pchapman

Thanks, I failed to really consider how most of the end cell line attachments are covered by the stabilizers, on most canopies with flares. Only SOME end cell flares aren't covered and protected. E.g, No stabilizers at all in photo 1 of a current Flight Concepts reserve. And no stabilizer protection for the A-line flares of a Glide Path canopy in photo 2. The colors make it apparent how the end cell flares are still there but covered by the stabs for the B,C, & D lines.

To add a little bit to all the time & altitude stuff, particularly what 980 and billvon wrote about, I timed some of the openings in two RWS Skyhook videos, just using a stopwatch, not frame by frame analysis. Time from cutaway to fully inflated canopy: 3 sec typically, from a straight flying canopy As we know, that's not the same as having a canopy flying stable. In one case on video, the canopy had a big swing on opening so it was 2 more seconds until the canopy was flying close to normally. (The RWS video with the slider down "100 ft" cutaways shows another example of the big difference between just 'open' and 'close to flying properly'.) From a spinning canopy, time to full inflation: 2 sec typically in the best cases 2.5 & 3 sec seen in cases where the reserve snivelled for a moment Time to extract the canopy from the freebag: 1 sec on the videos from flying straight 1/2 sec by billbooth's frame analysis, cutting away from a spinning canopy To go from cutaway to canopy extraction one needs maybe 8.5 ft for lines (PD-126 A-lines), at least a foot for the risers, a foot for the bag, maybe a couple feet for the stretched out canopy if you want to include that, and 7 ft for the bridle (Billbooth once posted 7 ft to bag to skyhook, plus 5 more to PC). Total 17.5 to 19.5 ft. In 1 second (ignoring minimal air resistance) one accelerates downwards 16 feet. If one starts with initial downwards speed, one has to add that on, e.g., 31 ft total vertical distance if starting at 15 fps down. (I'll leave aside just what the main canopy is doing, as one needs enough vector distance [Vector distance?

I repacked a modern GQ pilot's rig last year. It wasn't just a plain old round but one with a lot of interesting features clearly derived from their military experience, and a rating of 280 lbs at 200 Knots. Despite all that, it used a lowly MA-1. It seems that MA-1s have a lousy launch, lousy snag resistance, but if an MA-1 finally does find some clean air to catch, I guess it'll catch it very efficiently in any attitude. That's a bit of thread drift, but it is interesting to what degree reserve PC weight, and how it is balanced, affects the time for parachute deployment. A low altitude BASE jumper wouldn't be thrilled to tie a one pound lead weight to their PC's cap! Yet skydivers don't start right at zero airspeed, and plenty of different designs get TSO'd. (TSO requirements as I recall are sloppy in that there's no maximum speed specified for the low speed case?)

In general, canopies using flares are less common than those with direct line attachment. But both are considered acceptable in skydiving. I'd like to dig a little further into the issue to learn more, because there are some features that seem like they might make canopies with flares slightly less reliable. I've long wondered about canopies with flares, well before the hot issue at the moment about a structural failure on a reserve, apparently of a design using flares. (http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2177335;) Some possible issues: -- SLIDER STOPS ON FLARES MAY BE MORE LIKELY TO ENTANGLE WITH LINES: As I wrote in that other thread, is a slider stop which is a lump at the pointed end of a flare more likely to entangle with lines, than a stop that is embedded within a stabilizer on a direct line attachment canopy? On the latter, the stabilizer and associated fabric tapes are still flexible so it isn't impossible for a line to wrap, but it seems to be a better design in that particular regard. -- FLARES SEEM TO BE LIKE PACKING WITH THE SLIDER PARTIALLY DOWN: Flares (and their slider stops at the end cells) keep the slider quite a few inches away from the canopy in the pack job. This would seem to make it harder for the slider to control the initial stages of opening, and harder to tune the design for good, consistent opening characteristics, although obviously plenty of canopies do work OK with flares. It might be OK for big F-111 but get tougher for small zero-P canopies. (I just looked at a fuzzy photo of the Flight Concepts high performance canopy, the Rage. I can't tell whether it has flares, but if so, they must be tiny ones!) It certainly isn't the same as a sloppy pack job with a slider a few inches off the stops, for the design with flares still keeps the slider in a consistent position on the four line groups, promoting a symmetrical opening. -- FLARES COMPLICATE RESERVE PACK JOBS slightly, at least in relative terms for those who are more used to direct line attachment canopies. The flares effectively extend the length of the canopy, sometimes making it harder to get the S-folds to neatly shorten the canopy to go into the freebag. Also, after the S folds, the grommets don't end up near the base of the pack job, but are pushed up into the pack job by whatever length there is in the flares. (Glide Path and Flight Concepts manuals that I recall seeing, show pulling the canopy tail down to the bottom of the flares when cocooning the pack job, before S-folding it.) Both because the grommets are buried in the pack job, and because they may be at the fold point of the first S-fold, it becomes harder to control the slider's position. (Of course, riggers have to control the pack job, whether or not they consider a particular pack job easy.) -- FLARES COMPLICATE MAIN PRO-PACK PACK JOBS: This is a minor point. The added length of the flare just makes it harder, for a given size canopy, to reach down inside the canopy and flake it. -- FLARES MAY INTERFERE WITH SLIDER MOVEMENT: I've seen some main canopies where the slider stops are arranged so that when the slider is tight up against the canopy, parts of some of the flares do or can go through the slider grommets. To what degree does this increased bulk going through the grommets increase the chance a mal with the slider stuck up on the flare with some sort of tension knot? I recall a Manta canopy mal with the slider hung up, that was blamed on a packer who admitted being frustrated and jamming the slider up against the canopy very hard, apparently getting some of the flares into the grommets. While it may be comforting to have as little bulk as possible going through slider grommets, Paraflite did have reserves (with direct line attachment) that used slider grommets much smaller than the regular #8. So big grommets aren't considered the only way to do things. I don't have any big bias against flares, but am more comfortable with direct line attachment canopies. I realize that canopies with flares do seem to allow a more gradual transfer of loads from lines to canopy, with less point loading to deal with. Despite any structural advantages there, using large flares does still result in significant increased bulk. Maybe jumpers with more 1980's experience, when canopies with flares were more common on main canopies, might be able to comment on whether flares were seen as a complicating factor or not.

Over in Europe you know more about him and must have some reason to make fun of him. But when all the recent high altitude attempts got going, there were about 4 or 5 people going for it. I don't really know the situation, but the only ones I hear really doing anything are Fournier and Stearns. And even Stearns gave up the attempt for a while. Fournier actually travelled to his launch site a number of times in preparation to go. He had various problems like a torn balloon, or a vital ground crew member with a heart attack. Unless it was a big scam, it seemed as if Fournier was truly trying to get ready to launch, and not just taking a holiday in Saskatchewan, Canada for some reason. So maybe he's an odd fellow, or isn't current in regular skydiving, but on the surface he has significant credibility in the high altitude race relative to his competitors. I really don't know the details so I am curious why he's such a joke!

(etc) Pilot rigs have just one chute. The plane is their "main", the rig on their back is the "reserve". 99%+ of the time it is a round canopy. There's no required training. There are usually a couple pages in the manual about how to use the chute - how to deploy, how to steer, how to land. For most pilots, it's a matter of getting out of the airplane, getting clear, pulling the ripcord, and worrying about everything else when that time comes! For any knowledge beyond that, it is up to the pilot to educate himself. Some pilots will ask a few more questions when buying the chute or when talking to their rigger. PS - One save I know of is by a rigger named Julian who started jumping in the Toronto area but later was at Chicagoland or thereabouts. He got one or two saves a few years ago from the pilots of a Christen Eagle aerobatic aircraft who had to bail for some reason.

I've done stall turns from time to time. - On my big old 265 ft sq. F-111, no problem. Fun to scare the newbies on the ground, and have instructors tell their students, "No that's not a mal, that's just Peter". - On a Sabre 135 at 1.25 WL: If the brakes are left set, it flies beautiful rear riser stalls. So one can do nice stall turns from the condition where the whole canopy is slightly stalled. Turns and flight are very stable and controlled. The canopy basically maintains its shape, but isn't fully inflated inside. - On an FX 88 at 1.9 WL: I've occasionally done few stall turns using rear risers with brakes set. That keeps the dynamics a little more controllable. Slow it close to the stall, stall one side to get the rotation going, and spin away. The exit back to normal flight can be a little tricky for the novice. I have to make sure to ease off slowly to give it time to reduce the rotation rate, to avoid line twists. It's not great for spectators since I've only done this stuff up high, say 3000'. A friend then started doing the same type of turns on his VX 79 but using the brakes. So there must be others out there with stall turn experience on small canopies.

As you'll know Airtwardo, Rick's original bailout was similar to Sean T.'s, involving a failure in the elevator system. But when he went in he didn't get out of the cockpit (NTSB #ATL96FA051). The accident I referred to was a Su-29 near New Orleans just a month later (FTW96FA151). As for rig thickness, it may not usally be a big deal, for all I know. Rig design probably influences comfort a lot more, and as was said, the canopy gets spread out over a large area (Although there are some cramped cockpits where the pilot does need a specific shape of rig to fit well.)

Pilots often seem to consider just about any TSO'd parachute "good enough" because it is so unlikely they'll get the chance to use it. So they'll put their spare cash into something else that they feel matters more. The thinner and more comfortable the rig, the better. Attitudes changed somewhat after 1996 when one fellow bailed out of a Sukhoi at high speed (220+ kts) and blew all the lines off his light weight chute. (I don't know if he would have had the altitude to slow down.) Acro pilots started looking at the max weight and speed numbers. There's an American aerobatics mailing list that I'm on. A couple years back there was a discussion of round vs. square. Although squares were seen to have advantages, there was a lot of discussion back and forth about which opened faster, and whether a tumbling pilot would end up with line twists and an uncontrollable parachute anyway. So there was still a lot of hesitation to go for a "fancy" square system with a lot of unknowns for them personally. For me there's confusion about what size of square canopy a pilot would want. I guess the biggest canopy of the Aviator line (280 ft. sq.) is pitched the most, because of its special brakes & "anyone can use it" characteristics. If a pilot wanted to get a square rig that's no more bulky than the Phantom / Aerostar 24, they'd have to go to a Raven 150 for the same canopy pack volume. (At least according to one set of those ever-variable pack volume charts.) But if a pilot accepts the bulk of a more solid canopy anyway (e.g., like a Strong 26' LoPo at 487 in. cu.), then it probably doesn't add much in bulk to go to the biggest Aviator. (A Raven IV of about the same quoted size is 506 in. cu.) In the end there's still a lot of learning to be done about squares for pilots, and Sean Tucker's case will likely be well discussed. (But so far the only report from him that I've read, focuses on the airplane not the parachute flight.)

I looked at my photocopied manual -- While you may want the full manual in the long run, in practical terms what's needed is a copy of the few pages that cover setting the brakes. (There's also brake line trim info in the manual.) I could scan the manual but it sounds like you'll soon have other sources. Otherwise the manual just shows a basic old style reserve flat pack, with the last part covering how to put the Swift canopy into a Swift rig. The tail is flaked normally despite not having brake lines to the back corners. I once came across a Swift that had had the brakes assembled incorrectly. It was missed by 8 different riggers, in the US & Canada, military & civilian. It was only discovered after a friend of mine had to use it. Only the 'fly away' lines went through the guide rings, but not the lines to the toggles. No big deal; he just made sure he didn't let go of the toggles once he popped them!

It must be one of a very few bail-outs ever done with a ram-air in an emergency rig?? Not a lot of those rigs around it seems.

Clearly the well-discussed issue of line stowage affects whether a random line might catch around a flap. Another issue affecting the chance of entanglement might be the design of the side flaps. Perhaps one wants to avoid very soft (easily deformable) sections next to very hard, stiff sections. Either keep the whole flap stiff, or the whole flap soft. Sharp taper on a flap may also be beneficial. That's just a theory for discussion, and I'm wondering to what degree manufacturers have taken it into account. Flap stiffness was part of the discussion after a couple accidents where lines wrapped around the top flap of the European Omega rig, but mainly in relation to that particular design. Surprisingly, I didn't see it really discussed in relation to the fatality in Texas on a Javelin. Some brief experiments: I played around at home with some rigs and a spare piece of line, trying to catch the flap in both of two ways: a) a full loop in a line catching around a flap, getting pulled in opposite directions, (fig. 1 of attachment) or b) a line pulling from one side of the flap only (fig. 2). For now I won't try to predict what's more likely in actual flight, and how it differs from ground tests. The fig 2 version is more like what was shown when people were experimenting with the Omega rig. 1. A mid 90's Racer. It has no plastic stiffener in the side flaps, unlike most rigs, only a webbing reinforcement near the grommet. This made it very hard for a loop of line pulled tight to catch the flap without sliding or twisting itself off. The Racer design is very good in that particular way. 2. An old Vector 2. Here it was relatively easy to catch a flap, because the side flaps are very thin and deformable, allowing the line to tighten on the flap, but with a heavy plastic reinforcement near the grommet, preventing the line from sliding off. (The side flaps are 2 layers of cordura, with no foam layer, on this particular rig -- Vector design did change over the years.) It's this sort of design that I worry about the most. 3. A Mirage G3. Here the tendency to catch a flap was fairly low. The side flap design tapered sharply (see fig. 3) which made the line tend to slide off without digging in and catching. There was still a less tapered part before getting to the hard plastic grommet reinforcement, but the line didn't easily catch there because that part had a light weight, flexible plastic stiffener in it. (The rig being fairly narrow might make it easier to taper the side flaps sharply.) It all makes one wonder about how flexible flaps should be. They still need to bend, and avoid things like having cracking plastic stiffeners in them. But it may be good to have some stiffness other than just near the grommet. Additional binding tape, webbing, or sewing (which can greatly stiffen multiple layers of fabric) might be useful, especially along the top and bottom edges of side flaps.

Yes they get that. To which frustrated paraglider pilots say there's no jumping involved, that they inflate the canopy and fly off the mountainside! Or they have to start into an careful explanation of the differences between paragliding, parasailing, hang gliding, and BASE. As for the original skydiving question, I usually go with one of the answers like, "Because it's incredibly fun, challenging, and exciting." Other things to add in are that the view is great, there's incredible freedom in the sky, that it's my preferred way to catch a nice cool breeze in summer, or that it can be very relaxing.

That's the way it works at the C-182 DZ I frequent. (With a ceiling check exception that's already been mentioned, if the DZO OK's the flight.) It's easy for the jumpers to discuss in the air whether to ask the pilot to try for more altitude, and together take the risk that they'll pay for high but jump low. But what typically happens for a Twin Otter, where it's harder to have a meeting and arrive at a consensus? On the loads I've been on, it seems to have been the pilot's decision and you trust he'll try for a good judgement. Or is there an agreed plan before leaving the ground, that isn't changed in the air? (As mr2mk1g mentioned.)

One study showing current draw for a Cypres is at http://www.pcprg.com/cyprespc.htm It doesn't sum up the current draw over time, but one can easily do that mentally. (Eg, when the LED is on, the current may be high, but only for a few seconds.) If the data is accurate, it suggests turning the Cypres off at the end of the day is worth it -- both for a flatland jumper and especially for the person driving home in the mountains.

Years back I made some weights myself using steel shot from a hunting store. It had the advantage of avoiding lead dust, but because of the lower density, I ended up with pouches of less than the standard 1 pound per bag. The steel wasn't perfectly clean either, as it was rusty coming out of the bag. I put the shot in small plastic bags before it went into the pouches, but that also increased bulk. There are weights made with about 1 inch square plates of lead, avoiding much of the lead-on-lead grinding problem. I don't know the source of the lead. About four are sewn in a row into a pouch, making a beautifully flat weight, which is very comfortable in a vest. (Bulk isn't as critical for the often superior weight belt.) The flat weights I saw were built & sold by John Moore of Alberta.

N/A

A friend had a compatibility issue when using a Vigil AAD in a Mirage container. The Vigil cutter (unlike the Cypres cutter) has a plastic sheath that, I am told, protects the loop where it passes through the cutter. After having been installed for just one packing cycle, the Vigil cutter's sheath was found to be cracked and broken when the rig was opened for a repack. This was on a very small, tight rig. The Vigil company is sending the jumper a free cutter, but didn't propose any long term solution. I presume they are looking at the issue. The apparent cause: On a Mirage rig (with the cutter moved due to the PSB1204 service bulletin), the cutter is pressed between the hard cap of the pilot chute, and the various hard flaps & grommets stacked above the cutter. On many other rigs, the cutter is not squeezed between two hard surfaces (E.g, it might be between a flap and the soft deployment bag). I don't know to what degree the Mirage's optional new concave topped pilot chute might be an improvement. I haven't seen the cutter yet, and don't know with what frequency this problem has happened.

Just food for thought: A DZ I jump at just moved to a location where the land around the DZ is 200' higher in some directions, particularly towards the most common exit spot. The DZO is suggesting Cypres' be set for a landing offset of 200', but is leaving it at the jumpers' discretion. (Student reserve FXC's will be set to 1200' rather than 1000' as before.) Just curious what other DZ's have done, that have similar or even higher terrain near the DZ. There are obvious arguments both ways. (Plus some less obvious ones about altitude offsets that require careful understanding of one's AAD manual.) With 200' difference, realistically I expect most jumpers won't bother to set an offset. (It's a piston Cessna DZ too, so we don't have as much altitude to play with to begin with.)

Anyone have an electronic copy of the manual for the Westway Innovator I container? I know there's an "Innovator.pdf" file out there somewhere. I've got the Innovator II manual but discovered that for some reason I didn't have the Innovator I manual.

To the end of '05, 501 repacks 18 known saves The first 2 saves were when I made a poor dock on a buddy during a CRW dive. At least it cost us nothing to get packed up again. I have been fortunate to receive a few good bottles from customers.

It seems we're talking about that last aft bit of stabilizer, between the D lines and the trailing edge. Where I jump, it is known as the "J", from its shape when students are taught to flake it when flat packing their mains. I don't know if anyone else uses the terminology. It has always been logical to me to flake it to the outside like everything else.

The Aussie document is about taking wheelchair dependent people up as tandem passengers, leaving the chair on the ground. I understood that the RWS document is the same type of thing.

Re - tandem skydiving with 'wheelchair dependent persons' Yeah I tried contacting RWS a couple times about it last year. (Starting before the whole falling-out-of-the-harness accident thing.) They said they had misplaced the paper copies during a move of one of their departments, were planning to get it updated or something, but I never heard back. One document that is floating around somewhere is the 1995 "Tandem Skydiving with Wheelchair Dependent Persons" by Paul Murphy from Australia. It's a 128k Word file that has some recommendations plus results from a survey of DZ's for their policies and procedures. I have a copy which I might have found on dropzone.com during the long discussions on that accident last year. It has some useful info for those of us who aren't familiar with all of the complications of spinal cord injury etc.. As for procedures to use, the document discusses a few different techniques, but still leaves it open to judgement what is best or sufficient in any particular situation.

To address one of the topics in this thread, let's have a look at the issue of scaling people up and down, and how that affects wing loading and stresses on the jumper. It is useful because the effect of scaling laws are non-linear, and as someone said, we don't naturally think very well in non-linear terms. While this stuff should help to understand the effect of scaling alone, there are of course other at least as significant factors that have already been mentioned, like jumper skill, body position, and body shape. People probably don't scale up and down perfectly evenly (such as in the percent of muscle mass, or proportion of torso to limb length, or whatever). The proportion of skinny or more solidly built people may also vary depending on their height. ========= The basic physics of scaling are that volume (and mass) increases with the cube of the length, and area increases with the square of the length. As an example, consider a 6 ft tall jumper vs. 5 ft tall jumper, OF THE SAME BODY SHAPE: The taller one is 20% taller, would have a 44% larger wing area, would have a 73% greater mass, and therefore would have about at 20% higher wing loading. WING LOADING EFFECTS: This square & cube law thing is the primary reason why ants hardly notice a long fall, a mouse may brush itself off uninjured, a cat might limp away injured, while a human goes splat. The 20% extra wing loading translates into more speed at a similar glide ratio. Basic aerodynamics then says the glide ratio doesn't change. But additional factors might change things. (It isn't quite the same situation as for a jumper under a parachute, where the same person under a smaller, higher wing load canopy still has the same body drag area, same line thickness, etc. as under a larger canopy, like tso-d_chris wrote about.) Who knows, there might be some small tendency that at the same wing loading, a larger wingsuiter would have a better glide ratio. This is like swooping with weights and a larger canopy at the same loading. Crinkles in the fabric may not tend to scale up much, harness webbing stays the same size, etc., so their disturbance will be proportionately lower for a larger wingsuiter. MUSCLE STRENGTH EFFECTS: As for the comment about small people being able to outdo the tall & skinny, by better being able to hold a good body position, one can keep on playing with the effects of scaling. The taller person's arm is longer, the load is greater, but the shoulder size and muscle size are greater too. In the end, there's both a 73% increased muscle mass and 73% more force needed. But that doesn't even everything out, as the cross sectional area of the muscle has only gone up 44%. So the stress per unit cross sectional area is 20% higher on the taller person's muscles. Even without knowing the biological details, I expect that that is important to what force the jumper can apply. It goes right back to the idea of volume being cubed, but area squared. (I did run basic engineering calculations on this to confirm the numbers. The jumper's arm can be considered a cantilevered beam supporting a spanwise distributed load, with a muscle applying an inwards counteracting force at the bottom of the root of the beam.) So the scaling laws suggest the bigger person person is at a strength disadvantage, if the person is of the same body shape and proportions as the smaller person.