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Deimian last won the day on August 13 2021

Deimian had the most liked content!

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  1. I disagree. Engineering and technology are like a gold mine. If there is a gold vein, you can extract gold with simple tools. You'll be faster with power tools than with a mattock and a shovel, but in both cases you can get lots of gold in short time. That's what happened 100+ years ago. But if the mine runs dry you need to dig much more to get a tiny bit of gold out of it, if at all, even with the best possible tools. That's where we are now. Aviation started at a vein, and slowly but surely the mine is running dry. It ain't magic, there are limits to what can be done, and the closer you get to the limit the more difficult it gets to push the envelope. You can't make gold out of nothing. But if you are an optimist you can always hope for finding a new vein that would help to push things faster. Or maybe there is still enough gold to be found, spread in some cubic kilometres of useless rock. Maybe there is a new battery technology about to be discovered, or maybe we can refine sufficiently the existing technologies to make the electric aircraft a practical reality. But maybe not, and that'd be it, the electric airplane would never be mainstream.
  2. This is solid advice. But this particular question can be at least partly answered without a coach IMO, of course taking into account that communication in person can be more accurate than in a forum, since the chance for miscommunication is lower in person. To answer the original question: There are many many things that influence how long you can keep in rears. It is not simply a matter of "Crossfire vs JFX". Let me go over some of them. The fact that a canopy is trimmed flatter than another one, does not mean that it holds longer in rears. It is almost the opposite. When you pull on your rears you are effectively altering the trim of the canopy. If the trim is already flat, you have less giggle room to produce changes in the canopy behaviour without stalling it. Cross-braced canopies are more efficient due to the way the top skin holds its shape (21-27 "compartments" instead of 7-9 cells). That means that all other things being equal, they create more lift, which means that the same input on rears have a greater effect in producing lift at a given airspeed. Another thing that greatly affects how long you can hold in rears without sinking is airspeed. The higher the airspeed, the more lift the canopy produces, so the longer you can keep on rears. So you might hold longer on a Crossfire going at a certain speed, than in a JFX going at half of that speed. But JFX is a more steep canopy, so at the same wingload you are probably going to be faster on a JFX than on a Crossfire. Yet another thing is parasitic drag in the trailing edge. So a canopy with miniribs will have less parasitic drag, and is therefore more efficient, and can hold longer on rears than one without. On that sense, a JFX 2 is better than a JFX 1 for instance. So, to summarize, the *chances* that you can hold longer on rears on a JFX than on a Crossfire are very high, but you can't say that in all circumstances you can hold longer on rears on a JFX.
  3. Be careful with stall practices. Stalling with rear risers happens quickly but recovers for the most part gently. Stalling with toggles takes normally longer, but the recovery can be more problematic and through you in a spin/twists if done asymmetrically. You don't want that close to the ground.
  4. I don't think that is a big problem (it might be a small problem though, as toggles are not where you expect them, and if you are low, every second to grab your toggles help). But uneven release of riser covers during opening can very easily put you in twists. If you have line twists under your reserve, and the reserve starts spinning, then you have a big problem. There have been a few fatalities like that. I think Eric is coming out as an angry-whiny man with some agenda to cover, as some others pointed out. But this does not invalidate the argument, it simply makes the person with the argument annoying. I think it is a good thing that flaws, big and small, are pointed out. Just knowing the issues the gear has, can the gear be improved. And manufacturers do not always see the issues in their product straight away. A friend of mine had a very serious incident some years ago due to a design issue on his gear. I would have preferred that someone coming out as a whiny annoying old man with limited online social skills found out before my friend, so my friend wouldn't have shat his pants or worse.
  5. Line twists are caused by asymmetries during opening, which can be caused by various things. In skydiving, wind gusts is not one of these things. Don't overthink it, they can happen. Don't get too relaxed about the canopy flight though. Once you are able to fall and pull stable, they are one of the most dangerous part of the sport, specially when you start getting smaller canopies (and by smaller I mean simply smaller than what you have now, not small, you don't need an 80 sqft canopy to get hurt or hurt somebody else) Welcome and have fun!
  6. GT-R is a more advanced canopy and not really adequate for somebody flying crossbraced for the first time. Think of it like a Valkyrie, Leia or (W)airwolf. For going from X-Fire to something more advanced probably JFX2 or Gangster are better options.
  7. I believe most webbing work is sewed with size 5 and 6 nylon cord.
  8. As the saying says: An extraordinary claim requires extraordinary proof.
  9. A friend of mine died 5 years ago. He had 2 rigs that used regularly. On one he had a Stiletto 120. On the other one an Odyssey 120. They were even the same colours (mostly). These 2 canopies have quite different recovery arcs. He made a low turn. I don't recall which canopy he used on that jump, but I wonder if he was jumping the Odyssey, but expecting the recovery arc of the Stiletto. I think that is something very important to consider if you go for 2 different canopies in your rigs.
  10. Strictly speaking, he's right. Actually, strictly speaking, there is no skydiving canopy that has a Schumann planform. The "original" (for lack of a better word) Schumann planform is a planform for gliders, with very high ellipticity on the leading edge (towards the wingtips), and a straight trailing edge. Gliders have wings that have a much longer span than any skydiving canopy, so no skydiving canopy can have a Schumann planform, if we are strict with the terms. But if we abuse the term and apply to "high ellipticity on the leading edge and straight trailing edge", I think it is not bad if we abuse it a bit more and apply it to "high ellipticity on the leading edge and straight-ish (as compared with the leading edge) trailing edge". And that applies to all the canopies I listed, if I am not mistaken.
  11. You are right, but changing planform does not necessarily mean "optimize everything for performance". Things like openings, and harness responsiveness have nothing to do with performance. Other stuff, like how far the wing can carry you in rears for a given airspeed has to do with performance, but has nothing to do with the aggressiveness of the canopy (aggressiveness is for me, in this context, how much speed you can produce by making it dive). The top line is both very high performant and very aggressive. Nothing speaks against having high performance (lift produced, distance in rears, flare power) and medium aggressiveness (don't dive until the end of days) One can always tweak and tame down some aspects. A "VC" with Schumann planform is not necessarily a VK. The Gangster from Fluid Wings is Schumann, but dives less than the VC for instance. The X-Fire is Schumann and it is not even cross-braced, and it dives less than the Gangster. A "VK lite", with the great openings of the VK, its rears, its harness responsiveness, its flare power, but with a shorter dive sounds good to me. I can imagine a future PD progression like SA3 -> KA2 (updated Katana with a bit less dive than the actual one, but all the good things of canopies like the X-Fire) -> "VK lite" -> VK In any case, that's just my view, I am also not a canopy designer. Maybe I am just missing something.
  12. I see a few reasons: - Schumann planform canopies tend to have more lift than traditional elliptical canopies, and they tend to hold longer in rears. I believe that is one of the reasons why paragliding canopies have been using this planform for a long time. - They tend to open better. At least I haven't seen any Schumann canopy that does not open nicely and on heading most of the time (X-Fire, all the Fluid Wing canopies, Valkyrie, Petra, Leia, Odyssey EVO). Maybe it is just coincidence, but seems like a big coincidence to me. - They tend to be more responsive on harness. - Connected to previous point: All the advanced cross-braced canopies are Schumann nowadays. I think an entry level cross-braced Schumann canopy would make the transition into the advanced ones a bit more natural Asking the other way around: why not? I think the only reason not to do it is that it requires a bigger investment in R&D than a smaller update of an existing canopy. But since we have high end crossbraced canopies and advanced 9 cell regular canopies using Schumann planform, I see no reason to don't think it is a good idea. Entry-level crossbraced canopies are right in between these 2 categories.
  13. Don't get me wrong, I think the JFX2 is a nice canopy and definitely an improvement over the original. But I think they left some interesting things on the table. The (probably) most important one is having the chance of having a Schumann planform canopy suitable for people that is jumping cross-braced for the first time. Just my 2 cents.
  14. The same is true for almost all manufacturers. The entry-level cross-braced canopies are all old designs, except the Gangster from Fluid Wings. The JFX2 is a nice refreshment, but looks to me basically like a JFX1 with a couple of small changes, not a completely new canopy. I really would like to see in this category a canopy with inflatable stabilizers, miniribs, and Schumann planform. Maybe these things would drive the manufacturing cost too high for this category? BTW: The Katana also needs an update
  15. That is what skydivers that don't go to tunnels regularly think. Tunnels have evolved pretty much in the same direction than skydiving. To offer a carnival ride kind of experience for people that want to try it once and move on to the next thing. All of the tunnels I know have their main source of income in first timers that will never come back (or at least not regularly). Protecting themselves from bad press or liability when a first timer come with a bad shoulder is just common sense. Now, in this case, this is not a first timer, so they might act differently.