crwper

Indeed. I haven't seen the GPX format before, actually. It's a bit heavier than CSV, but would probably not be an issue to write. My main concern would be the increase in file size. Also, looking at the GPX spec, I don't see any velocity fields. Am I missing something? Michael

Yep, right now it's fixed memory, which is cheap and small. I am considering moving to microSD for upgradability, but the bulk is a bit of a challenge. Who'd have thought I would ever be calling microSD bulky? Exactly. The interface is absolutely minimal, partly because I found that when I jumped with my Palm Pilot prototypes, there was too much draw toward analyzing the data afterward. I figure someone will want to look at the data now and then, but I really wanted the focus with this one to be flying, so it's kinda like the iPod Shuffle of GPS units. The external interface consists of a USB connector, audio jack, power switch, and three indicator lights. Michael

This doesn't really help the OP, but I noticed the discussion of output formats, and wanted to ask a couple of questions here. Development of my audible GPS has been a bit slower than expected, but I should have the first prototype built in a month or so, and will know shortly after that how well the GPS receiver performs. If all goes well, I should be getting a few samples out to testers sometime in July. As it stands, the unit acts as a USB drive when plugged into a computer. When jumping, the plan is to log jumps as separate files, like images on a digital camera. The files will be a simple CSV format which records position-velocity-time either at the native rate (10 Hz) or at a slower rate (say 1 Hz) to save space. At 10 Hz, I'll be able to store about an hour worth of data on the device (so, maybe 20-30 jumps). I have two questions: 1. Is this enough capacity? I can probably go to a larger capacity (thousands of jumps), but it would increase the price of the unit (about $200 now) by perhaps $25. 2. I figure raw comma-separated CSV data is about as versatile as it gets, but wanted to make sure this is actually usable by you guys. Thanks for your input. Michael

If I understand correctly, it's fairly common, at least with long distance running. This is part of the reason why, even on a warm day, they will hand out thermal blankets at the end of some marathons. The body gets used to working at an elevated temperature, and when you suddenly stop, it doesn't adjust quickly enough. Michael

This will be as simple as changing a setting in a configuration file, I should think. Which is "better" really depends on what you're trying to do... If you just want to see how slow the suit can fall, then vertical speed is your thing. If you want to see how far you can go, then glide angle/ratio will be it. I've found a tiny 10 Hz GPS receiver which I'm going to try using in the next prototype. It's pretty cheap, so it won't affect the price of the unit. If it performs well, I think it will dramatically improve the "responsiveness" of the device. The plan, at this point, is to build a second prototype sometime in the next few weeks, using the 10 Hz GPS and a small chip antenna. If it goes well, I'll make a few and send them out to experienced wingsuit flyers for testing, just to make sure the design holds up in field conditions. Michael

The type of vario you're describing would perhaps be useful for indicating fall rate, but this is different from indicating glide angle. Flying a suit for minimum fall rate, and flying it for maximum distance, are two completely different things. In addition, pressure measured near the body suffers from considerable variation due to changes in body position. This is one of the main challenges in designing a reliable AAD. In freefall, most of the usual problems with GPS (e.g. multi-path) are eliminated. If you want to measure true vertical speed, and especially if you want to measure horizontal speed, I'd say GPS is the benchmark, not atmospheric pressure. Michael

I've had good results mounting a Bluetooth GPS on the back of my leg, and was thinking of doing something similar with the standalone unit here. The unit is about 50 x 50 x 20 mm, so I was thinking of mounting it on a 50 mm wide elastic strap, for example, with a buckle. This could be wrapped around the thigh, and it wouldn't take much to run a headphone cable from there to your ear, under the suit. What do you think? Michael

Interesting. The only hitch, which seems to be the case with many Bluetooth GPS units, is that they only list NMEA communication. Unfortunately, NMEA never gives vertical speed, and using finite differences on altitude to get vertical speed is a notoriously bad idea. However, it wasn't until recently that I learned SiRF III units can be put into a binary mode in which they will provide full PVT data. Perhaps this unit can do something similar. I'll be finishing off testing of the first prototype in the next couple of weeks, and then I think I'll plunge ahead with the second (USB) prototype. This adds a bit of complexity, so I'm not completely sure what the timeline will be. I'll have to give a bit of thought to what kind of help I can use. I am pleasantly surprised by the interest level, and I'd love to move things ahead as quickly as possible. To recap: At the moment one of the biggest questions in my mind is whether it is better to have a built-in GPS, or to interface via Bluetooth with an external GPS. As I see it, there are benefits to both sides: Bluetooth - Flexibility - Possibly a higher update rate Built-in - Fewer parts - No need to purchase separate GPS Cost of the unit itself isn't really a factor, since the cost of the Bluetooth module and GPS receiver are about the same. Any feedback here would be appreciated. Michael

Thanks. A couple of years ago I was working on a PDA version as well. I started adding lots of logging functionality, plots, and so on. But, at the end of it, I felt like the focus was shifting away from what we really love to do, which is, of course, flying. My goal with the latest device has been to create something you can just plug into, and fly. Later on, if you're interested in the data, you can download it to your computer and do all the analysis you want, but I think putting that analysis on the device itself makes complicated something which should have been very simple. At the end of it all, I'd love it if this thing felt more like plugging into a "sixth sense", and less like obsessing about numbers after the jump.

I'd love to hear your thoughts. The last time we talked, I think I was gearing everything toward the Garmin GPS 10, since it was the only GPS I could get to put out full PVT data. However, I've recently found that I can put SiRF III receivers into a "binary" mode which will give me the same information. I have not yet experimented for myself, but I think it may also be possible to increase the rate at which they return data. Michael

A couple of years ago, I started work on an audible glide angle indicator. I put together a prototype based on a Palm Pilot and Bluetooth GPS, and did a bit of testing. There was a small amount of lag, but the information was usable. I recently started playing with microcontrollers, and thought I'd work on a hardware incarnation of the device. You can see what I've got so far in the attached photo. The device connects to a Garmin Bluetooth GPS. and uses velocity data to calculate the glide angle. This is converted into a periodic tone whose pitch varies depending on your glide angle. By plugging a pair of in-ear earphones into the jack, you can listen to this in freefall, and get nearly instantaneous feedback on your true glide angle. Other highlights are: - Device measures 50 x 50 x 20 mm. - Rechargeable battery (charging circuit built-in). - Logs data to microSD card. As you can see, I'm just finishing off this prototype. I've been thinking about what I'd like to do next, and a couple of things come to mind: - Recharge and transfer data through USB. - Built-in 20-channel SIRF III GPS. With a built-in GPS receiver, the new device would be mounted on the back of your leg, with headphone wires running up the inside of your suit. The upshot of a built-in GPS receiver is, it costs about the same for me as the Bluetooth module, and makes for fewer components in the system. The downside is less flexibility. With the Bluetooth setup, if a higher rate GPS becomes available, you wouldn't need to replace the whole thing. Anyway, I figured I'd write up a quick post to put the idea out there, and to see if anyone has ideas, suggestions, or is interested at all in where this is going. I realize this kind of thing is not everyone's cup of tea, but if it is yours, I'd love to hear what you think. Michael P.S. As with my previous work, I'd be happy to make this stuff "open source", so interested jumpers could build their own. If demand exists for a finished product as well, I'll look into that. Cost will be under $200, I think.

ZP 125. It's nothing fancy, but it doesn't like to spin, and it was cheap like dirt. Michael

If you're having a lot of trouble getting the canopy into the d-bag, you can break the s-fold down once more. It's similar to the instructions that Sid posted, but instead of doing a single s-fold and then tucking that into the bag, you fold the canopy back on itself and put that fold in the bag. With the first fold controlled by the bag, you complete the s-fold and put the top of the canopy into the bag (looks like photo #4 now). Finally, s-fold the bottom of the canopy and put it in the bag. I've used this trick for new zero-p canopies where it is difficult to maintain even a single s-fold long enough to get it into the bag. Michael

I just started flying a PF tracking suit this year, so a lot of this is fresh in my mind. The suit is quite leg-dominant, and I think we're all used to flying a little lazy with the legs. The biggest thing that helped for me was to fly with the legs quite wide and toes pointed. This will keep you from developing asymmetry and oscillations through the legs. Also, as willh said, get used to flying the suit a little head-low. The suit needs forward speed to work, so if you're flying too flat it will be twitchier than usual and your track will suffer. Michael

It appears that he rolled through the canopy as it deployed, so that the bridle attachment point was trapped somewhere near his body. The canopy looked more like a flag than a parachute. Time top to bottom was 6.0 seconds, only a little longer than freefall time. I'm a big fan of body armour, and I think it certainly played a part in Jason's surviving the incident, but as Jamie said, this was one in a million. In my opinion there are plenty of other, more tangible, reasons to wear body armour. I think Jason described it thus: The injuries he sustained were extremely life threatening, but it turns out that if you survive them, "recovery" is relatively fast. As with many major injuries, the initial recovery was astoundingly fast, but closing the last 10% takes a very long time. Jason will always have slightly limited mobility in his shoulders due to the spinal fusion, but it's not something you'd notice if you saw him. I suppose I'd say his recovery was surprisingly quick, but you have to bear in mind that initially there was little doubt in anyone's mind that he was dead, so it wasn't too hard to surprise. Michael

This thread (such as it is) appeals to me more than the other one. Doesn't it strike you as odd that a group (BASE jumpers) which contains so many independent thinkers is so quick to argue over which slot their BASE jumps fit into? The same thing comes up repeatedly with the question of whether unpacked jumps are "real" jumps. In the end, I can't think of any way that such questions serve the individual jumper. The only reason I can think of for categorizing jumps like that is to compare them in a very limited way: "How many buildings have you jumped?" I don't see how that kind of comparison would bring jumpers together, so ultimately it seems like a divisive force to me. There are other ways we categorize and compare our jumps, too. Suppose someone has 1000 jumps doing the same thing off a single object. I suppose what I'd like to know is, how do we use this information? Why is it interesting to us? When this kind of thing comes up in the forums, the information is used mainly to minimize the accomplishments of that person, or to say they aren't "real" jumps. What kind of horse shit is that? Are we really so petty as a group that we can't celebrate someone's accomplishments without also looking for a way to make them seem smaller? By extension, I would ask: Why does it matter if what you just jumped "counts" as a building? Surely any reasonable human being realizes there will never be meaningful consensus on that issue. When the topic is discussed, it seems less like the intent is to work toward a common understanding, and more like an attempt to weed out the posers, thereby increasing the value of our own jumps. Again I ask, do we really need to devise artificial methods of comparing ourselves with others in order to give meaning to our own jumps? What could possibly be the benefit of convincing another jumper that what he thought was a building wasn't "really" a building? I've spent more time than I intended on this post. As I get more experience with life and with BASE jumping, I find I care less about the lines others draw, and I am more able to answer honestly the question: "What do I want to do?" Ultimately, it makes little difference to me if someone else wants to argue the definition of a building. But if someone reads this thread and finds peace in the idea that it doesn't matter whether or not someone else thinks it's a building, then it's a positive contribution to the forum. Michael

For what it's worth, he also seems to be wearing some kind of back protection. This guy's obviously very good at what he does. Michael

To change your brake settings, you will need to remove the old "eyelets" and install new ones. This is done by taking a small length of line and "finger trapping" it on each end into the brake line. If you feel around the existing eyelets on your gear, you'll be able to feel the difference in thickness because of the finger trapping. Once the line is in place, it needs to be sewn in. This is easy enough if you have a sewing machine. You may also need to remove the old eyelets before installing new ones. In that case, you will spend a while picking the original stitches (with a stitch ripper or scissors), remove the short piece of line, and install the new one. To do a good job of it, you'll need to have attention to detail, but not a rigger's seal. As with anything in BASE, a rigger isn't required, just rigging skills. If you aren't completely sure that you can remove the old eyelets and install the new ones where you want them (obviously the sides need to be even, and you will need to be able to account for "shrinkage" due to finger trapping), it's best to have someone with the relevant skills do it for you. Michael

The night cliff, I suspect. I've only ever done one cliff in light so dim that I had a hard time seeing the edge of the rock, and it was wildly different from jumping the same cliff in the daytime. Michael

No need. You just pull when you hear the Noise! Noise! Noise! Noise! Michael P.S. Regarding the possibility of being rescued by the gent on the hill: I heard he's really quite thoughtful these days. Something about a heart problem. Is there any truth in that?

Hey all, I'll be in the Whoville area December 25, and was wondering if any of the locals could show me around. I've heard of exit points on Mount Crumpit, the 3000 metre peak just north of town, and was wondering how much of this is usable altitude. The pictures I've been able to find on the internet look wildly overhung, like something out of Dr. Seuss. Should I bring a slider? A wingsuit? Thanks! Michael

Cool. Looks to me like the "hybrid" part is because the pin flap can go either way, right? Can anyone tell me why you'd want the pin flap to go one way in some situations, but the other way in others? Thanks! Michael

As in a hybrid between fold-over and thread-through flaps? How does that work? Michael

I don't keep track of everything, but almost all of my static line jumps are in winter, with temperatures around -10 Celsius. The 111' span is at an elevation of about 3500' ASL; the 165' and 140' jumps are at about 2500' ASL. Most of my s/l jumps are from the latter object. Unfortunately, because there isn't much variation in the conditions I've jumped it in, I can't really quantify the effect of temperature/barometric changes. I've usually used shallow brake settings on s/l jumps. This seems to reduce surge when the brakes are released. It's a bit of a balance, though, since a too-shallow setting will result in a lot of surge before the brakes are released. Too-deep will put the canopy closer to a stall on opening, and encourage a surge after the brakes are released. Michael

I don't have too much to add here, as bps has pretty much covered it, I think. Nevertheless, I'll add my two cents. First and foremost, this is something that you need to work down to. There are a few skills which need to be learned very well, and along the way you'll learn a lot about how conditions affect low jumps. 587 and I made about 50 jumps from 165' and 140' in one winter before jumping anything lower. Oscillation is a very important factor in low-altitude static line. The two main ways you can induce oscillation are a hard launch and unstowing your toggles too aggressively. The key points in avoiding this are: 1) Learn to drop straight off the object. This should feel a lot like you're stepping off the curb. If you launch too hard, it puts your mass ahead of the canopy on opening. The canopy will surge forward to compensate, and you'll lose a lot of altitude in the process. If you drop straight off, this surge is minimized. 2) Learn to unstow your brakes in a controlled manner. If you unstow your brakes too quickly, the canopy will surge ahead and you'll lose altitude. If you unstow them too slowly, you'll lose altitude because you've spent too much time in deep brakes. The trick is to pull the toggles down in one quick stroke just to the point where they clear the white loop. Then let them up more slowly until you are in full flight. With practice, you will learn to feel how quickly you can let the brakes up. I'm about 145 lb and fly a Fox 245 vtec. For me, 165' was a good altitude to practice these things from. Unless I am terribly careless about my launch and brake release, there is still plenty of time to fly after opening. In contrast, a friend of mine who flies a Troll 305 MDV, and loads it more heavily than I load my canopy, found the flight from 165' quite short. Once you've determined a comfortable static line altitude that gives you 10 seconds or so of canopy flight, practice the skills above. If possible, find a site where you can make multiple jumps in quick succession, and see how far you can fly from the object. This is a great way to dial things in. Make plenty of jumps from that altitude. It's important to realize that if you go from 160 feet to 140 feet, you're not just cutting off 12.5% of your altitude. Your minimum static line altitude will (optimistically) be about 110 feet. So you're actually going from 50 feet above the minimum to 30. Think of it as a 40% reduction in your working altitude. For the same reason, if you've not already done so, invest in a good laser rangefinder. If you can, try to find at least one object whose altitude is intermediate between your practice altitude and the 120' S. Make some jumps from it. You should be able to pop your toggles and fly a bit before you have to flare. By this point, you'll have some idea whether or not 120' is even a good idea for you. Even with all the practice jumps, it's likely you won't know exactly what to expect when you do jump from 120'. As I said above, it's all about how high you are above your basement. You will never know exactly where the basement is, so try to keep a realistic idea of the error of your estimate. Changing conditions will also have an effect on the basement altitude. Once you have an idea where your basement is, you'll be in a much better position to judge the safety of the jump you're looking at. Even at that, knowing that there is a margin of error on your estimate of the basement altitude, keep the following in mind: 1) You probably won't have time to unstow the toggles. Spend plenty of time practicing your PLF. Plan to PLF on the first jump, even if it looks like you might be able to unstow the toggles. 2) Pick a night with no wind. A tail wind will delay your opening slightly, and a headwind will cause you to drop straight down, which makes it much harder to do a good PLF. 587 and I found dramatic differences jumping with no wind, or with a 3 mph headwind. 3) Know how you will get your broken body out of the landing area if you have misjudged your basement altitude. Well, that's about all I can type in one sitting. I hope I've managed to convey the importance of working down to that altitude, and give you some idea what to work on. A d-bag will give you a bit more altitude, but is not a silver bullet. If you plan to d-bag the thing, you'll still want to spend plenty of time working on dead launches and good brake release technique. I prefer static line because of repeatability, but it does cost you a bit of altitude. Hopefully 587 will chime in about the tard option, since I can't think of anyone more qualified. However, my general impression is that unless you have tremendous low-altitude tard experience, this would not be a good idea. Have fun! Michael