Tornolf

uh, why? A waddling elephant seal is the cutest thing in the entire world. -TJ

I just looked in my logbook, 1 of my first 20 jumps was above 300 feet, with 15 being freefalls from 270-300. Hell, most of my jumps now are from 270 and below. Living in a flat area sucks sometimes. A waddling elephant seal is the cutest thing in the entire world. -TJ

I told him that. He says if there were a million blanks he might try it. Now he is trying to tell me jumping from a plane is like playing russian roulette. This could be a long conversation. It is like Russian Roulette, there's just a hundred thousand or so blanks. Maybe more if you include blind stupid luck where someone can have a double total mal and still live. People with no background in statistics or higher level math shouldn't be allowed to make comparisons like this. Ever. A waddling elephant seal is the cutest thing in the entire world. -TJ

I wanted to base jump around 6 months before I did my first skydive. Before I did my first base jump I had the following: 350 jumps in less than a year, 150 within the past 3 months. 250 jumps on a F1-11 9 cell loaded at .9 75 jumps on my base canopy, working on accuracy/canopy control on every single one. All jumps within 4 months of first base jump. ~20 CReW jumps on my base canopy ~20 CReW jumps on my other canopy Though I didn't take a base course or anything and didn't really have a mentor, just a bunch of guys who are like family. Also, I started base just after I turned 18. This is one reason why I have absolutely no clue why some people start base with less skydives/experience/whatever and say they can't afford it or anything - especially if they live in a 1st world country. A waddling elephant seal is the cutest thing in the entire world. -TJ

that is adorable A waddling elephant seal is the cutest thing in the entire world. -TJ

and meeting them in person, and jumping with them perhaps? A waddling elephant seal is the cutest thing in the entire world. -TJ

BASE jumper only board/database >> anybody board/database. that's my only concern about this new thing, and why I prefer your database thingy. A waddling elephant seal is the cutest thing in the entire world. -TJ

Saw a base video online and decided I wanted to base jump. So I made 400+ skydives in less then a year, then started base jumping. Don't really skydive anymore. A waddling elephant seal is the cutest thing in the entire world. -TJ

when you had the off heading this morning, it made me excited to get my new rig! then you turned it and landed next to me anyways A waddling elephant seal is the cutest thing in the entire world. -TJ

At least one has a German TSO. None are FAA TSO'd. The only way to jump a (only) base rig in the US out of a plane (with a front mount reserve) legally is to do the foreign visitor thing when the FAA will accept other countries' TSOs. A waddling elephant seal is the cutest thing in the entire world. -TJ

Wouldn't the effect of the PC be largely counteracted by the weight of the jumper distributed through the lines, which will be concentrated moreso on the A/Bs due to line trim and distribution of lift? Personally, I can't tell the difference on either of my canopies (245 and 220) between a 38 vented, 42 vented, 46 vented, or 48 unvented. I don't get much flying time to compare the differences though. If the PC was making that big of a difference, shouldn't the center cell be visibly distorted due to the PC pulling the fabric up and back? I don't think back would be very noticeable, but it would cause the center cell to be slightly narrower when viewed from above due to the vertical component. A waddling elephant seal is the cutest thing in the entire world. -TJ

Civil engineers don't make nearly enough money to deal with this headache A waddling elephant seal is the cutest thing in the entire world. -TJ

Take practice tests. You can get good books from the library. They helped me do very well on the SAT. A waddling elephant seal is the cutest thing in the entire world. -TJ

no. A waddling elephant seal is the cutest thing in the entire world. -TJ

20+. yes. less time to linestretch. sub 180 A waddling elephant seal is the cutest thing in the entire world. -TJ

I'm fairly sure you're talking about "jerk." It's da/dt, the change in acceleration with respect to time. A waddling elephant seal is the cutest thing in the entire world. -TJ

Based on what reasoning..? It inflates quicker? Less time to line stretch..? More comfortable opening? or rather...why wouldnt you use a 46? I plan to progress to things which require a stowed pilot chute. This allows me to slowly work my way to that and get accurate info on altitudes and time to linestretch on specific objects with a 42 hand held. I have no desire to stow a larger pilot chute. With regards to low stuff, I spend a lot of time and energy on analyzing past jumps and using that data to model future ones. It allows me to get a very good idea of what's going to happen on the jump and therefore I can make an informed decision if the risk is worth it. The other reason is that for multiway freefalls from below 240, it allows me to more safely open lower than with a larger pilot chute. I can take the same delay with a 42 and be open lower than a 46 with less variance compared to taking a slightly longer delay with the 46. I'm mainly trying to minimize freefall time in these situations, as that will give me a larger buffer with the ground than more freefall with faster openings. Due to my weight, canopy size, line length, etc, the risk is much smaller for me to be the low guy than nearly everyone I jump with. With all that said, I currently have a 52" ZP PC being built. Also note that nowhere did I say using a 42 will be less risky than a 46/8 on a normal low freefall jump. I believe it to be more risky in that situation. A waddling elephant seal is the cutest thing in the entire world. -TJ

Ditto, I'll use a ZP 42 above 210 or so. Can you tell the difference between PCs? I'm jumping a small, light canopy and can definitely tell the difference on these jumps. A waddling elephant seal is the cutest thing in the entire world. -TJ

yeah, but what does that have to do with break cord relating to the base jumping environment? edit: nm. forgot 689/m2c/sam were talking about loading it that way. A waddling elephant seal is the cutest thing in the entire world. -TJ

I'm fairly certain the properties of the break cord change when gradually loaded and stretched. This most likely explains why all force is not equal when applying it to break cords. It could be anything from the style of the cotton weave to the electromagnetic interaction of polymer chains at an atomic level. The latter seems like it could plausibly explain the reason why it breaks at 96lbs of shock force but can easily suspend more than that. I think I'll ask one of my professors next week about it. He taught a class I took last semester which dealt with things like this. Do you have any ideas? A waddling elephant seal is the cutest thing in the entire world. -TJ

F = dp/dt all my tests show breakcord breaking at the knot when a 100lb weight is dropped from 3-4 inches. every time. your real world tests do not accurately model a static line base jump. breakcord's breaking strength is shock load, measured by dp/dt, not m*a. suggesting that knots do not noticeably degrade tensile strength goes against decades of scientific and practical (rock climbing) knowledge. I'm pretty sure this knowledge will go back centuries/millenia as well, but I don't know for sure. to plausibly disagree with this precedent, you're going to need a lot of math and evidence exactly how did you do your tests? there is a very good reason labs and private companies spend hundreds of thousands of dollars on measuring equipment. edit: I phrased "breakcord's breaking strength is shock load, measured by dp/dt, not m*A." wrong. technically it is measured by m*A. however, in this case, A is more easily described as dv/dt since A will not be constant, and is definitely not equal to gravity. A will be a vector going in the opposite direction of the load, which is usually in line with gravity's vector. A waddling elephant seal is the cutest thing in the entire world. -TJ

Pretty sure if you wrap on the static line you're fucked unless you get lucky. I'm looking at you, twoply! A waddling elephant seal is the cutest thing in the entire world. -TJ

Keep in mind that the break cord has to overcome relatively little momentum to get the canopy out and to linestretch. It's very possible that whatever caused the first cord to break early will do the exact same thing to the second cord, but not break early because the first cord significantly reduced the momentum of the canopy. dp/dt yo A waddling elephant seal is the cutest thing in the entire world. -TJ

You're right on both counts. As long as the first cord has enough room to stretch and break, the cords will be loaded separately. Also, A PM I got made me realize I might not have been as clear as I could have. My main point was that there is absolutely no fundamental difference (neglecting an extra inch of freefall) between 2 break cords of equal length and 2 break cords of unequal length. The reason to use different length pieces is that it gives all the advantages of 2 equal length pieces along with a couple others. Any advantage to using 2 pieces of equal break cords is also an advantage to 2 different lengths, but not the other way around. A waddling elephant seal is the cutest thing in the entire world. -TJ

and no, it isn't supported by the above calculations. It is, however, common sense. A waddling elephant seal is the cutest thing in the entire world. -TJ