crwper

The following is a bit off-topic, but it seems to have come up quite a lot in this thread, and I think it bears repeating. The wingloading issue has been discussed quite a lot in the past. One of the best guidelines I've seen is this one: Many factors which affect the performance of a canopy do not scale linearly with wingloading, so that someone who weighs half as much and is flying a canopy half the size will not experience similar performance. Michael Edited for clarity

I'm certainly not saying using an F111 pilot chute will kill you. I use them, too. I'm just saying better solutions are possible. Michael

My feeling is that the pilot chute doesn't really have enough momentum to pendulum as a result of "overshooting". The oscillation that we see is, I think, a minimum-energy mode for the pilot chute. Think of a pot of water which is heated from the bottom. Rather than maintain a simple temperature gradient from bottom to top, it will tend to form current loops which transport the heat. This has the net effect of lowering the energy of the system. In two dimensions, an asymmetric pilot chute would just tend to be pushed off to one side, until an equillibrium is reached between the force of the air being spilled out the side and the force trying to restore the pilot chute to the "vertical" position. However, in three dimensions, we have extra "modes" which allow a more efficient release of the energy. In particular, it's possible for the pilot chute to move in a circle horizontally. This dynamic mode actually allows the pilot chute to reach a better trade-off between the two forces. Unfortunately for us, it also means the canopy is being pulled around in a circle. Michael Edited for clarity

The problem with going to F111 is that you gain some porosity, which makes the pilot chute more stable, but at the same time it also produces less drag. An F111 pilot chute is not optimal because it's letting air through everywhere. A better design would be a pilot chute whose porosity is controlled so that it produces a maximum of drag, but also lets air through in just the right places to stabilize. That's the idea behind a zero-p pilot chute with an annular vent. Michael

I have a Perigee Pro without 3-rings. Most of my jumps are in the mountains, so water isn't a problem. I've jumped this rig at the popular bridge in the US, including one landing in the middle of the river. On the water landing, I first tried to swim to shore without getting rid of the gear. By the time I tried to get out of the rig, I was getting tired, but getting out was nevertheless pretty easy. I remember thinking, when I was in the river, that if the water was moving fast it would have been a desperate situation. Obviously 3-rings would make it easier to get out of the rig even in slow-moving water. I'm not sure if they would be a lot of help, for example, if the canopy landed on top of me. In that case, it seems like lines snagging with my body is a much bigger concern. Still, if the option was available to me, I would seriously consider jumping with 3-rings at the bridge in the future, since it would make at least one part of the extraction process much easier. When I jump over fast moving water, I have always used a rig with 3-rings. I've never had to land in trees, but my feeling is that if I can't extract myself without cutting away, I might be better to wait for help, anyway. I don't do many urban jumps, but if a quick getaway was required, I would probably consider jumping with 3-rings. As far as the advantages, I really like the simplicity. It eliminates one mode of failure by eliminating what is generally a non-critical system for me. This is a bit like eliminating the reserve in BASE rigs--sure, you might use it some day, but in the mean time it's also a potential source of problems. The 3-rings can fail (although it seems unlikely). The cutaway handle presents another snag point for branches, fences, etc., and it's a very dangerous bit to snag. My other rig has a "hidden" cutaway loop which tucks behind the main lift web, but even that loop sneaks out from time to time and could snag on something. I also like the intellectual honesty of removing the cutaway system. We all know we can't cut away a BASE canopy if it malfunctions, but I think there's a part of every one of us that likes to see the 3-rings on there just because it's something familiar from skydiving. By eliminating that familiarity, I force myself to think of the equipment in a different way. If I had just one rig, I would probably rather it was a rig with 3-rings. The rings really are unlikely to fail, and you will almost certainly jump objects where you would rather have them. If you're buying a second rig, consider one with integrated risers. Michael

Also, with a d-bag, the canopy is often folded like a caterpillar into the bag, rather than just with a couple of big folds. This allows the canopy to be extracted more or less in the same orientation in which it will open. Take a look at slow-mo video of a static line jumper sometime. As the canopy is lifted off the jumper's back, it takes on angular momentum. This continues until line stretch, at which point the pack job is often horizontal, with the lines making kind of a 90-degree bend at the bottom of the tail pocket. When tension comes onto the lines, the pack job is jerked into a vertical position. If I was going to jump something shorter than 100 feet, I'd do a few test jumps on higher stuff first to determine if the d-bag might do the job better. But at that point your canopy isn't really flying when you land, so I think there are probably other considerations which are more important than d-bag vs. static line. On higher jumps, I think there are certainly more important considerations (for example, convenience). Michael

It's been my experience that launching hard (or at all, really) on anything lower than about 140 feet can cause wicked oscillations on opening. If I was considering a static line system for very low jumps, I'd build it around a dead launch. If you're jumping a low solid object, probably your best option for an off-heading is to ride it into the ground. Removing the anchor for very low jumps makes little difference. I tested both configurations on a 111-foot span and got basically the same results out of both. Unless you actually have time to fly, the PC doesn't seem to change anything. No point removing the PC, in my opinion. Michael

What, specifically, do you mean by "bust"? I got caught by a security guard one night after jumping a crane, but after we talked a bit, he realized the paperwork wasn't worth it and let me go. Michael

Usually if I fold the canopy in the wrong place, I get "warps" across the fold. By adjusting the location of the folds, I can get rid of these. A friend of mine bought a Troll MDV a couple years ago, and when he folded it by the tabs, the warps were there. To get rid of the warps, we had to move the folds a couple of inches away from the tabs. I've always packed so the fabric lays flat. This also usually means the first two folds are about the same size, and the third one is smaller. I'd be interested to hear what the manufacturer says. Michael

I was very happy with the article in Maclean's. Kudos to Michael Friscolanti. Michael

Same pic as above, but renamed so it will open as a JPEG. Michael

I think I have a pair of yellow big-grabs in my kit at home. If you're looking for big-grabs (and if they're actually there), they're yours. Michael

This is one of my all-time favourites. Michael

This is one of my favourites at the moment. Michael

There have been lots of discussions in the past about the Hanwag and Crispi paragliding boots. Try searching the forum for those two names and it will get you started. I've been jumping in Asolo Cliff mountaineering boots for the past five years. They served me well, but have hooks. I'm divided on how useful the full shank has been. It's always felt like it offered a lot of support, but what it does is stiffen the boot against front-to-back bending. I'm not sure that really does much to protect the ankles, and it adds quite a bit of weight. Michael

Hi all, I've been shopping around for something to replace the mountaineering boots I've jumped in for five years, and the Scarpa Pro Ascent approach boot caught my eye. Why? They seem to have good ankle support (though I haven't yet had a chance to try them on), there are no hooks, and they are relatively light. The sticky rubber seems like it might be an asset scrambling to some exit points. http://www.scarpa.com (Sorry, can't figure out how to get a direct link out of Scarpa's website.) My concern is that the "tread" is pretty minimal to start with, and seems like it might be slippery as hell on (wet) dirt. Anyone out there have experience using approach shoes on dirt trails? Michael

I was in town a whole week and Abbie never once hit on me. I feel so invisible. Michael

The issue isn't whether or not we as jumpers are capable of making the jump safely with a helicopter in the landing area. Next time you're driving through a controlled intersection, think how secure you'd feel if you thought there was a real possibility that someone waiting at the red light would try to dart through a gap in the traffic. That's the problem. In some cases, individuals pursuing what is best for themselves will result in a situation which is considerably less than optimal on the whole. In general I place great value on individual freedoms. But for the few minutes it takes to care for an injured jumper, I think we can put some of those freedoms on hold so that the medics can work more efficiently. Nobody's worshiping them as heros. But with a little consideration we can help them get their job done more efficiently. Michael

I ran into a motion sensor a few years ago with 587 on a local A. We had climbed a 10-foot fence and were getting geared up next to the building when we noticed an audible alarm inside. Looked up and there was the typical sort of white box mounted on the building, pointed at the A. We were back over the fence in a flash. We sat in the car for a while to see if anyone showed up, but nobody did. By that time the day was wearing on, so we headed to a nearby S. Still, if I ran into one of these things again, I'd probably do the same thing. I don't really want to stick around to find out they sometimes do alert security. Michael

Hi all, Jason is doing well. He's been transfered back to Calgary. They've removed the second chest tube, so he's just got the cannula with a minimal amount of oxygen flowing. They're restricting him to bed for the moment, while the neurosurgeons at home have a look at a second round of scans to double-check that things are okay. His breathing is doing very well, and it looks like he'll be released from hospital in the next few days. I finally had a chance to look at video of the incident. That's been difficult for me, and has brought back to the surface a lot of hard questions I was asking myself the night of the incident. It's difficult to make sense of it all, but it's important to me that I not look away from the questions, and somehow find honest answers that I can live with. Along these lines, I'm going to add something to the points raised above. Looking at the video, it's easy to see that the conditions certainly aren't ideal. I imagine this is why so many people have brought that point up in this thread. However, it seems to me that the admittedly marginal conditions, and indeed probably the other three points I have raised, while very good lessons to take away from the jump, are not actually the root cause of this incident, but are rather symptoms of the root cause. A few of you have pointed out that the jump seemed rushed and poorly planned. That's a hard one for me to recconcile. Certainly I had some reservations about the jump, but I chalked these up to the technical difficulty of the jump. Perhaps, in reality, these were warning signs that we were moving too quickly. At the time I did not see that. I still believe all three jumpers involved were up to the technical challenge, but had we allowed more time for the plan to develop, we might have recognized the importance of matching exit velocity as well as timing. The scary part about this particular lesson is that I'm not sure I could have learned it any other way. I could post until my fingers bleed about the importance of slowing down, but it's unlikely to deter the adventurous jumper who thinks that feeling in the pit of his stomach is the result of technical challenge, and not poor planning. After all, he's not rushing things, it's just that the jump is demanding. There are, of course, well-planned technically challenging jumps. How can we explain the difference to jumpers who have not experienced it first hand? I can't begin to express how fortunate I feel that Jason survived the jump. That he will walk away from it with so few and slight permanent injuries is more than it would be reasonable to ask for. Take care, Michael

I would have no problem at all putting my pilot chute in Nick's hands again. We had done the jump once previously, had noticed that there were exit timing issues, and incorrectly assumed this was the root cause of the freefall problems. We did the jump a second time in order to sort out the exit timing issues. It turned out they weren't the only problem on the first jump. All three jumpers would have been more than capable of matching momentum for the launch if we had realized the problems on the first jump went beyond exit timing. I want to make this very clear. I think it's important to realize this jump went badly not because of a mistake made during the jump, but because of a mistake made before the jump, namely, in our analysis of the preceding jump. I've seen a lot of post-jump analysis in the forums degenerate into a mess of minute details and finger-pointing which I will never recall at the exit point. I have learned three things from this jump which will probably be foremost on my mind in any jump I plan in the future. They are: 1. The importance of stability at pull time. 2. The importance of an in-sequence deployment. 3. The importance of matching timing and momentum on linked multi-ways. They say last learned is first remembered. I'd hate for this incident to be chalked up in someone's mind to insufficient skill or some personal grudge, rather than three simple and objective errors. Thanks guys, Michael

The importance of stability in freefall. I think this seems obvious in the context of stable exits, but I've learned that I should take very seriously anything which could cause an unstable deployment. Michael

Hey all, Thanks to everyone who's been sending good vibes Jason's way. It helps. The mood at the hospital has been really upbeat. Jason's doing well, and the chances look very good for a full recovery. He'll be in the ICU at least one more day, but should be out of there soon. He's been up and walking a bit, although the few tubes and hoses which are still attached limit how far he can go. Still, the progress he's made over the last few days has been phenomenal. The technical discussion has been pretty well covered here, I think. Still, I'd like to add my own viewpoint to the mix anyway. I think if we look too closely at stills and video, quite often we wind up isolating factors which are much too small and not unique to the particular jump, so I'm going to try to keep things pretty broad. We had done the jump with the centre three on one previous occasion. That time I had experienced some instability as a result of exit timing issues, but things had worked out reasonably well anyway. We reviewed the video afterward, which confirmed the timing problems. When we decided to do the jump a second time (to clean it up), we went over the exit timing quite thoroughly. What we did not take into account was the difference in momentum of the jumpers coming off the bridge. The two outer jumpers were going up and out, and the centre was going down and out. Things were a bit hurried at the exit point, but not enough to set off major alarms in my head. I did ask myself a number of times, "Is there anything about this situation which you are missing because of the hurry?" I still think the answer is, "No." The factors which I believe caused this incident were built into the jump, and did not result from conditions at the exit point. At the time we jumped, I believe the conditions were acceptable. Immediately following our exit, I noticed a small amount of separation building. I received only a small input from the bridle tension because the pins released relatively easily, but the Velcro on Jason's rig did not release so easily, and tension on the bridle put him into a barrel roll. Jason rolled through the lines of his extracting canopy, and it seems also that when his pilot chute came back up to the canopy, it managed to choke the canopy off completely. Although the lines of the canopy likely snagged on Jason's armour, I don't think the exposed armour was a major contributing factor. A light shirt over armour will prevent lines brushing by from snagging, but a line wrapped around an arm with tension will lock onto a bare elbow. Reports from several others who saw the jump confirm my impression that Jason fought with the canopy as long as he could, and then when he realized impact was imminent, he made a quick adjustment to land on his back. Tom has suggested letting go of the pilot chutes as a possible "out" for jumps like this. I've talked with Tom in person a bit about this, and agree it is a good thing to have in mind. However, I think it would be dangerous to give the impression that it's a good out. It is very important to practice the exit many times in such a way that you can guarantee the three jumpers have not just the same exit timing, but also the same momentum when leaving the exit point. Thanks again to everyone who has expressed their well wishes. Jason has used 12 units of blood in the course of his treatment, which has made us particularly aware of the importance of blood donations. If you are able, please donate. Michael

I'm going to build in kind of a "cutaway handle". If the altitude data is completely out to lunch, and the beeper is really pissing me off, I'll just pull the cutaway. The whole mess (GPS, PDA, and earphones) will just fall away, and with any luck I'll have forgotten about the whole fiasco by the time I land.

Sorry, Palm only. Michael