base736

It is a pretty kickin' mustache. Still, I'm with the "stay clear of the FAA" folks. We had (emphasis on "had") a local cliff from which jumping was tolerated. A visitor knocked some rock down from the exit point, scaring the crap out of a group of climbers below. They were pissed (quite rightly) and called in the rangers. Rangers handed out warnings (phew), because like the FAA they have to respond, but now my favorite cliff is hot, and the next time it'll be gear confiscation and a court date. A few weeks later, I understand the climber regretted having called in the cavalry, but some things you can't take back. What's lost is lost. Sometimes we're given a choice. Often bringing the authorities into it is not, in my opinion, the wise choice.

I've seen such crosswinds have an effect at two or three seconds even with a pretty mild crosswind (10-15 mph, say). Offhand, I'd say the answer is in the 3-5 second range for most crosswinds... Of course, there are two effects at play. First, the relative horizontal wind is getting smaller as you get pushed along with the airmass (as you point out). This one would be difficult to calculate. More important, I suspect, is the fact that the relative vertical wind is getting dramatically bigger. Suppose, three seconds in, you've still got a 10 mph crosswind. That PC is going to take off deviated by less than ten degrees. My experience has been that a 10 mph wind doesn't get a person moving more than maybe 1 or 2 mph i the first rhree seconds -- a small contribution compared to the above. Edit to add: As noted above, the effect on heading is really much more important -- a fact that supports the observation that a person just isn't pushed that much by the wind in the first few seconds.

I'll start by noting that I agree with your recommendation to "Get on, get up, get off". Although my understanding is that the effects of RF radiation at the usual antenna doses are temporary, they still suck, and cooking yourself for longer than you have to is probably a bad idea. Still, the above strikes me as a grossly inaccurate characterization of our understanding of the risks of RF radiation. I have read only two technical papers on the subject, but between them, the one by Motorola (done for OSHA) restricts itself to a few specific recommendations for tower workers and makes no comment on the effects of exposure, while the one by the FCC states that the literature is inconclusive on the existence of non-thermal effects (while the thermal effects it lists certainly couldn't be called the "kiss of death" unless you're having lunch in front of a directional microwave antenna). I'd be grateful if you could share a citation for one or two "kiss of death" University studies.

My bad. My physics is fine, but my unit conversion, apparently, sucks. 89 mph should be a piece of cake. I'll shoot video.

As I recall from a discussion along the lines of "skydive Mars", the balance between lower gravity and the fact that that lower gravity holds a thinner atmosphere sits heavily in favour of the latter. The short of it: 500 square feet on Mars would be sporty. Even at 0.079 m/s^2, a fall of 10 km puts you at a speed, without the aid of appropriate drag, of a little better than 200 mph, so "sporty" translates as "ouch". (Does it ever translate any other way?) The practical thing to do, I think, would be to buy the cliff and move it over here, where the atmosphere's nicer.

The static line always pulls with 80 lbs of force (or 160 lbs, or something in between -- cue debate). It's like a poorly-executed PCA in that, even after the canopy has been successfully extracted from the container, the static line insists on pulling on it some more. It deforms the pack job. The argument, backed up by experience, is that if the canopy would open faster in the deformed configuration, you would have chosen to pack it that way. Which you didn't. A d-bag is like the ultimate PCA. There long enough to put a canopy in the air, but with zero resistance after that.

Well, that's eerie... I'm a month into recovering from nearly identical injuries... scapula, 2 vertebrae, 5 ribs, tailbone, and two collapsed lungs (BASE) Heel (BASE -- launched hard on a low exit point) Ankle (skydiving -- dropped toggle) Wrist (basketball) Edit to add: Okay, I gotta ask... Which vertebrae? I burst fractured T5/T6.

After two weeks in hospital, I'm on to the long, tough bit.

I just take whatever the other guys say their delay was and add a half a second. Or the word "fat". It makes me look hardcore.

No kidding. 80% equipment my ass -- it's clearly 100% equipment failure. The parachute was designed to save his ass, bringing him to a gentle landing below. It failed to do that. Stupid BASE gear...

The general concensus, as I understand it, is that a TARD opens slightly faster than a static line jump, while a McConkey opens slightly slower. That's certainly been consistent with my experience. To put more solid numbers to the "slightly slower" bit, my jumps last weekend were done from ~250'. Had I taken as long a canopy ride as I could (I landed on the slope instead), I'd have had maybe 10 seconds, plus or minus, of canopy time. I've seen much more xperienced jumpers take McConkeys somewhat lower, but with the caveat that that'd probably be a terrible place to do your first. I'm inclined to agree.

I very nearly went that way, but had this feeling that I'd dislodge a toggle or something and not really be holding onto it. In the end, I just held onto the rear risers near the toggles, which wierded me out less.

Just got back from a 260' S a little west of here. I'd seen it done on TV, and had stayed at a Holiday Inn the night before, so decided to go ahead with my first unpacked jumps -- two TARDs on Saturday, two McConkeys on Sunday. Woohoo! Anyway, we were chatting stalling at the exit point and got to wondering about the whole hands-on-the-rear-risers thing when doing a McConkey. I've seen it a million times, and did it myself, but what is it for? How important is it? I'm guessing it has to do with heading performance and/or being on your shit that much faster. Am I on the right track?

'100,000'. Because, at my core, I'm soft and always looking for a reason to quit anyway. ... Or, alternatively, for the reasons you and I have already discussed :). Actually, I incorrectly voted '1'. But in addition to being soft, I'm also not that bright. So, you know, whatever...

103 jumps, just the one object strike at jump number ~95. The linked post, I think, pretty much lays out my answers to the above.

I've had three incidents I would characterize as particularly significant learning experiences during my BASE career thus far... One was a cliff strike that I learned a great deal from, as I expect most people do when they walk away from that. The second was a tailgate hangup that never cleared, teaching me in vivid detail the importance of using tan elastics on the tailgate. Somehow the third stands out to me as worthy of note, though... I was on top of a local 140' silo. We'd had some problems earlier with an extendable ladder that released when I touched it, and had come back a half-hour later pretty confident that security was come and gone, if they had come at all. We were wrong, as it turns out, and I had reason to suspect that I was minutes from having some unwelcome company. Anyway, I was on the top when I realized that the rail I'd originally planned to tie off on wasn't going to work, and started looking around for an alternative. I decided to use the cage surrounding the ladder I'd climbed up on. Looking down, I was a little wary -- the rusted metal of the ladder and landings looked poised to reach out and grab my pilot chute. "What the hell," I said to myself, "I'll just give it a bit of a launch to get clear." I launched, never having seen the guard I expected, and gave it a pretty good push. I oscillated ("Hey -- what the...") back, foward, and hit hard, but walked away with a broken heel. So, umm... If you're standing at the exit point on a static line jump and thinking, "I'll just give it a bit of a launch", know this: If you don't push hard, your pilot chute might snag on the stuff below, and you'll be out a pilot chute. But if you do push hard, you will oscillate on opening, and maybe you don't have time for that.

You're fooling nobody. What was is Jaap calls you? Pooky? In the name of remaining on-topic, though... What would naming names publicly do to improve matters? Those who need to know, know. Half of what was written on the recent cliff strike didn't even get the sport right -- do you really think the guy sitting down to read the paper with his coffee cares who was involved? As to the positive/negative press issue, Jaap is absolutely right. The more people are let to believe that BASE jumpers are reckless people, the more they'll feel a need to protect somebody from themselves, or to save me the 0.4 cents (do the math) that it cost me for the most recent rescue. Edit to add: p.s. 0.4 cents well spent...

Just watch any Bridge Day video [...] I think we might be talking about different things entirely.

I'm inclined to agree, and I'll cite the fact that I have found I can predict off-headings in certain scenarios (say, crosswinds on a static line) with great repeatability as evidence. I suspect that shoulder-dropping on an otherwise clean jump is one such scenario. I also think Tom's on the right track. We could sit here and BS about it for weeks, or somebody could bomb out to a forgiving 'S' and do five in a row with each shoulder low. I know what's on my agenda for my next trip south. Heck, I might give it a shot on my next trip west, though that'll be largely S/L and less forgiving objects.

The important thing to remember, I think, is that (as somebody else said above) we're all adults here. If you want to tell a friend that you think something he's doing is reckless, then that's absolutely fine. Don't talk around it -- just tell him. ... And if, at the end of the day, he chooses to disregard your thoughtful advice, then that's just the way it is. You're his peer, and you've helped to make his decision (because, in the end, he chooses his own path) better informed. My experience has been that you'll save yourself a lot of grief if you remember that.

Gotta agree there. One thing that would put me off a BASE helmet entirely -- regardless of what else it offered -- is poor crush material. Carbon fibre is snazzy, but at the end of the day it counts for nothing if the liner sucks. Polystyrene foam (a la most snowboard helmets) gets top marks. The softer foam in a ProTec is a distant but acceptable second. The quarter inch of pillowy softness found in most skydiving helmets is worse than useless in a BASE environment.

I dunno, man... If that's the case, apparently he's been opening a lot of new objects...

Man, that's a relief. Here i thought you just didn't love me anymore.

I think that's probably a great idea, but for what I feel is a more positive reason... While I'm generally a very happy, positive guy, me at the bottom of a jump makes that pale by comparison. I'm not sure anybody who cares about me could watch a jump, talk to me at the bottom, and not immediately know why I did it. I also don't think anybody who really cares could help but be a little concerned for my safety -- I know I am. That much is their job, and I'm glad they're doing it.

My experience has been that one has to be careful about two things with very deep brake settings... (1) Winds. In deep brakes, the canopy will get blown around easily by headwinds or crosswinds. Be aware of this -- all of the riser correction in the world won't get you away from that buttress to your left if there's even a moderate crosswind toward it. The solution is straightfoward... Understand that you may need to pop your toggles to get out of that situation. (2) Turns. A canopy in very deep brakes -- particularly the sort of brake setting that one can easily access with a vented canopy -- may not respond to riser input at all. You'll need to go to toggles (not my recommendation) or haul down on both rear risers to generate a little speed backward before turning (my choice). Perhaps some will argue that this is a symptom of brakes set too deep? Really, I figure hauling on both rear risers should be the first response anyway. Neither of these is a disadvantage, really, but certainly they're things you need to be aware of. Going for a shallower brake setting would probably alleviate both, but there are trade-offs, of course.