pchapman

The standard idea is that the top jumper will chop only once he's clear of lines & canopy. Nobody normally chops if they're still caught up on something, which would tend to lead to having even less 'canopy overhead'. I'm not that experienced with CRW so I won't get into more detail, but there are ideas in CRW basics articles here: http://www.dropzone.com/cgi-bin/safety/detail_page.cgi?ID=39 and here: http://crwdog.servebeer.com/CRWdog/CRW%20Emergency%20Procedures.html

Regarding "inadequate coaching" -- Not that many jumpers learn CRW these days, so they don't get used to the finer points of maneuvering canopies near each other. Yet then people like to do things like bumping end cells, which is a reasonable thing to do, but are left to learn the lessons on their own... Large rates of closure when two jumpers aren't flying perfectly parallel, I found that's something that can surprise someone new to CRW style flight. When both jumpers are perfectly parallel, the lack of relative motion may make one feel one is just floating along. But as soon as a component of one's fast forward speed is converted to sideways motion, things can happen quickly. It was nice that the other jumper went right through the lines (technically an 'entanglement') instead of getting his body wrapped up in lines & canopy (a 'wrap'). The standard entanglement procedure is for the top person to chop first, as when you chop at the bottom, your risers could recoil up and entangle the top jumper. (I've also been in an double chop, but with dacron lined CRW canopies.) I'm not sure how jumper B's conversation with you saved your lives, but in any case it is normal to communicate so both jumpers are OK with whatever the plan is. As for the other jumpers continuing to the DZ instead of following gear, that can be questioned, but they were there and know better about the terrain (eg, the suburbia), skills, what gear they had in sight, etc.

Tdog, your ideas sound fine. The pull/pull altitude/pull stable concept is still OK for discussion on the ground, but students should walk away with something clearer in their minds to use in the air -- something about pulling in any case if pull altitude is reached. Then the next rule can be about stability -- only if one is sure one has extra altitude (and still checks one's alti), should one try to fix a stability problem. The consequences of pulling low vs. pulling unstable would be compared. I don't myself have any perfect phrasing worked out, and haven't had to teach that stuff specifically.

A good part of the problem, in my opinion, that as experienced jumpers we may know things fairly 'instinctively' (through experience) but haven't thought through how to teach it. So the student gets told a bunch of rules but not how they interrelate, and which take priority over others. All bad in terms of Hick's Law. So students end up with just a list of rules, to land into wind, land in the direction others are landing, don't land in a turn, and don't hit obstacles. Sometimes they're told to "always" do something, or to "try to" do something, or "you should" do something, without really understanding why or how important these things are. Occasionally students do something that's a bit hazardous because they were more frightened of their instructor than the ground -- "But I was told to always..." Another example of muddled instruction is the bit about "pull, pull at the right altitude, pull stable". That may be fine for discussions on the ground but the logic can be a bit confusing to work through, and it doesn't provide a clear decision tree for someone to work with (at least in my mind!).

I've jumped with a couple 280 or 285 lbs guys, out of the DZ's C-182 - thankfully it is a widebody version. Yes the novelty does wear off! Definitely not the thing to do until one gets some experience as a tandem instructor. At least IF they don't fight you, big students are easy in freefall -- "they know which way gravity is". (As opposed to the light girls who tend slide around under you.) Biggest girl was 265 lbs, and quite tall so she wasn't totally round. All these jumps were still within the gear limits for lighter instructors like myself, 6'1" and 150 lbs, using the Sigma rig certified to 500 lbs & 180 kts EAS. The landings under Sigma 370's or 395's were normal enough but one does want to have good cooperation from the passenger. One scare on a jump with one of those big guys was finding a 3-ring flipped-through after opening. And no, I'm sure it wasn't flipped through before hooking up. The cutaway cable was jammed slightly into the grommet by the force on the white loop. I nervously figured if things had held during opening, it would be OK to land it. The riser rings were dented from the opening so the riser was retired after that. My best guess is that at the start of opening shock, which tends to be less smooth at high weights, one riser 'whipped' and unloaded momentarily, flipping the ring. Surely a very rare event, but having a large passenger makes any problem worse.

You're right that the ad is a good analogy for the economy of Denver. But what screwed it up was the caption "Actually John H...". Technically true but implying that he is something he isn't. Not that being a skydiver is that exclusive an achievement. Is that where where I'm being too serious? -- "How dare a mere (maybe) 1-tandem near-whuffo compare himself to our exhalted ranks?" If the video wasn't about puffing himself up -- and if people truly don't care about skydivers' picky distinctions between different types of jumps -- then the video could have shown him doing a tandem without the expense of editing. Or, the whole video could have shown a solo skydiver while he did a voice over about political issues. As it was, he still carefully & deliberately took the time & spent the money to misrepresent himself in a manner that might imply he's daring, decisive, and not just a boring guy in an office. It's the type of deception that counts, not the magnitude. Perhaps I still look at this with too much of an engineer's viewpoint, not that of a marketer. I don't expect that his lack of good aerodynamic body control skills should have an effect on his ability in office. Yeah, one has to be able to take a joke, even if one gnashes one's teeth at some factual error. Interestingly, this video is still unlike most representations of skydiving that skydivers argue about, for it is one of the most realistic adverts I've seen that used a skydiving scene. Also, the video did not in any way make fun of skydiving or the people who participate in it!

One reply: In other words, deception is OK if most people don't notice it? Another reply: That was a nice defence of entertainment. But the video is still massively untruthful -- a fabrication, a lie, deliberately hoodwinking and deceiving people. It wasn't done in a style where it was obvious it was all a humour piece and a studio job -- like showing a video of him hanging in a harness from a crane, while a fan blows in his face. The video is of those things where a politician can try to weasel out and say that it was truthful simply because they didn't specifically claim anything untruthful in writing. Words overlaid on the video stated something like "Actually John H..., Actually 13000 feet" during the tandem freefall with everything but John edited out. Technically correct. Other scenes show a full sequence of events, John by the aircraft with a rig on his shoulder, John starting out the door of the airplane, the freefall, a solo jumper with the same solo rig and clothing deploying, and so on. Technically, they never specifically claimed that the other jumpers were John, or that he was actually going to jump with the rig he was wearing, nor that they had altered the video content. They would claim innocence -- if people happen to believe his carefully crafted deception, to make it look like John was doing a solo skydive, so be it. (All this assumes John only actually did a tandem jump.) It's still fraud. I'm saying that in the general dictionary sense of intentional deception; I have no idea if it qualifies in a more legal sense, "intentional deception to cause a person to give up property or some lawful right" as one dictionary put it. Who knows if trying to take someone's vote through deception counts...

Hi, I'm trying to get a contact phone # for Bernie Williams. (Older fellow, Welsh in origin, had lived in Michigan & Ontario, not easy to forget if you've met him...) PM me if you have info. Lost track of him after he recently moved.

It's an OK bit of humour poking fun at skydiving from an outsider's perspective. I'm just sorry it is still based on misconceptions -- they still seem to be thinking of '60s belly mount reserves and early round canopy landings. There should at least be an element of truth behind what's being joked about. The H2G2 site seems to mix humour and seriousness; it all depends on what individual contributors choose to write. What bugs me is when serious publications get it all wrong. Consider the entry in the 1600 page Webster's New World dictionary of 1988 that I happen to have kicking around: "Skydiving: The sport of jumping from an airplane and executing free-fall maneuvers before opening the parachute, often at the last possible moment".

Interesting opinions! Aironscott found many a Swift Plus needed rework, while Riggerrob inspected a few dozen with none needing rework. The original bulletin was a bit vague: I've only dealt with a few Swift Plus's over the years, but recall that ParaFlite bartacks generally looked wider than I'd like. But it was so consistent, one sort of got used to it as 'normal for ParaFlite'. The way the issue was presented to me (through the CSPA rigger bulletins), I had learned to look for bartacks that didn't capture the finger trapped line, and never found one where the stitches seemed to miss. Is that really quite the same as having "ample material" as in the bulletin?? What's just ugly and not ideal, vs. actually significantly understrength? I'm not passing judgement here. It's just an example of where experienced riggers have different interpretations. (While I focused on the bartack width, Aironscott also noted the issue of the bartack needing to be centered. I can't recall enough to comment on that.)

The same booklet also had suggested shortlining limits: For a Mk 1 PC, minimum 18'. And descent rate won't increase noticeably if shortened to 20' (if over 190 lbs "jumper weight") 19' (if under 180 lbs) 18' (if under 150 lbs) (Sounds like they were perhaps thinking of the actual jumper's weight, not weight with gear.) All I have are a booklet and 3 PC jumps...

Gary Lewis' Para-Commander handbook only says 21' to 22.5' for a Mk 1 PC that hasn't been shortlined. Being a PC newbie, that seems to be a rather inexact spread. PS - a more descriptive subject line would help, not many people curious about line length issues in general are going to be ParaCommander jumpers...

One does hear the jokes about the 'boots and helmet meeting behind one's back' on terminal belly mount openings! At least it was a S/L jump, and I think with the center pull reserve, Skypuppy wanted to keep the reserve lower. It's a novelty to jump the old stuff, or to jump it again for some folks. But I don't think it'll become my regular canopy...

This looked like the appropriate thread to put it in, so here's my experience from last weekend. It's nothing particularly exciting, just longwinded details of a couple jumpers putting rigs together with Para-Commander style canopies and jumping them. ======= Round canopies came out this past weekend at Skydive Toronto. After years of thinking about it, Rob Price (a.k.a. Skypuppy) and I had put together rigs with Para-Commander style canopies and made a couple jumps. Skypuppy wrote, "One reason I wanted to jump these rigs was because when talking to the regulars at STI, which I figure is a fairly typical dropzone, most of the jumpers had never even seen a round parachute. The ones that had [other than a very few], had seen a round reserve used once. These jumpers believed that round parachutes were old and antiquated and dangerous (sort of like me, maybe?) and to jump one was almost akin to the kiss of death." Skypuppy had sufficient round experience, having started in '79 and made his first 40 jumps or so on a Sierra, a light weight Para-Commander style canopy. I started jumping in '88 and had two previous round jumps. One was as an licenced jumper in '95 when visiting a DZ that had been forced out of the national organization because it still used round mains for students. There I got a belly mount signoff and jumped a Para-Commander style canopy. Then in 2002 a CRW oopsie left me under a Phantom 24 reserve, which I landed backwards in 15-18 mph winds. That was the last time a round had been flown at the DZ. Now Skypuppy had acquired a Niagara Parachutes Cobra, generally like a Para-Commander, but specifically more of a copy of an Eastern European PS-06. The sleeved canopy was in a beaten up fore / aft student rig with R-3 releases, converted from 3-pin ripcord to a static line with pilot chute assist. Rig and main came from a retired DZO. The belly mount reserve was an early 1970's Pioneer 23' TriCon with taffeta fabric. The reserve was borrowed from Bill Cole, a.k.a. Chuteless. I had discovered a black and gold 1975 Mk I Para-Commander in a garbage bag in the former rigging trailer on the DZ. Stamps on the chute showed it had belonged to the US Army Parachute team, and stitch holes showed where "USA" had once been lettered on the canopy. Somehow this ex-Golden Knights canopy had made it to Ontario to become a student canopy in the 1980s! I went with the old Para-Commander but with a more modern rig, an '80s 3-ringed piggyback system. With a Phantom 24 reserve, one would be committed to landing a round canopy in any case. Three ring risers were spread open at the top to accept the L-bars of the canopy, and then tacked to avoid link movement. The steering lines that normally go to the front risers on a Para-Commander, were routed to the modern risers' normal steering toggles, but that's not ideal and is temporary, as the steering lines end up rubbing across other lines. Holders for elastics were put into the top of the d-bag to hold the crown lines, although that's likely more elaborate than necessary. The Para-Commander wasn't going to fit my old accuracy rig, even with the 2 1/4 lb cotton sleeve removed and replaced by a bag. (As a modern jumper, the use a sleeve reminds me of trying to stuff a whole freefly jumpsuit into one's pack job.) So I sewed up an add-on main container, that velcros over top of the original container. The original top flap & pin protector flap are used, while the other three flaps are new. The old main flaps are tucked away underneath the new backpad. Large straps and velcro go around the rig's backpad and laterals to hold the new container in place (with a little supertack to be sure). The rig works although is quite long, with a bit of a reach down to the BOC. I thank the Australian accuracy team at the 2003 Worlds for the idea -- some of them had professionally built removable add-on containers to hold accuracy canopies in their small rigs. Packing ideas came from Skypuppy and another jumper with round experience, Brian diCenzo. Plus I was armed with Gary Lewis' booklet on the Para-Commander, which was purchased for one dollar from Para-Gear in '03, apparently getting rid of the last of their stock. When assembling the gear at home, the canopy was too long to pack anywhere in the house, so it was taken to a local park to tension and pack it. Saturday when the clouds rose enough for a 3500' load in light winds, I static lined Skypuppy out the C-182 door and followed with a hop and pop. The Cobra seemed to descend faster than the Para-Commander, perhaps due to loading it more, it having a built in turn that had to be countered, and the design seemingly having bigger holes in it. So when he put the canopy down in front of the watching jumpers, he really had to roll it out. I ended up further from the audience, but was able to stand it up. (…as I imagined the cool jumpers who owned Para-Commanders used to do. With a split saddle harness, one couldn't just touch down with straps undone and walk away from a sling saddle, as shown in the Gypsy Moths…) I got another Para-Commander jump the next day. The standup landing 20m from the target was softer than before, perhaps because I tried the trick of lifting oneself by the rear risers just before touchdown. On that hop and pop from 4500', another jumper, Marc Downing, videoed while circling me with his JVX canopy. Despite turning, he staying with the Para Commander a long time while in deep, deep brakes. A couple other jumpers flew by or circled later too. It felt like getting buzzed by a swarm of bees. With the Para-Commander's good turn rate, I could spin the canopy much faster than anyone could spiral around the outside.

One of manifest's Halloween pumpkins was liberated last year at the DZ. I took it up for a jump and returned it to nature. The medium sized pumpkin (maybe 8 or 10 inches diameter) fell faster than belly, but slower than sitfly (from my perspective as slower faller.) This pumpkin had already been hollowed out, which didn't change the weight all that much but allowed it to catch air in odd ways if it tumbled. So it tended to float around in one area a bit, then go zinging off in some random direction for a ways. Aggressively going after it seemed like great practice for catching wayward AFF (or Canadian PFF) students!

It has already been mentioned that line twists, while initially disconcerting to the static line jumper, are no big deal. Another minor issue is that the jumper sometimes notices the bagged parachute being dragged across / past their shoulder and arm, as they fall away from the aircraft in an arch. Sometimes disconcerting but not a problem. [This assumes a direct bag system.] Since a static line student gets a lot of canopy flights, try to to make good use of the time. There's always instructional emphasis on the exit from the plane, in order to progress to practice pulls and freefall. Don't neglect the canopy flight part. Make sure the instruction system also provides things to work on under canopy -- wind checks, canopy control, accuracy practice, riser turns, incipient stalls, or whatever might be called for by the DZ or national standards.

As for the sub-thread on different material strengths, it doesn't look like we have a definitive answer. To summarize: Type IIa (normal closing loops) is 225 lbs. Type III Coreless (no actual milspec) is 100 lbs but we don't quite know what it is used for. Type III Cored is the old 550 cord parachute line, but may or may not be related to the Type III Coreles. Gutted 550 cord (550 cord sheathing), which has sometimes been used instead of Type IIa in the past, could be either : (a) 100 lbs (if the Type III Coreless is supposed to be like Type III Cored, minus the core) or (b) 225 lbs (if it is like the Type IIa material that it resembles).

Thanks! Sparky, just to be absolutely sure: The Type III coreless is actually the sheath of Type III MIL-C-5040, which is the 550 cord, not some other "Type III Coreless", right? I now see Poynter's manuals do list III Coreless, but without a strength. Since there's no actual milspec, I wonder if the 100 lbs is actually a conservative strength?? Type IIa and the type III sheath sure have a similar look and feel (other than the IIa being manufactured flat and having the dotted stripe). Taking the numbers at face value: If one guts old 550 cord for a closing loop, the material is only good for 100 lbs. But if you use the similar looking Type IIa, that's good for 225 lbs. (When formed in a finger trapped loop the strength is of course higher, I guess roughly doubled, minus a percentage for the knot.) While both may be adequate in strength, I'd prefer not to use the gutted cord option unless necessary. I've seen people confuse the two, calling them both 'sheathing', either thinking both were 100 lbs or both 225 lbs.

Sometimes the type of aircraft makes a difference in perception for a hop and pop. I'm usually a Cessna DZ person, with some Twin Otter DZ visits, and and have no problem going out low. But at one demo it felt weirdly low when looking out the door of a Twin Otter at "only" 3000'. At that demo one jumper with thousands of jumps tumbled out the door unstable. The rest of us wondered what the heck happened. She had simply been in a Twin Otter mind set, started to dive out the door like diving for an RW formation, but part way through suddenly remembered she'd prefer doing a poised exit like most of us were planning. Net result was an amusing tumble before she went stable.

Is the sheath of gutted 550 cord actually equivalent to the Type IIa Coreless cord, that is the most common closing loop material? The spec I see for Type IIa is 225 lbs. But when I took my rigger's course in '91, my notes show "100 lbs" for Type II casing or Type III casing (where the former would be gutted 400lb cord, and the latter, gutted 550 cord) One old time jumper also always assured me the gutted cord is 100 lbs. Why was I getting that information? Since it came from more than one source, I doubt it was a typo. Was it some sort of misinterpretation, old standards, a conservative rule of thumb, or what? I've never been able to figure it out.

Ok, perhaps the problem is that once one explains to a jumper how their body in a track ISN'T acting like a wing in normal flight, then one should really explain how it IS acting. So the simple answer, you might suggest, is just to talk about lift and drag without worrying exactly how that is being achieved. Understanding those differences does matter in some specific cases. For example, if a wingsuit design adds a pillow between the bottom of the rig and the jumper's butt, how much of an influence will it have on glide ratio? If one believes there's fully attached flow over the person's back, one might think the pillow would have a much greater effect than if one believes the flow is unattached (where a little bit of smoothing out of the jumper's profile won't really matter). Yes, more or less. Few basic aerodynamic teachings say much about post-stall lift. They show a graph of an airfoil's lift increasing up to the stall point, then suddenly dropping, but nothing beyond that. So here's a graph to demonstrate what billvon is talking about, for a commonly studied airfoil (NACA 0015). The lift coefficient is plotted against the angle of attack. Well past the stall angle the lift goes up again, almost to what can be achieved pre-stall. Since the airfoil is pretty much acting like a plank (without the leading edge acting in the 'special' way that airfoils do when unstalled), the best lift ends up around 45 degrees angle of attack. [Edited to add paragraph on drag:] While one can achieve good lift well past the stall, drag keeps on going up rapidly past the stall. (Generally rising sort of like half a bell curve from zero angle of attack to a maximum at 90 degrees.) For that reason, someone in a wingsuit would still like to have as much attached flow on their wings as possible. As to what is actually happening over a wingsuit's wings, that's another topic. 180 lbs of skydiver at 120 mph = 58 hp :)

Here's a little story about someone's sport parachuting experiences, largely before WWII. I wrote it back in 1993 for a Canadian skydiving magazine, and have edited it slightly, although I left in a lot of the local references. I figured it was worth adding to the dz.com collection. The early equipment, techniques, and certification standards are particularly interesting. ================== A couple of years ago I made a presentation about our sport, as speaker of the month for a chapter of the Recreational Aircraft Association. When I asked the audience who had skydived before, I expected a couple people to have made a jump. One man, Cam Warne, said that he had made 50 jumps. When he said that he had made them from 1938 to 1952, I knew I'd want to talk to him after the meeting was over. In the records of parachuting history, some subjects are more written about than others. Parachuting for sport is relatively neglected until the post WW II era, with it's stories about first World Championship in 1951, Jacques Istel, the sleeved canopy, and so on. While the organizations that eventually became the Canadian Sport Parachuting Association were formed post war, sport jumping did exist in Canada before the war. Most of this article is based on Cam's recollections. A 1938 Toronto Star article and a 1985 Canadian Aviation Historical Society article on airfields in Toronto were additional sources. Cam Warne made his first jump in 1938, well within northern Toronto at the NE corner of Wilson Avenue and Dufferin Street. [At the time it was open fields north of the city; now it is well within the city of 2.5 million.] The de Havilland aircraft company had a field to the northwest. Eventually both sites would be covered by today's Downsview airport [only used by Bombardier's de Havilland division, and by a military reserve helicopter squadron]. Jumps were also made at Barker field, somewhat further south. An experienced jumper by the name of George Bennett had been instructing in a number of cities, and at this time was in Toronto. I don't think his work was entirely a private venture, for government sponsored flying clubs and the Irvin company may have been in some way involved. Ground school was held in rented space with a long hallway, to allow packing the round canopies. It took a couple evenings per week for four weeks to complete the course, which included packing Irvin chutes according to the manufacturer's manual. One test of packing ability hasn't changed, as the instructor would tangle up a canopy for the student to sort out. On a windy day, canopies were taken outside to practice collapsing them. Thirty four students completed ground school in the spring of 1938. For Cam and four others, the big day was May 15. They wore a standard Irvin pilots' seat pack, containing a 24' canopy, with the harness adapted to take another 24 footer in a lap pack. The lap pack was like a chest pack but with the pack mounted lower. Boots, coveralls, and a padded leather helmet completed the student's gear. Plane and pilot came from the main tenant at the airfield, the Toronto Flying Club. An instructor took each student in turn up to 2000' to 2500' in an open cockpit, two seat de Havilland Gypsy Moth biplane. The spectacle of parachute descents drew nearly 1000 spectators that day, reported a newspaper. The student climbed from the front cockpit onto the lower wing, put his left hand on the ripcord to avoid mid air fumbling and panic, jumped at the pilot's signal to go, counted to three, and pulled. All of Cam's jumps would be freefall. Static lines for civilian students only became popular after the war, during which static lined paratroop chutes had been refined. After the jolt of a canopy first, unreefed deployment, the student was left under an unsteerable, unstable, 24' silk canopy. Very rough landings are what we expect to hear from the early days of parachuting, but it was common during Cam's time to avoid this by simply deploying both parachutes. The reserve, with no pilot chute, would be hand deployed after the main was open. While two rounds won't downplane, they may still move significantly apart and speed the descent. By pulling the risers on the "inside" (nearest the other canopy), the canopies could be kept side by side. The reserve, no different in design from the main, was treated as just another canopy to be packed or deployed by the student. Experienced jumpers might still use the two canopy technique, or save a pack job and land the main alone. Those who continued jumping at Downsview called themselves the Canadian Parachute Club, with experienced jumper and pilot Ray Chesney as president. By passing the hat among the crowd that would assemble whenever parachutists leaped, the club was able to reduce their costs. The equipment shared among the club members was just one full set of gear, with two 24' canopies. Jump aircraft were usually two place flying school aircraft such as the Moth or Piper Cub, although larger planes were arranged for group demos. Based on having completed the rigging-intensive ground school course, and made one jump, Cam received a certificate stating that he was qualified to pack, service and jump all Irvin parachutes. Cam also became an instructor, the certificate for which could be received after six jumps in total. [Let's repeat that: One jump to get off student status, and six jumps to become an instructor.] Some of the sillier descents by jumpers at Downsview included carrying a dog or rooster as passenger, and one person did trapeze artist stunts after opening the canopy, such as hanging on by a mouthpiece alone. (As for early tandem human jumps, I've seen a photo of such a jump done under a large round canopy in France in 1937.) Cam's lowest jump was from 800', made that low to get him into a tight landing field. Club members made downwind landings if possible, which didn't affect the ground speed of chutes that were unsteerable other than by sideslipping. Downwind landings better allowed the jumper to see what he would hit and eased preparation for a landing roll. When using two canopies out, landings could be stood up. Despite the hard openings of what were in effect pilots' emergency parachutes, terminal velocity openings were made. If a hop and pop wasn't planned, a typical jump might start at 5000 6000', freefalling down to normal opening height, which was eyeballed since an altimeter was never carried. Some rigs used were actual emergency bailout rigs, that hadn't been modified for a reserve attachment. In that case a reserve could be worn on a separate harness, or occasionally not bothered with at all. A couple types of chair chutes had been built at the time (and can be found in Vol. 1 of Poynter's Parchute Manual), designed to be hidden in the passenger chairs of airplanes and quickly donned in an emergency. One pilot who had such a chute for his Howard airplane wanted to see how well it functioned, so Cam test jumped it without a reserve. Pictures of such rigs show relatively conventional shoulder straps with a chest buckle, and a seat sling not unlike some 1960's military gear. But instead of having leg straps to prevent coming out of the sling, it had only a seatbelt like strap to cross both legs. Cam was among a half dozen parachutists making demo jumps in 1939, for three evenings during the Canadian National Exhibition. The only large obstruction free area near the Exhibition was Lake Ontario, dictating water jumps. In place of smoke grenades, flour was released from leggings closed with a drawstring. The group jumped without reserve canopies, as they had trouble enough getting hold of even one parachute for each of their "large" group of parachutists. For water landings, jumpers might deliberately set themselves swinging before impact, so that the canopy would be less likely to settle on top of them in the water. One evening the pick up boats were recalled because of approaching bad weather. The jumpers, already airborne without radios, could not be contacted. Private boats eventually fished the abandoned jumpers out of the water. With World War II came a demand for parachutists, who were valued for their packing skills. The Canadian Parachute Club disbanded and many members dispersed to the rigging lofts of military flying schools to train new personnel From 1946 to 1952, Cam jumped with a group at the Oshawa airfield, east of Toronto. War surplus parachutes were cheap, and an airplane could be rented from the flying club. Aircraft ownership wasn't common for what were true clubs in the early days. One demo water jump near North Bay [about 200 miles north of Toronto] was a high one from 9000', exiting from the back seat of a Harvard military trainer. Freefall technique was primitive, and Cam was unlucky to enter the dreaded flat spin. Deploying immediately has always been the basic way out. Cam pulled high, ending up safely under canopy at 6000', but with a wind driving him further offshore. Again co ordination with the pick up crew failed. The crew continued to relax on the beach, beer in hand, without noticing the canopy up high. A pilot elsewhere on shore saw the parachute and jumped into the nearest vehicle, a Piper Cub on floats. As the pilot had never flown a floatplane before, he taxied it the entire way to retrieve the parachutist. Cam had his share of minor incidents, but only one small injury, a twisted ankle, and one malfunction. The mal was in '39 while jumping an Irvin rig with a 28' main and 22' reserve. Stability in freefall and for opening weren't a great concern. Parachutes, after all, were designed for pilots who were expected to bail out, and then pull in any orientation. This time the pilot chute wrapped on his foot, horseshoeing the main. The reserve was tossed out and deployed cleanly, the horseshoe was cleared, and the descent was made under both chutes. Cam's wife picked a poor day to watch him jump one time at Oshawa. After a normal main deployment Cam tossed out the reserve. The mass of fabric didn't billow upwards as usual. It dropped down between his legs, and began to inflate behind him, with lines caught on the metal frame of the seat pack main container. Cam was suspended horizontally by the two canopies. As a belly flop landing was unappealing, Cam struggled to clear the mess. Having done so, he looked up and was surprised by the sight of apparently only one canopy. He then realized what had happened: the reserve had managed to inflate itself within the main canopy, the two canopies nesting neatly together. Scenes like that didn't impress his non aviating wife, leading Cam to give up jumping in 1952. [Cam went on to recreational flying and homebuilt aircraft, and did a lot of video production work for the EAA Oshkosh aviation convention.] Peter Chapman

Any other tips on ParaCommander packing out there? (I've checked other PC threads at dz.com too.) I'm not in any huge need, but will gladly take suggestions. I have the Gary Lewis book and a couple friends with ParaCommander experience. (The book was available from ParaGear for a dollar a couple years ago but I think they're out of stock now.) Some questions: - Number of folds: Just fold as appropriate for the size of the deployment device, eg a half fold, thirds, or quarter fold? - Stabilizer folds: The Lewis book suggested not folding the stabilizers across the air channel, to avoid stabilizer hangups. On the other hand, someone showed me a packjob with a trifold of everything (folding in thirds), which does put the stabs across the center. - Bags: How non-ideal are bags, as opposed to sleeves, in terms of malfunction risk? I have a bag to use, but at least will pack the canopy side to side which has been recommended for bags. (And I put elastics inside the top of the bag to stow the crown lines.) It was also suggested to me that when using a bag, to try to hold the canopy together a bit more during opening by first doing a 90 degree fold of the bottom of the stabilizers and the bottom of the canopy, before doing the long folds. (I've also heard it called a 45 degree fold since the fold line is at that angle, while the skirt changes orientation by 90 degrees.) - Slack in the center lines (the apex lines): I think I have a Mk I PC to play with. When I first got it, it had a few inches of the center lines stowed in an elastic at each of the rear links, where the two center lines attach. Is it important to stow any slack at all in such an elastic? Or is a few inches no big deal? The Lewis book only mentioned center line slack (I think) for the Russian PCs, and had the slack stowed in an elastic at the pulled down apex. - Line lengths: How even should the canopy skirt be, given that over time lines that get different loads get stretched different amounts? The factory specs would have the skirt all even, right? Tolerances on line lengths are quite generous? - Canopy identification: The one I have just says that it is a ParaCommander, and is from 1975. Since no model is listed, I assume it is a Mk I? I borrowed the canopy from the back room of the DZ I instruct at, and have been getting it ready for flight. I think the DZ used PC's for students until '86 or so. The canopy is black & gold, has a US Army Parachute Team stamp inked out, and has stitch holes where lettering used to be on the canopy. Guess it was a Golden Knights canopy, something I didn't expect since the DZ that owns it is in Ontario, Canada.

Oh yeah, neat aerodynamics. Although the aerodynamics are different, they remind me strongly of modern high wing loading parachutes: When one has a crappy glide ratio, diving for extra speed gives one the energy to create an effective flare and plane out long enough to gently ease down to a landing. So the issue still remains, how to describe the type of aerodynamics that are "pre-stall" ... in terms of conventional aircraft wings, not lifting bodies or vortex flow low aspect ratio deltas or whatever. The best I could come up with was 'attached flow aerodynamics'. Can you think of a good way to describe it to those not trained in aerodynamics, other than just saying 'like a normal wing when it is flying'?

All in all I see Gary's point, but I think his short post can be misinterpreted, and can seen to be too hard a criticism of Kallend's letter, which was also pretty short. (... for engineers, anyway.) Kallend's letter in turn doesn't invalidate what Ralph Glasser was trying to get at, even if Glasser didn't understand lift correctly. Kallend says what Glasser got wrong, not what he got right. Point by point: -- John Kallend is right about the definition of lift. -- Yet the concept of Ralph Glasser's criticism of Atmonauti can be valid, given the over-enthusiastic claims of some Atmonauti supporters. Glasser didn't get the concept of lift right, but what he means is that skydivers aren't creating the kind of lift we normally think about from a flying airplane wing -- with lift that is from attached flow, or 'pre-stall' lift. That's to be distinguished from lift that is barn-door in nature, or from unattached flow (on the upper surface), or 'post-stall' lift. I'm not sure what to call it myself, even though it is such a fundamentally important concept in aerodynamics and aviation. So IF some Atmonauti supporters keep talking about how their bodies are like wings and are truly flying, then Ralph's criticism may be valid. I have seen diagrams published for Atmonauti which also show a misunderstanding of the definitions of lift and drag. -- Pressure differences between top and bottom have to be the source of lift, whether a wing or object is flying pre-stall or post-stall. If there were no differences, one couldn't create any lift. And de-arching couldn't provide a better track. -- As for the implied issue of wings vs. barn doors, or deflection vs. pressure differences in Kallend's letter, that's an old debate of Newton vs. Bernoulli for how an airplane flies. The simple answer is that both are true and are part of the process of lifting an object aerodynamically: Pressure differences create the lift force, and when that lift pushes a flying object one way, the air gets deflected the other way. -- Dearching has been shown to be very useful in providing a good track, so it does need to be taught. One interpretation of Gary Peek's words indicates that he objects to that, but I think what he means is that he objects to suggesting that it helps due to providing extra attached-flow lift. I'm not an expert on tracking, but it seems that the lift we skydivers make is basically all post-stall lift. As Glasser says, the body isn't very aerodynamic. Also, consider the angles: Even if a superb tracker were able to get a 1:1 glide, or nearly that good, a common "good tracking position" is only slightly head low vs. the horizon. So we might have a down 45 to 55 degree flight path combined with a body oriented down 15 degrees. This gives an angle of attack of 30 to 40 degrees. Definitely post-stall lift at that high angle! (Even if one were talking about a wing, not a lumpy, ultra-low aspect ratio skydiver.) As to whether one should be, say, 10 degrees dearched, vs. 5 degrees (or even 0 degrees dearch), that I'm not sure about. Certainly for inexperienced trackers, one has to emphasize dearching, otherwise they may retain some arch withought realizing it. In the end do I agree with Gary Peek about his concerns about telling people to "make their body the shape of a wing"? I agree that people shouldn't learn that one is truly flying like a wing normally does (with attached flow lift). I'm strongly against that misconception. But the idea is still a useful basic analogy and training tip, even if it shouldn't be taken too far and used as an explanation of the physics involved.