pchapman

I joke that I'll just keep shouting louder at a student until they relax, sort of like 'the floggings will continue until morale improves'. Seriously, I agree that "relax" does indeed always need extra explanation. But is there any better word to use? One doesn't want a student to go limp on the one hand, but one doesn't want them to get nervous and do a totally wrong body position (e.g., look down & dearch), nor go rigid with tension (which can pull someone from an arch into a flatter position), nor be so stiff in the arch that they 'chip' in freefall, nor try too hard to push on the air (e.g., moving an arm in freefall will control your movement, but you can't just punch the air as you can lose surface area and lose control). While in teaching one wants to emphasize the positive and the correct way to do things, in this case it is hard to say what is right without showing what is wrong.

It was fun in the old days when you could downsize any way you wanted and nobody would give you any hassle. (Mind you, one didn't plan to start hucking big swoop turns.) As for wing loading when a canopy starts to get exciting, it seems to me to be around 1.2. Story time? OK, these were the bit scary downsizes for me: a) jump 33. I had been on rental Mantas with about 3 jumps on smaller 240-250 canopies, when an experienced jumper tried to sell me a Firelite 172 in a rig with a 22' low speed reserve. Even in 1991 that sounded stupid, but I put a jump on the gear. The canopy was very responsive so I flew it gently but the landing turned out fine since there was a ton of wind that day. b) jumps 205-208 on a Jonathan 92 (1.8 loading) when I only had a dozen jumps on canopies under 200 sq ft, with the smallest being two jumps on a Sabre 120 (1.4 loading). Exciting! Running out the imperfectly timed flares was a bit tough on the ankles but all else was fine even on no wind hot summer days. That's the old school way to downsize: Do at least two jumps on a canopy to get the hang of the flare and you're good, jump down two sizes if you want, and don't worry about square vs. elliptical c) At jump 550, after only 90 jumps at 1.2 loading or more, when I usually jumped accuracy canopies, I borrowed an FX 88. That first crossbraced jump was interesting. Pop the brakes and it felt like the floor had dropped out; those canopies dive so much more. With the wind noise it felt like for the first time I'd need ear plugs for the canopy ride. The crazy descent rate (as it then seemed) did require close attention to flaring, but at least one had the speed to have time to adjust the flare. The first few flares were wobbly -- never before had I had to flare quite as evenly with both hands to avoid diving to the side.

Interesting question. Here's the little I dug up: [Slightly edited because Alpha Para Equipment was the company name, and Telstar is the rig name, but it looks like Telstar might unofficially and later officially also have been used as the company name.] Poynter's I has Telstar at 5.130 and 9.2: - In 9.2 there is just a list of company addresses - 5.130 has half a page on Bob Boswell's company in Kentucky and their rigs. Alpha-Para Equipment built the AL-1 and later the AL-2 Telstar. Web searches: Another site (not updated for some years) says about the Telstar rig: "Packing information obtained from Bob Boswell (Owner / operator of now out of business Telstar Systems). Bob Boswell now owner of Kentucky Balloon Loft, 502 477-6333" And a retired jumper (who I actually know) made a comment on someone else's site: "At the time, I jumped a red & blue (TelStar pattern) Mark I ParaCommander. " I also have a set of graphics showing round canopy colour patterns (from Beatnik or someone on this site). The page showing the official 1968 Pioneer PC colours has one that is "New dark blue Telstar" -- dark blue with 6 red stripes basically. How ever that pattern got to be known as the Telstar pattern, perhaps the ones that passed through Bob's loft, or ones that went into his rigs, got stamped Telstar? PC's didn't seem to normally get stamped with any identification of their colour pattern name.

Re: Hitler does Gangnam style Meanwhile I hate it when people post links without a full description of the subject matter. Doesn't matter if it is Brian Germain showing his latest wisdom, or some acquaintance saying, "check out this cool video on youtube". Really? A video on youtube? I would never have guessed! There are some nicely produced Gangnam parodies out there. The Hitler one isn't very sophisticated, but it nicely brings the memes together.

99%of your posts are great but I'll have to comment here: I'm not sure what you are criticizing in this case. Most of the rigs in the whole industry? Racers have two different pilot chute sizes available, which is a rarity. Everyone else (?) has the same PC whether it is for a 99 reserve or student gear or a tandem. I thought there should be. We call it "staging" as you know. We had rigs with staging loops in the early 80s but everyone went to container friction to stage instead. Except for UPT who went back to an optional staging loop not because they wanted to for all rigs, but because the Skyhook, for all its good, adds a lot of complexity to a rig's function. (They added complexity to deal with complexity...) So yes indeed there are a million variables and we haven't solved how to have every rig extract the bag at exactly the same speed (based on pilot chute pull force vs. bag mass vs. container friction) in every desired direction. I thought we mostly still accept that at some low speed, it is better to have a pilot chute trail and not extract the bag, rather than have the bag just dump & tumble out. Heck, one area of concern among skydivers is rigs that encapsulate the reserve bag possibly too tightly, and it seems like Racers are some of the least stiff and constricting ones on the market.

The Reflex actually uses a molar freebag I believe. So no tunnel (like is nicely done on an Icon) needed. But yes one wonders a bit about that design aspect of the Racer, even if it seems to work OK in practice. The loops get pulled through under tension and ideally remain in tension during the pack job (but I'm not sure that always happens in practice). The manual does say the buffer strips are supposed to provide protection, but I'm not sure that that happens on every pack job in practice. (And the manual still shows what seems like a 1960s military practice, as an option, to do a whole bunch of tacking through the loop. Yikes.)

FXC's may indeed be kicking around and essentially free at any DZ that converted away from them. You might also figure out the proper mounting on a belly reserve. The problem that skydiving authorities always insist on following manufacturer's directions for maintenance --- just as for one's Cypres. So then if you want to have a LEGAL AAD on the reserve, you're on the hook for the $160 or $200 ???? every 2 years for the disassembly & inspection at FXC Guardian, plus shipping. That's not to say that I haven't thought about rigging up a KAP3 to a reserve and telling the authorities to prove to me that the 40 year old device needs maintenance.

AAD rules really make it tough to jump old gear. One can still find old gear kicking around but it may be simpler to just jump an old main rather than old main/reserve/rig. If going with a belly mount, and you can get around the stupid AAD rules, it is nice to have a decent more modern reserve too (especially if one isn't light), and get something like a diapered Strong Lopo. Nicer for deployment than some old military style reserves (even if the military ones are very strong). And the Strong Lopo is still tougher than the wimpy light weight round reserves skydivers used for a while. For a main, something like a ParaCommander is a little more practical than a T-10 for providing some forward speed. I don't know about T-10s, but PC's land relatively soft. (And by being able to counter moderately low winds, that also reduces total velocity on impact.). Put it on 3 ring risers, with a bag and regular throw out pilot chute. (There are minor complications - crown line stowage, brake line positioning, but that's for later.) One standard answer is to find old student gear to put a round main in. Even that may not be big enough, as a ParaCommander in a bag (not even a bulky sleeve) is quite a bit bigger than a ParaFoil 282 which I think offhand is bigger than a student canopy. So then one would do some sewing to rebuild flaps to accommodate a larger canopy. An alternative to that is to build a separate main container that velcros on over top of the existing smaller main container, so one doesn't wreck the original rig, if it is ever going to be used for other canopies. That's what I did for an accuracy rig to convert it to a ParaCommander. (It was a tip I got from the Aussie style & accuracy team a decade back.)

Hmm, doing the calculations, it does look like it takes some speed to get much drag out of a reserve pilot chute. We know that in practice, a reserve pilot chute won't always extract the bag when someone is flying at lower speeds. The calculations are just there to compare to theory. Hope I didn't do the numbers wrong, but if one does the standard drag equation of drag = half * rho * V-squared * reference area * Cd, I get 18 lbs of pull force only at 41.5 mph, if the reference diameter for a Racer reserve pilot chute is 30". That's about what I measure for one as the finished, constructed diameter. (If somehow one used a more generous 36", the number would be 34.5 mph). The drag coefficient is taken to be Jumpshack's own reported value of 0.83. For a lighter, maybe more practical 10 lb extraction force, 31 mph are needed. If one is considering a scenario where other rigs' reserve pilot chutes are no more efficient, and are no larger than 36", then the above 34.5 mph value will also apply as a minimum speed to achieve 18 lbs of force. Now I don't think that the Racer freebag would normally take 18 lbs of extraction force, but that's a number that was in a JumpShack document about what they consider to be maximum acceptable bag extraction forces for any rig at most angles, and was mentioned by the original poster. (Reference: http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3922046; Still it is a surprise that the reserve didn't get pulled out while the jumper was still at higher speed during the main canopy deployment. The minimal info presented so far doesn't suggest that there was any factor causing a hard extraction of the bag from the rig.

Oh man, Argus's AND Racers all in the same thread. This is gonna be fun. One does wonder about the timing of the Argus fire relative to the jumper's speed through the air.

Is it just the City of Zhills doing this on a whim or is there something behind it? DHS? FAA? Federal funding? I've been at a couple medium sized airports (in Canada) that got fenced in over the last 10 years and it is a pain to walk from one hangar area to another, or to even walk around a hangar & office area as there are fences separating 'airside' from 'out back'. If this is anything but a whim by someone on city council, I bet this will have to be fought with meetings & facts & graphs & comparisons to other businesses & airports, not by a list of skydiver names.

Attached: A screen cap of the fb page of the helmet DFF modified. No zoomed views, but something for the non fb'ers. So what kind of helmet is it anyway? Bike, paraglide? You have some sort of weak link in the chin strap, as the release mechanism? What force is needed on it to break it? I'd kind of like to grab your helmet and try to wrench it off your head, and see how your neck survives, to see if you do have everything figured out... But everyone agrees (without using capitals) that skydiving helmets are crappy for shock absorption.

A little bit of an update: I got in touch with a senior person at Aerodyne. Although their public statement left too much out in my opinion, which attracted my criticism, they do have some additional information. -- The reserve was a Smart 160, a perfect size for the Icon I5. -- They have since tested with someone pushing down a moderate amount on the top flap, but haven't been able to lock up the pilot chute that way. -- The reserve loop lengths suggested in the manual could use some updating and they'll look at that. -- When that particular rig was closed, a rigger could push down hard on the pilot chute and pull up with a bar and pullup cord, and get 7/8" of slack in the reserve loop. So there was indeed a lot more slack than one normally expects. -- Aerodyne didn't just blame the rigger and wash their hands of it all when the statement was issued. They're still interested in more evaluation & testing, despite not being able to replicate the issue so far.

Nice to know Dacron is still reasonably good (and of course long lasting) even for smaller sizes. Normally one only hears of the occasional cameraman Dacron lining a normally somewhat faster canopy.

So, what lines are they using on such high performance CRW canopies these days? Still all dacron? Or center and ends dacron or what? (NZA web site doesn't show any JFX CRW canopies.) Edit: No Dacron? Even for their Matrix CRW canopy, the order form is generic across all their canopies. On it one can order Spectra / Vectran / Technora, but Dacron is listed only for tandem canopies...

Awareness of body position, orientation, and movement will certainly help in skydiving. In freefall we rely a lot more on aerodynamic forces, rather than the initial impulse of momentum like in gymnastic sports. The momentum aspect still matters (eg, tuck up tight to carry through) but aerodynamics matters too for the start of the maneuver (eg, legs are still out while upper body tucks down, if one wants to start the flipping forward motion), and aerodynamics matters for stopping a maneuver (eg, arms forward to stop a front flip) Of course the aerodynamics are always there throughout the maneuver, but the gymnastic momentum aspect becomes relatively more important during the middle of a maneuver. I'll let others address the details of front and back loop technique.

Good point. It all depends on what kind of "surge" we are talking about. All canopies pick up forward speed at the end of the opening sequence so how much more is a short duration surge adding? Who cares if a bigger canopy surges when you'd be moving much faster with a sub 100 crossbraced canopy anyway? If it is the type of surge forward that happens after a stall, then the canopy doesn't have much forward speed to begin with, so it is safe in that way. But since stall behaviour can be more unpredictable and unpleasant the smaller the canopy, you don't want even minor stalling on opening. [Experienced jumpers: Yeah Sigma reserves are interesting...] While a surge on its own may not be an issue, controlability is. If the forward dive is sudden enough, it may unload the lines a bit and especially if one is bouncing around a little at the end of opening, or not perfectly symmetrical, or the canopy is hunting in direction during the opening, loss of some line tension could allow one's body to twist enough to twist up under the canopy. So it is all a matter of degree. Every canopy varies in how much distance it takes to open and then picks up forward speed, but if a surge is enough to reduce line tension significantly then it could become a problem.

The obvious guess is that NZAerosports made them in house since it is a NZAerosports test jump video. Risers that hang a 3rd canopy off 3 rings added to the main canopy risers have been done before by different folks I think. Wasn't that the sort of setup that Rob Harris had a problem with when he pulled things out of sequence and died? I can't recall. (Don't chop the regular main if it is still in the pack with the 3rd canopy attached and flying.) Airshow cutaway demos by military teams have been done in a similar way? Think so but not sure. What I don't like is the cutaway system (for the 3rd canopy) that's up on the risers, one on each riser. It makes sense from a construction point of view, but getting the cutaway system caught up in line twists is possible especially when using it with experimental high performance canopies. In the video, the jumper manages OK to grab the handles while twisted up, but still. See a similar system in the pics at post 50 of http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3965994; (A single point release not on the risers was used there, but one side I think accidentally released when the risers stretched out way from the yellow cables --but that part of the system was a bit jury rigged without housings for the yellow cable.) I guess I'd rather have a 3rd canopy anchored off a ring attached to the harness rather than off the main risers. There are a few ways to do that. Your url clickfied: http://www.youtube.com/watch?v=WD9oy73c5Ns

No time for a careful answer but it can be "both". The canopy's descent rate is lower, which is the big thing. But forward speed is down too, the actual glide ratio (thru still air) is probably better, if one is comparing zero to moderate brakes. Somewhere in deeper brakes though, there the glide ratio might get worse. Even then, one might still be doing better in getting back, having a better glide ratio over the ground. (If it is windy enough, a piece of confetti will get back to the DZ, even though it's glide ratio is roughly straight down in still air...) As usual, things depend somewhat on canopy style, as to at what point adding brakes makes the glide ratio in still air worse and not better. To really understand glide ratio in still air and the glide in wind, one needs to understand "glide polars" and how to shift them for wind. If one found some glider pilot resource on the web that would help, but I don't know of any site off hand. In typical cases, what one loses in forward speed from going to brakes, is more than made up for by having lower descent rate, when there's a tailwind that's giving you "free forward speed" over the ground. But that's when it is fairly windy. When winds are lower the answers are less simple regarding what canopy controls will be best for your canopy that day. In practice once can of course try to use the accuracy trick of seeing whether one's target of the DZ is moving up or down in one's visual field, and play with brakes or risers to see what works with the current conditions on your canopy.

Hey, the messier the lines are, the more money I make as a rigger sorting it all out on the clock. But for the owner, it is nice to have lines neat. And a card keeps line groups from falling through each other and making a tangled mess. But so does connecting links to each other, and so does tight daisy chaining, or even just using an elastic to keep the links together in one place.

[EDIT: Looks like Twardo has made the point already but anyway:] There is actually a happy medium in the debate on "go for a road" vs. "go for a field": I say, go for near a road, but not right next to it, and only to the limitation of your own skill. Some people make a beeline back towards the DZ and when they can't make it, end up in the middle of some muddy or crop filled field. Better to make the decision early and head for someplace safe but easier to get home from on the ground, like near an access road. If you don't want to deal with gravel or pavement on roads, telephone and power wires, ditches, fences, etc, then land a short ways into the neighbouring field -- 50 m, 100m, whatever is in your comfort zone based on the conditions. Personally I've swooped under a wire stretched across a road and then run the landing off into a ditch at dusk, so as not to spook an oncoming car too much -- but that doesn't mean that's the normal smart thing to do... So "go for a road" should be interpreted as "near a road but a safe distance away from related obstacles". (And wolfriver, thanks for countering the "wind at one's back" misconception!)

a) As I pointed out, that's based on a factory statement about the correct loop length is 1/2 cm shorter than the shortest listed in the manual for three different sizes of reserve in the manual (which vary in a range of 2 cm). b) Therefore Aerodyne is saying that the loop is too long compared to their own secret knowledge of the correct length. c) It supposes that there is zero variation in allowed loop length. If Mr. Factory Rigger in Florida says "3 inches" is normal for a particular rig, am I a bad rigger if I use a 3 1/4" loop in winter in dry air where I am? d) As you pointed out, a little slack has always been considered acceptable after being packed a long time. (Although having much slack is now less common with small rigs and leverage devices to make rigs super tight.) It would all be easier if they just said that with the rig packed, they could push down on and compress the pilot chute and pull the pin & loop up an extra X" of slack, whatever that number might be.

Well that's what Aerodyne is saying based apparently on the video, but it isn't clear whether that is true. The first frame of the video given to Aerodyne shows someone holding the pin end of the ripcord. I don't know why Aerodyne assumes only that that's how the reserve was popped. Maybe it was, maybe it wasn't; one can invent scenarios for both. If the rigger did pull the pin out from the pin end, while pressing down on the rig, that could indeed let the pilot chute start to expand only slowly, making it easier for friction of all the flaps to hang it up. As for the rig not being worn, OK, that does affect geometry. But does one want a rig where the company says that the reserve does "table total" occasionally? And to reiterate from a prior post, since we don't know what the reserve canopy is or how much slack there really was in the loop, I'm not sure we can say that the closing loop was terribly long. Longer than ideal, sure, but how much is unclear. I also don't want to have a rig where it table totals because of a half inch too long loop. The Icon is probably no worse than other rigs, but Aerodyne's response could have been much more convincing.

Good point. At http://www.cypres-usa.com/, there's "CYPRES User Selectable Activation Altitude" April 2012, which links to http://www.cypres.cc/index.php?option=com_content&view=article&id=396%3Acypres-2-neu-auswaehlbare-einstellungen&catid=84%3Atechnik-aktuell&Itemid=178&lang=en But that is the info that has been in this thread already, and makes it sound like the new feature hasn't yet been implemented. So is it available currently or not? Anyone asked SSK or Airtec? (As much as I like Cypres' functionality, additional future modes would be so much easier for users to adopt if the Cypres had a dot matrix display like the Vigil. )

A few notes on Aerodyne's reply: -- They partially fault "initiating reserve deployment in an unconventional manor" (sic). But it isn't clear whether the reserve was popped by pulling on the cable under the pin cover flap or not; they need to talk to the folks in Sweden more. The first frame of the video they received does show the rig on the ground and the pin in a person's hand, but it isn't clear what happened before that. Was the pin pulled manually with the rigger's hand perhaps against the top flap as Aerodyne suggests, or was the pin pulled the normal way, the pilot chute didn't launch, and then they put the rig on the floor and got out the camera? -- They show the "excessively long" loop to be 7/8" above Aerodyne's specs. (But see my next point too! - it isn't that much.) But how much actual slack was there? That is, before pulling the pin, how much could a rigger compress the pilot chute and pull up excess loop? Plenty of rigs have loops that are above some manufacturer's spec, some of which are more realistic than others. The loop sounds longish but I wonder if that amount should be considered dangerous for an ideal rig. -- Aerodyne claimed: "Typically, we would use a 115mm (4 ½”) with this combination." This specification is below any in the manual whether for a smaller, medium, or large size reserve. And the specs are shown only for Smart reserves. Looking in my Icon manual dated August 2011 (which is still current), it shows loop lengths of 12.0 to 14.0 cm for the Smart 150 to 175 reserve, in an Icon I5. Although the rig is an I5, we haven't been told what reserve was in use. If it isn't a Smart reserve, then there is no exact directive as to what the proper loop length will be. (The loop in the incident was 13.7 cm, within the range suggested for the rig, depending on reserve size.) So while the loop length may have been long in that it allowed for slack when packed, Aerodyne has done a very poor job in showing what length it should be according to the manual. -- For the first time, we see that this was a case of popping the reserve with the main in place. The first photo in the pdf is a good example of how the main can interfere: The main side flaps just slightly overlap the stiff reserve bottom flap, making it harder to lift up. That flap in turn adds resistance to the reserve side flaps, which in turn resist the pilot chute. At least Aerodyne attended to the matter quickly and tried a variety of tests, and had the pilot chute always fire. Although they got limited info from Sweden, both of their claims as to the cause of the problem are a bit weak. To summarize: a) it isn't clear if the reserve was activated the unconventional way they said b) it isn't clear how much slack there was in the loop, and their own claims on what the loop length should be do not match their own manual Google translate of the Swedish portion is below. Pretty mangled though. Is it saying the grounding is lifted or not?