pchapman

It has also been pointed out that a reserve is not pulled slowly 'from a standing start'. There's some force to remove the handle from its pocket (not measured), then it may move easily for some more inches until the slack in the cable is taken up. Then the momentum of ones arm moving all of a sudden yanks on the pin. The pin even gets the chance to move a bit before the slack is taken out of the seal thread, and that force is added. There may also be some effect from the dynamic friction while the pin is moving, being a bit less than the static friction to get it started. So the forces one apply can easily be quite a bit more than static pull tests indicate. The Great Bearded One (Bill Booth) mentioned some of that kind of stuff in threads 491650, 144383, and 942674. (Use the search function too, Hackish!) Now I bet a fair number of reserves are packed with pull forces a little bit higher than the 22 lb maximum. One tends to get that with some super tight pack jobs. A day's cooling off period tends to bring the force back down again so in practice it doesn't become an issue. And a rigger can get a feel for what is on the tight side but reasonable, vs. ridiculous and on the way to ripping the Cypres loop while packing.

[Old thread but the topic is right.] I've been at a DZ where instructors do give a cutaway command, although the emphasis all through the static line course is that the student makes the decision. WHEN NOT TO CUT AWAY A related issue is when not to cut away. If a student has a mal but doesn't deal with it and gets low, at some point one will want to make sure the student doesn't cut away. This can be an issue both at DZs that give and don't give cutaway commands. No more calls for a cutaway if they're spiralling through 500 ft under a lineover. My DZO seems to have a point that at such a time, it's pretty much a case of having to lie to the student. The idea is to reassure the student, have them prepare for the landing roll, that sort of thing, as if it were all very routine. Nothing is said about any emergency, that might invite a chop at 200 ft when they finally notice the ground approaching quickly. TERMINOLOGY Instructors at the DZ are careful about terminology when using the radio. Usually the instructor would say something like "Use your Emergency Handle!" (as it is a one handle system), being very clear of course about which student is being addressed. The instructor might instead say, especially if the student isn't responding, "Look, Grab, Pull!" because those are the words the students learned while practicing the motions during the first jump course. Instructors never use those words for anything else, to avoid confusion. Many many years ago, an instructor must have told a student something like "pull your right toggle, come on, pull, pull!". The student only registered the "pull!" idea and cutaway, thankfully high enough for the reserve to open. GETTING FOOLED EVEN WITH CAREFUL USE OF TERMINOLOGY Recently an instructor was dealing with a student who was not particularly responsive to the radio. While normally students are addressed by "jumper #1" etc., we have their names recorded as a backup. In this case instructor tried to get the student to respond by using his name: "Luke, Luke!" You can guess what that sounds like. From under a good canopy, the student chopped. Again, they were plenty high enough to get under a good reserve. It's hard to anticipate every eventuality...

Which brand of gear was that one?

If you've got 'em, post 'em. Or at least give us a gist of the type of thing to watch for. It's a big book so errors are possible. I'm curious how obvious the errors are. If they are obvious to even a newer skydiver, then perhaps it isn't that bad a problem. The nature of the errors may still say something about whether other ones lay undiscovered, and more likely to trip up a new or experienced rigger.

[Note: Thread applies to CANADA] I'd go right to the CSPA's Coaching Working Committee (CWC) site. The page is http://www.cspa.ca/cwc/relativework.htm It is a little confusing that some of the best stuff on the CSPA site is "hidden" under the CWC section. CoP study guides and info on all Endorsements are at the CWC site. The blueplanetweb site mentioned in post #3 seems to be a development site for the CWC stuff?? The page mentioned is almost identical but bit shorter than the one I mentioned. I can't tell which site would be most up to date at any given time, but the official one would be the CWC one. So the CWC page on the 2 way RW endorsement does list what is to be done on the minimum five jumps. However, the list still still requires some interpretation by an instructor. At my DZ (the 'other Toronto one') we've got charts for this sort of thing, taking the CSPA guidelines as a starting point to create a curriculum. Spread the word about the CWC site -- it isn't perfect but is useful and not as widely known as it should be!

No issue with propacking that I know of. I think flat packing is done simply because it works fine for big old F-111 style canopies, and because propacking large canopies can get awkward. Propacking may even make it easier to apply certain nose & tail treatments, like rolling the tail a lot, if that is one's preference. (For those taking Parafoils to terminal, it seems that everyone has different packing variations anyway, to try to get a decent opening.) While I've flat packed my Parafoil, I know a fellow with thousands of Parafoil jumps who propacks his all the time.

Regarding the rocket activity: This is just like skydiving operations having other pilots flying overhead, oblivious to the skydiving activity. The DZ may be frustrated because they have already done everything correct with the FAA, when it comes to NOTAMs etc. But additional effort is necessary to "get the word out" into the local flying community about the hazard. Send notices out to other airports to put up on their bulletin boards...

Are there particular concerns you can mention, whether or not the the risks turn out to be valid? A major one would be how well a particular design operates under heavy load.

Thanks Ryan, I have left a message for the DZO suggesting he can contact you, if for whatever reason he isn't getting the payment issue resolved. I don't know any of the details.

Fun to check the logbooks. Not exactly a typical progression for me: -- jump 41 first set of own gear: used Racer & Titan 265 -- circa jump 600, 11 years later: different used Racer & Sabre 135 (hey, the Racer was cheap and as a rigger I could make some changes) -- circa jump 770, 1 1/2 years later: same Racer & Icarus FX 88 (But due to doing a lot of accuracy on another rig, I only had 32 jumps on the 135 before going to the 88) Currently 1950 jumps. (I have accumulated some other odds and ends but the above has been my main gear.)

I know a DZO who decided to try accepting Skyride certificates because he didn't know the whole controversy, not being a big internet user himself. He has accepted maybe a dozen students arranged through Skyride, and now can't seem to get them to pay him for the jumps the students made... (Now that jumpers found out and filled him in on the story, he's no longer planning to do any business with Skyride... except hopefully get what he is owed.)

I'd like to know what the real strength of chest strap adapters are, whether the one for the 1" webbing, or the traditional wide-webbing MS70101 design. Although they are somewhat wimpy pieces of metal, they are much maligned as everyone keeps quoting the 500 lbs number. "Rated strength" does not tie in directly with ACTUAL STRENGTH. It's all a bit mysterious and I've never gotten good answers (or found them in DZ.com searches). RATED STRENGTHS have different safety factors depending on the standards for that type of item. For example: -- Webbing: Poynters suggests that a rated webbing strength is the minimum at which the webbing would break. If there is not more to the story, the manufacturer would make sure that for any variation in material and manufacture , their webbing will break at that strength or somewhat higher. There is no extra safety margin built in, above the quoted strength. (I'm discussing the new webbing alone. It's another matter how it is used, given stitch pattern strengths or UV and mechanical wear) -- Rapide quick links: The loads listed on them are Safe Working Loads, with a 5 times factor to the Breaking Load. The Proof Load that they must withstand without permanent deformation is half of the Breaking Load (or therefore 2.5 times the quoted Safe Working Load) -- Parachute hardware: (At least for the US style milspec hardware) Poynters #1 is vague. It says that hardware is proof loaded, and that there is a 100% safety factor. So I guess but don't know that if hardware is quoted as "500 lbs" then it is supposed to hold 500 without permanent deformation, but also to survive 1000 without actually breaking (if the load is applied in the intended manner). If this is correct, then it suggests that in the quoted scenario, then the stitch pattern of 900 lbs max may actually be fairly well matched to chest strap hardware that could well go to 1000 lbs before failing.

Kefran: Regarding "don't play the 'YOU'RE A DUMBASS ...' with me ok?" Riggerrob was probably curious because you wrote "my certification as a tandem camera will allow me to follow them in the sky". Your profile shows your home DZ to be in Canada, at a CSPA affiliated DZ. I don't know of any certification required in Canada to allow anyone to do tandem videos. Educate me. You were simply being called out on something that someone probably believed to be inaccurate. Perhaps the DZO has a strict procedure to qualify people to do tandem video, or likes to closely follow manufacturer's recommendations regarding RW with tandems, or perhaps English isn't your first language. But you still say you have a certificate: "regarding my certificate i really don't have to show it here ". True, but we may not believe you if you don't, and we may still be curious what certificate is required to film tandem video. I seem to be missing mine...

The stalled chute is not the problem. It won't overtake the jumper so to speak. The issue is coming out of a stall, where a sudden reinflation with zero brakes applied can cause it to shoot forward to the horizon and result in slack lines. This is more of a problem if the canopy was either well stalled for a long time (completely collapsed and vertical speed has picked up a lot) or the canopy had just swung far back as the jumper has entered a stall in a very dynamic manner. Proper stall recovery technique is advised. I can't recall whether anyone has managed to gift wrap themselves with a skydiving canopy, although dropping into slack lines could easily cause problems. Who knows, you might be able to do it if you tried. More likely with a high performance parachute would be to get an opening that isn't on heading, which when combined with lack of line tension, would result in a spinning diving line twist situation requiring a cutaway. (With much lower drag, long lined paragliders, grift wrapping has happened.)

Billvon's reply gives a perfect example of what I was writing about -- a simple looking thing to do (a launch with just a little 4 ft drop) turned out not to be so simple. So to have a high chance of success with no scary moments, someone doing a building launch should be very comfortable with paragliding or ground launches. Otherwise they may not instinctively recognize the precise position, orientation, forward speed, pitch rate, lift, drag, etc. of the canopy at the moment of deciding to go over the edge... Just my opinion.

I'm usually at a fairly large static line DZ with FXC's on their gear. I don't recall or recall any talk about any unintended FXC firing over the last 5 or more years. (The exception was one FXC that went bad and fired while the student was flying around at normal descent rates.) Student AAD's are turned off in a descending plane. When the DZO was looking at expanding the range of rental rigs available, I did a few test jumps with a bag of 3 FXC's. I couldn't get any to fire when doing toggle spirals at a 1.3 wing loading on a Sabre 135, but two went off at 1.4 wing loading. (However, I only did a single jump at each wing loading. In the spirals I was trying to achieve by feel the fastest possible descent. ) The tests gave some assurance that even for a lowly FXC, even when trying hard to fire them, it can take quite a high wing loading to get that to happen. I don't have the FXC firing specs in front of me but another post by an experienced rigger suggested 40+ fps (approx 28 mph).

CanuckInUSA had a good and detailed reply. I'm not current in paragliding, but in that sport cliff launches are generally considered to be dangerous and not normally done. The sharp corner tends to cause turbulence and odd wind gradients, and the sharp corner also means a launch is more of an all-or-nothing deal than the usual launch down a slope. If someone were launching off a building, I'd suggest they should to be really comfortable kiting their particular canopy in turbulent conditions, whether for forward or reverse inflations (facing back at the canopy to see it better while inflating it). It should be easier for a low aspect ratio skydiving or BASE canopy compared to a high aspect ratio paraglider. Being really familiar with ground launching the canopy off other slopes too, would help in gaining that split second awareness of what the canopy is doing and how to control it. Kiting and launching canopies, and dealing with different winds, is a real skill, that takes time to acquire. Still, who knows, maybe one doesn't need all that kind of practice to accomplish a successful building launch. I just don't know.

Winsor wrote: Although jumpers might at times say they are basing their separation "on ground speed", in reality they may only be using observed ground speed to modify what they already know -- they're already familiar with the aircraft they are jumping and are used to the typical separation times needed, for an aircraft of that airspeed. This doesn't change the whole discussion about what is a simple but not too simple way to decide separation. But I think it makes things look a little less pessimistic about jumpers who seem to be looking at ground speed only.

Just to clarify the terminology, as used in aerospace engineering and aviation: Lift is the force perpendicular to the direction the flight vehicle is moving. Drag is the force opposite to that movement. Together, lift and drag combine to perfectly oppose weight, if the vehicle is in steady motion and not accelerating. See diagram. L=lift, W=weight, D=drag, V= velocity So a tracking jumper creates lift. Lift is contributing to keeping the jumper from falling faster, even if that lift is not from Bernoulli style flow, moving smoothly along the object's surface like on an airplane wing. In a sense the lift from a tracking jumper will be like that of drag, just a force from having a rough, non-aerodynamic, blunt object forced through the air. Since that blunt object is at an angle to the air, the force created ends up angled away from the direction the object is moving. We then represent that single overall force by the forces at right angles to each other, which we define as Lift and Drag. A 180 lb jumper in a steady track will have lift and drag combine to a 180 lb upwards force, no matter how good or bad the track is. (Indeed, it will be the same when the jumper is under canopy.) Thinking about lift and drag for skydivers is a little messier than for airplanes. For planes the angle of attack is so small that for a first approximation, one can think of drag as "towards the tail" and lift "up" relative to the airplane flying level. But for a skydiver at maybe a 0.5 glide ratio in a track, with lets guess a body angle 10 degrees head down from level, that's an angle of attack of 53 degrees. So Lift and Drag directions are not "straight up away from your back" and "towards your feet", nor "vertical" and "horizontal". No big deal, but it makes thinking about lift and drag less intuitive. In the end, when it comes to tracking: As the combination of lift and drag stays the same, the issue becomes how to achieve that combination with a lot of forward speed, or a high glide ratio, depending on your goals. A lot of drag and a lot of lift are both helpful in achieving those goals.

Given a choice I'll usually pick up my rig with the 88 in it, not the rig with the 282. Still, acccuracy approaches are a good opportunity for careful concentration & focus that are absent from many other more ordinary landings. A good challenge in other words. And Gary, perhaps you saw the thread on the PD Optimum reserve which got sidetracked into discussing how a couple PD jumpers were shooting accuracy with their Optimum 113s at the Canadian Nationals. They had to learn fast and were having a blast. (http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2910184)

At a Canadian DZ that's a little different but has a carefully thought out program: Yes, SOS for static line rigs. Keeps it simple for the vast majority who do just one jump. Then for freefall progression after static line, rigs are also SOS, with hip mounted main ripcord. (Allowing FXC AAD's both on main and reserve.) Then when students have their Canadian Solo certificate (no longer requiring direct instructor supervision), they convert to "regular" skydiving gear with TAS and BOC. Since this is a big step from their previous gear, there is a 3 jump transition program to properly teach them TAS emergency procedures and BOC main activation.

Given the car door issues, I find it funny how the Vigil's web page mentions its patented, accurate calculation method, that computes time left until activation altitude, and then activates when the right altitude is reached if the speed exceeds 35 m/s. I'm curious just what the pressure vs time graph is for a slamming car door. Exactly what kind of skydive does the Vigil think is happening? Flying along level in a plane and then accelerating downwards with a rocket attached, in order to exceed 35 m/s within a second? The whole car door pressure spike can't take very long. Maybe I'm way off base as to how messy the pressure variations are during some car door slams, but it would seem simple enough to filter that sort of thing out. Off the top of my head, the nearest kind of skydive, that could be confused with a door slam, would be a low bailout or low cutaway, where there might only be a few seconds between "OK" and "fire at 840 ft or less, and 35 m/s". If it really is so tough to deal with car door slams, perhaps Advanced Aerospace could better explain to us why it really is so, instead of having so many people be sceptical.

The songs that relate the most to skydiving do tend to get over used! A reasonable one I've found for tandem vids is "Let You Down" by Three Days Grace [edit: group name corrected], that has lyrics that are interestingly appropriate: == Trust me There’s no need to fear Everyone’s here Waiting for you to finally be one of us Come down... You may be full of fear But you’ll be safe here When you finally trust me Finally believe in me [...] == A classic is the song on Norm Kent's From Wings Came Flight: "I'm standing on the edge, with a vision in my head, my body screams release me, my dreams they must be fed"

Re my yellow helmet post: The padding on that inside face is quite thick so that there is space for the bolts without being close to touching the camera. Still, a little extra foam over them wouldn't hurt. The LANC connector isn't forced in, but if the camera moves more than I think, it can get stressed by pushing on the edge of the hole around it. You're right, a little more room around it might be good. I've also heard of people building a little extension for the LANC, so that the extension can stay in the LANC port all the time instead of plugging and unplugging every jump. Rather wear out the extension instead.

Summary: Protec with home made fibreglass helmet box for an HC-42. Camera was factory refurbished off eBay. Extra padding inside the Protec to make it fit snugly. Skysystems chin cup, Bonehead cutaway system, Cameye LANC system. Cheap, interesting project, but lots of hours to work out the details. Didn't spend enough time epoxying and sanding to make it beautifully smooth, but it's functional. How the helmet went into service: Showed up with it at the DZ for the first time. Very busy weekend and DZ low on cameraflyers. Ended up being put into the cameraflyer rotation. First jump ever with a camera helmet was a working dive, with no briefing. At the Cessna DZ, did 8 camera jumps that day. At least as a tandem instructor, I've been on the other end plenty of times so I just copied what I remember watching others do. It wasn't exactly a by-the-book initiation into camera flying… All the details: (irrelevant unless building a box oneself) The details don't matter until one has to solve the issues that are so simple in concept but messy in detail, like saying "And then you simply bolt the box to the helmet." Box built over a male mold of hard insulating foam built off the dimensions of the camera, with I hoped enough spare space for bolt heads etc intruding into the box. To some degree, nuts and bolt heads are towards the corners of the box, where the camera tends to be rounded and thus offer more free space for such things. Box was built essentially rectangular except for an extra angled face on the lower half of the side towards the helmet. That's where the helmet sides curve inwards for the ear covers. So it wasn't built to conform exactly to the complex rounded helmet shape. Box attached with 3 low profile bolts going in from the box, screwing into low profile internally threaded hardware -- essentially female Chicago screws. Therefore on the inside of the shell there are only very thin, couple millimeter thick pieces of attachment hardware; no thick bolt heads between my head and the helmet shell as I've seen on other quick homemade jobs. To align the fairly rectangular box with the rounded helmet, washers were used if needed to provide the right amount of gap at each of the three bolts. Light fibre washers were used. Each bolt also had one rubber washer between the non-parallel sides of the helmet and box, to better distribute the stress. An anti-line-snag aluminum angle was epoxied into the bottom of the box, to fill the gap between the box and helmet. The box hinge was bolted on, although I could have used rivets instead. Nuts for the hinge and closure were epoxied into the inside of the box after the basic structure was made. Box hinge is at the bottom, so that the Allen-threaded machine screw used to close the box, is at the top. Less snag hazard than the bottom mounted screw on, say, a Rawa box. Painted with Krylon spray paint for plastic. This goes on thin and needs a lot of layers, and seems to scuff easily enough. So I will soon cover it all in a final layer of epoxy for protection. Sky Systems chin cup. Seems to be good quality. Bonehead cutaway system with mods to move handle location. Basically it uses a cotter pin through the attachment pin, with a spring to push the attachment pin out when the cotter pin is withdrawn. The inside of box has a small cutout for the LANC connector to fit into the camera while in the box. The right angle LANC connector from the Cameye unit was shaved down in thickness too. (Just got rid of some insulating plastic). There's some slack in the cable inside the box so the camera can be pulled out some distance before one needs to reach in to disconnect the LANC cable. Unlike some skydiving cameras, the plastic cover over the on-camera ports was not cut off in order to expose the LANC port. Instead, a hole was drilled in the plastic cover, large enough that the LANC connector would fit through the hole, retaining the rest of the cover. The Cameye on/off button was installed as a snap fit through a hole made in the helmet. The location was chosen as one where it was unlikely to be accidentally bumped. (As it might be, say, at the center back of the helmet.) I don’t know if the location is ideal, but it is OK. The hand strap on Sony cameras can be very thick, with heavy leather-like padding. Some of this was removed and rebuilt to make the strap much thinner so that it can be left on the camera and still fit in the box. Most skydiving cameras have the strap cut off. Particularly with a non-matchbox style camera, it is nice to retain the strap. (Given the strap, heads of bolts attaching the box to the helmet, and the LANC connector, there needs to be a little extra space between the camera and the inside face of the box. So the box is a bit wider than a minimum sized box would be.) A Protec normally sits loosely on the head with quite hard foam. In order to make it more comfortable with a tight chin cup, and to keep it from shifting side to side with the weight of a camera, I had to build an additional foam liner. (Not in the photos.) The first simple version uses a number of pieces of open and closed cell foam, which were roughly sewn into a thin fabric cover. It does not fill the entire top inside of the helmet; there are gaps at places to allow for ventilation through the normal Protec ventilation holes. Some helmets' linings use a fleece cover. While comfortable, it seems like it would be warmer than necessary in summer. I'd rather have a cool helmet, so the fabric used for the liner was thin, sheer material. Direct cost was low -- about $145 US for the helmet assembly & box, excluding the Cameye as that's not part of purchased systems. Plus something for the fibreglass and epoxy, which I already had. Compare that to $395 US before shipping and taxes for a common, "inexpensive" full-box system, the Rawa.