crazy

That's a bold statement. I'm wondering what makes you think so. The responsiveness to toggle input depends a lot on other factors. The trim, the airfoil, the aspect ratio and the setting of the toggles are likely to have more effect than the planform. Some elliptical canopies are very sluggish; some square are very responsive. Anyway, "responsiveness to toggle input" is a ragbag expression including things not necessarily bad from the safety point of view. For instance, a canopy can be responsive in terms of turning rate, while another can be responsive in terms of diving. In case of a panic turn, the first one is much better than the second. Back to the initial question, some elliptical canopies are relatively forgiving (long command stroke, turning relatively flat). In addition, they are easy to land because they have a good bottom end flare. Finally, they also have a very short minimum recovery arc. These canopies can be a safe choice for some beginners, if their style and skills are appropriate. At the same wing loading, i don't really see why a square like a sabre would be safer than a sluggish elliptical like a cobalt. -- Come Skydive Asia

Why would you do such an assumption? Hamza is known for misinformation and contradiction. He strongly endorsed the Iraqi opposition. Apparently, to some extent he was the puppet of Woolsley, Wolfowitz, and other partisans of the regime change. In addition, his so-called expertise of Iraqi nuclear program is doubtful. I'm not claiming that Hamza is only a liar, like Scott Ritter from the UNSCOM did, but i think it's time to sit back and watch the sales of the book (and movie) soar. -- Come Skydive Asia

You give the answer: You can even go a bit further: the wind is defined by it's average direction, it's average speed, and one characteristic of the turbulences (max speed of the gusts). Each gust of wind (faster than average) is, by definition, compensated by a lull (slower than average). Each left crosswind (from the average direction) is compensated by a right crosswind. When you are moving in the air, you will feel the turbulences if they are strong enough. But you can't tell the direction and the strength of the wind, just from the turbulences, because they cancell out. If you can't tell, then your canopy can't tell either. However, there might be an explanation why so many people are convinced that a canopy turns downwind: on windy days, you notice much more the distance covered while the canopy is going downwind. Hence, you remember much more the occurences where a canopy is going downwind. -- Come Skydive Asia

Siam Air Sports I think they got their new aircraft (C-206). BPA rules. tight landing area. -- Come Skydive Asia

Bowstrings and suspension lines are completely different things. They are not built the same way, they don't serve the same purpose. Are you sure it's a good idea to put archery wax on your lines? I might be damn wrong, but as far as i know, the main purpose of wax on bowstrings is to keep the strands together (apart the center serving and the end loops it's just free strands). The addition of silicon in the wax is supposed to lubricate the strands during bow firing. Both are irrelevant for suspension lines. Now, there are good reasons why you don't want anything too sticky on your suspension lines: it makes checking for wear way more difficult, and it will stick to other parts of your equipment. Another thing that you might want to consider is that archery wax is not supposed to take heat; on you lines, it will. I'm not saying it's a bad idea, just trying to highlight some possible issues, for those willing to do the same as you. I actually don't know what would be the benefit. -- Come Skydive Asia

I do want to think about what might have happened, because I jump with an RSL. Can someone complete this scenario? I might be visualizing this wrong, but I don't think rapid reserve deployment would have been a problem. Well, it could be a problem, but you summarize it perfectly here: Put a skydiver under a lightly loaded intermediate canopy (~1.1), opening with a shitload of line twists and a spin. Now evaluate these scenarios: -1- No RSL, reserve opened 2000 feet lower than the main opening altitude -2- A RSL and the reserve pin is pulled while unstable which one is more scary? When you think about the whole meaning of these 2000 feet, or when you witness it, scenario -1- can be really scary. -- Come Skydive Asia

On the average, binocular disparity (the difference of parallax between the two eyes) can detect parallactic angles of 3 arc second. Roughly this is the parallactic angle of an object at 200 feet. It doesn't mean that it works up to 200 feet, but that it has a contribution up to 200 feet. Roughly, the contribution is very significant up to 50 feet for people with two good eyes. As a slight addition to Bill's comprehensive information, the combined effect of physiological cues (mainly binocular disparity and visual motion parallax) and psychological cues (retinal image size, linear perspective, haziness, overlapping, shades and texture gradients) enhances depth perception greatly. This means that if you are in a perfectly unknown environment, without binocular disparity you'll have a very hard time. In a familiar environment, you'll be fine with one eye only. Speed is also an important element. In a static environment, the brain will easily use the full detail of all the available cues to make up a realistic perception of depth. In a fast moving environment, you don't have enough time to integrate all the small details and binocular disparity would make a significant difference. Actually, many people hardly use binocular disparity; they just use a bit more all the other cues. Visual motion parallax can be trained to some extent. The psychological cues are learned, hence they can also be trained. Some people have a perception of depth with one eye almost as good as the average binocular vision. However, for most people, landing after losing a contact lens can be tricky, particularly at high wing loading and under unusual circumstances (late sunset for instance). Personally i wear contact lenses, and i won't take the risk to jump with loose goggles. -- Come Skydive Asia

Great, you have less than 400 jumps, your skydives are 50-60 seconds, you are the perfect candidate for the beer (2 cases i think: 1 from AndyMan, 1 from listo). You can use a stopwatch, because they didn't specify anything about this. If you count, with minimal training you'll most probably be within the +-5 seconds as well, but it will be a long and boring jump (but it's 2 cases of beer!). [AndyMan: you thought you could save the brewery? :-)] Anyway, the point of counting is to consciously keep track of the time since the last altitude check (eyeballed, read on the alti or heared from the audible) in order to know when to do the next one. Hence, usually you don't have to count more than 20 seconds, even if your freefall is 60 seconds. It could be something like: exit, count 20 seconds, eyeball the altitude, count 20 seconds, check the alti, count 10 seconds, wave & track, count 5 seconds, wave & pull, count 3 seconds, check canopy. Of course, instead of (or in addition to) "count xx seconds", you can use other triggers for your altitude checks: time related triggers (subconscious feeling of time or planned checks), or altitude related triggers (subconscious visual reference, an audible...) then you might count faster or slower and the track of time will be more inaccurate. A clock is a clock, a good clock is a bonus. Counting or not, you still have eyes and an altimeter. Check on your altimeter, cross check with the ground. BTW, can you tell me when you check your altitude? -- Come Skydive Asia

[Pruned from "Re: [AndyMan] Students jumping WITHOUT an altimeter"] You are definitely right if you assume that there is only altitude awareness and no time awareness at all. However, most people can count 20 seconds accurately (much better than +-6 seconds) with minimum ground training. Thousands of skydivers actually had to do it, and succeed, to be signed off for the next exercise: reading the altimeter and pulling at a specified altitude. A significant number of instructors used to think that even for the 20 seconds delay, the student had to jump without an altimeter, else, he would be able to cheat (you owe beer to many people :-). From this point of view, the increased safety provided by the training seems to outweight the risk of jumping without an altimeter, if any (please listo, voice your opinions about students jumping without an altimeter in the appropriate thread). I understand why some people think that jumping without an altimeter is scary. However, it's easy to understand why some instructors emphasize so much on time awareness: it's the tool that you're supposed to use to keep your altitude awareness. The only reason why you are able to keep your altitude awareness between two altitude checks is that you are aware of the time elapsed since the last altitude check (eye balled, visual alti or audible). As soon as you lose track of the time, you lose track of the altitude. Basically, people forget to pull because they lose their time awareness for a much too long duration. When you underestimate the importance of time awareness, you get funny things like: - Q: when do you first check your altitude after exit? - A: when i'm around 6000-7000 feet. Modern training and modern equipment emphasize more on altitude rather than time (altimeter vs. timer, altitude awareness vs. time awareness). However, counting consciously is an extremely valuable tool: easy to train (you can do ground training all day long while doing other activities), reliable (after a few jumps, losing the count rings an alarm) and free. At the beginning, it can be difficult to count while doing something else, but after a while, it's not even a distraction. Of course, most people are fine without counting. It's just an additional tool to the survival kit. It's much more reliable than the subconscious feeling of elapsed time (varies a lot with mood, health and activity) or eyeballed altitude guess (varies a lot with mood, health, goggles, weather, visibility, luminosity and landscape). Also works perfectly in combination with planned altitude checks (after the 4th point for instance). -- Come Skydive Asia

It used to be quite usual in several countries for SL training, for 5sec, 10sec and even 20sec delays. The objective is to train the sudent to actually count rather than relying on a mythical internal clock (or cheating with the altimeter) for time awareness. -- Come Skydive Asia

Here are the choices: -1- i pay the bill with my own money -2- my sister pays the bill with her own money -3- my insurance pays the bill -4- my sister's insurance pays the bill Personally, my choice goes to the 4th situation. Of course, it is much better if the insurances can settle the problem without going to court. I don't know how you do it in the USA, but in many countries, both parties send a letter to their insurances and then you just wait. they don't waste their time and money in court. For skydiving, it's the same thing. There is a significant possibility that i make mistakes that i can't afford. As a responsible skydiver, i have an insurance to cover the damage that i can cause to others (anyway, this is mandatory in most places). As a prudent skydiver, i have a personal insurance to cover my own medical bills. I expect other skydivers to be responsible and to have an insurance to cover the damage they might cause to me. Of course, when the parties don't agree on the description of the facts - or on the responsibilities - it can be more complicated. Then, the appropriate action depends a lot on the situation and the personality of the people involved. IMHO, setting the responsibility straight is the best thing to do. Putting the blame on a friend doesn't mean "you're a fucking asshole", it means "your insurance will pay". If he is your friend, he will be happy to have his insurance to help you, because he will feel extremely bad anyway. Once you're back from the hospital, he still owes you beer and once you're recovered you can still do your recurrency jump with him. to address your previous comment: Most people are unwilling or unable to pay for the care they might need after an accident. Last time i heared about the medical bill for a broken leg in the USA, it was way over 100000$. Insurances are brilliant, ain't they? They allow us to do so many wonderful things that we wouldn't if we had to be fully responsible of all the consequences of our (and other's) actions (driving, having children, sports, travel...) -- Come Skydive Asia

I had a skydiving accident, put the blame on another jumper and got my medical bills and damaged equipment reimbursed by his insurance. Do you mean that i should have paid the bills by myself? Do you mean that if i'm not willing to pay myself, then i'd rather not jump? -- Come Skydive Asia

hell i don't know. maybe different "f-111" material Or maybe because they have a higher aspect ratio -- Come Skydive Asia

Right, the chord and span are measured on the top skin. However, the name still reflects approximately the area of the bottom skin. So, what's the problem? From PIA documents (they also explain how to measure it practically): Chord: Standard definition: The chord is measured (in a straight line) from the farthest forward point to farthest aft point on the airfoil section. Measured with the canopy laid flat on side with very light tension and as many wrinkles removed as practical. If the chord is not constant, an average chord may be specified or the chord at each loaded rib may be specified; must also specify design (cut dimensions less seam allowance) or finished dimensions. Span: Measured parallel to the leading edge of the top surface, 6" behind the leading edge, with minimal tension (5 lb. or less); if the length of the trailing edge is not the same as the length of the leading edge, an average span or separate leading and tailing edge dimensions may be given and must be specified. Measurements shall be made with 10 pounds-force (or less) tension on the area being measured; at standard atmospheric conditions. -- Come Skydive Asia

Are you sure it's about the area and not the packing volume? Speed 170: chord=8.5ft, span=21.1ft. This is 180 sqft! -- Come Skydive Asia

Maybe i was just unlucky, but mine was almost 13 weeks -- Come Skydive Asia

Hi Bill, Do you have any idea why such an efficient system is not widely used? Eric Fradet got the thing designed almost 8 years ago. A short while later it was adapted for the advance from parafun, but no other manufacturer offered it. Is it the cost of the patent? Or are there any drawbacks with that system? Why did it take you so long before deciding to implement it on your containers? Did you design your own system, or did you make only minor adaptations to fit your container? -- Come Skydive Asia

I completely agree with you. I want suspension lines, not rahat loukoum. HMA can significantly improve both the fun, the comfort and the safety. Loss of trim has a significant effect on the flight characteristics, sometimes with unpredictable results and serious consequences (for instance slaming openings or collapsing). With HMA, no loss of trim, period. Right, normal wear is visible. Premature wear (for instance, abrasion from the grommets, or sand) is obvious. In addition, as these lines have no cascade, there is no excuse for not replacing them when they wear out; it takes less than 5mn per line and you don't need any tool. Proper inspection and maintenance is an important part of skydiving. Relying blindly on supposedly idiot proof technology is dangerous. Spectra won't save anybody from carelesness either. About the horror stories of snapping without warning, ban from germany and other rumors, some of them have already been discussed in that thread. -- Come Skydive Asia

great! now, we need a cost efficient way to launch a pilot into the landing pattern. If people could train at 5$/landing, then it would make the whole thing really interesting (and the spectacular biff-in not that occasional). Winching with a trolley (or a boat) for take off? Next step could be the indoor swooping festival. -- Come Skydive Asia

2 different things: spotting and clearing the airspace. For jumping in a place with extremely bad spots and no traffic, when it's possible i usually have an eye (if not both) on the spot, whatever the aircraft, whoever is in front of me. I clear the airspace only (and not always) when i'm at the door because it takes too much time. Anyway, at the Otter DZ were i went, i hardly saw anybody clearing the airspace properly. The problem is not the traffic right below, now; it's the traffic 1 or 2 miles away. It's impossible to see that far to the right side while standing at the door, even with the head a bit outside. It's obvious when someone actually clears the airspace... It's obvious when someone doesn't. I admire you all guys who are so conscientious that you do it on every jump, even from rear doors (looks like there are quite a few of you on DZ.com). I also had my fair share of landings off DZ, for blindly following the others. The worst was trusting a pilot: "you have to go... you have to go now... go, go...". The last one out heard the end of the sentence: "... i'm lost!". Nevertheless, as my own bad spots also sent people off DZ, i have no problems with trusting a good pilot. -- Come Skydive Asia

Really! Why would they tinker with the tailgate at that time? That's a strange requirement. In other places the spotters have to go on the tailgate, CASA C-212, CN-235 and hercules C-130 alike. You're kidding me, ain't ya? I'm sure you always anticipate the green light when you spot. [edited] Anyway, even watching through the windows helps to know approximately where is the DZ, particularly for someone who has been jumping there for 7 years. A spotter completely lost when the light turns green is a bit worrying, but that's just my opinion. -- Come Skydive Asia

if you are better spotter than the pilot, go on, take the responsibility to spot for a skyvan. Anyway, as long as you do it properly, if an asshole yells at you, it will be easy to shut him down (he is the clueless one and you know what you are doing, right?). Back to your initial story, did you land off the DZ? If the first groups made it back safely to the DZ, why did you have no clue about the location of the DZ when the light turned green? what were you doing during the red light? Were you actually watching at the ground frontwards, or were you just standing by the door watching below and backwards? With a rear door, standing at the door doesn't help to check for the traffic and it doesn't help much for downwind jumpruns either. If you were laying on the floor, actually watching frontwards, why were you unable to see the DZ? -- Come Skydive Asia

Why not spot during the red light? First, my definition of perfectly good jumpable jumprun doesn't include aircrafts, oceans and mountains. Then, assuming that the spot is ok, if the guy at the door has no clue about the location of the DZ when the light turns green, i doubt that he helps much in the prevention of skydiver-aircraft collisions. -- Come Skydive Asia

4 sec at very high speed can easily be much more than 1000 feet. If the green light means "jump", you'd better jump. If you don't jump, wasting thousands of feet of perfectly good jumpable jumprun, don't be surprised by unhappy reactions. Now, rather than yelling at you, he'd rather explain the appropriate procedure. -- Come Skydive Asia

On the same level as basic aerodynamics, i would put: - basic canopy manufacturing (lots of limitations of our canopies come from the way they are built) - advanced meditation training: keep a cool mind to do the right thing at the right time - martial arts or gymnastics: improved reflexes and better falling techniques - advanced stretching: a flexible body absorbs the impact more smoothly - dietetics: diets with lots of calcium strenghten the bones - enough blood credits - ... To avoid confusion, i checked the 33 fatalities in the US for the year 2001. there are 9 (27%) fatalities related to landing perfectly good canopies. 5 of them (56%) from apparently very experienced skydivers who hooked in or didn't flare for some reason. 4 of them (44%) are beginners to intermediate skydivers (1, 40, 80 and 210 jumps) who died because of a poor choice in the landing area and landing pattern (avoiding - or not - obstacles or turning into the wind). This raises some questions: - do you still think that if you don't plan to hook you won't die? The 4 last were probably thinking the same. - for the year 2001 in the US, where are the fatalities involving intermediate (200-500 jumps) skydivers who hooked in because they were trying to swoop? (they are the rationale for the regulation that you suggest, right?) - If you ask some regulation for the < 500 jumps who do hook turns and carves, shouldn't you ask some regulation for the very experienced skydivers as well (fatality #28 has 4700 jumps). They are a minority in the skydiving community and still represent the majority of fatalities related to landings, for the year 2001 in the US. bb -- Come Skydive Asia