How will it get around its big cylinder fast enough? During its spiral, it may still be diving fast towards the ground, but how much speed can it put into flying around the cylinder in the horizontal direction? In degrees per second, it just can't get around that big spiral nearly as fast. Will the speed change? Sure, maybe the canopy now dives faster than 60 mph, but it certainly won't increase to 600 mph either. It doesn't need the same degrees per second to maintain the same G's, since for a given rotation rate, a longer radius increases the G's. To maintain the same G's at 100' not 10' radius, it would have to fly 316% faster -- and I don't think the canopy will now fly at 190 mph! While the concept of a baseball swung around on a string doesn't really capture what is happening for a canopy flying a spiral, I think it was sufficient to understand the basic situation. OPTIONAL DETAILS: Why 316%? The basic formula for the simplified baseball on a string idea gives the force over the mass (which is a measure of G loading) equalling the radius times the square of the angular velocity. i.e., F = m*r*omega^2 Angular velocity being the radians per second or degrees per second or whatever, that the object moves around its circular path. So if you double the length of the string, and keep the same number of revolutions per second, the G load does double. If you double the length of the string, but only keep the physical speed of the baseball the same (same linear speed), the angular velocity is halved (same speed but twice as far to fly around the circle), and the net effect is a reduction in G loading. To get the same G loading with twice the line length, the answer will be somewhere between those two cases, needing 70.7% of the original angular velocity. Or, for 10 times the radius, G loading is maintained with .316 of the angular velocity, but with 10 times the distance to fly around the circle, that's 316% more speed. Let me know anyone, if I buggered up the math. (As a practical consequence of all this, when I turned a 97 square foot canopy into a 37 sq. ft cutaway-only canopy, I kept the original line length to try to reduce any potential G load issues if the thing spiralled hard.)

Single keels aren't in the greatest demand due to the way they fly, but they are the more common type. Double keels, though, they're really rare, fly nicer, and are in quite a bit of demand among the small vintage canopy community. For example, if I found one somewhere, I know at least 2 other jumpers who'd want to snap it up before I ever announced it in public.

N/A

Some "turbine DZ's" still keep a 182 or similar around, for slow days at the end of the season, hop and pops, etc. Does anyone shift students over to the small plane for spotting training? (Or are a couple lower jumps seen as being too limited for the student -- if paying all they do for gear & instructors, they can get more done going from full altitude.)

Guess he grabbed it just in the right place... only a few pounds pressure against the top of the little ring will keep it from flipping...

Obvious skydiving tip: When cutting away, your left hand has better places to be than grabbing your 3-rings. The full story, that I've been hanging onto for a little while: I've travelled around a bit this summer and met up with a rigger friend who gave me the details and showed me the video. I'll skip names / date / location and focus on what happened. One day a Sigma tandem instructor had a hung up toggle and ended up chopping and using the reserve. The left riser didn't release for about 4 seconds after the cutaway, so the main was still there while the reserve deployed by RSL/Skyhook. Lots of concern, and almost disbelief of the instructor's story. But the instructor actually happened to have a video camera atop his helmet that day, getting a video of one of his own tandems. At first look, the video confirmed his story. Suspicion first fell on the almost new UPT risers, but they looked fine, and nice and flexible. The video showed the tandem pair spiralling, then the cutaway, but the main is still attached at the left side. The main is still partially inflated, while the reserve deploys just in front of it. Reserve lines start out pretty slack, swimming around in front of his face, with the reserve coming out of the bag with a couple of line twists. The freebag (not in view) probably had bounced off the main in some way. Whatever the RSL & Skyhook were doing off screen, the reserve pilot chute can be seen bouncing off the bottom skin of the main. One reserve line snags on the toggle of the left main riser, but soon slides off. The left main riser then departs, missing the back corner of the reserve by a few feet. The tandem pair are left with a few twists under their reserve, but unwind without difficulty. So what really happened, why did the left riser not release? Looking at the video frame by frame, one started to see brief glimpses of knuckles & clenched fist at the bottom left corner of the screen, at the base of the "stuck" risers. Conclusion: The instructor's left hand can't have been grabbing the high mounted Sigma reserve handle as he said; it must have been firmly clamped on the left 3-ring, preventing it from flipping through. As soon as he let go, the main departed. Oops. Adding to this, it wasn't even a real mal. It was one of those toggle hangups that one hears of occasionally, where the instructor yanks down hard on the toggle, but doesn't pull it back away from the risers. Especially with new risers, the snap in the riser & toggle is very tough to release unless one (properly) peels the toggle away from the riser. On the ground, the toggle released just fine. And for a third strike, at some point while still trying to deal with the "stuck" right toggle, the instructor let the left toggle go completely, not holding the canopy straight, so they got into an accelerating spiral turn while he's trying to fix things. After some seconds he chops. The instructor is moderately experienced (1000-1500 jumps total?) but has jumped little this year. Nice guy, no other issues with him, but not all that current. It sucks for him that he videod his own screwup, but at least the cause was explained. Don't ask me what the DZ has done with him, as I haven't heard, but I understand they were planning to report everything properly, and the guy probably is going to at least stand down from doing tandems until he gets more current sport jumping. (One canopy flight exercise I recommend to jumpers for their own canopies, is to try popping one toggle after opening, getting a feel for how fast the canopy starts to accelerate into a spiral, and stopping it with that 'opposite' toggle or rear riser.)

Just clarifying -- are you still talking about Vectors? Their tuck tabs are rather long compared to on other rigs.

Yeah, that's an additional level of detail. There's the trim angle as constructed, the geometric stuff that I talked about. Then there's the angle at which the canopy trims in flight relative to the horizon, which depends on the overall aerodynamics, glide ratio, and the drag of the jumper.

So at the moment your options are to go with your British insurance (if the DZ is OK with it, whatever it might be for international 3rd party liability), or get a full CSPA membership ($85). The CSPA is working on a short term membership & insurance for visiting jumpers, but that's not yet available...

I guess one can stretch everything out on the floor, canopy on its side, tension everything, and start measuring. One issue is that we have no public standard known to normal skydivers, as to what reference points there are. Skydiving canopies tend to have fairly flat bottomed airfoils, so the bottom skin makes for a reasonable chord reference line. (Rather than some aerospace engineering standard of nose to tail, which could work, but suffers from parachute canopies effectively having the nose of the normal airfoil cut off, at least in canopies with continuous nose openings across the span.) If we measure the angle of the canopy, it has to be relative to some reference line -- from the confluence of the lines & risers, up to the canopy somewhere. For the location of where the lines come together, one would have to pick some typical length risers to add to the canopy. As for the point on the canopy, I don't know what other sources use - like Knacke or J.S. Lingard or the PIA or NASA or who ever has written something technical about ram air parachutes. The manufacturers must have some internal standard, whether or not it is industry wide. If I had to guess, how about a line up to the good old aeronautical standard of the quarter chord point.

Agreed now Rehmwa -- ideas to clean up ones body position are good -- and often people aren't taught how having legs too wide kills the ability to arch at the hips.

I've seen flexible people, especially girls, with "too good" an arch, with their shins angled way up from the horizon. If their lower legs are pressing on the air in a normal position, then extending them straight out (which is relative to the upper legs) doesn't add much more push on the air. That may or may not have anything to do with your issue. Remwha: Your post looks good for various ways to get someone to think about and recognize their leg position, and keep both legs the same. But the one about knees more together -- that may not work as advice against backsliding?? Bringing legs more together allows more of an arch to happen, if someone is trying to arch, and is sometimes taught as a modern technique to backslide.

From the article: Lawrocket is right: One can't compare the building to a bunch of solid blocks. This isn't physics for pre-schoolers with their building blocks. The point is that the falling stuff builds up some momentum when a floor of the structure collapses, before it hits the stuff below. So that 36% thing is silly. Compare to this scenario: Someone is trying to help me climb over a tall wall. I can stand on his shoulders and he can take the weight no problem. But I have to get higher, so he supports a 10' pole on his shoulder, and I shinny up it. But I slip, and can barely hold on to the pole, supporting only 36% of my weight on the pole and thus on his shoulder. I accelerate downwards towards the guy helping me. Wham! Big surprise, the truther guy at the bottom is mashed into the pavement. He can't believe I flattened him, as I was only exerting 36% of my weight as I fell... until I hit his shoulders...