lilryno 0 #1 March 15, 2004 I'm wondering about malfunctions and fall rates. Wondering if some of you smarter more experienced jumpers could check my assumptions regarding fall rates with malfunctions. I'm going to use these calculations in a malfunction simulator/drill on the ground. (I'm assuming a canopy with a 1:1 wing loading). These numbers are complete wags and NOT to be considered good. I do not know what I'm talking about which is why I'm asking for help! Assumption 1: Typical freefall results in loss of 1000' per 5 seconds. Assumption 2: Typical canopy performance results in 1000' per minute loss of altitude with a good canopy and no demand put on it. Assumption 3: A total malfunction results in 1000' per 5 seconds altitude loss. ASSUMPTION 4: A ball of crap, streamer, results in a fall rate of 1000' per 5 seconds (increase in drag from nylon offset by sitting jumper up in harness). ASSUMPTION 5: Bad Lineover malfunction results in 50'/sec loss of altitude (3000' per minute) with slider not down. ASSUMPTION 6: Linetwists result in 1200'/minute loss of altitude. ASSUMPTION 7: Any strong spinning malfunction results in 2000' per minute loss of altitude. Thanks very much for any pointers or corrections! "The value of man lies not in the knowledge he possesses, or means to possess, but in the sincere pain which he hath taken to find it out." - G.E. Lessings Quote Share this post Link to post Share on other sites
feuergnom 22 #2 March 15, 2004 1: why would/should you loose more altitude with line-twists than on a normal canopy without linetwists (if the canopy is flying straight, not turning)? 2: i guess you loose much more alti on a strong spinning mal than 2000 feet/min! i'm curious how you came up with these numbersThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites
riggerrob 558 #3 March 15, 2004 lilryno's guesses are close. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Quote1: why would/should you loose more altitude with line-twists than on a normal canopy without linetwists (if the canopy is flying straight, not turning)? >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because a canopy with a bad case of line twists will only allow the slider to come halfway down, the end cells will be closed, there will be major anhedral and you will be hanging under much less than a full canopy. In short less canopy equals faster rate of descent. Quote Share this post Link to post Share on other sites lilryno 0 #4 March 15, 2004 Thanks for your inputs. I read somewhere (very not scientific process on my part) that if you spiral down under canopy you typically lose 2000' minute. That does seem kinda low to me too. So I figured a spinning malfunction would have a similar descent rate.... "The value of man lies not in the knowledge he possesses, or means to possess, but in the sincere pain which he hath taken to find it out." - G.E. Lessings Quote Share this post Link to post Share on other sites pccoder 0 #5 March 15, 2004 yea, that spinning number has got to be wrong PcCoder.net Quote Share this post Link to post Share on other sites FrogNog 1 #6 March 15, 2004 Quotelilryno's guesses are close. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Quote1: why would/should you loose more altitude with line-twists than on a normal canopy without linetwists (if the canopy is flying straight, not turning)? >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because a canopy with a bad case of line twists will only allow the slider to come halfway down, the end cells will be closed, there will be major anhedral and you will be hanging under much less than a full canopy. In short less canopy equals faster rate of descent. Line twists come in different forms. The slider could be stuck up, come down, or in between. The increased anhedral issue could be large or small. The higher the aspect ratio of the canopy, the larger I would expect it to be. Also the higher the top of the twists, the larger I would expect the effect to be. Another thing to think about is a line-twisted canopy, if it twisted at opening, should still have its brakes set. Most canopies sink less in the mid brake range, as I understand it, so this is a factor in the direction of a slower fall. Edited to add blue text to unambiguate. -=-=-=-=- Pull. Quote Share this post Link to post Share on other sites psw097 0 #7 March 15, 2004 My Protrack recorded my last spinning line twist chop. The lowest point it got to was a little under 60 MPH - around 5000 feet/min - before the reserve activation shut off the recording. The wingloading was high, 2.2/1, though. Quote Share this post Link to post Share on other sites bch7773 0 #8 March 15, 2004 Quote ASSUMPTION 4: A ball of crap, streamer, results in a fall rate of 1000' per 5 seconds (increase in drag from nylon offset by sitting jumper up in harness). I think you fall slower than normal freefall speeds with a ball of crap... reason i say this is because some people who have bounced with a wad of crap or with a major main/reserve entanglement have survived with some relatively minor injuries... they couldn't have done that with nothing out. MB 3528, RB 1182 Quote Share this post Link to post Share on other sites lilryno 0 #9 March 15, 2004 This is great discussion. Thanks for all these inputs. "The value of man lies not in the knowledge he possesses, or means to possess, but in the sincere pain which he hath taken to find it out." - G.E. Lessings Quote Share this post Link to post Share on other sites Liemberg 0 #10 March 15, 2004 QuoteI think you fall slower than normal freefall speeds with a ball of crap... There you might be wrong. I remember seeing a video of a tandem malfunction where the tandempair + the 'ball of crap' started to move to the bottom of the screen. That might be since the camera moves up to film the opening but also keep in mind that the ball of crap puts you in an upright position, reducing drag on your body. On the video I saw, the cameraflyer in freefall had no trouble at all keeping up with the mall. "Whoever in discussion adduces authority uses not intellect but memory." - Leonardo da Vinci A thousand words... Quote Share this post Link to post Share on other sites feuergnom 22 #11 March 15, 2004 thanks for your input - i didn't think about severly and asymmetricaly twisted lines that make you spiral (my fault). maybe because all the line-twists i had so far were docile (lucky me!) and my canopy was still flying straight aheadThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites feuergnom 22 #12 March 15, 2004 i didn't think of a wingload that high. i just figured if i loose a lot of alti when intentionally spiraling down - how much more alti i might loose when i got a spinning mal. so your figures are more or less what i expectedThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites Join the conversation You can post now and register later. 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lilryno 0 #4 March 15, 2004 Thanks for your inputs. I read somewhere (very not scientific process on my part) that if you spiral down under canopy you typically lose 2000' minute. That does seem kinda low to me too. So I figured a spinning malfunction would have a similar descent rate.... "The value of man lies not in the knowledge he possesses, or means to possess, but in the sincere pain which he hath taken to find it out." - G.E. Lessings Quote Share this post Link to post Share on other sites
pccoder 0 #5 March 15, 2004 yea, that spinning number has got to be wrong PcCoder.net Quote Share this post Link to post Share on other sites
FrogNog 1 #6 March 15, 2004 Quotelilryno's guesses are close. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Quote1: why would/should you loose more altitude with line-twists than on a normal canopy without linetwists (if the canopy is flying straight, not turning)? >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Because a canopy with a bad case of line twists will only allow the slider to come halfway down, the end cells will be closed, there will be major anhedral and you will be hanging under much less than a full canopy. In short less canopy equals faster rate of descent. Line twists come in different forms. The slider could be stuck up, come down, or in between. The increased anhedral issue could be large or small. The higher the aspect ratio of the canopy, the larger I would expect it to be. Also the higher the top of the twists, the larger I would expect the effect to be. Another thing to think about is a line-twisted canopy, if it twisted at opening, should still have its brakes set. Most canopies sink less in the mid brake range, as I understand it, so this is a factor in the direction of a slower fall. Edited to add blue text to unambiguate. -=-=-=-=- Pull. Quote Share this post Link to post Share on other sites psw097 0 #7 March 15, 2004 My Protrack recorded my last spinning line twist chop. The lowest point it got to was a little under 60 MPH - around 5000 feet/min - before the reserve activation shut off the recording. The wingloading was high, 2.2/1, though. Quote Share this post Link to post Share on other sites bch7773 0 #8 March 15, 2004 Quote ASSUMPTION 4: A ball of crap, streamer, results in a fall rate of 1000' per 5 seconds (increase in drag from nylon offset by sitting jumper up in harness). I think you fall slower than normal freefall speeds with a ball of crap... reason i say this is because some people who have bounced with a wad of crap or with a major main/reserve entanglement have survived with some relatively minor injuries... they couldn't have done that with nothing out. MB 3528, RB 1182 Quote Share this post Link to post Share on other sites lilryno 0 #9 March 15, 2004 This is great discussion. Thanks for all these inputs. "The value of man lies not in the knowledge he possesses, or means to possess, but in the sincere pain which he hath taken to find it out." - G.E. Lessings Quote Share this post Link to post Share on other sites Liemberg 0 #10 March 15, 2004 QuoteI think you fall slower than normal freefall speeds with a ball of crap... There you might be wrong. I remember seeing a video of a tandem malfunction where the tandempair + the 'ball of crap' started to move to the bottom of the screen. That might be since the camera moves up to film the opening but also keep in mind that the ball of crap puts you in an upright position, reducing drag on your body. On the video I saw, the cameraflyer in freefall had no trouble at all keeping up with the mall. "Whoever in discussion adduces authority uses not intellect but memory." - Leonardo da Vinci A thousand words... Quote Share this post Link to post Share on other sites feuergnom 22 #11 March 15, 2004 thanks for your input - i didn't think about severly and asymmetricaly twisted lines that make you spiral (my fault). maybe because all the line-twists i had so far were docile (lucky me!) and my canopy was still flying straight aheadThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites feuergnom 22 #12 March 15, 2004 i didn't think of a wingload that high. i just figured if i loose a lot of alti when intentionally spiraling down - how much more alti i might loose when i got a spinning mal. so your figures are more or less what i expectedThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites 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
psw097 0 #7 March 15, 2004 My Protrack recorded my last spinning line twist chop. The lowest point it got to was a little under 60 MPH - around 5000 feet/min - before the reserve activation shut off the recording. The wingloading was high, 2.2/1, though. Quote Share this post Link to post Share on other sites
bch7773 0 #8 March 15, 2004 Quote ASSUMPTION 4: A ball of crap, streamer, results in a fall rate of 1000' per 5 seconds (increase in drag from nylon offset by sitting jumper up in harness). I think you fall slower than normal freefall speeds with a ball of crap... reason i say this is because some people who have bounced with a wad of crap or with a major main/reserve entanglement have survived with some relatively minor injuries... they couldn't have done that with nothing out. MB 3528, RB 1182 Quote Share this post Link to post Share on other sites
lilryno 0 #9 March 15, 2004 This is great discussion. Thanks for all these inputs. "The value of man lies not in the knowledge he possesses, or means to possess, but in the sincere pain which he hath taken to find it out." - G.E. Lessings Quote Share this post Link to post Share on other sites
Liemberg 0 #10 March 15, 2004 QuoteI think you fall slower than normal freefall speeds with a ball of crap... There you might be wrong. I remember seeing a video of a tandem malfunction where the tandempair + the 'ball of crap' started to move to the bottom of the screen. That might be since the camera moves up to film the opening but also keep in mind that the ball of crap puts you in an upright position, reducing drag on your body. On the video I saw, the cameraflyer in freefall had no trouble at all keeping up with the mall. "Whoever in discussion adduces authority uses not intellect but memory." - Leonardo da Vinci A thousand words... Quote Share this post Link to post Share on other sites
feuergnom 22 #11 March 15, 2004 thanks for your input - i didn't think about severly and asymmetricaly twisted lines that make you spiral (my fault). maybe because all the line-twists i had so far were docile (lucky me!) and my canopy was still flying straight aheadThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites
feuergnom 22 #12 March 15, 2004 i didn't think of a wingload that high. i just figured if i loose a lot of alti when intentionally spiraling down - how much more alti i might loose when i got a spinning mal. so your figures are more or less what i expectedThe universal aptitude for ineptitude makes any human accomplishment an incredible miracle dudeist skydiver # 666 Quote Share this post Link to post Share on other sites
