Newtons2nd

What do you mean I haven't answered it? The pressure changes when the protrusions assume some of the wind which will scrub speed. You are looking way to far into this. When the speed changes think "why". I don't care what you do, you cannot increase pressure on a board beyond terminal if it is horizontal and there is least possible drag from a body, unless you ac/decelerate. If you mean that I didn't answer it "literally" then I now see why it is not obvious to you. Besides the only "obvious" (one by the way) is after the statement that you do not have a mode of power behind the board causing additional force, that means a motor of some sort. So since that is not obvious then I will say it more clearly: To all skydivers: You do not have a motor attached to your back when you are skydiving. I know that this should be obvious, but since it may not be, consider yourselves warned. As far as the assumption, there was none, and I don't care to explain my background, as I was only trying to help not argue. ALthough I guess I ended up doing that just a bit too (obviously).

I am sorry to hear about your misfortune. I guess I should have remembered that some of you older guys have fallen out of condition and protrude in all of the wrong areas. You know they have programs for your kin. Aerobics would be a good start. I did want to add one more thing to my last post but can't seem to find an edit button: I assume you know when calculating the pressure on a board while decelerating you use F=MA (force, mass, accel) and then use P=f/A (pressure, force, area) p.s. look up PARSIMONY (science definition) it will make your mathematical life much easier

Billvon seems to have the only simple yet correct approach. I am not guessing at this or late for work, this is how it works. P=F/A with the force being your exit weight and the area being the board plus the body parts exposed (which does need to be accounted for considering the amount of error in the first place). It would be best to draw a quick sketch from a "whuffo's" point of view on the ground (with good binoculars). The exposed arms drawn in two dimensions is probably enough and although over shooting actual, will make up for the other small protrusions. The most amount of pressure you could inflict upon the board is having it horizontal to the earth with max poss velocity. Any decrease in this would be due to more bodily protrusion and can simply be subtracted using the exposed surface area of whatever it is you are sticking out. The most important thing to remember is that in most cases you will increase velocity by tilting the board in which case the pressure is now in vector form and far less (surprisingly) at even higher speeds. So again simply subtract the area exposed as you decrease velocity. You should not use any square of anything unless you have a mode of power behind it to drive a board in the same plane to a higher velocity, which is obviously not what you are dealing with. If you want to take it a step further--there is one more greater force, and that is when you decelerate from 130-110. This can simply be figured by using Newtons2nd (imagine that) and you would have to just use the change in velocity over the change in time and then add it to the pressure you already have figured. Notice again that everything is adding and subtracting, there is no complicated anything with this math. The other posts are correct if you have eliminated all variables and have more knowns, otherwise you will bring in more error than it attempts to eliminate.

Thanks, I have been to the appropriate analysts and just need a brace. There is no surgery available for what my shoulder has gone through. I have had the same laxicity since I was a young boy (29 now) and it comes out at will no worse than it ever did. It is not even painful anymore, however I lose total control of the arm until I am under canopy, so this makes deployment a bit spinny as I am unable to stabilize with my left straight out to my side.

I just dislocated my shoulder for the 5th time while doing backflips last weekend. I was told by a few instructors that there are braces out there that will help with this and that the two names mentioned above were people who had tried these braces. If you either know of the brace and where I might find it or know of these two people and can kindly let them know I am in need of the info, it would be greatly appreciated.

Although I have only posted a few times, I have been reading posts now for quite some time. You guys could really kill about 10 birds with one swift kick. It seems that there has been a common thread (whether the connection has been made by others I am not sure). It might do some good to have one long confidential poll that combines entries from other sites. Rather than ask everybody to guess, why not have a poll similar to this but have something to check for each user (registered or not) that lists the number of jumps from each object and legal v.s illegal. during a 12 month period and then lifetime. In addition to the skydiving training that preceded. Let it run for a few months (have a moderator keep it at the top) put another one on each other site, state some rules about only taking one poll. Send some emails to friends get them to fill it out. Have them forward the email etc... I have seen many concerns over the past that could all be answered within a few months of this. Keep a moderator on this to keep it confidential and then throw it into a program that will spit out every statistic you need. If you get a few thousand entries you will have some solid data worthy of publishing (assuming it is pretty enough), who knows, you may find it is worse than you thought, but I doubt it. The deaths and injuries may have to be entered by somebody manually. For those who care to keep the discipline looking clean, some true statistics might help. It will also be essential in the future when BASE becomes bigger and more prevalent than it already is. A lawyer may also have a bit more fighting power (from a great deal of past experience) if the statitics can be shown. I am sorry if this has already been done before I came to this sight and I am stating the obvious. I know I have read a few moderator/experienced posters argue about how many jumps have been made legal vs. illegal so I don't imagine that these statistics exist. I must say when I was a little tike I first went skydiving at a place that had some statistics, as soon as I saw that I was more likely to win the Lotto AND get struck by lightning before I would die skydiving, I was signing in the dotted line. Although I have won a 4/6 and been struck by lightning while driving:)

Ok here is a response and a question for the other students out there. --Let's say I have a reputation to protect. I see many other experienced jumpers with little info in their profile. --I had a bad mishap when I was 22. I raced Superbikes in 97 and 98 and had a local reporter go nuts because I was about to set some record that really wasn't that big of a deal. He blew it out of proportion and included all sorts of other interests in it, including what I ride on the street. Well there was an incident on the street in some old canyons where the speed of pursuit averaged 140 and had half the roads blocked. Well that guy got away due to his knowledge of the area and his ability to ride without allowing adrenalin to overcome acute judgement. My house was surrounded a day later and I was thrown in jail on a pure hunch. They stated that because of all of the information and PICTURES in tha article, that beyond doubt it had to be me. Worst of all they impouded not only my street stuff but all of my race gear. Well as you can imagine I beat it in court, but it adversely affected my business (not to mention my attitude toward police)which I had spent years after recovering. I would drop business cards, and people would say "aren't you the one who was arrested last month" for outrunning the police? I am sure this is ringing a ton of bells right now with jumpers who may or may not want their personal info out there. So the question is what part of the profile will really make my posts more worthy? I almost did fill it in, but I didn't want to put my real name and personal info and then introduce myself at some exit point as the guy who put a bunch of false information. So here is another question: I live very near an "S"and "B" that have rarely been jumped succesfully without the wrong onlookers. I ride my bike up and down the "S" daily and study the currents and the wind dreaming of the day that I get to pull it off. I have studied the people, the boats, the patrol, and the cameras so that I have a vast knowledge of the right time to go without risking drawing attention. What do you experienced jumpers do in a situation like that. Do you keep the stories and suggestions to yourself, or do you just post anyway with your name being public information? [Laird] -I didn't say I won't share an exit with somebody who hasn't a PhD in physics, I was saying that I think it is a good idea for the NEW students coming over from skydiving like myself to at least understand a few basic concepts about motion.

Calculus, and everything form of motion, from molecular to black holes, most of it in his 20's, in the early 1700's, and with no other knowledge, in fact everything that he read was flawed in some way so he had little to build on. Most of it is still used actively, and most of it still checks out to be spot on, yet he couldn't see half of the planetary motion or molecular motion he was postulating. It only starts to collapse (so to speak) when it is used at the atomic level, which is where QM and QED comes in (quantum mech, and quantum electro dynamics).

Lets see.... I asked Tom a question and got a few other responses, then responded to those, then received a message asking for some more advice on Physics books. Not sure how that is trolling... However since I am new to the forum, I assume since you have a big "D" listed under experience that everybody else shares your view. I am doing what most highly qualified instructors say to do...ask lots of questions and start understanding the world of BASE. This thread is titled "what to look for in a student" doesn't that mean that I, with little experience should be in this thread asking questions and stating my concerns, as well as getting feedback? I don't have a profile, I have 0 jumps, I only have jumped out of planes, and saw the thread and thought this would be the place for students and teachers to swap views. oh wait...nevermind...I just realized what the "D" stands for, because the last guy who told me to get out of the thread that I created, also had a "D" Sincerely, The guy who will probably piss somebody off before I make any friends.

Does "Thank you" mean quit offering suggestions, or thank you for the suggestions?

Well then it is time for me to bow out--if there is a physicist out there who has been involved with base that long, surely he will know more than I do about the combination of the two, as well as the general knowledge of the BASE crowds he is invloved with. I am sure he will know of a classic conceptual book called "Conceptual Physics" by Hewitt. We were all insulted in our transition to upper division when the professor suggested this book, but although it teaches one as if he/she is in third grade, it is very helpful for somebody who is not quite understanding the qualititative (visual) idea behind some of the more advanced theories (relatively advanced--so to speak:) You know there would probably be some decent money in a publsihing of a small handbook that combines all of the basics in a "guide for falling bodies in a fluid medium and the dynamics of the microclimates that might hinder ones judgement or save ones life, and other bonus hints on just how things work" forgive the title I am being mostly sarcastic. Atlthough a book like this with all of your charts in the back that are more updated than that of the recommended PC's for the modern 1980's jumper.

I have read the books you list and found them quite helpful. I am actually a physics student so I have studied fluid dynamics. In fact half the reason I returned to school was to learn about all of the phenomena that I have experienced in my early twenties. I agree that the books are great, but what I was saying is that doesn't teach the physics of the actual jump. I feel like I really don't have a right to say much more. I know if I had somebody commenting on how one of my well accomlished sports could be made better when he/she hadn't yet actually done it, I would be a bit put off. I wasn't suggesting that the mishaps are due to lack of weather knowledge, I was stating exactly what you said in that most accidents are due to misjudgements, and that some of those misjudgements could be avoided if the calculations were either made better or made in the first place. And back full circle to my original comment: I would hope that new students coming over from skydiving like myself would open a basic physics book and at least learn how to make some calculations. I know of a few that I tell all of my fellow athletes to read. You know it is bad when the ask what Newton discovered. I will try to dig through my collection and find a short compact book that explains the basics of newtonian motion and fluid/thermo dynamics. I would feel comfortable recommending that, because by the end of the summer I will be standing atop an object next to a person that will hopefully understand it. Cheers, and hope to meet you by the end of summer.

I am steadily accumulating jumps now with intentions of finding a course similar to yours (hoping for 200+ by then). I have a long list of accomplishments, education, life experience, life-flight rides etc...I am currently a semi-pro cyclist coming off of a superbike career blah blah blah Here is what I don't understand-- I posted last week with a question about cameras, not so I could jump with a camera but so I could use it now in my other sports and have the knowledge of how it performs, and just generally get used to filming for my own education. Well as you probably noticed, I was given shit for even asking, as if I am not qualified to ask about cameras. So no worries, I understand.. Yet I see these replies to my posting and most others (with jumps well over 1000), and yet half the postings I read make it clear that these "experienced" jumpers have no concept of physics or atmospheric science. Why is this knowledge not a recommedation? Maybe this IS why the mishaps are so frequent? I know that I don't want to jump along side of somebody who has little or no education on those two matters. I have seen first hand a half dozen deaths, and well over 100 accidents/injuries and nearly every one of them were "the best" anybody had seen. Well were they the best or were they just getting lucky all of those years? I have also seen some of the most educated in the adrenalin sports make it uninjured because they won't do it unless it is calculated first. I guess this isn't really a question, just a comment. I hope it doesn't offend anybody. I see the book you recommend (Dennis Pagen I believe) and that has some good stuff in it, but there is still a great deal of physics and calculations that need to be made by somebody who is not with a person who does understand this. How about the simple math to figure out how long it will take to reach a certain altitude based on a variable fall rate? Is it acceptable to just rely on past data and other's suggestions?

Alright let me word this again, I am sorry I don't have the lingo correct and the number of jumps necessary to get a proper opinion but... "equipment is the same" is really helpful, but I was really looking for something like: Oh hello there, welcome to our forum, it was really nice of you to log on and tell all of your friends about this website where people are friendly and offer some specific advice. It has been my experience that skydiving and BASE alike use the same cameras, most prefer the blah blah 324, but some use the blah blah 824. I think the blah blah 924 is very expensive but since you said money didn't matter then it may work well for you. That is a great idea to strap it on a 180mph vehicle first to find it's weak points and learn to compensate. Since you already skydive you might find it will take some getting used to so I would advise using it for a while first before you attempt to BASE with it since BASE requires a great deal of focus. In my opinion it would be wise to steer clear of any videos while you are learning worry about the jump.

I can appreciate that, but I am actively skydiving now and wanted to start taking shots so that I can learn the equipments charachteristics. I didn't mean that I am trying to take primo shots on day one of BASE camp, as I said I wanted to know what is used so that I can start using the equipment now to understand it better so that 'without thinking about it' I can take some shots at some point. I am posting in the BASE zone because I assumed that equipment might vary a bit from classical diving. In addition, becoming the best at anything (for me) requires visualization--I have taken a half dozen sports to the top and attempted four fold that many, and I have yet to find a sport that doesn't change ones perception of relativistic time. Meaning that watching a video of ones actions while ones heartrate is 35-40 and the hormones in the bloodstream are minimal, may allow for quick realizations that time is relative to the frame of mind or even more important that small mistakes have been made that would have otherwise gone unnoticed.