Colm

disclaimer: I'm a pilot not an engineer Reynold's number, in a sense, has to do with the drag of the fluid (air) over the surface of the object (the jumper). It is useful in scaled experiments such as small wind-tunnel models. Finding the critical reynolds number (somebody correct me if I'm wrong) on the model will help predict important airflow characteristics over a full-size version. So you can subject a small model to wind tunnel tests that you couldn't do on a real person, and get useful information. Angle of attack is the angle between the chord of an airfoil (i.e. a straight line from a tracker's head to his toes) and the wind vector. If you wanted to estimate your AOA while you jumped 1) install an AOA vane on your body somewhere, or 2): - use video to determine X while you track, where X is the angle between the horizontal plane and the chord of your body - Determine your glideslope, Y, equal to the angle of your descent path as you track--get this from GPS data (90°=straight down, 0 = going perfectly horizontal) - Subtract X from Y to estimate AOA (did I get that right?) Note in the model picture, the AOA is approximately zero or slightly above. As others have noted, this is only possible in a very limited set of circumstances. It's not very useful, because unlike simple vector math, you can't just get a stream snapshot at 90° and also at 0° and expect any useful interpolated data.... the important stuff has to be determined experimentally. It would be interesting to see it at about 5-10 degrees higher AOA, and slightly less camber, I think. Another thing you'll notice in the model picture is the distinct difference between the laminar flow over the top of the model and the highly turbulent separation underneath. This is basically what an inverted stall looks like... with excessive drag and poor controllability. If you adjusted the camber (i.e. the tracker lifted his forehead a little) I'd expect that to change. But of course, the AOA is probably unrealistic anyway so it is fairly moot. Coefficient of lift... using C sub L at a given angle of attack, you can predict lift force based on certain factors. If you know the critical angle of attack and calculate C sub L for that configuration, you can find the max theoretical lift. Combine it with coefficient of drag, do some college math, and you can figure out a host of things such as L/D(max), best glide speed, best rate of descent, etc. Many things that might be useful to a nerdy tracker! I'm sure I've botched the theory terribly... maybe someone like 460 has some insightful comments. I just want to echo how fascinating this is... I have never heard of anyone looking at tracking in a windtunnel before. That body-wing that flew whats-his-face over the english channel probably went through the wringer too. It's a start.

Lovely pictures! A few nerdy questions. Can you post some of the aeronautical data? How did you select angles of attack for the wind tunnel tests? What are your thoughts on the turbulent layer beneath the model? How does it respond to AOA? Reynolds number? Center of gravity? Coefficient of lift or C sub d on any of the models / victims? Have you looked into winglets or leading edge slats?

That attitude is quite foreign to me. Such fees should be payed to offset legitimate costs, not to "keep someone happy," to paraphrase you. I already happily pay taxes on goods and services I purchase. The businesses I patronize are further taxed on the profit they make off of me. Why single me out for more, just because I brought a parachute with me? If all tourists are to be taxed, without regard to their pasttime, fine. But don't single out BASE when we are a drop in the bucket. In this case, the cost is payed for by vigilance and action, not by graft, which is what your suggestion amounts to. Pay em to keep em happy... sounds more like Tammany Hall.

Nor would I suggest that the town does so... I merely offer the point here as a concession to those who correctly point out that some organized events using public resources, including BASE events, can conceivably burden a town in minor ways. I've made my points... I'm writing a letter.. I'm going to bed!

Touche- The editorial makes several points. Some of them are valid, some are not. Before I complete my response to them, I will be sure to carefully consider the angle. They say exactly this: "The simplest and fairest solution, for starters at least, might be to charge BASE jumpers a modest use fee--say, $10 per person per day." I read back and checked the context, and it is not very clear to me that they only imply this charge in the context of an organized event. Furthermore, what constitutes an organized event? If your charity group coordinates shutdown of a traffic lane, ok that is organized. But is memorial day an organized event? That's debatable. Who's the organizer? If I "organize" myself and 3 buddies to take a trip there during the summer, is that organized? I dispute your paragraph above. It sounds explicitly like they want to charge "the quiet, daily jumpers." If I burden the town next labor day when I go and jump, please let me know in what way I burdened them, and I'll pay 'em back. I will gladly agree though (as I PM'ed to another guy), that if an organized event seeks to deplete a public resource, they may be liable to the public for repayment. A town board would be well within their rights to seek compensation for a quantifiable loss. It is entirely a separate debate, whether or not the town should reclaim such compensation from charity events. The burden to the town seems trivial to me. And, BTW, I don't think it counts as a burden to simply use the town's air ambulance as long as you don't stiff them on the bill. After all, it's their job to be there for those who need them. I believe that in a post-Memorial Day newspaper article, someone involved in rescue even said that they spent far more time on lost snowmobilers. The article said, "it's time to start a serious local discussion about managing it." That's a great idea, and that's partially taking place in this forum. But they also said, "it's not our responsibility to underwrite it[BASE], either." Yet as far as I can tell, they have not quantified their supposed underwriting, and I am very confused on what exactly they have underwritten. If they want to ask me for money to jump, I would like them to first be able to tell me how much I cost them otherwise. Otherwise, they are just taxing me (and you) for the hell of it.

Are you referring to the insurance fees that would cover such an event, or to the actual cost? If you mean the latter, do you have any idea what an air ambulance ride actually costs? What is important here, is whether or not I fully compensate the public for any debts I incur as a result of a medevac trip. Whether I pay for that out-of-pocket (i.e. self-insurance) or through a purchased insurance plan is entirely irrelevant to the town. And to answer your question, yes I do have a good idea of what an air ride costs. Let me further suggest that if the alternative was death, I would pay far more. Wouldn't most folks gladly give their last dime, and their last worldly posession, if the alternative to a medevac ride was to die in the canyon?

as much as i disagree with their "opinion", i have to disagree. newspapers are printed for one reason and one reason only... to MAKE MONEY. forget all that BS about spreading "news" and informing their "people". furthermore, an editor's page or opinion page is designed to stir up shit. more pissed off people fuel more readers and more money. unless the paper is biased, or your letter is out of line, they should print it as well. i look forward to yours and those like it .

I bet at least some of those editorial authors have at least one of those ubiquitous "Support the troops" stickers on their cars. Well, it's time for them to put their money where their mouth is. Gee, thanks for the verbal support... But if they can't handle a once-in-a-blue-moon charity event that does nothing but slow down traffic, what kind of "support" did they possibly have in mind?? Being proud that their town could host a unique fundraising event would be a far more laudable attitude in my opinion... instead it sounds like they are saying, "Sure, raise scholarship money for a kid whose parent is killed in Iraq, but be sure to give us our cut." It's Godd-mn F-ing disgusting. The authors should be ashamed. Police and other government agencies get involved in charity events all the time. Should they bill a charity car-wash in an urban parking lot, because there's a statistical 0.0001% increase in policing costs as a result? So they want to charge me $10 a day? To walk on a sidewalk? You've got to be f$*king kidding me. I already pay their taxes and buy their services every time I visit. I may only do legal jumps, but I can live without Twin if it ever comes to that. If I ever (God forbid) need an air ambulance ride, I'll gladly pay. I'll pay the police department for the paperwork they filed, and I'll pay anyone else who was inconvenienced one iota due to my goof-up. Oh, and, the people who would pay 10$ a day... how many days a year do you go there? Guess what, it starts to add up if you like to go for a week at a time, a couple times per year. Maybe you don't bust your ass year round so you can take your only vacations there. Maybe that's not the only jumping you get, though contrary to what some people here assume, not everybody has an object nearby. And, maybe, not everybody is morally comfortable trespassing. What about the locals? Do you honestly think it's even remotely reasonable for them to pay a $3,650 tax to jump year round? If you answer yes, well then, I don't usually resort to personal attacks, but you are a complete idiot. The taxes on the house I live in do not even cost that much. Will they jump every day, no, but that's not the point. I'm writing a letter to the editor tonight. It will be polite, articulate, and as diplomatic as possible, but my position will be resoundingly clear. I hope everyone else does too.

A personal favorite site... Rob, you still have to head down there!

No need to apologize... I even considered the possibility of mixup beforehand, I was just too lazy to wake up an hour earlier and check! Regardless, I ended up having to miss bridge day anyway. Looking forward to it this year!

I'm a little confused. Registration (and/or server crashing) seems to have started 2 pm east coast time, but it's Daylight Savings Time here, which is only 4 hours behind Greenwich, not the 5 for EST. Thus 1900 GMT = 1500 east coast time. So registration should start at 3pm local. (If my memory isn't wrong, I thought in a previous year the Daylight Savings was factored into the time properly.) It doesn't matter now for this year, but perhaps we can make it more clear next year. You are absolutely correct, sir. Jason made the same mistake last year when I was living in Japan, I waited until EST (not EDT) and missed my #1 slot!!! Of all the outrages. I didn't say anything because I figured I was the only one who cared. No hard feelings Jason-

http://news.yahoo.com/s/ap/20060624/ap_on_re_us/chicago_s_skyscrapers I hope some folks out there are taking advantage of this.... firsthand?

This is perhaps more of a question to the website administration, than feedback or a suggestion, but I'm not sure which forum is appropriate to use. I am interested in asking the management here, what DZ.com's opinion is on proposed federal network neutrality legislation and what effects, if any, it would have on a dz.com user's online experience while using this site. Thoughts? Thanks, Malcolm

N/A

Perhaps... makes no difference to me...base jumpers seem make more of a habit of breaking bones?

I'm sure this would in no way apply to any jumpers that I know. http://news.yahoo.com/s/nm/20051226/hl_nm/alcohol_damages_bones_dc Study shows how alcohol damages bones [here's the kicker:] ...Though excessive drinking has been shown to promote bone thinning and fractures, some studies have suggested that moderate drinking may actually help protect bone mass...

That looks like the one. Thanks.

I hope to be able to offer some much more close-up photos in a few months.

I have been informed that sometime in recent history there was a multiple-fatality skydiving incident in Antarctica. Forum search turned up nothing. Can anyone offer information, a report, or analysis? Thanks Colm

Would like to PM any jumpers who are familiar with Antarctica. I may be able to do some recon...

Davedlg, Thanks for bringing this up here. The BASE community often talks about teaming up with other back-country interests to help fight for fair access. This is an opportunity where we & various groups can act in that spirit. It would be a dark day if some mining conglomerate ever "claimed" the LZ under the potato bridge. Not saying it could/would happen, but... I agree the possibilities are frightening. And call me cynical, but I doubt an individual jumper, without any political connections, could compete for a deed sale against any sort of corporate entity. I'll write a letter too.

Wow, I musta missed something, a US Marshal was there? I am friends with a Marshal. He works with murderers, rapists, and crack dealers. He hasn't told me any stories about tracking down BASE jumpers yet. I didn't think we were that dangerous. Seriously, what was his purpose there?

I will be arriving in Christchurch later this month, and am very interested in meeting some locals. I can meet you anywhere on the South Island if you are interested in getting together. Colm

Need to sell my bridge day ticket, too. :( Please PM if interested! Malcolm

Getting into SLC on evening of the 30th. Returning on Tuesday morning. Any carpoolers? Haven't decided if I'm going to camp out or do a hotel. Cheap is good, but so is a real shower. Any camping out there, besides the KOA? Colm