kallend 2,027 #1 January 17, 2004 Alex and Bill go for a balloon jump. They decide to do separate solo head down jumps. They are both good freeflyers and won't track or backslide inadvertantly. They have the same fallrate. The winds are OK on the ground, but at all altitudes above 4000ft are around 20kt. In fact, they are the same strength all the way up to 13,000ft where they will exit. They decide they need 400ft separation at opening for safety. The balloon takes them to 13k, and the pilot's GPS readout shows a groundspeed of 50 ft per second (just over 20kt). They calculate that a 8 second delay will give the required 400ft of separation (8 x 50 = 400). Alex jumps. Bill accurately counts off 8 seconds and jumps. After 10 seconds Alex's round reserve prematurely deploys. Bill is looking at the horizon in the opposite direction and doesn't see this. By what horizontal distance will Bill miss Alex?... 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
SkydiveMonkey 0 #2 January 17, 2004 300 foot edit = fuck. he's through the canopy edit again = actually he'd miss it (assuming the reserve has SOME forward movement)____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
freeflir29 0 #3 January 17, 2004 In the static environment I'd guess 300 Ft. You really can't figure it out perfectly because you didn't give the descent rate of the round reserve. Although....would a round canopy and a free falling skydiver have the same drift rate over a given distance? My guess would be yes but I'm mathmatically challenged. Quote Share this post Link to post Share on other sites
lawrocket 3 #4 January 17, 2004 Actually, I'm having a problem seeing any separation. Sure, they may be separated by ground distance, but it would seem that, in the air, he'd be directly below the whole time, since the balloon has no relative wind due to its assumedly zero airspeed. Thus, balloon hrizontal airspeed is zero. Alex's horizontal airspeed is zero. Bill's horizontal airspeed is zero. They all have the same groundspeed. I think they'll hit each other. Then again, I've never jumped a balloon, and I'm lousy at math. I just think that zeroes don't provide much separation. I could be wrong. My wife is hotter than your wife. Quote Share this post Link to post Share on other sites
freeflir29 0 #5 January 17, 2004 Oh yeah.....totally forgot about the balloon. Yep.....ZERO seems to be the correct answer. In a vacumn of course. The "normal" procedure I've always seen on balloon jumps is to wait until deployment before the next group exits. Quote Share this post Link to post Share on other sites
Hooknswoop 19 #6 January 17, 2004 QuoteBy what horizontal distance will Bill miss Alex? 0 ft if the round reserve has no airspeed. Derek Quote Share this post Link to post Share on other sites
AirCav 0 #7 January 17, 2004 What is the frictional coefficient for the balloon? ( it's ground speed is probably not 20MPH) What is the frictional coef. for the skydivers? ( that would determine how fast they would decelerate after leaving the balloon) And again, what is the frictional coef. for the round? (once open it 's ground speed would accelerate) Not enough information to answer the questionGW685,D3888,C5052,SCS843 Quote Share this post Link to post Share on other sites
kallend 2,027 #8 January 17, 2004 QuoteOh yeah.....totally forgot about the balloon. Yep.....ZERO seems to be the correct answer. In a vacumn of course. The "normal" procedure I've always seen on balloon jumps is to wait until deployment before the next group exits. Balloons don't fly too well in a vacuum, nor is there much wind.... 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 2,027 #9 January 17, 2004 QuoteWhat is the frictional coefficient for the balloon? ( it's ground speed is probably not 20MPH) What is the frictional coef. for the skydivers? ( that would determine how fast they would decelerate after leaving the balloon) And again, what is the frictional coef. for the round? (once open it 's ground speed would accelerate) Not enough information to answer the question Friction with what?... 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
AirCav 0 #10 January 17, 2004 The air. Any object moving through a fluid is going to have a resistance to motion. IE drag. (Proportional to velocity squared)GW685,D3888,C5052,SCS843 Quote Share this post Link to post Share on other sites
iowa 0 #11 January 17, 2004 Alex, Bill and the balloon are all still in the same column of air. Bill hits Alexes round and Bill. They both die. Keith ''Always do sober what you said you would do drunk. That will teach you to keep your mouth shut.'' - Ernest Hemingway Quote Share this post Link to post Share on other sites
jkm2500 0 #12 January 17, 2004 400 ft edit: Wait I have thought about this and I have to change my answer to like 3 feet. If the reserve canopy descends at all it will be a very close call.The primary purpose of the Armed Forces is to prepare for and to prevail in combat should the need arise. Quote Share this post Link to post Share on other sites
lawrocket 3 #13 January 17, 2004 Quote( it's ground speed is probably not 20MPH) Actually, the facts stated that the GPS indicated a ground speed of just over 20 kts. Therefore, I would say that, under the hypothetical, it is. My wife is hotter than your wife. Quote Share this post Link to post Share on other sites
riddler 0 #14 January 17, 2004 Woohoo! 13K balloon jumps. I'm in!Trapped on the surface of a sphere. XKCD Quote Share this post Link to post Share on other sites
kallend 2,027 #15 January 17, 2004 QuoteThe air. Any object moving through a fluid is going to have a resistance to motion. IE drag. (Proportional to velocity squared) Is the balloon moving through the air? If so, what is its source of thrust?... 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
Dagny 0 #16 January 18, 2004 QuoteThe balloon takes them to 13k Balloon rides to 13K!!! Oooh, I want that...wait, was there a question somewhere? I'm sorry, I read balloon to full altitude and all forward thought just stopped! Take me, I am the drug; take me, I am hallucinogenic. -Salvador Dali Quote Share this post Link to post Share on other sites
kallend 2,027 #17 January 18, 2004 QuoteQuoteThe balloon takes them to 13k Balloon rides to 13K!!! Oooh, I want that...wait, was there a question somewhere? I'm sorry, I read balloon to full altitude and all forward thought just stopped! Highest ever jump was from a balloon - what's the big deal?... 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
benny 0 #18 January 18, 2004 QuoteQuoteQuoteThe balloon takes them to 13k Balloon rides to 13K!!! Oooh, I want that...wait, was there a question somewhere? I'm sorry, I read balloon to full altitude and all forward thought just stopped! Highest ever jump was from a balloon - what's the big deal? What was the altitude? Never go to a DZ strip show. Quote Share this post Link to post Share on other sites
SkydiveMonkey 0 #19 January 18, 2004 Joe Kittinger____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
DeNReN 0 #20 January 18, 2004 Hmmmm...assuming the round canopy will travel at 50 ft per sec. that will only give Bill 2 sec of seperation...100ft. Does the 1st correct answer win anything? Quote Share this post Link to post Share on other sites
kallend 2,027 #21 January 18, 2004 QuoteHmmmm...assuming the round canopy will travel at 50 ft per sec. that will only give Bill 2 sec of seperation...100ft. Does the 1st correct answer win anything? Bragging rights, but someone else has them already.... 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
mjosparky 4 #22 January 18, 2004 102,800 ft. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
DeNReN 0 #23 January 18, 2004 When can we expect you to announce who is correct? And the explanation? (plz spel it out) I'll assume again....0 ft? Edited to add.....bragging rights are cool...but a beer would be better Quote Share this post Link to post Share on other sites
b1jercat 0 #24 January 18, 2004 I would go with 0 also. blues jerry Quote Share this post Link to post Share on other sites
kallend 2,027 #25 January 18, 2004 OK - the answer. Alex and Bill unfortunately end up on the fatality database. Separation is NOT groundspeed x time, except on the ground.... 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
