crwper

From Poynter Volume I, Section 4.040, describing MIL-C-5040... Cord Tensile Identifying Core Feet Type Strength Marks per (lb) Pound Type II 400 Black dotted stripe 4-7 315 Type IIa 225 Coreless 495 Type III 550 Plain 7-9 225 Type III coreless Plain Coreless Tensile strength for Type III coreless is, for some reason, missing. My impression has always been that Type IIa is just coreless Type II, but I could be wrong on that. There's a green dotted stripe on the white loop on my risers. Michael P.S. Tensile Strength in the above table is the minimum tensile strength; Feet per Pound is minimum feet per pound.

Now that is how you write an 8th grade essay. Michael

Except if the white loop breaks. Michael

Kleggo, I dig your list. It reminds me of the diversity of reasons people do this. Michael

Sure, these things aren't as obvious in the real world as they are inside your head, but that doesn't mean they aren't there. You need to look for them, because it's not as easy as the stuff in your head. It all looks different. It's somehow messier than the crystalline visions of one person. But the real world is surprisingly versatile and adaptable. I speak from experience when I say, if you think the world is playing catch-up with your grand vision, you need to look a little more at the world around you, and a little less at the world as it exists inside your head. Michael

I don't think the housing is the problem here. If you pull on the housing, it should not apply an extracting force to the yellow cable. It should just tug on the white loop. The exposed section of yellow cable on the far side of the loop is a problem, though. Perhaps this could be hidden better. Michael

Where did the loop fail? A the fold, or at the base where it inserts into the riser? Michael

I just had another thought on adjustable brake settings. It puts a little bit of a "bump" in the line, but at least may be appropriate for slider-down testing. The idea is to take your lower control lines, say 12 inches above the brake settings, and finger-trap a third of a 12-inch piece of 900 lb dacron from about the 12-inch point to the 16-inch point. This can be bartacked in place or otherwise securely sewn. With the other two-thirds, skip about three inches and finger-trap from about the 9-inch point down to the 5-inch point. This leaves one inch of line coming back out at the 5-inch mark on the control lines. The bottom finger-trap should not be sewn in place. To shorten your brake setting slightly, you would give a bit of a tug on the one-inch tail at the bottom. This will compress the three-inch gap in the middle. The four-inch lower finger-trap should take most of the force, but just for good measure you could throw a couple of turns of tacking through the control line and finger-trap. My biggest concern about using this on slider-up jumps, I think, wouldn't so much be the deployment (worst case your slider would stall about 9 inches above the bumpers), but hesitation that might be caused by pulling the slack section through the slider grommets (for example when flaring). For slider-down jumps it seems like a robust, simple way of adjusting the brake lines until you've found a setting that works. Someone want to check me on this? Michael

Perhaps because they are not as low-profile as three-rings, so in addition to aesthetic issues they would be more prone to getting knocked by steel, rocks, etc. on the way to the exit point. I've never actually used Capewells, but my impression is that if the cover got knocked loose, you would be one step closer to an accidental release. But also I'm curious about your reasoning... I would have thought that the only time a BASE canopy needs to be cut away is when it is under tension, e.g. pulling the jumper downstream in rapids. Otherwise, for maintenance and such, you could just undo the links. What did you have in mind? Michael

I have two containers with three-rings, and one with permanent risers. I got that last rig without rings because I couldn't think of a really good reason to have them on there, and also because it is simpler. When I went to the bridge in Colorado last year, I chose to use one of my rigs with rings, because the water below was moving fast enough that cutting away seemed a useful option. So I guess what I'm wondering is this... How often do you need to cut away a canopy for maintenance and such? Part of my decision going with permanent risers is that I do this infrequently. If you need to cut away, for example landing in fast-moving water, then you need three-rings, or some similar quick-release system. Off-hand, I think Capewells would be more prone to accidental release in the BASE environment, where you might bump against the steel getting to an exit point. I'm not sure something like a karabiner would be easy enough to operate in a high-stress situation. Also, it would be difficult to remove risers from a karabiner if they were loaded, as I imagine they would be in the fast-moving water scenario. There is quick-eject hardware that might fit the bill, but it's bulky and not as simple as the three-ring system. Michael

Just so we're clear, if McDonalds wants to pay the bills, I'm not too proud to wear a clown outfit and jump a Happy Meal canopy. Michael

Not everyone loves extreme stuff. There is still a substantial part of the population which is just waiting for things to go wrong so they can be validated in their non-participation. In response to the recent fatality of a jumper at a famous Paris landmark, the response here was quite positive. The response at a forum with a much broader base of readers was not as positive: http://forums.fark.com/cgi/fark/comments.pl?IDLink=1489332 There are 6.5 billion people out there, and most of them aren't as philosophical as you are about BASE jumping. Maybe some of them are musing that the world is on the brink of embracing lawn bowling. Michael

Taking the odds of dying on a particular jump as 5%, your odds of living through your first 100 jumps would be about 0.6%. If the odds of getting injured are 15%, then your odds of getting through your first 100 jumps unscathed are about 1/100,000 of 1%. In ideal conditions. I keep seeing these relatively larger perentages thrown out there, but I really don't think we have an appreciation for how big a 5% chance of dying is. That's what the russian roulette experiment is about. Imagine pulling the trigger on a revolver with 20 chambers and one bullet (okay, big revolver). If the chamber is empty, you live. If it's occupied, you die. No, "Well, maybe if I'm quick enough." That's the end of your life. You will never walk out of that room. When we say that we have a 5% chance of dying, we aren't talking about a 5% chance of a 180 or something. By the time we hit the "positive" result in that statistical experiment, we've already used up all of our options. We are categorically dead. There is a 100% chance we will not be going out for drinks with the crew later. We won't be watching our own lives, and the lives of those around us, unfold. The ride, for us, is over. If you seriously think you have a 5% chance of death on each jump, maybe it's time to quit. Because you almost certainly will not live to see your next 100 jumps. Michael

Look for "80 LB BREAK TAPE - MIL-T-5661". Michael P.S. 500 yards will last you and your crew a lifetime, so you might be better off to buy a few yards from a gear manufacturer.

Jaap, on a long enough timeline everyone's survival rate drops to zero. Not just BASE jumpers. Michael

Just to be clear, I'm not raggin' on ya for using the wrong word here. But this post reads totally differently if you know what "osculation" is... http://dictionary.reference.com/search?q=osculation Michael

I've thought about this quite a lot before. Consider the following to be the thoughts of someone who focusses maybe too-much on semantics. I believe that if we can make our meaning as clear as possible, most problems just solve themselves. I think if someone honestly believed they had a 50/50 chance of dying doing something, there are only a handful of (possibly suicidal) people who would actually do it. I don't mean to speak for the people who make these statements, but maybe only to explore the question a little bit. I've heard lots of people say, "It's one thing to talk about doing a BASE jump, but it's a whole other thing actually to do it." Anyone who has jumped, I think, feels this. I propose that, "It's one thing to talk about having 50/50 odds of survival, but it's a whole other thing actually to put yourself in a situation which gives you those odds, strictly speaking." For someone to convince me that they know what 50/50 odds are (and are therefore capable of making that comparison with a BASE jump), I would like to see them at least once have pulled the trigger in a game of russian roulette, with half the chambers full. Otherwise, I think what we have here is a misunderstanding of how impossibly bleak strict 50/50 odds of survival is. I don't think this stops at what we would usually think of as "bleak" odds. If someone honestly believes they have 1 in 1000 odds of dying on a particular jump, I would encourage them to find something akin to a 1000-chamber revolver with which to calibrate their guess. I want to be clear that I am not talking about rolling some dice and saying, "I would have died if that one came up a seven." That would be like walking up to an exit point and saying, "I could have done it." What we're talking about here is a test where, when you've pulled the trigger, there is no question you know what those odds feel like. Nor is the most important part of the experiment the moment when you pull the trigger. What does it feel like to anticipate something like that? What does it feel like if you live? What's it like to know that you put that much on the line for statistical chance? I'll likely never know, because after giving it a lot of thought, I've come to think that I will never play russian roulette. Michael

Dayblazing usually happens when a non-local is passing through and decides they can get away with a jump in broad daylight. Whether or not they get caught, they will probably be seen. After they've left, it's the locals who have to deal with the ongoing attention brought to the object. In addition, a jump like that shows obvious disregard for the law. That's an image the local crew will be saddled with, which means when they are caught, they will probably have to answer for the dayblazer as well. Alternatively, even a well-planned jump can go badly, and someone might get caught. In this case, the object is still probably burned, and it's good form to let the locals know what happened. This kind of thing can't be avoided, since it's pretty much inevitable someone will get caught eventually. Everyone just has to wait it out until things calm down a bit. The flip side is that if everyone keeps the locals apprised of what goes on at their sites, then they can let others who are passing through know what not to jump. This keeps everything low-key. Michael

If I'm not mistaken, a lot of the distortion on smaller skydiving canopies results from the fact that they are very high aspect ratio. This means it is much easier to pull the center of the canopy back with respect to the endcells, for example. Because a BASE canopy is relatively low aspect ratio, I wouldn't expect a lot of distortion even with larger pilot chutes. For what it's worth, we were jumping a 111-foot span a while back and noticed that the canopy never really had a chance to start flying before we touched down. I normally use a 48" F-111 pc for backup on the static line, but thought this would make little difference from such a low height, and might make a difference in the flight characteristics. So I did one jump without the pilot chute. There was no noticeable difference in the degree to which the canopy was flying when I hit the ground. I should also mention, Dwain later pointed out that most premature breaks occur fairly late in the deployment sequence, so he hypothesized that a pilot chute likely would be helpful as backup even on a very low object. Michael P.S. Edited for clarity.

The photo at the top of this thread looks pretty dark on some displays. I've attached a gamma-corrected version which looks considerably better on my display at least. Michael

Hey Steve! Sweet video. Two Calgarian thumbs up. Michael

As I understand it, only Jaap gets shots that close from the boat. Michael

I assume this would be for use slider-down only? My concern with slider up would be that the extra bulk in the cascade attachment might cause the slider to hesitate coming down. Michael

At the risk of adding yet another crummy diagram to this thread, you'll find my rendition of the problem attached. Let me first note, we only noticed the problem with the floating bridle for CRW, which is essentially just a piece of 900 lb Dacron running through the eye of the pin. With this setup, it's not obvious, but there are two very different ways to route the line through the pin. I suppose I should add that, in the accompanying diagrams, the pilot chute is pulling from the bottom right. In the diagram labeled "bad", pulling the bridle toward you (i.e. out of the screen) forces the end of the pin into the container. Most of the time this will clear itself, but it can result in a pilot chute in tow. In the diagram labeled "good", the same pull will result in the pin being arched away from the container, as it's supposed to. Although the problem is easily duplicated with a 900 lb dacron line, I don't think I've been able to duplicate it with a regular bridle. It could be that this condition is very unlikely with that kind of setup. I think the difference is that if we put the bridle attachment on the "wrong" side of the pin, it will just slide around to the right side, whereas with the Dacron line it winds up kind of locked in place. So, I think the condition is not likely to occur with the bridles we use in BASE, but perhaps others can try to duplicate it on their own gear. Michael Edited to add: I also forgot to draw the closing loop, which should be imagined in the obvious location.

Put another way, imagine if you had the hardest material imaginable. Nothing could break it. To protect your head, you build a helmet out of this material. Now imagine that you hit a rock because of an off-heading opening. The force of the impact will be transmitted directly to your head, because the shell material is so hard. Now, it might be spread out a bit spatially (i.e. instead of getting all the force on a sharp edge you'll get it over a large part of the surface of the helmet) but it will not be spread out in time. A good helmet does both, which is the point of having some kind of crush material on the inside. Now, if you were building a helmet for minor impacts and light weight, you would probably be smart to choose a light, strong shell with a lightweight liner for comfort. That's what most skydiving helmets are built for. Like the other posters, I don't really know what testing the manufacturers of these helmets do, but I know I'm not really comfortable using them in the BASE environment. Michael