Icon134 0 #1 September 22, 2004 I seem to recall someone mentioning in a previous post that the canopy would deploy faster (i.e. less time to get under canopy from free fall...) in a sub-terminal opening versus a terminal opening. My question is this... Is the reason because the airspeed is lower thus reducing the force on the slider allowing it to move down the lines faster consenquently reducing deployment time? Or is it something else? I only ask because I have heard people say that when the deployed just coming out of a head down position (i.e. increased airspeed) they had an extremely fast opening... which would be counter to the above theory? Scott btw: I'm an engineer/scientist type... don't be afraid to get technical... ----------------------------------------------------------Livin' on the Edge... sleeping with my rigger's wife... Quote Share this post Link to post Share on other sites
krkeenan 0 #2 September 22, 2004 My experience and information indicates higher deployment speed = faster opening. Whoever said that sub-terminal deployments give faster openings was incorrect. Kevin K.====================== Seasons don't fear the Reaper, nor do the Wind, the Sun, or the Rain... Quote Share this post Link to post Share on other sites
mjosparky 4 #3 September 22, 2004 There are two measurements in a canopy deployment. Time and distance. In a sub-terminal opening the time is greater but the distance is less. At terminal the distance is greater and the time is less. The important thing is to be open before impact. SparkyMy idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
Shotgun 1 #4 September 22, 2004 Just from my personal experience (don't have any technical info for you)... I have found that the faster I am going at pull time, the quicker (and harder) my canopy opens... But there are other factors involved such as how the canopy was packed, what type/size of canopy it is, etc. Try pulling directly off someone's back in a rodeo - you'll see how fast your canopy opens from that speed - Ouch! (No, don't really try it - I am an idiot for doing that. It was painful, and if I was any heavier it might have blown up my main.) Quote Share this post Link to post Share on other sites
Icon134 0 #5 September 22, 2004 QuoteThere are two measurements in a canopy deployment. Time and distance. In a sub-terminal opening the time is greater but the distance is less. At terminal the distance is greater and the time is less. The important thing is to be open before impact. Sparky Assumptions: 1. packjob is same for all openings (yeah, I know... not really valid... but for S&G's) 2. Relative Vertical Velocity is the same after deployment in both conditions (i.e. Final Velocity same...) OK... Making sure my logic engine is working right... Subterminal: time greater & distance less Velocity at subterminal is lower so in time it takes for canopy to deploy (i.e. similar to applying brakes in car...) is greater becaue slower air causes slower opening but it takes less distance because the initial velocity is less and it will take less distance to reach final velocity. Terminal: Time less - Distance greater Canopy opens faster(i.e. less time) but due to higher initial velocity more distance will be traversed before reaching final velocity. Scott -----------------------------------------------------------Livin' on the Edge... sleeping with my rigger's wife... Quote Share this post Link to post Share on other sites
cvfd1399 0 #6 September 22, 2004 That is how I see it also. sub-terminal=your not hauling ass=less distance traveled. Quote Share this post Link to post Share on other sites DrewEckhardt 0 #7 September 22, 2004 QuoteI seem to recall someone mentioning in a previous post that the canopy would deploy faster (i.e. less time to get under canopy from free fall...) in a sub-terminal opening versus a terminal opening. A sub-terminal opening consumes less altitude but takes longer. Quote Share this post Link to post Share on other sites diablopilot 2 #8 September 22, 2004 QuoteQuoteThere are two measurements in a canopy deployment. Time and distance. In a sub-terminal opening the time is greater but the distance is less. At terminal the distance is greater and the time is less. The important thing is to be open before impact. Sparky Assumptions: 1. packjob is same for all openings (yeah, I know... not really valid... but for S&G's) 2. Relative Vertical Velocity is the same after deployment in both conditions (i.e. Final Velocity same...) OK... Making sure my logic engine is working right... Subterminal: time greater & distance less Velocity at subterminal is lower so in time it takes for canopy to deploy (i.e. similar to applying brakes in car...) is greater becaue slower air causes slower opening but it takes less distance because the initial velocity is less and it will take less distance to reach final velocity. Terminal: Time less - Distance greater Canopy opens faster(i.e. less time) but due to higher initial velocity more distance will be traversed before reaching final velocity. Scott ----------------------------------------------------------- Don't forget the vector. On a hop and pop* you're not headed directly at the planet on exit. At terminal you are. Sounds like the question being asked is how far do you drop (down) *edit: Out of an airplane, not a helo, balloon or other stationary platform.---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites Icon134 0 #9 September 22, 2004 Quote Sounds like the question being asked is how far do you drop (down) *edit: Out of an airplane, not a helo, balloon or other stationary platform. Yes, I am interested in the vertical component of the vector only in other words loss of altitude... I realize that exiting an aircraft there is a forward component (often refered to as throw... I think...) that will have an effect on the opening of the canopy... Assume a forward velocity of less then terminal. I believe that is typically the case. I do recall hearing a story about the first ever civilian C-130 jump where there was a misunderstanding of the "Go" command... and some people left the aircraft while it was still traveling too fast... subsiquently injuring themselves... Scott -------------------------------------------------------------Livin' on the Edge... sleeping with my rigger's wife... Quote Share this post Link to post Share on other sites dnewcomer 0 #10 September 23, 2004 Quote"I realize that exiting an aircraft there is a forward component (often refered to as throw... I think...) that will have an effect on the opening of the canopy..." When you exit a plane moving foward at 80 - 100 knots, your body continues to move forward at the same speed as the plane (due to inertia) for a very short time, but as soon as you exit, the wind resistance begins slowing your forward motion. If you shoot video, you can observe this effect first hand on film by watching the plane for 5 - 6 seconds after exit. That forward motion for practical purposes stops after a few seconds....maybe 8 - 10. During that time there is also a vertical component to your direction of movement that is the same as if you jumped from a stationary object. The vectors of these two movements combined determine your actual direction of travel through space. After exit, the vertical vector of travel gradually increases as the horizontal vector decreases. I don't like to call this "throw" because you don't get "thrown forward" by the plane any faster than it's forward speed. "Throw" implies something that isn't happening. You will actually begin to trail the plane as soon as you exit and hit the air stream. If you pull your PC about one second after exit, you'll have dropped very little in a vertical direction by the time your canopy comes out because the on-rushing wind from your body's forward motion alone (not fall rate) will be enough to activate deployment. If you jump from a hot air balloon, on the other hand, there is no significant forward motion (no horizontal vector to your direction of travel) -- even if you push off the side of the basket with your feet, for all practical purposes you go straight down. Your body will have to pick up enough speed before PC can release closing pin. This may take a few seconds....maybe 4 or 6 (depending on gear, size of PC, tension on closing loop, etc.). Base jumpers could fill us in better on this. If you're not stable, your bridle could wrap a leg or other body part before your canopy comes out. Quote"I do recall hearing a story about the first ever civilian C-130 jump where there was a misunderstanding of the "Go" command... and some people left the aircraft while it was still traveling too fast... subsiquently injuring themselves..." Not sure why that happened. I don't know how fast they think that plane was going, but you can safely exit a plane (without any injury) traveling much faster than a regular jump plane.....two or three times as fast. At the 2004 WFFC, a CASA flew a "high speed pass" by going into a dive right before exit and the pilot told us the exit speed was in excess of 250 knots. Don't know whether this is accurate.....just repeating what the pilot said. I've jumped high speed passes from other CASA's and C-130's traveling at 200+ knots and didn't find it to be that big a deal. I don't understand what happened on that C-130 jump you heard about. Maybe jumpers were attempting a formation exit and people were thrown into each other. It IS definitely possible to do a safe skydive from a plane traveling very fast. Jet pilots have ejected from planes traveling even faster yet in emergencies, but is that really a skydive? My experience jumping different size Triathlon's has been that the faster my freefall rate is, the faster the deployment sequence occurs. This makes intuitive sense because the only thing pulling your canopy out of the bag is the air stream. Faster air....faster deployment. I believe the manufacturer says my canopy is "made to withstand 130-135 mph airspeed at deployment time." There is probably a margin of error in that number so it might withstand somewhat faster speeds -- but not recommended. Since your canopy deploys faster at faster fall rates, the difference in distance traveled vertically is probably very little when comparing slower fall rates to faster fall rates. We're talking the difference between perhaps 105 mph and 130 mph (not 50 and 200). Blues, Dave WEB SITE: www.newconthenet.com Quote Share this post Link to post Share on other sites mjosparky 4 #11 September 23, 2004 Quote Jet pilots have ejected from planes traveling even faster yet in emergencies, but is that really a skydive? That is like comparing apples with dirt. The canopies used in ejection seats are round and built to withstand greater forces then even a sports reserve. Then they are reefed down so deployment is 250 KEAS or less even if the ejection was initiated at 600 KEAS plus. QuoteI believe the manufacturer says my canopy is "made to withstand 130-135 mph airspeed at deployment time." You main and reserve for sure is designed to withstand a deployment speed far greater the 130-135. There is a good chance they will take a faster deployment then you can without damage.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites billvon 3,123 #12 September 23, 2004 >but you can safely exit a plane (without any injury) traveling much faster >than a regular jump plane. True, but it often happens anyway. There were a lot of injuries on the first high speed jet pass (people weren't prepared) and there were a dozen or so injuries on the C-130's in Thailand even when people _were_ expecting it (and that was only 140kts or so.) It's hard on your body and your gear. Quote Share this post Link to post Share on other sites billvon 3,123 #13 September 23, 2004 >You main and reserve for sure is designed to withstand a >deployment speed far greater the 130-135. Well, it's designed to withstand an opening at the speed listed in the manual. It will probably survive a faster opening, but not for sure. It's like the difference between working and tensile strength of a climbing rope - a rope might have a tensile strength of 9000 pounds but a working load of only 2500 pounds. There is a difference because it's designed to hold 2500 pounds even when normal wear, normal environmental conditions etc are taken into account. Similarly, most reserves are tested far in excess of their rated loads/speeds, so that even an acceptably worn reserve, deployed in a poor position at a high speed, will meet the lesser loads. Quote Share this post Link to post Share on other sites mjosparky 4 #14 September 25, 2004 Quote>You main and reserve for sure is designed to withstand a >deployment speed far greater the 130-135. Well, it's designed to withstand an opening at the speed listed in the manual. It will probably survive a faster opening, but not for sure. It's like the difference between working and tensile strength of a climbing rope - a rope might have a tensile strength of 9000 pounds but a working load of only 2500 pounds. There is a difference because it's designed to hold 2500 pounds even when normal wear, normal environmental conditions etc are taken into account. Similarly, most reserves are tested far in excess of their rated loads/speeds, so that even an acceptably worn reserve, deployed in a poor position at a high speed, will meet the lesser loads. All reserves are designed and tests to 1.2 times the speed and weight listed in the manual. That weight can be no less then 265 lb. and 180 KEAS for single harness parachute assembles, 480 lb. and 210 KEAS for dual harness parachute assemblies. (tandem) But it can be more. And trust me, opening at 180 KEAS, 207 MPH, will hurt you at any weight. The only reefing on a sports square, reserve or main, is the slider and at that speed is is not that effective.My idea of a fair fight is clubbing baby seals 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
DrewEckhardt 0 #7 September 22, 2004 QuoteI seem to recall someone mentioning in a previous post that the canopy would deploy faster (i.e. less time to get under canopy from free fall...) in a sub-terminal opening versus a terminal opening. A sub-terminal opening consumes less altitude but takes longer. Quote Share this post Link to post Share on other sites
diablopilot 2 #8 September 22, 2004 QuoteQuoteThere are two measurements in a canopy deployment. Time and distance. In a sub-terminal opening the time is greater but the distance is less. At terminal the distance is greater and the time is less. The important thing is to be open before impact. Sparky Assumptions: 1. packjob is same for all openings (yeah, I know... not really valid... but for S&G's) 2. Relative Vertical Velocity is the same after deployment in both conditions (i.e. Final Velocity same...) OK... Making sure my logic engine is working right... Subterminal: time greater & distance less Velocity at subterminal is lower so in time it takes for canopy to deploy (i.e. similar to applying brakes in car...) is greater becaue slower air causes slower opening but it takes less distance because the initial velocity is less and it will take less distance to reach final velocity. Terminal: Time less - Distance greater Canopy opens faster(i.e. less time) but due to higher initial velocity more distance will be traversed before reaching final velocity. Scott ----------------------------------------------------------- Don't forget the vector. On a hop and pop* you're not headed directly at the planet on exit. At terminal you are. Sounds like the question being asked is how far do you drop (down) *edit: Out of an airplane, not a helo, balloon or other stationary platform.---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
Icon134 0 #9 September 22, 2004 Quote Sounds like the question being asked is how far do you drop (down) *edit: Out of an airplane, not a helo, balloon or other stationary platform. Yes, I am interested in the vertical component of the vector only in other words loss of altitude... I realize that exiting an aircraft there is a forward component (often refered to as throw... I think...) that will have an effect on the opening of the canopy... Assume a forward velocity of less then terminal. I believe that is typically the case. I do recall hearing a story about the first ever civilian C-130 jump where there was a misunderstanding of the "Go" command... and some people left the aircraft while it was still traveling too fast... subsiquently injuring themselves... Scott -------------------------------------------------------------Livin' on the Edge... sleeping with my rigger's wife... Quote Share this post Link to post Share on other sites
dnewcomer 0 #10 September 23, 2004 Quote"I realize that exiting an aircraft there is a forward component (often refered to as throw... I think...) that will have an effect on the opening of the canopy..." When you exit a plane moving foward at 80 - 100 knots, your body continues to move forward at the same speed as the plane (due to inertia) for a very short time, but as soon as you exit, the wind resistance begins slowing your forward motion. If you shoot video, you can observe this effect first hand on film by watching the plane for 5 - 6 seconds after exit. That forward motion for practical purposes stops after a few seconds....maybe 8 - 10. During that time there is also a vertical component to your direction of movement that is the same as if you jumped from a stationary object. The vectors of these two movements combined determine your actual direction of travel through space. After exit, the vertical vector of travel gradually increases as the horizontal vector decreases. I don't like to call this "throw" because you don't get "thrown forward" by the plane any faster than it's forward speed. "Throw" implies something that isn't happening. You will actually begin to trail the plane as soon as you exit and hit the air stream. If you pull your PC about one second after exit, you'll have dropped very little in a vertical direction by the time your canopy comes out because the on-rushing wind from your body's forward motion alone (not fall rate) will be enough to activate deployment. If you jump from a hot air balloon, on the other hand, there is no significant forward motion (no horizontal vector to your direction of travel) -- even if you push off the side of the basket with your feet, for all practical purposes you go straight down. Your body will have to pick up enough speed before PC can release closing pin. This may take a few seconds....maybe 4 or 6 (depending on gear, size of PC, tension on closing loop, etc.). Base jumpers could fill us in better on this. If you're not stable, your bridle could wrap a leg or other body part before your canopy comes out. Quote"I do recall hearing a story about the first ever civilian C-130 jump where there was a misunderstanding of the "Go" command... and some people left the aircraft while it was still traveling too fast... subsiquently injuring themselves..." Not sure why that happened. I don't know how fast they think that plane was going, but you can safely exit a plane (without any injury) traveling much faster than a regular jump plane.....two or three times as fast. At the 2004 WFFC, a CASA flew a "high speed pass" by going into a dive right before exit and the pilot told us the exit speed was in excess of 250 knots. Don't know whether this is accurate.....just repeating what the pilot said. I've jumped high speed passes from other CASA's and C-130's traveling at 200+ knots and didn't find it to be that big a deal. I don't understand what happened on that C-130 jump you heard about. Maybe jumpers were attempting a formation exit and people were thrown into each other. It IS definitely possible to do a safe skydive from a plane traveling very fast. Jet pilots have ejected from planes traveling even faster yet in emergencies, but is that really a skydive? My experience jumping different size Triathlon's has been that the faster my freefall rate is, the faster the deployment sequence occurs. This makes intuitive sense because the only thing pulling your canopy out of the bag is the air stream. Faster air....faster deployment. I believe the manufacturer says my canopy is "made to withstand 130-135 mph airspeed at deployment time." There is probably a margin of error in that number so it might withstand somewhat faster speeds -- but not recommended. Since your canopy deploys faster at faster fall rates, the difference in distance traveled vertically is probably very little when comparing slower fall rates to faster fall rates. We're talking the difference between perhaps 105 mph and 130 mph (not 50 and 200). Blues, Dave WEB SITE: www.newconthenet.com Quote Share this post Link to post Share on other sites
mjosparky 4 #11 September 23, 2004 Quote Jet pilots have ejected from planes traveling even faster yet in emergencies, but is that really a skydive? That is like comparing apples with dirt. The canopies used in ejection seats are round and built to withstand greater forces then even a sports reserve. Then they are reefed down so deployment is 250 KEAS or less even if the ejection was initiated at 600 KEAS plus. QuoteI believe the manufacturer says my canopy is "made to withstand 130-135 mph airspeed at deployment time." You main and reserve for sure is designed to withstand a deployment speed far greater the 130-135. There is a good chance they will take a faster deployment then you can without damage.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
billvon 3,123 #12 September 23, 2004 >but you can safely exit a plane (without any injury) traveling much faster >than a regular jump plane. True, but it often happens anyway. There were a lot of injuries on the first high speed jet pass (people weren't prepared) and there were a dozen or so injuries on the C-130's in Thailand even when people _were_ expecting it (and that was only 140kts or so.) It's hard on your body and your gear. Quote Share this post Link to post Share on other sites
billvon 3,123 #13 September 23, 2004 >You main and reserve for sure is designed to withstand a >deployment speed far greater the 130-135. Well, it's designed to withstand an opening at the speed listed in the manual. It will probably survive a faster opening, but not for sure. It's like the difference between working and tensile strength of a climbing rope - a rope might have a tensile strength of 9000 pounds but a working load of only 2500 pounds. There is a difference because it's designed to hold 2500 pounds even when normal wear, normal environmental conditions etc are taken into account. Similarly, most reserves are tested far in excess of their rated loads/speeds, so that even an acceptably worn reserve, deployed in a poor position at a high speed, will meet the lesser loads. Quote Share this post Link to post Share on other sites
mjosparky 4 #14 September 25, 2004 Quote>You main and reserve for sure is designed to withstand a >deployment speed far greater the 130-135. Well, it's designed to withstand an opening at the speed listed in the manual. It will probably survive a faster opening, but not for sure. It's like the difference between working and tensile strength of a climbing rope - a rope might have a tensile strength of 9000 pounds but a working load of only 2500 pounds. There is a difference because it's designed to hold 2500 pounds even when normal wear, normal environmental conditions etc are taken into account. Similarly, most reserves are tested far in excess of their rated loads/speeds, so that even an acceptably worn reserve, deployed in a poor position at a high speed, will meet the lesser loads. All reserves are designed and tests to 1.2 times the speed and weight listed in the manual. That weight can be no less then 265 lb. and 180 KEAS for single harness parachute assembles, 480 lb. and 210 KEAS for dual harness parachute assemblies. (tandem) But it can be more. And trust me, opening at 180 KEAS, 207 MPH, will hurt you at any weight. The only reefing on a sports square, reserve or main, is the slider and at that speed is is not that effective.My idea of a fair fight is clubbing baby seals Quote Share this post Link to post Share on other sites
