mnischalke 0 #226 February 21, 2004 I do things the hard way, I guess. I used the 990 you gave me minus the 440 from the 11 seconds x 40 fps. Oh well Btw, you certainly are the professor, with all that distracting bs mixed in there. I guess, I could have pared it down further, but this is what I used: Quote at 2500ft agl. an easterly wind is 40ft/sec. at altitude the winds are westerlies 50ft/sec A team leaves the Otter. open at 2500ft. a second team leave after 11 seconds. How far from (the center of the first group) is the center of the second group, and is there a risk of collision between groups? Thanks for the fun! mike Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills. Quote Share this post Link to post Share on other sites
kallend 1,623 #227 February 21, 2004 QuoteQuote50 x 11 = 550ft. Don't you have to subtract the 40 x 11 = 440 ft that group one drifts while under canopy since the uppers and the lowers are heading in opposite directions? -Jason How can they drift when there's no wind (remember the cigar smoke).... 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
eames 0 #228 February 21, 2004 QuoteHow can they drift when there's no wind (remember the cigar smoke). They are the wind. Uppers and lowers are pointing in opposite directions. 11 sec in the door at 50 ft/sec in one direction, then 11 sec under canopy at 40 ft/sec in the other direction. I guess I'll have to think about it more. -Jason Quote Share this post Link to post Share on other sites
mnischalke 0 #229 February 21, 2004 Methinks kallend is fucking with us... My head hurts already after second guessing myself earlier... On another note: Don't we got a freshly-painted otter to play with tomorrow? hehe mike Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills. Quote Share this post Link to post Share on other sites
velo90 0 #230 February 21, 2004 Excellent quiz Kallend You tell a nice stroy as well, I really liked the guy messing with his booties. It's rather sad that 550 ft did not pop into peoples head straight away. But there again, unless you forget about the ground you will let all the references to the ground in your story affect how you answer. What's more, unless you ignore the ground, you never see all the other useful hints in your story. Quote Share this post Link to post Share on other sites
eames 0 #231 February 21, 2004 QuoteIt's rather sad that 550 ft did not pop into peoples head straight away. But there again, unless you forget about the ground you will let all the references to the ground in your story affect how you answer. I don't think I'm considering the ground at all. In fact, if the guy in the balloon saw another balloon in the upper winds, and used his handy laser rangefinder, he would see it moving 90 ft/sec. He would still see the Otter moving at 50 ft/sec in the other direction. The Otter and the upper balloon would be moving away from each other at (90 + 50) 140 ft/sec. So the groups gain 550 ft of separtion from the upper winds and the plane, then lose 440 ft due the first group reversing direction in the lower winds for the 11 seconds before the second group opens. Would you explain to me why I'm wrong? -Jason Quote Share this post Link to post Share on other sites
eames 0 #232 February 21, 2004 Can you explain to me why I'm wrong? Quote Share this post Link to post Share on other sites
eames 0 #233 February 21, 2004 I hear bells ringing.... Now that I think of it, who cares about 50 ft/sec x 11 sec? That's not how fast the plane is flying through the upper airmass. 140 ft/sec x 11 sec = 1540 ft in the upper airmass. -90 ft/sec x 11 sec = -990 ft (because of the difference in speeds of the air at exit altitude and opening altitude). 1540 ft + (-990 ft) = 550 ft Ding, ding, ding. Man, if I had only plugged the numbers in according to how I've been preaching the whole time! Sorry for being slow. Yay, we all agree! -Jason Quote Share this post Link to post Share on other sites
eames 0 #234 February 21, 2004 QuoteAll you need to know is that the plane is going 50ft/sec faster than the balloon, and multiply that by the exit delay 50 x 11 = 550ft. This is (of course) a better way to do it. But it took doing it with the real numbers to understand why. Now I really have it down... conceptually and practically. Thanks for the quiz. -Jason Quote Share this post Link to post Share on other sites
diverdriver 5 #235 February 21, 2004 QuoteAnd real circumstances exist where blindly relying on groundspeed might kill you. And what do you see me doing on days we have uppers out of the west and lowers out of the east? I fly south to north or north to south offset along the river (Fox River next to SDC). Seperation.....no problem. (and then I can go back to relying on my groundspeed is god warm blankee )Chris Schindler www.diverdriver.com ATP/D-19012 FB #4125 Quote Share this post Link to post Share on other sites
kallend 1,623 #236 February 21, 2004 QuoteQuoteAnd real circumstances exist where blindly relying on groundspeed might kill you. And what do you see me doing on days we have uppers out of the west and lowers out of the east? ) In another thread I said I spent a lot of time watching a master. Did I ever mention that all but one out-landings I've had were when a certain DZO was spotting?... 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
kallend 1,623 #237 February 21, 2004 QuoteQuoteAll you need to know is that the plane is going 50ft/sec faster than the balloon, and multiply that by the exit delay 50 x 11 = 550ft. This is (of course) a better way to do it. But it took doing it with the real numbers to understand why. Now I really have it down... conceptually and practically. Thanks for the quiz. -Jason Now you're pleased that I didn't tell you, 'cos when you figure it out for yourself you're more likely to believe it.... 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
diverdriver 5 #238 February 21, 2004 QuoteDid I ever mention that all but one out-landings I've had were when a certain DZO was spotting? You know, if he couldn't see the ground he was right on! But man, if it was a clear day look out! LOL...I had him climb out early on me so many times. God Bless him. That sure was funny.Chris Schindler www.diverdriver.com ATP/D-19012 FB #4125 Quote Share this post Link to post Share on other sites
freeflybella 0 #239 February 21, 2004 Sorry for coming into this late - especially when everyone now seems to agree . . .a question from a right-brained thinker. On a normal jump day (normal conditions, ie, uppers same direction as lowers) what are the 'experts' agreeing to? That groundspeed should or should not be used to determine time between exits? If not, please explain? Please explain in a very practical way (look at ground winds, winds aloft, jump run direction, number/size of groups, etc.) instead of numbers and equations. Action expresses priority. - Mahatma Ghandi Quote Share this post Link to post Share on other sites
diverdriver 5 #240 February 21, 2004 QuoteSorry for coming into this late - especially when everyone now seems to agree . . .a question from a right-brained thinker. On a normal jump day (normal conditions, ie, uppers same direction as lowers) what are the 'experts' agreeing to? That groundspeed should or should not be used to determine time between exits? If not, please explain? Please explain in a very practical way (look at ground winds, winds aloft, jump run direction, number/size of groups, etc.) instead of numbers and equations. In the true form of talking about exit seperation the ground plays no part. However, the error caused by using groundspeed to reference seperation adds in an error that potentially increases actual seperation at opening altitude. So, that is why even after all this discussion it is still ok to use groundspeed AS LONG AS the upper winds are blowing in the same general direction (not opposite of) as the lower winds. Does that help?Chris Schindler www.diverdriver.com ATP/D-19012 FB #4125 Quote Share this post Link to post Share on other sites
VectorBoy 0 #241 February 22, 2004 QuoteQuoteIf the ground is irrelevant you could never have a bad spot Nobody is talking about spotting here... we're talking about separation. Of course the ground is relevant for spotting: You're trying to land on a specific "spot" on the ground. -JasonQuote But people use the ground as a reference for their separation from the previous group. What do you do when it apears that you are far from the DZ. Follow the procedure and allow what seems to be ridiculous interval between groups, wait till the previous group reaches the 45 degree point or just come out right on top of the group before you, say 2 seconds of separation? This is why I bring it up. Quote Share this post Link to post Share on other sites kallend 1,623 #242 February 22, 2004 QuoteQuoteQuoteIf the ground is irrelevant you could never have a bad spot Nobody is talking about spotting here... we're talking about separation. Of course the ground is relevant for spotting: You're trying to land on a specific "spot" on the ground. -JasonQuote But people use the ground as a reference for their separation from the previous group. What do you do when it apears that you are far from the DZ. Follow the procedure and allow what seems to be ridiculous interval between groups, wait till the previous group reaches the 45 degree point or just come out right on top of the group before you, say 2 seconds of separation? This is why I bring it up. Ask for a go-around?... 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 VectorBoy 0 #243 February 22, 2004 Ask for a go-around? Sometimes you can, sometimes you can't as in the extreme jumprun example that I describe in my first post to this tread relating to Extreme winds aloft. Try asking for a go around at WFFC or some major boogies. Some places talking to the pilot is verbotten ( to explain why you want a go around ). If the spot is good and the pilot can proove it there may be no go- around, you always have the option to ride down. Quote Share this post Link to post Share on other sites bmcd308 0 #244 February 23, 2004 >>So you are willing to bet your life on the reliability of the air at exit altitude and on the ground for landing, but at opening altitude you consider it unreliable. Interesting concept. << What is worse, an off landing or a collision? When I "rely" on the wind at exit altitude and on the ground for landing, all I'm doing is making sure that I land on the dz. If the wind dies at exit altitude, I wind up long. If the wind dies at 0 AGL, I might have to run out my landing. While an off landing might be a contributor to an incident, an off landing is less likely to be an incident than a collision between a jumper in freefall and an open canopy. I'm not sure the concept of being wary of allowing canopy drift to create separation is all that odd. I don't advocate basing the entire exit separation decision on groundspeed, blindly assuming that canopy drift will not create problems. I am not even sure that anyone has advocated that position in this thread. However, I do not advocate planning to have everyone open at the same spot over the ground, blindly assuming that the wind at 3 grand will push the previous group out of the way, either. The policy implication of my position is that on days when the lower winds are roughly consistent in direction with the uppers, you use groundspeed to maximize separation between the groups, stringing them out along the available jump run. On days where the winds at opening altitude are roughly opposite the winds aloft, you run jump run crosswind or in an arc (like both DD and Mullins do). Brent ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites kallend 1,623 #245 February 23, 2004 Quote>>So you are willing to bet your life on the reliability of the air at exit altitude and on the ground for landing, but at opening altitude you consider it unreliable. Interesting concept. << What is worse, an off landing or a collision? When I "rely" on the wind at exit altitude and on the ground for landing, all I'm doing is making sure that I land on the dz. If the wind dies at exit altitude, I wind up long. If the wind dies at 0 AGL, I might have to run out my landing. While an off landing might be a contributor to an incident, an off landing is less likely to be an incident than a collision between a jumper in freefall and an open canopy. I'm not sure the concept of being wary of allowing canopy drift to create separation is all that odd. I don't advocate basing the entire exit separation decision on groundspeed, blindly assuming that canopy drift will not create problems. I am not even sure that anyone has advocated that position in this thread. However, I do not advocate planning to have everyone open at the same spot over the ground, blindly assuming that the wind at 3 grand will push the previous group out of the way, either. The policy implication of my position is that on days when the lower winds are roughly consistent in direction with the uppers, you use groundspeed to maximize separation between the groups, stringing them out along the available jump run. On days where the winds at opening altitude are roughly opposite the winds aloft, you run jump run crosswind or in an arc (like both DD and Mullins do). Brent Hasn't this discussion left any impression? In the context of separation between skydivers at canopy opening time the ground is irrelevant. A fixed point over the ground is irrelevant. Canopy "drift" relative to the ground is irrelevant. The only thing having any relevance is the behavior of the air between exit altitude and opening altitude, inclusive.... 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 bmcd308 0 #246 February 23, 2004 OK. I'll give up trying to explain myself. ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites Prev 5 6 7 8 9 10 Next Page 10 of 10 Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. Note: Your post will require moderator approval before it will be visible. Reply to this topic... × Pasted as rich text. Paste as plain text instead Only 75 emoji are allowed. × Your link has been automatically embedded. Display as a link instead × Your previous content has been restored. Clear editor × You cannot paste images directly. 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kallend 1,623 #242 February 22, 2004 QuoteQuoteQuoteIf the ground is irrelevant you could never have a bad spot Nobody is talking about spotting here... we're talking about separation. Of course the ground is relevant for spotting: You're trying to land on a specific "spot" on the ground. -JasonQuote But people use the ground as a reference for their separation from the previous group. What do you do when it apears that you are far from the DZ. Follow the procedure and allow what seems to be ridiculous interval between groups, wait till the previous group reaches the 45 degree point or just come out right on top of the group before you, say 2 seconds of separation? This is why I bring it up. Ask for a go-around?... 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 VectorBoy 0 #243 February 22, 2004 Ask for a go-around? Sometimes you can, sometimes you can't as in the extreme jumprun example that I describe in my first post to this tread relating to Extreme winds aloft. Try asking for a go around at WFFC or some major boogies. Some places talking to the pilot is verbotten ( to explain why you want a go around ). If the spot is good and the pilot can proove it there may be no go- around, you always have the option to ride down. Quote Share this post Link to post Share on other sites bmcd308 0 #244 February 23, 2004 >>So you are willing to bet your life on the reliability of the air at exit altitude and on the ground for landing, but at opening altitude you consider it unreliable. Interesting concept. << What is worse, an off landing or a collision? When I "rely" on the wind at exit altitude and on the ground for landing, all I'm doing is making sure that I land on the dz. If the wind dies at exit altitude, I wind up long. If the wind dies at 0 AGL, I might have to run out my landing. While an off landing might be a contributor to an incident, an off landing is less likely to be an incident than a collision between a jumper in freefall and an open canopy. I'm not sure the concept of being wary of allowing canopy drift to create separation is all that odd. I don't advocate basing the entire exit separation decision on groundspeed, blindly assuming that canopy drift will not create problems. I am not even sure that anyone has advocated that position in this thread. However, I do not advocate planning to have everyone open at the same spot over the ground, blindly assuming that the wind at 3 grand will push the previous group out of the way, either. The policy implication of my position is that on days when the lower winds are roughly consistent in direction with the uppers, you use groundspeed to maximize separation between the groups, stringing them out along the available jump run. On days where the winds at opening altitude are roughly opposite the winds aloft, you run jump run crosswind or in an arc (like both DD and Mullins do). Brent ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites kallend 1,623 #245 February 23, 2004 Quote>>So you are willing to bet your life on the reliability of the air at exit altitude and on the ground for landing, but at opening altitude you consider it unreliable. Interesting concept. << What is worse, an off landing or a collision? When I "rely" on the wind at exit altitude and on the ground for landing, all I'm doing is making sure that I land on the dz. If the wind dies at exit altitude, I wind up long. If the wind dies at 0 AGL, I might have to run out my landing. While an off landing might be a contributor to an incident, an off landing is less likely to be an incident than a collision between a jumper in freefall and an open canopy. I'm not sure the concept of being wary of allowing canopy drift to create separation is all that odd. I don't advocate basing the entire exit separation decision on groundspeed, blindly assuming that canopy drift will not create problems. I am not even sure that anyone has advocated that position in this thread. However, I do not advocate planning to have everyone open at the same spot over the ground, blindly assuming that the wind at 3 grand will push the previous group out of the way, either. The policy implication of my position is that on days when the lower winds are roughly consistent in direction with the uppers, you use groundspeed to maximize separation between the groups, stringing them out along the available jump run. On days where the winds at opening altitude are roughly opposite the winds aloft, you run jump run crosswind or in an arc (like both DD and Mullins do). Brent Hasn't this discussion left any impression? In the context of separation between skydivers at canopy opening time the ground is irrelevant. A fixed point over the ground is irrelevant. Canopy "drift" relative to the ground is irrelevant. The only thing having any relevance is the behavior of the air between exit altitude and opening altitude, inclusive.... 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 bmcd308 0 #246 February 23, 2004 OK. I'll give up trying to explain myself. ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites Prev 5 6 7 8 9 10 Next Page 10 of 10 Join the conversation You can post now and register later. If you have an account, sign in now to post with your account. Note: Your post will require moderator approval before it will be visible. Reply to this topic... × Pasted as rich text. Paste as plain text instead Only 75 emoji are allowed. × Your link has been automatically embedded. Display as a link instead × Your previous content has been restored. Clear editor × You cannot paste images directly. Upload or insert images from URL. Insert image from URL × Desktop Tablet Phone Submit Reply 0
VectorBoy 0 #243 February 22, 2004 Ask for a go-around? Sometimes you can, sometimes you can't as in the extreme jumprun example that I describe in my first post to this tread relating to Extreme winds aloft. Try asking for a go around at WFFC or some major boogies. Some places talking to the pilot is verbotten ( to explain why you want a go around ). If the spot is good and the pilot can proove it there may be no go- around, you always have the option to ride down. Quote Share this post Link to post Share on other sites
bmcd308 0 #244 February 23, 2004 >>So you are willing to bet your life on the reliability of the air at exit altitude and on the ground for landing, but at opening altitude you consider it unreliable. Interesting concept. << What is worse, an off landing or a collision? When I "rely" on the wind at exit altitude and on the ground for landing, all I'm doing is making sure that I land on the dz. If the wind dies at exit altitude, I wind up long. If the wind dies at 0 AGL, I might have to run out my landing. While an off landing might be a contributor to an incident, an off landing is less likely to be an incident than a collision between a jumper in freefall and an open canopy. I'm not sure the concept of being wary of allowing canopy drift to create separation is all that odd. I don't advocate basing the entire exit separation decision on groundspeed, blindly assuming that canopy drift will not create problems. I am not even sure that anyone has advocated that position in this thread. However, I do not advocate planning to have everyone open at the same spot over the ground, blindly assuming that the wind at 3 grand will push the previous group out of the way, either. The policy implication of my position is that on days when the lower winds are roughly consistent in direction with the uppers, you use groundspeed to maximize separation between the groups, stringing them out along the available jump run. On days where the winds at opening altitude are roughly opposite the winds aloft, you run jump run crosswind or in an arc (like both DD and Mullins do). Brent ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites
kallend 1,623 #245 February 23, 2004 Quote>>So you are willing to bet your life on the reliability of the air at exit altitude and on the ground for landing, but at opening altitude you consider it unreliable. Interesting concept. << What is worse, an off landing or a collision? When I "rely" on the wind at exit altitude and on the ground for landing, all I'm doing is making sure that I land on the dz. If the wind dies at exit altitude, I wind up long. If the wind dies at 0 AGL, I might have to run out my landing. While an off landing might be a contributor to an incident, an off landing is less likely to be an incident than a collision between a jumper in freefall and an open canopy. I'm not sure the concept of being wary of allowing canopy drift to create separation is all that odd. I don't advocate basing the entire exit separation decision on groundspeed, blindly assuming that canopy drift will not create problems. I am not even sure that anyone has advocated that position in this thread. However, I do not advocate planning to have everyone open at the same spot over the ground, blindly assuming that the wind at 3 grand will push the previous group out of the way, either. The policy implication of my position is that on days when the lower winds are roughly consistent in direction with the uppers, you use groundspeed to maximize separation between the groups, stringing them out along the available jump run. On days where the winds at opening altitude are roughly opposite the winds aloft, you run jump run crosswind or in an arc (like both DD and Mullins do). Brent Hasn't this discussion left any impression? In the context of separation between skydivers at canopy opening time the ground is irrelevant. A fixed point over the ground is irrelevant. Canopy "drift" relative to the ground is irrelevant. The only thing having any relevance is the behavior of the air between exit altitude and opening altitude, inclusive.... 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
bmcd308 0 #246 February 23, 2004 OK. I'll give up trying to explain myself. ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites
