Shark 0 #51 July 16, 2004 Quoteok ok Looks like I opened a can of worms here. Still debating on a helo jump at SDSD though..hum???? Dude, do you find this thread laughable as I do??? Why didn't you just ask for opinions regarding HELO jumps! Just do it!!!! You may freak out the pilot and will probably be the only one on the skids. At 340 lbs., don't be too concerned with reaching terminal. Quote Share this post Link to post Share on other sites
kallend 1,623 #52 July 16, 2004 QuoteThanks, Kallend, so it's a small but measurable effect. I'm going to say that old bullet thing, about the rate of drop being independent of forward velocity, must be wrong. I guess urban legends can exist in the world of physics, also. I'd expect some aerodynamic effects on a bullet fired from a rifled barrel that would change the analysis.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
pccoder 0 #53 July 16, 2004 uh, yea everyone got that one? PcCoder.net Quote Share this post Link to post Share on other sites
BASE813 0 #54 July 18, 2004 QuoteI have a boss who is at odds with me on the time it takes to get to terminal from a stationary object. (helo/ballon) What amount of time would it take to get to terminal and about how many feet would it take. Only guesses here based on 120mph terminal. I use the following table for calculating proposed delays and distances fallen in BASE jumping (ie dead air exits): Sec Ft/sec Cumm Ft 1 16 16 2 46 62 3 76 138 4 104 242 5 124 366 6 138 504 7 148 652 8 156 808 9 163 970 10 167 1140 11 171 1310 12 176 1485 13 176 1660 14 176 1840 15 176 2010 Quote Share this post Link to post Share on other sites
billvon 2,400 #55 July 18, 2004 >But the person exiting the otter has airspeed they can use to fly at > an angle from "down" on the relative wind. And that relative wind can cause a jumper to either accelerate towards the earth faster than 9.8m/s or slower than 9.8m/s. In my experience, a good 4-way launch does neither. Big-way launches from the back of a skyvan seem to have an equal chance of getting steep and generating downward lift and being flat and "sailing." Hence there is often a difference in the picture when you're a diver on the same plane as the big-way base; sometimes it's far below you and sometimes it's closer to your level but farther away horizontally. Edited to add - a lot of this is academic. After 10 seconds you're really close to terminal velocity. If air pressure didn't change you'd never truly reach terminal velocity; you'd just get closer and closer to it until you could barely measure the difference between your speed and "true" terminal velocity. However, at some point in the skydive you stop accelerating and begin to decelerate (in terms of absolute speed) since the air begins to get thicker. I did the math a while back and discovered that this happens at around 15 seconds, but at 10 seconds you're so close to terminal (it was something like 118 vs 120mph) that you're essentially there. Quote Share this post Link to post Share on other sites
