pchapman

At least one can pack the speedbags extra carefully so that no knots protrude through the other flap.... But there still is a lot of drag from just the rubber on the fabric edges of the flap. I wondered that if a manufacturer doesn't like the security of a single safety stow, why not go with two safety stows. Then you don't have the problem of "if one stow gets loose everything can dump out", but you still get to work with smoothly sliding grommets and fabric covered stows, that last a long time. It might be harder to get good tension on all stows though. And I suppose bag lock concerns might be be worse with safety stows next to each other that don't easily break, although they could be spaced out. If one doesn't like safety stows, then do two rows of milspec elastics through grommets, stowing the rest of the lines in a conventional pouch. You get extra security compared to a single stow, without the problems of a large number of rubber stows through fabric holes and a large number of long line stows next to each other. (The problem of rubber reacting with grommets gone with nickel plated ones, right? The situation is still a bit confusing to me. In 2004, NancyJ from JumpShack wrote, " It takes two to three years of extreme temperatures for a Mil Spec rubber band to break down, and frankly, brass has nothing to do with the deterioration. It's a heat and loss of moisture problem." Maybe the chemical reaction issue was more something with cheaper non-milspec rubber bands? ) Hope the good milspec style elastics last a long time on a speedbag. Safety stows often last a decade and still can provide significant retention even if all the interior elastics have broken at the ends of the zigzag sewing. (Although I try to replace them by then even if some other riggers aren't as finicky about that.) I accept that the reserve speedbag seems to work when it is yanked with some speed, which seems to 'pop' the elastics out better than if tested at very slow speed where many elastics can all grip the fabric flap and really increase the forces. It's almost like it is John Sherman's "pulling the table cloth out from under the dishes" trick. But I'd still like to learn more to be fully convinced.

What I did like is pointing out that among the freefliers, there are different levels of freeflying, something that not everyone might take account of if just thinking "big to small": Experienced head downers will drift back less than people doing a casual sitfly. So instead of just "belly then freefly" it may be "belly then slower freefly then faster freefly". I didn't like the concept of "prop blast penetration" in the second sentence, despite it being enclosed in quotes. Prop blast itself clearly isn't a factor except right at the aircraft. Aircraft forward speed is the factor. Surely there's a better term available? Horizontal penetration? Drift back tendency? Maybe we don't have a standardized term yet. Also, the spacing is determined not only by the relative forward penetration, but total time in freefall and thus time exposed to drifting back by the wind. In an instructional article one can't forget that second of the two main reasons for separation changes. (For jumpers falling down the pipe and not inadvertently moving horizontally, which then is an additional issue). (E.g., Two groups could do identical head down exits with identical horizontal penetration, but if the second switches to belly half way through the dive, their drift angle will change and they'll drift back towards the first group.) The "canopy tracking" term may be a little silly but is a nice way to create a mental reminder for people.

I had seen them and agree that they are good. One point the pin orientation page misses is why happy or sad creates less force. It depends on where the pin is being pulled from. A comment of mine about to be moderated, in the pin-orientation page: "It just forgets to add one more point: fundamentally, what matters is whether the fabric in the eye of the pin, is pulling near the axis of the hole through the loop, or whether it is pulling from further away. When it is pulling from further away from the axis, then the pin rotates up away from “flat on the rig” easily — as when the fabric is pulling from the “top of the smile”. When pulling near the axis, it is more like prying up a straight pin, and it takes a little more force to get the pin to flip up away from the rig, whether by rotating the pin or having the fabric twist and move around the eye to where it can pull the pin easier. For all I know about BASE bridles, the extension from the bridle to the pin may always be on the same side, so the sad orientation may always be better, and that’s what the author cares about. But for bridles and pins in general, it will depend on which side of the eye the fabric normally lies." One skydiving bridle and rig of mine uses the packing method where the bridle comes up from the bottom and goes back down to the bottom. Depending on which side of the bridle faces up, I can either pack it so the happy face would have less force to extract, or the sad face would have less force, because it changes whether the fabric tends to be pulling from the one side of the eye or the other. (And often I pack it in a "more force" orientation because in skydiving I'd rather have a little more force to start the extraction.) [inline imag5794adj-pin-pull.jpg] To the OP: Having the pin aligned with the bridle is something some may suspect as encouraging a bridle piercing. While a very rare problem, some may like to keep the tip of the pin off to the side of the bridle, rather than under it, where a little bit of sliding around might more easily allow the tip of the pin to slip over the edge of the bridle. Bridle piercings are still a bit of a mystery so there's still debate about what practices to follow.

Which one was that?

Peguet makes the real Maillon Rapide links. Their chart online shows a Working Load Limit of 280 kg (617 lb) for stainless #4. The "BL", breaking load, is shown as 1400 kg. The ratio perfectly matches the idea that the Working Load Limit is set at 20% of the breaking load, or a 5 times factor, which is also mentioned in Poynters. 1400 kg is 3087 lbs. (I don't know what the Yield strength would be for that steel, at what proportion of the breaking load -- the Ultimate load -- the material would not deform permanently.) #4 Stainless are ok for all PD reserves, right? The manual (Revision G is current) just suggests #5's may work better with bulky reserve risers.

Parachute School of Toronto. (not set up for competition now?, although it has been used for that before) Nouvel Air (Montreal) (have had the nationals there using the pond - I guess it is a permanent one now?)

Depends on where 'around' is. He's up in my area, Toronto, Canada, along with a big pile of wingsuits, maybe for a couple years, although he still make trips south of the border. First time I saw him at a local DZ, Skydive Toronto, I walked up to him and said that he looks kind of like DSE. Which DSE probably would....

Certainly one could get into courses for different types of camera flying, or for the particular type of equipment used at a particular DZ. The OP was probably just thinking of the very first course one would take, perhaps a mandatory safety course rather than optional advanced techniques. Someone like DSE could probably set up a dozen different courses without a lot of overlap, on basic camera safety, videoing 4 way, basic tandem video techniques and equipment, stills techniques and equipment, advanced techniques, and on and on ...

Good video is when the red light is blinking. I think the idea here is about camera safety for the GoPro crowd, not whether one can set up an artistic scene or debate SLR shutter speeds.

I find it reasonable to have both an official name for something, and a commonly used term. Both FS and RW are still in common usage so someone new to the sport will want to learn both. Just musing: Both official and unofficial names have their down sides. Historical names sometimes stay in common usage even if they are quirky and don't fully reflect modern methods or emphasis. Official terms can both clarify and update our understanding of something, or confuse by becoming too official and all encompassing. One might talk about the ambulance service whether or not locally they come up with some name like the Integrated Emergency Services Health Unit. The FS official name has the big problem in that there are all sorts of body positions that qualify as skydiving in formation with others. The term "belly flying" has become more accepted generally too, and isn't just an insult from head-downers. Nobody likes to be forced to use a certain term if it isn't what they learned and thought was reasonable and appropriate. (My dad in his 80s will always say "Negros" for example.) But if the use of "RW" slowly fades away and is some day only used by old timers that's ok too. I've had a newer jumper ask what the "Delay" in the logbook meant. That makes it sound like freefall is still a weird and unnatural thing to to! And if someone shouts at you, "DIAL 911!" you don't run off and look for hours for a rotary dial phone.

Some people will just exit back to wind holding a bag and pilot chute. DZO's might not like the risk of that if it isn't a really high tailed aircraft. Others might have someone else IAD them out the door, so they can concentrate on the exit while someone else handles doing a clean deployment. Or someone might have the bag set up as a direct bag that someone holds while the jumper exits. Leaving aside the pros and cons of each method, with my cutaway harness, I wanted to get rid off any sort of loose bag and pilot chute in the airplane or any requirement for trained assistance in the plane. Therefore I used the cut-off main container to construct a belly container. Since it was awkward to use the top flap which was so integrated into the reserve bottom flap, I built a new custom top flap. Pretty much just cordura and some plastic for the stiffener. No need for binding tape, just folded edges, since it wasn't going to get a lot of use. The main container then just had loops to tie or hook it to tie down points on the cutaway harness. They don't have to be structural of course, but just keep the belly container in place and allow you to swing it open on one side to allow getting into the harness. The risers enter the belly pack at open slots at the top corners and I did put some velcro closures there to keep things in place. The risers of course go down from the 3 rings on the cutaway harness, down one's chest and into the belly pack. I didn't consider them to be too much in the way, especially when one is normally just doing a back to wind hop and pop with no more than a few seconds freefall. But I also put some 'wraps' with a little bit of velcro closure along the cutaway harness main lift webs, so the risers could be partially covered and secured on the way down to the belly pack. Oh yeah, the cutaway handle:I built a new cutaway handle/ cable to be a big white loop handle so its colour and shape is different from the nearby pillow on the regular rig I'd be wearing. I wanted that for intentional spinning mal tests. Velcro was added to the chest strap so the cutaway handle could be moved to a central position if desired. (The cable length and flexibly mounted end of the cutaway cable housing worked ok for that on my particular cutaway rig.) Since the container for the 3rd canopy is the old main container, it still had the BOC on it. So one could exit on one's back and just do a left handed pull on the BOC. The closing loop anchor changed to be from the bottom flap to the backpad/top flap area. This allows a large variation in canopy size by varying the closing loop length, while still providing pin tension. The whole system isn't fancy but is adequate.

Hey Bill, no luck with google? Although some info found from google may be old, there is someone by that name on facebook, from NZ, with various skydivers among her friends. Can't guarantee that she checks her messages though...

I can see that point of view: But unfortunately there is no standardized first-camera-jump-course , whether in the US or even in the UK (as far as I know), even with all its course requirements for freefall and canopy flight. In Canada, the cameras requirement is a B license , only 50 jumps minimum, and was reduced from a "C". Compared to a C license (200+ jump) rule, that does help novice coaches and jumpmasters film their students. Whether one likes the rule or not, that is open to debate.

What's your weight or wing loading? An agressive canopy at a light loading can be more docile than the design suggests. That would help a lot, although it still doesn't mean it is necessarily an appropriate canopy for you. It is also an older Spectra-lined canopy where it could quite well be out of trim by now. (Are line sets still available?) Between that and talk of a lot of deliberate production variations at the time, each canopy could behave somewhat differently for openings, maneuvering, and flare. It's like buying an old Sabre 1 -- it could be easily be a great deal or it could be a bad one. But that's general speculation, as I have only very limited experience with Jedei's.

Update on my original post from last year: I found out that the Aerodyne Solo's at the DZ I jump at, are different than most others: They are full zero-p canopies, rather than the hybrid design that the Solo normally is. As I understand it, the DZ requested full ZP Solos for longevity and perhaps a tiny bit more performance in the long run. The canopy is marked no different than normal as far as I know, and perhaps the configuration was just a production change at the client's request, and thus perhaps got no testing. That could explain why my DZ was having hard openings, while others report nice and soft Solo openings. However, there are still a few other reports of hard openings on DZ. (Which can happen with any canopy.) (I posted at picture of a student's bad opening on a PFF jump I was on, in another thread at http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4659162#4659162 ) Recently we did receive bigger sliders for the Solo 250's, which apparently had the worst problem at the DZ. The new sliders are about the same width, but something like a third longer front to back. The DZ has had instructors (including myself) make a couple jumps on the new system, and we got nice soft snivelly openings. (Still, the instructors were tall lanky types -- we'd want to test it on a more rock-like instructor too.) Now the DZO is concerned that the apparent 800' openings -- based on just alti readings on two jumps -- will be too much for students, so is going to try the Solo 270 sliders instead, which are somewhere in between the size of the old and new Solo 250 sliders.

February 1983 Soaring Magazine to be specific. Well that was interesting. That mysterious new skydiving planform explained -- just a planform I've seen on sailplanes for decades. Basically has the benefits of an elliptical planform for spanwise lift distribution, but tapering the leading only, with some benefits in terms of airflow (specifically, trailing edge separation and crosswise flow). But actually applying it on parachutes is a newer thing, and takes a little more thought given that we jumpers tend to hang somewhere under the leading edge, making the geometry more complex than when designers would taper the trailing edge a lot and the leading edge just a little. Paragliders and speedflying canopies seemingly have been big on that style planform for a lot longer than it has been seen in skydiving.

Dlcobbett kindly showed UPT's take on things. The US tandem industry also have something similar for filming a tandem in their "19 commandments" -- easy to find online. The USPA has not officially adopted them or a slightly shorter variant in the SIM, but I get the impression they consider them a generally good idea to consider. Even if you are at a DZ that doesn't follow those very stringent rules exactly, any dz these days will probably want you to be a really decent relative worker to jump with a tandem. One might need the agreement of the tandem instructor, tandem passenger, and DZO. The experienced jumpers need to be confident that you're the type of RW jumper who can be trusted to fly consistently with safe dives, close-in flying, and breakoffs. Not the dude who who is still a little sketchy, overexcited, and sometimes drops onto the the formation they are chasing.

Ok, I'll go a little overboard on musing about some of the factors, as sometimes I just can't leave well enough alone. Your opinions may differ: It just isn't going to be mass market both due to costs of operation, and the unusual skills required, which are a barrier to entry. You'll likely need to be a reasonably experienced skydiver and some pilot's license might be required by authorities, and then there would be some pretty specific things to learn to fly this aircraft, without benefit of dual instruction. It isn't that people can't buy expensive things, after all, financially successful people learn to fly, build up a bunch of hours, and buy 4 seat airplanes for travel, or Pitts Specials for fun. I'd think the Wingboard would be neat for airshows or promotional videos, sort of like Yves Rossy's jet powered wing. WING LOAD Back of the envelope wing loading calculation: 12 ft span was suggested. Fairly big chord in the preliminary concepts, say 3 1/2 ft max, thus say 42 ft sq ignoring details. All up weight in the 300 lb range, leaving 100+ pounds for structure + parachutes. So about a 7-8 lbs/sq ft wing loading. That's still fairly low for a light aircraft. The Hummelbird, a minimal sized aircraft, is at about 9 lbs/sq ft at gross. So even if it gains some weight it isn't a really high wing loading. A few big challenges come to mind: STANDING PILOT POSITION One is the whole standing up thing. Whatever the technical challenge, it seems freaky, although obviously part of the attraction too. The idea, according to Wyp's site, is to weight shift control the glider, but also with force sensors in the bindings and tow bar for aileron commands. (So would it be all electronically controlled and powered electrically?) The web site mentions the idea of doing spectacular aileron rolls on tow. Sounds fun but that's getting into expert territory. Gliders have been rolled while on tow as an airshow maneuver, but it is very rare. There would be more feeling of freedom in not just sitting on an open-air aircraft but standing. Even just sitting in open air is more typically something for classic ultralight aircraft pilots in summer at lower speeds. Parts of the project are easier to conceptualize if one saw it as just a very compact, ultralight glider, with a pilot in a reclined sitting position ontop (and more conventional aircraft controls). Various tailless, small gliders have been flown, the BrightStar Swift most notably. (Although it is an efficient high aspect ratio aircraft) Center of gravity needs to be carefully controlled on such a small tailless aircraft but it is doable. Standing up certainly adds a bunch of drag. Despite the light weight it will be pretty draggy on takeoff as speed builds, so it won't act quite like some light, streamlined glider. At least despite the high drag, the total weight to climb with will be much less than when towing a full size two seat glider. Ok, so I guess it is likely doable without an unusually high powered tow aircraft. (C-182s and the like tow banners, although they would be unusual as glider tow aircraft). DRAG My quick drag calculation for a person's drag would be say 125 lbs at 100 mph, maybe a little less when crouched. (One can calculate from terminal freefall drag and speed as a rough approximation and reduce by the velocity-squared rule.) Wyp's site mentions "The tow line splits the forces between the rider and the board. The WingBoard takes half of the force, reducing the force the rider must hold by half, only 80 lbs at a speed of 100mph." Whatever the numbers are, that's still a lot of force to deal with. Jumpers don't like holding onto a jump plane for very long at 100 mph. (And that may be when hugging the boundary layer and turned sideways, although sometimes with extra prop wash) Wingwalkers can go much faster but with a sturdy torso support behind them for much of the time when up on top. While first impressions can be wrong, mine is that the fun could quickly go out of flying a Wyp, if one is holding on with only arms and feet in bindings. With a solid back brace, or some harness with straps angling forward to the vehicle, that would help a lot. Maybe speeds can be a little lower for the tow plane and still keep it in the air - even 80 mph would reduce forces 35% - but in general I see the wind forces as a challenge. With all the person's frontal drag, and a short aspect ratio aircraft, it isn't going to glide well. The website suggests both parachute and rolling landings are possible. Landings could be a bit challenging but people with experience do manage to land low aspect ratio, draggy parachutes at high speed, or high sink rate gliders (Me163). Rolling landings imply free flight without a tow. Then one is down to using bindings only for staying in place, not even a tow rope to take loads with. So you'd really better be leaning forward into the wind! CONTROL Control will be a challenge too. I guess the weight of the device is within the range that can be weight shift controlled, and hang gliders are after all weight shifted on tows from the ground (starting on wheeled dollys that stay on the ground). Stability will be a little different with the pilot weight on top than below -- the big mass up top (say 200 lbs over a 100 lb aircraft) is destabilizing, particularly if pitched or rolled away from level flight. On the other hand, what with radio controlled airplane technology, there are plenty of acceleration sensors that can be used for artificial stability systems. Still, I'm not sure what the authorities would accept. You can have a homebuilt aircraft with an uncertified autopilot, but that's just an add-on that can be switched off or overpowered, not an essential primary flight control required to fly safely. PITCH CONTROL Pitch control is the next thing that comes to mind. Weight shift as mentioned can work for towed hang gliders. But I'm thinking that the pilot of this thing better maintain a pretty steady position -- Given that the pilot's drag is such a big part of the overall system drag, and it is so high off the wing, just crouching down or twisting one's body more sideways could lead to some some sudden pitching moments. PARACHUTES So there are supposed to be two parachute systems -- one for lowering the whole aircraft and pilot (as Rossy does), and one for the vehicle only if it is jettisoned. The aircraft & pilot one is a little trickier than Rossy's because the parachute, vehicle, and pilot aren't all attached in the same area. I'm not going to take opening shock with a 100 lb wing just dangling from my feet! So that also suggests that there would have to be additional harness connections between pilot and vehicle. Would the aircraft/pilot parachute have to be a TSO'd dual parachute system? Hmm, not sure what the standards are for an airplane that normally lands by parachute, since planes with parachutes only use them for emergencies. But it would seem sensible to treat it as a personal parachute system in effect and go with 2 canopies, and the authorities might want that. (At least in the US, one has a lot more freedom to design and build one's own homebuilt aircraft, while oddly, there is no such category for parachutes. You can copy an airplane design and just build it as a homebuilt -- with some basic safety inspections along the way -- but you can't just build a rig without a TSO and jump from a plane. B.S.!) ATTACHMENT SYSTEM My final big concern that comes to mind right now is that the whole attachment system for the pilot is just too unstable. Two bindings and a towrope in hand? Will you start to tip over - or even fall down on your butt - if you hit a bump on the runway on takeoff, or if the towplane bounces a bit and there's a yank on the towrope? At least if you aren't already an expert. What's that going to do to your aileron controls if they are force sensing the bindings or something in the tow bar? Whip the aircraft into a hard bank just as it lifts off? Would aileron sensors instead need to be more like some handheld game controller thumb switch? Weight shift control errors may be acceptable if speeds are slow (e.g, learning to snowboard and falling down), or if there's some natural stability (e.g. hanging from a hang glider, one can screw up how to properly weight shift, but one doesn't fall over). While other light aircraft may have minimal structure and crush distances around the pilot, this one certainly has nothing but jumpsuit and helmet if something goes wrong on takeoff or (optional) rolling landing. Would I want to test fly the thing? No way standing up, not as it is presently envisaged. Sitting on the wing with some support and bracing, so that any inputs (whether by weight shift or other means) can be applied without gross errors? Yeah that's easier to envision. I'm still a bit conflicted about how much I'd want to fly the thing. Would I rather just go skydive if I want to get my body in the wind, and fly an aerobatic glider or power plane if I want to swoop an aircraft around the sky? I'd like to see some stability and control calculations and numbers on stall speeds, flight speeds, and forces. Who knows, one might be able to do a decent simulation in the X-plane simulator. The inventor's small scale remote control tests will be valuable. Although getting the behaviour similar enough due to mass and momentum scaling effects can be tricky. Overall I'm a little sceptical about all the hype but it doesn't mean some sort of cool towed mini glider can't be made and flown.

"This baby is certified to 1949 standards!" Oh, never mind. (Just a cheap shot for anyone who knows their TSO's.)

True on its own, but is does matter if you are led to believe that both links are equally strong, but they aren't. So it is, "Hey, this reserve and harness are both good for 275 lbs and 150 kts". But then one finds out that that in that case (with the added 1.2 factor), the reserve can create 4000 lbs of force and the harness's tests only created 3000 lbs of force. Maybe the harness is strong enough, but it hasn't actually been tested to the same level as the reserve. And you wonder, what speed and weight your two link chain really is good for. It isn't like a paragliding harness where I think certain certification pull tests are done on the ground. (Not that that is perfect either, if one picks the wrong test cases for a harness. Like the Squirrel Stronglite BASE rig when deployment forces are in a certain direction.) And thanks Hooknswoop who remembered that the compatibility stuff is in AC-105.

If you don't mind something pirate-y, a few articles can be found at Libgen.org: (http://libgen.org/scimag/index.php?s=skydiving) Although I once saw someone say that they block access from US IP addresses. Don't know if it is true. Otherwise one wants to be at a university library and use their resources. A few papers on fear and risktaking have been discussed on dz.com before. Jason Laurendau wrote a few papers over a decade back and did skydive at the time.

Wow, that low? They must have found a nice soft opening reserve! C-23d does allow using any reserve that still meets the 3 second opening rule. (Ref: AS8015B, sec 4.3.4 and 4.3.6, with slight mods for higher weights) In this thread we've seen the opening forces at max weight & speed (*1.2) can vary a lot. Is it correct there's no requirement for a C-23d harness to withstand the loads listed for a C-23d canopy installed in it? So they can test the rig with a soft opening canopy but you can put in a canopy that opens a whole lot harder? (at the maximum limits) The rules looks similar in TSO C-23f / TS-135. I recall some discussions about stuff like this but not the details.

I used gaffer's tape on the buckles of one rig to increase the friction. At least one other dz.commer has done the gaffer tape fix too. That particular buckle variant had a very slippery surface finish and later wasn't seen on that major brand of rig. If the gaffers starts to peel at least it is easy to replace. The jumper loved the result. Before using the tape I tested putting in other webbing -- like type 12 as one company has done or rougher type 4 tape as another company suggested to me -- but the buckle still tended to slip a little under load, despite the increased bulk. My fix was a traditional style of buckle, center piece sliding on the main buckle, not the free-floating 2 piece ones. So your mileage might vary. The tape wasn't needed on the slider, just on the part of the main buckle that the webbing jams up against.

Nice data! The info we have here is all still a bit fragmentary, but shows how much variation there is, between brands, between sizes in the same brand. Sometimes the smaller canopies open harder, sometimes the variation with size looks almost random.

The problem was all the spins "all the way coming down". If you tell a tandem instructor that doesn't make you feel good, they shouldn't be doing it. It's about your fun, not his. And there is almost no need ever for any skydiver to continuously spiral. So not being able to spiral a lot shouldn't be a problem. Since you are particularly prone to motion sickness, it might be a problem for you in skydiving, but it might not. If the airplane is rocking around a lot on a hot, bumpy summer day, maybe that won't be good for you. People do acclimatize to new types of motions, although that can take time. So it is all hard to tell. I can understand an instructor wanting to play it safe. On the other hand, it is possible that you'll have no serious problems when learning to skydive. (Just like someone learning to fly might throw up if taken up for aerobatics, but do fine during regurlar flying. And if regular flying also makes them queasy, which can happen, then they just can't go flying as many times a day or for as long. With skydiving one isn't up there that long, so you're only committed for 5 minutes at a time, at the most, once out the door. Before that point, one can choose to ride back down with the plane, although that may cost something.)