crazy

Glide path released the final grounding bulletin early in 1994 (approx january), but there was already a recall bulletin early in 1993 (approx april). However, many nova owners used to jump it long after the final bulletin. Some still jump it nowadays. BB Come

About canopies supposed to collapse because of their design I completely agree for the Nova and a few other canopies before this. All this is more than 10 years ago. The Nova was grounded even before the release of the Stiletto. Anyway, in the context, my question was implicitely about canopy designs newer than the stiletto. The crossfire? as far as i know it is not a problem of design. Officially it was a problem of manufacturing. I don't think that the manufacturer would take the risk to keep any crossfire in the air without any fix if it was a problem with the design. Now, you probably have good arguments to backup your claim. Don't you? The Chaos? Never heared about any problem with its design. Can you provide more accurate references, or is it just rumors propagating the same way there were rumors about the stiletto when it was released? BB Come

You are talking about bad design here, not about people flying into turbulences, right? Can you be more specific and tell me which canopies are supposed to collapse and kill people because of their design? So, what's your point? Basically, you're just highlighting that the stiletto can collapse and that the guy had a really close call. How can this example possibly show that the stiletto is better and safer than newer designs? Looks like just the opposite. For many modern canopies it's so improbable that it's quite unlikely to witness this type of incident. BB Come

You can't be serious. Don't you think that your canopy would fly better if it had been instrumented on a rolling test harness? or if the variance of the inertial position had been correlated to the 4 point riser load data? BB Come

Well, now that you're talking about it, people there tried to kill me a few times with terrible advices: offering budveiser when i need beer :-) BB Come

I strongly disagree. Our everydays life doesn't prepare us to this. We usually trust the experts in disciplines that we respect (for instance doctors) and many beginners tend to trust their instructor and the other experienced skydivers. I understand your frustration when you are unable to save someone who is not willing to listen to your sound advices. However, when i read the title of this thread and some of the comments, i also think about at least one fatality and several serious injuries which are the result of very bad advices. When you are at a large DZ, like Perris, with lots of incredibly trustworthy people, it's easy to know who you can trust. In smaller structures, you don't have much choice. Come

Is this only for people who ignore your advice, or for people ignoring advice in general? Any idea why some people choose to ignore some advice? Couldn't it be because there are bad advice (bad content or bad presentation)? Even though i have no doubt that yours are alway good or excellent, i tend to think that the average level of the advice at many DZ contains a lot of noise. I'm not only talking about the beginners proud of their new knowledge, but also about experienced and very experienced skydivers propagating urban legends, commonplaces and wrong information in an authoritarian manner. I actually did (and will) choose to ignore advice very often indeed, and i am worried that you might hope i break my femurs. Blue Skyes Come

The flaws in the design of canopies 25 years ago are not exactly my main considerations when i choose a canopy. Even the Nova was grounded more than 10 years ago. At that time, the knowledge, the methods and the technology available were quite different from what we have today. As a matter of fact, over the last 10 years, i wonder if there were any obviously flawed canopy designs put on the market in europe, north america, new zealand (as far as i know, the problem of the crossfire wasn't a problem of design but a problem of maufacturing), australia or south africa (i would even add russia, but i'm not sure). I'm talking here about tens (if not hundreds) of new designs, some of them being very innovatives.So, i have good reasons to think that most of the canopy designers are experts willing to do a good job. I can trust people who are experts in domains where i know shit; all of us do this all the time (food, transports, buildings...) Watching over their shoulder what they do will not help them to do their job and it is a very arrogant behavior indeed. Either i trust them and let them do the job, or i ask somewhere else. Anyway, your views are quite interesting. I guess that you are very interested in the tests of new canopy designs, right? How did you get enough knowledge to be able to make a sound estimation of the reliability of the tests performed by the manufacturers? Did it take you a lot of time? Would you mind posting a summary of the overall knowledge required? Blue Skyes Come

No, i don't have any idea how any of my canopies were tested. And you know what? I don't care at all. For me it's enough to have enough confidence in the designer and the manufacturer. If i can sincerely believe that they do their best to produce good and safe products, i'll consider buying their products even without testing them. If they never quit patting themselves, bashing the others and making inaccurate claims, i won't even consider testing their products. Dan can tell whatever he likes about kiting, wind tunneling, instrumented flight, high speed fata, 4 load risers data point, inertial position data, micro miniature wireless video camera... I'll get severe headhaches much before even starting to understand the words. So i prefer a designer who saves me the pain, who spends less time trying to impress the chick with his high tech equipment and who uses whatever techniques he feels appropriate for the job. BB Come

Now, i'm really curious. Apart for the type of lines and maybe the quality of the fabric and the reliability of the manufacturing process, what are the differences between the old ones and the new ones? Did they change the airfoil, the planform, the structure or the trim? Ok, its old. And what? Is it really safer and better than most of the newer designs in its category? BB Come

What did this design prove exactly? Doesn't it have a few flaws that many other (usually newer) canopies don't have? What makes you fly it with complete confidence? Why wouldn't you be as confident flying a newer design? BB Come

Go for it, jump! Just make sure that you are safe and that the jump will not be all wasted. If you stick to 2 ways sit/stand for the first few jumps you don't take such a big risk as long as you follow some elementary rules: never be straight above or below, keep eye contact, avoid collision paths, avoid linked exits, avoid grips or docks. The first rule, you know why, you did the mistake already. Don't forget that corking is not a mistake (it will happen), but being above somebody who does cork is a dangerous mistake. The linked exits, grips and docks are not good because when you hold a grip or dock, you can pull or push the other enough to make him tumble. It's a good way to get kicked in the face. In addition, it can be a fun challenge to chase an unruly skydiver moving all over the big blue sky, while it's kind of boring to tumble helplessly with a moron who doesn't want to release a grip. BB Come

Not sure but there is at least one reference Rampage - We Getz Down (Remix) from the album "Scout's Honor By Way Of Blood" Now two Buffalo girls, go around the outside, round the outside, round the outside Two Buffalo boys go around the outside Make sure you hold your partner Now two Buffalo girls go round the outside, round the outside, round the outside Now two Buffalo boys go round the outside Flipmode about to hold down your partner I don't know why Eminem might refer to this BB Come

Right, most (if not all) modern containers are safe. But this doesn't mean that all are perceived equally safe by everybody. On some "detail", there are still some rigs one step behind perfection (pin or bridle protection is an example). These are out of the competition imo. It's a trade off between many things: meeting my requirements, comfort, ease of packing and maintainance, customers service, price, bulk and esthetics. In this order. So, i can't vote for your poll because each element is relevant to several categories. For instance, bad flap design, can be a safety issue, an increase in bulk, an hasle to pack and maintain or ugly. If it's just ugly it is not really important, if it is a safety issue, then the container is not on my list. Container size is a safety issue if the smallest that i can get (with my chosen reserve size) is 3 sizes bigger than my main. For the options, i don't give a shit to embroidery but hip rings are important for my comfort. There are a few other important elements: the customer services, the information provided and the credibility of the company. b1s Come

I guess this is me. Right, i destroyed my rig and it's still painful more than 2 years after. But i still use a large D-ring. You're right, there is a problem: people accidentally snagging your reserve handle. But there are at least two types of solutions. A passive one: make the handle less likely to snag. An active one: educate yourself and the people you jump with. Educating yourself (and the people jumping with you) has no possible drawback (as long as you're not too lazy and not prone to complacency), so there is no reason (and no excuse) for not doing it. In my case i think it's good enough. Soft reserve handles might have possible drawbacks (including no/late pulls, but also additional types of accidental pulls) and its efficiency is far from proven (there are accidental pulls of cutaway pillows in freefall). If i was used to have a backup device to open my reserve if i fail to pull, maybe i would change my mind. Or maybe, if there were more candidates to play chicken with soft handles... ooops sorry, this is the safety forum :-) You're definitely right, it's a matter of personnal choice. Unfortunately, for many people it is not a wise and experienced choice, it is the choice of somebody else. There are people prejudiced and myopic on both sides and it can be quite difficult to fully understand what are the real risks. Come

An important "benefit" for fun jumpers is... fun. If your definition of fun is longer swoops, use front risers. If your definition of fun is risks and thrills, use the toggles. Pendulum effect and ground rush are much better with toggles. About the safety aspect, "risers are safer than toggles" is a dangerous oversimplification. Come

here are the different structures: 0) [ | ] old traditional design 1) [/| |\] tri-cell with non continuous cross-braces (fx, vx, velocity, chaos, ninja) 2) [/ | \] quad-cell with continuous cross-ribs (onyx) 3) [/|\] polarbear-cell If the main objective was to reduce the lateral sliding of the whole top skin above the bottom skin, you woul be right. But the main objective is to have a top skin as flat as possible. As the distance between the loaded ribs is the same in all the cases, the angles in 3) are much more open than in 1) and 2). The force transmited by the cross rib has a vertical component and an horizontal component. Only the vertical component is good. The 3 or 4 small bulges in 1) or 2) are better than the 2 big bulges in 3). However, the vertical position of the unloaded ribs in 1) is directly controlled by the cross braces (and a little bit by the bottom skin). In 2) the vertical position of the unloaded rib is like in 0), except that the cross ribs reduce by 50% the lift pulling that rib up. If you really like ASCII art, there are plenty of unexplored possiblilities :-) - suppress the vertical loaded rib on 1) and 2) - replace the vertical unloaded ribs by oblique ribs 4) / /\ \ no more useless vertical ribs 5) / / \ \ with irregular spacing - use mixed ribs (vertical ribs forking at the bottom, or cross ribs sewed on the unloaded ribs rather than on the top skin) 6) [ | ] [/\ ] 7) / | | \ / / \ / \ \ You can even exaggerate and have something like a middle skin, kind of bottom skin with a huge distorsion, and cross or vertical ribs on top of it. Come PS: Personally i don't like the name "quad-cell" because vertical unloaded ribs are completely different from cross-ribs.

Are the cross ribs continuous? Do you have any front view to compare the distorsion with other cross braced canopies? What's the anticipated release date? Nice canopy! Come

If i assume that the weight of the canopy (and the lines) is negligible, i think that the length of the lines don't affect the banking angle (still at the steady state). However, the length of the lines will affect the time required to reach the steady state. It will affect the radius of the turn as well (but not that much). Anyway, you convinced me, i'll ask directly John LeBlanc. I'll post a summary of the discussion on the forum. Come

I assumed that both canopies with the same proportional input have the same proportional distortion. At the steady state, assuming that the lift/drag coefficients are the same, the same force diagram applies to both. Scaling the diagram doesn't change the angles. I agree with the fact that the seams, the thickness of the fabrick and the lines don't scale. This might give a lower lift/drag coefficient for the smaller canopy, which might make the smaller canopy dive more. But i have good reasons to think that this can be neglected as a first approximation. BTW, i said an input of 2 feet for the small canopy and 4 feet for the big one. I meant 2.8 feet for the big one (the area increases with the square of the scale factor) I would really enjoy to have the opportunity to tolk with somebody as knowledgeable as him. However, before wasting his time with my questions i want to be sure that i'm able to understand. These people's time is much better used designing canopies than explaining basic flight dynamics to ignoramuses

Very interesting article indeed. I would have probably understood a bit more if i knew the definition of "responsiveness" and if i could figure out the meaning of "the physical and aerodynamic laws don't scale with the parachute". So, is there anybody on this forum to give me additional pointers, or even better, to help me to solve the following problem. Consider two jumpers (SG is light, FB is twice heavier) jumping at the exact same loading, two canopies perfectly scaled (including lines and command lines). I understand that a toggle input at shoulders level is actually a deeper input for SG than for FB, because the risers are the same length. Similarly, i understand that if both bury a toggle all the way down to full arm extension, SG has a deeper input because the length of the arms is not proportional to the weight. But, if both have proportionally the same input, let's say SG pulls a toggle 2 feet down, while FB pulls a toggle 4 feet down, what happens? Who's canopy will bank more? Who will have the higher maximum turning rate? Who will dive more? Who will feel the most airspeed? Who will feel the strongest acceleration? For me it's quite hard to believe blindly that the answer is SG for all questions. So, as a first approximation, i assumed that both canopies would bank the same and then i drew a few diagrams. I was obviously wrong because my conclusions were quite different from John LeBlanc's statements. So, can anybody explain? Blue ones Come

Steelex wrote: > Like I said, I was taught that a reserve should be retired after 6 years from DOM. So, who taught you this? Is it your rigger examiner? If so, i'd really like to know. In any case, please can you check with several manufacturers, or with other examiners of the federation, then talk to the guy who taught you this. > It never hurts to ask when in doubt. You're definitely right. However, given your professional responsibilities (you advertise on your webpage that you are a rigger) and your position at the SPA, this question on a public forum lets me puzzled. When in doubt, ask to the manufacturer. Come