crwper

This is not quite the distinction you're talking about here, though. A few years back I opened a local big-wall. I didn't know for sure at the time if anyone had jumped it before, but I definitely had not heard of anyone who had (or received beta from them). The jump was scary as hell because of that fact. If I had found out afterward that someone else jumped it first, would it change the experience of "leading"? I think more important than whether or not it's been jumped before is whether you are doing it with or without beta. Of course, it's a lot of fun to jump something which hasn't been jumped before. But the question of whether someone is a leader or follower, I think, depends entirely on what information they have when they jump the site. Michael

Here it is! I had a chance to test the new changes this weekend, and everything looks fine. It was a bit windy, but I was able to make two jumps. The data from the second jump is attached. On the first jump, I tracked straight into the wind. The software seemed to give almost immediate response to changes in body position. For this jump I maintained a glide ratio of about 0.3, so I set the program with a range of 0.1-0.4 for the second jump. On the second jump, I decided to try something a bit different. Immediately on exit, I tracked crosswind. The audible beeped like crazy. I changed to a more neutral body position. It was still maxed out. So I turned into the wind and tracked that way. This brought the glide ratio down. I turned crosswind and tracked a bit more, increasing the glide ratio, until shortly before pull time when I returned to a neutral position. This is all shown in the attached screenshot from the software. Note that the sharp increase in glide ratio around 40 seconds is me pulling. Sorry, no simulated audio to upload yet. The software is now capable of dumping out GPS data to a comma-separated file. I've attached this file as well. I’ve done some analysis on the data. It looks like the “black box” Garmin uses to calculate vertical velocity is not well-suited to this application. In particular, I’ve attached a plot of the vertical velocity over time. It seems pretty clear that they are fitting chunks of data to a quadratic function, which does not match velocities estimated from altitude data very well. I'll be thinking about ways to improve this. Finally, I've attached archives with installation files and a bit of documentation ("bin.zip") and source code ("src.zip"). If you use the software, your feedback would be much appreciated. As it stands, the program will work with any Garmin GPS which can be connected either by Bluetooth or through the cradle connector. You will need a GPS, Palm OS handheld, and a pair of earphones you can hear in freefall. Coming soon: Multiple graphs of data for post-jump analysis (like Tracking Derby) Store and view more than the most recent jump Audible feedback for values other than glide ratio That's where I'm at. Let me know what you think. Michael

It's a long shot, but... Several years ago I had a copy of Groundrush which I got second-hand. It had been "library-ized" with a beefy jacket. I think my name and address were inside the cover, although the address would be wrong now. When I was done reading it, I thought it would be happier traveling the world, so I sent it on its way. It passed through lots of hands and I was able to keep track of it, but at some point it went missing in, I think, the UK. As I understand it, some readers photographed themselves and sent the photos along with the book. I'm suddenly feeling sentimental and would love to see the photos. If you know of the book's whereabouts, please PM me. Thanks! Michael

I think Sourceforge might be overkill for this one, but I'm open to the idea. Will send a PM. I should have the current porting work (to Garmin instead of NMEA) done by the end of the week, and will be posting the code I've got, as well as PRC's. Michael

Actually, as it turns out I don't need to do the averaging at all. Here's why: If I use finite differences on position then, yes, the results are very inaccurate. The positions themselves carry a bit of error (the vertical about twice the horizontal), and finite differences compound the problem. To get reasonable glide angles, you need to average over a few seconds. However, I have been able to use a proprietary Garmin 3-D velocity sentence. This velocity is actually calculated in the GPS using the drift of carrier phase (i.e. Doppler shift), and is accurate to about 0.1 knots. At freefall speeds, this is plenty accurate for my purposes. The problem is, most people don't jump with the GPS 10, which as near as I can tell is the only one using that sentence. So, I'm currently porting my code over to the Garmin format instead of NMEA. In that format, the GPS actually sends a single packet of data containing time, 3-D position, and 3-D velocity. The best part is, every Garmin GPS made today is capable of sending that packet. There will still be a bit of lag. There's about 1 second lag just because the GPS doesn't send data that often, and there is an unknown amount of smoothing done in the GPS to calculate velocity (velocities are calculated in a "black box"). However, the tests I've been able to do so far seem to indicate that there is no more than a couple of seconds' lag in the data. So you just have to hold a position for a couple of seconds, and you'll know if that's a better flying position. Michael

I went to Norway and Switzerland with a group of four a couple of years ago. We rented a car (Ford Mondeo station wagon) in Amsterdam, drove to the popular fjord in Norway, drove to the popular valley in Switzerland, then returned the car in Frankfurt. The whole thing was very economical. Coming from Canada, we're used to pretty long distances, so the drive from Norway to Switzerland (especially with four drivers) was surprisingly quick (12 hours or something, I think). We were a bit bummed when we found out we were renting a Ford, but that didn't last long. The Mondeo still felt stable going 230 km/h through Germany. Gear for four people fit nicely into the back. I have also traveled through Europe by train. Although I am very impressed with the rail system there, if you're going with a group it will probably be cheaper (and more convenient) to rent a car. Michael

Actually, no joke. What I had in mind is that if the loose end came out of the sleeve, it's better that it's on your left hand than your right (pull) hand. Michael

I assume the extra loop is on your left hand? Michael

Martin hit the nail on the head. Go with either of those rigs and, a few jumps later, it will be your new favourite rig. Michael

I've heard a lot of audio taken with the stock mic in a video camera, and it always sounded aweful as soon as the wind picked up. A couple of years ago, my brother picked up a couple of high-end lav mics and mounted them on either side of his helmet. The audio from these things is phenomenal. Even the sound of the wind picking up will get your blood going. It really made me realize how much high-quality audio can make or break a good video. Michael

The pivot point at the top of the stem can be really greasy inside. If you're wearing your rig, be extra careful going through there. Michael P.S. Had my first experience recently with the style of crane where the cab is between the stem and boom. It was locked. I had to wonder, where is the trust?

Grain silos. Michael

Even if it doesn't have Bluetooth. Reading from the cradle connector on the Palm is almost identical to reading from Bluetooth, so I've now got that part implemented. Of course, you'll have to have the appropriate cables, but that's cheaper than a new GPS at least. Michael

I've been doing some experimenting this weekend looking for an alternative to the proprietary 3-D velocity sentence. I can get horizontal speed in the NMEA format from, for example, the GPVTG sentence. However, I'm still stick with taking finite differences of altitude to get vertical speed. The result of this method is nowhere near as accurate as using velocity data directly from the GPS. I've done more research into velocity determination in GPS units, and came up with this. The velocity data calculated by the GPS and returned, for example, in the proprietary Garmin sentence I've been using, is actually calculated from phase shifts in the carrier. This is considerably more accurate/stable than velocities derived from finite differencing. Other than the Garmin proprietary sentence, I can't find any NMEA sentence which contains a 3-D velocity. However, there is a single record in the Garmin Binary format which contains both 3-D position and velocity data, and should be output by any Garmin GPS unit. I am considering the switch to Garmin Binary format for this reason. My question to everyone who might be interested in using this software is: What make/model is your GPS? Michael

How does this affect the flight characteristics of the canopy? I would have thought the effect would be minimal, since you're really just choking off a very small part of the canopy's tail. Michael

I will definitely be adding support this weekend for non-wireless GPS units and those which do not transmit the PGRMV (Garmin proprietary 3-D velocity) sentence. You'll still have to figure out cables, but it will lower the barrier a bit. I was thinking the same. I have a couple of thoughts on this... One is that the main piece of information is relative change, so you can see if you are improving your glide angle with a change in body position. In that case, wind effects wouldn't really matter too much. However, since the sound is scaled to cover a range of glide angles, it is possible that the wind could put you outside that range. One possible solution is to have an option to subtract some bias from the horizontal velocity. This would be an assumed wind velocity at altitude. However, I'm still unsure if this would be helpful or just confusing. The options are limited only by the data we have to work with. Everything else is just a programming problem. I'd like to start simple, but would love to hear suggestions from anyone with experience interpreting freefall GPS data. I've been using the PGRMV sentence (mentioned above). This provides 3-D velocity data. Up to this point I've assumed the GPS used phase drift information to calculate this (since they specify an accuracy of 0.1 knots), but on further reasearch I think they may just be smoothing the position data. In any case, for units which do not output the sentence I'll need to calculate distances (using the haversine formula) and do some smoothing myself. I'm not too concerned about window size. Even a 5-second running delay in feedback would give a lot more info than is currently available. Any suggestions on the smoothing function? I'm sure I can come up with something. Michael

I think you're going to have to be a lot more specific about: 1. What kind of gear you're jumping. 2. What you're doing. 3. What's not working. Michael

Not completely true. Those choices can be made at the exit point, but as soon as your feet leave the object, they can no longer be made. After exit, you have a different set of choices, and a lot of things which are not a choice at all. The commitment in, say, a long-term relationship, is ongoing. The same decision (stay or go) must be made constantly throughout the relationship. In BASE, on the other hand, the most obvious commitment is momentary. After that, it doesn't really matter if you're commited to the jump. You can never really say, "You know what, this jump isn't working out so well. I'm through with it." Obviously there are still choices to be made in frefall and under canopy, and particularly on long delays/flights it might seem overly dramatic to say there was a momentary commitment and then only hopelessness. But I think every jumper eventually experiences a situation where the inevitability of BASE jumping becomes obvious, for example if you're under canopy in turbulent conditions with no "good" landing options. Just then, you might wish you could walk out on the jump. Not that it's all bad. One of my favourite things about BASE jumping is having to make hard decisions in a stressful situation. It wouldn't be the same without that. Michael

Hey Tom, I usually wrap the lines in the primary stow pretty lightly, since I'm (probably unnecessarily) worried about having a "primary stow hangup". I'm sure my primary stow is not as effective as it could be, and your post has me thinking this might be a very useful area to improve. I'm not too eager to be a test-jumper on that one, and am curious if anyone has done much experimenting with how many times they wrap the primary stow. What kind of rubber band do you use there? Large/small? Tan/black-death? Michael

I haven't noticed anything. Maybe the small hole down the the middle of the earpiece (for sound) is also allowing pressure to equalize. The problem is the data cable. Initially I experimented with a Garmin Geko using serial cables to attach to the universal connector of the Palm. I think maybe 20% of the time the connector actually stayed in place through gearing up. Most of the time, though, I'd be walking to the door and the cable would come undone. I thought of doing it that way for a couple of years, but I'm not that good with electronics so it looked like the project would never see the light of day. Then one day I realized I could turn it into a programming project. My hat goes off to anyone who can do this in hardware only. I'm currently using NMEA data through a Bluetooth serial connection, so it wouldn't be that hard to go through the Palm's universal connector as another option. I had dismissed this option because of difficulties with early prototypes, but I will add it back in, since interest seems to there. It looks like the weather here is taking a turn for the worse, so maybe I'll have more time than I expected to work on things this weekend. Michael

Hey all! For the past couple of years, I've been working on a system for providing audible glide angle info to a jumper in freefall. I'd like to put a couple more jumps on it before I put it out here, but will likely post what I've got in a week. In the mean time, I can't help letting the cat out of the bag a bit early. What you will need: I am using a Garmin GPS 10 and Palm Tungsten T. Any Palm with Bluetooth capabilities will work at the moment, but until I make some changes, the Garmin GPS 10 is required. One of the first things on my list is to make this work with any Bluetooth GPS, so if this interests you please let me know. I am also using a pair of ER-6i earphones, which are easy to hear in freefall. If you have something else you can hear in freefall, that will work, too. How it works: Wear the GPS as usual. Connect to the GPS using the software before exit. In freefall, it calculates your glide angle using velocity data from the GPS, and beeps like a vario in your ear. Higher pitch/rate means better glide angle. You set the range, so this is useful for trackers as well as wingsuit pilots. At a preset altitude, the thing stops beeping, but logs until you pull. When you land, the software shows you a profile of your jump. You can click on the profile to get specific values. What I'm working on: First, compatibility with other Bluetooth GPS units. Second, additional displays. Horizontal and vertical speed as well as flight paths are in the works. What's waaay on the back burner: Sync data to a PC. This is not a high priority for me, since the main objective here is in-flight feedback with some analysis functions after the jump. Hardware requirements are pretty simple. I've experimented with wired systems, and it's a nightmare, so I'll probably keep this one wireless. The GPS is worn as usual. The Palm can be kept in an inside pocket or belt. The only wire is for the earphone, going from the Palm to your ear. This setup is very simple and really quite easy to use. The software will be completely free. If you're interested in the source code, that's also free. I've tried to make the software as easy to use as possible. It's not idiot-proof, but I'd definitely say it's up to commercial standards, so it's not like you have to have a degree in computer science to play. I'd like to hear any suggestions you might have, and I'd be really stoked if anyone out there is interested enough to give it a shot themselves. Let me know! Michael

Although I believe there are benefits to free-stowing the lines, and use this technique myself, I am somewhat suspicious of your proposed test. The reason is that if you leave the tailpocket open for the second test, the lines will be free to apply force directly to the stow, which will exaggerate the motion of the tailpocket side-to-side. If I was doing the test, I would prefer to keep everything except the stows the same between tests. I suspect having the lines pass through the constricted opening of the tailpocket will reduce somewhat the motion due to the stows. Reading this thread, one thing which comes to mind is the freebag on Aerodyne's Icon. This bag uses a strip of elastic material on each side, tacked at regular intervals, for line stows. The result is a more consistent pull force than would be achieved with rubber bands. Such a system would slow your pack job a bit, but would avoid some of the problems associated with rubber band stows. Me, I'll keep free-stowing for now. Michael Edited for poor Engrish.

Looks like 6 feet or so. Sorry, couldn't resist. Michael

Regardless of Gus's experience, I'm glad that got thrown in there. How far you go depends not just on how good your track is, but on how low you pull. It's easy to start pulling lower in order to get the extra distance when we're aiming for a mark on the ground. I definitely think it's useful to have an idea how far good trackers are getting, but it's also important to remember that if you have to pull ridiculously low to get there, you might be missing the point. Michael

First, I don't quite understand the "willing to die" thing. Isn't that a bit like being willing to fall when you step off an object? Second, I don't think we can ever be comfortable with our own death. We can be comfortable with the idea of our own death. But it's been my (limited) experience that the idea and the thing itself are two completely different things. To accept mortality (of ourselves and of those around us), I think we need to realize how much it's going to suck, and that we have no way of mitigating that, and then we need to make choices with that information in hand. Pretending that the loss of someone close to us could be a positive experience is denial, not acceptance. With that said, I think we learn to accept mortality by experiencing it. No matter how smart we are, or how philosophical, there is no substitute for real-world experience here. Although there are (unfortunately) cases of 16-year-olds with a great deal of real-world experience in these matters, as a general rule this experience comes with time on the planet. The value of this experience with mortality is that it gives us a slightly clearer picture of what we're getting into. I'm not saying that youth should exclude someone from learning to BASE jump, but I certainly think it should raise some red flags. Michael