The111 1 #1 December 3, 2003 I am a pretty inexperienced jumper, but I am very familiar with physics and aerodynamics; I've read Bryan Burke's essay and seen Kallend's trajectory model and I agree entirely that horizontal separation is much more important than vertical separation. Yet I have been to two DZ's in FL recently (well-known, respected ones) who have mandated that FFer's go first. As a solo FFer, I'm often forced to go right before a big RW group (in windy conditions), knowing they'll give me 6-7 seconds MAX (no matter what I ask for, try debating physics on jumprun) and I'll almost certainly drift into their airspace... this usually results in me tracking away from jumprun like mad for the last 2k feet of freefall and opening lower than I'd like to. I'm curious about two things. 1) Why do they do this? Are there any benefits? I'm aware of all the benefits of RW before FF, but I'm not aware of any for the opposite, save vertical separation, which again is not too important and very hard to control. 2) What should I do? I'm a person who likes to try to correct inefficiencies I observe, but as a 100 jump wonder it's pretty pointless to try to ask a DZ to change their policies for me on my first day there. I guess the obvious answer to the question is don't jump there if I don't like it. But these are good DZ's! At one of them, I asked the manifest lady "why?" after she explained the mandatory exit order to me. She said she didn't really know, but they had tried several different orders and this was the one they decided was best. Another jumper standing in the office looked at me and said "FFers fall faster!" I really didn't want to get into a debate so I let it stand, but part of me still feels the desire to get this trend to change.www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
Hazarrd 1 #2 December 3, 2003 Im sure the dropzone wouldn't be offended if you just asked someone there. The best person to ask would be the S&TA. Im sure he can offer you a good explanation. .-. Quote Share this post Link to post Share on other sites
billvon 2,466 #3 December 3, 2003 >Why do they do this? I've heard several reasons. 1) Some people believe in the 45 degree rule and believe that a simple scheme like that is much better than a complicated scheme that involves winds and freefall speeds. 2) You mentioned it yourself - vertical separation. Some believe that freeflyers get so much vertical separation that they're practically landing before the RWers open. 3) In hot climates, freeflyers like to be near the door. Often this can be accomplished by believing in a FF-first exit order scheme. >What should I do? Give a LOT of time between the last freefly and the first RW group - on the order of 25-30 seconds, depending on winds. If anyone complains, you can point out that not only does it help with horizontal separation, it helps with vertical as well. Quote Share this post Link to post Share on other sites
freakydiver 0 #4 December 3, 2003 Make a report showing your beliefs and prove them. Use Kallend's piece of software and Burke's essay as proof - treat this as any other research expedition. The way our sport is progressing, the problems are only going to get worse before people start realizing the importance of seperation and exit order. -- (N.DG) "If all else fails – at least try and look under control." -- Quote Share this post Link to post Share on other sites
SkymonkeyONE 3 #5 December 3, 2003 Making a model and showing it to someone is not going to change the mind of a head-strong DZO. Raeford put's freeflyers out first unless there is a bigway on board. While I didn't like it for a number of reasons, it does, in my opinion, make for less traffic in the landing pattern. Having the faster-falling freeflyers open and well below me when I was doing RW or working with students made for much less congestion. Chuck Quote Share this post Link to post Share on other sites
Ron 7 #6 December 3, 2003 QuoteI am a pretty inexperienced jumper, but I am very familiar with physics and aerodynamics; I've read Bryan Burke's essay and seen Kallend's trajectory model and I agree entirely that horizontal separation is much more important than vertical separation. Vertical kills....Horizontal only if you really try...This used to be an "A" license question. "What is most dangerous Vertical seperation or Horizontal?" Now the simple fact is if you look at a post Here I asked the same question....I got attacked by several folks for it also. I have seen a 4way drift right over a FF jump..And the S&TA was watching it with me...He said "Well, I guess we should do croswind jump runs today." I agree that Flat should be first...It is safer. However, FF can be first it just risks extra passes...And as I was told more than once..."It's not your fuel." Yes sometimes the pilots bitch, but Im not going to do something unsafe to make them happy. Then there is the simple question of where do you put a new FF? A FF can move across the sky much faster than a backsliding Flat guy....And I doubt that the newbie FF can tell what he is doing, or what way the jumprun is. And what do you do with FF who open high? As a rule Flat first makes sense....But since I don't own the world I just have to make the current rules work....And that means taking extra passes if I feel the need. Oh well...."No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334 Quote Share this post Link to post Share on other sites
freakydiver 0 #7 December 3, 2003 While I fully understand where you are coming from - and agree with you that there are head strong DZOs out there - this type of attitude will be the demise of our sport. -- (N.DG) "If all else fails – at least try and look under control." -- Quote Share this post Link to post Share on other sites
The111 1 #8 December 3, 2003 QuoteVertical kills....Horizontal only if you really try...This used to be an "A" license question. "What is most dangerous Vertical seperation or Horizontal?" Separation is not dangerous. I'm a little confused. Are you saying vertical separation is more important? I guess in theory it works just as well as horizontal, but in practice since it's much more difficult to achieve repeatably, I'd say horizontal is more important to obtain. This may be what you're trying to say, but like I said I wasn't sure exactly. QuoteAs a rule Flat first makes sense....But since I don't own the world I just have to make the current rules work....And that means taking extra passes if I feel the need. I agree, but like I said if I am the last FFer, I can't control what the RW group after me does. I'm going to assume they probably won't give me enough time. As far as FFer's opening high, it shouldn't matter if horizontal separation is adequate.www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
Ron 7 #9 December 3, 2003 QuoteSeparation is not dangerous. I'm a little confused. Are you saying vertical separation is more important? I guess in theory it works just as well as horizontal, but in practice since it's much more difficult to achieve repeatably, I'd say horizontal is more important to obtain. This may be what you're trying to say, but like I said I wasn't sure exactly. Maybe I didn't say that right.... The question read "Which is MORE dangerous, Vertical or Horizontal?" Read: If you are going to collide, which will cause more damage? A vertical collision (Like from one guy comming down through your group...) Or Horizontal (Like a guy docking hard, but on level)? The answer is that a Vertical collision is much more dangerous....It is very easy to understand how a guy corking can kill you. I have heard of very few accidents where two people have collided that had a high Horizontal speed that produced injuries. GK diamond track being the only one I can think off. QuoteI agree, but like I said if I am the last FFer, I can't control what the RW group after me does. I'm going to assume they probably won't give me enough time. As far as FFer's opening high, it shouldn't matter if horizontal separation is adequate. Well you can't control the next group...which is why the safest plan should be the one you use....The one that INCREASES seperation. But the high opening FF does matter...If he is opening high he is not if freefall as long . And that reduces his horizontal seperation (Now if he is after the flat group this just ADDS seperation.) And he is open earlier than normal. So if the FF guy is opening high then you would need to add even more exit time to be safe. And if the guy is not good and flies all over the place. (Like I do when I do FF)...Then he should not be before the flat group."No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334 Quote Share this post Link to post Share on other sites
bmcd308 0 #10 December 3, 2003 It think what Ron was saying is that RELYING on vertical separation is more dangerous than relying on horizontal separation. If you open 300 feet away from me to my left, we have lots of time not to collide. If you open 300 feet away from me directly over my head and cut away, things could get exciting. If you plan to open 300 feet above me and snivel longer than you thought you would, things could get interesting. If you plan to open 300 feet above me and I have a premature, things could get interesting. All of these concerns go away if you are off to the side. Brent ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites
The111 1 #11 December 3, 2003 QuoteIt think what Ron was saying is that RELYING on vertical separation is more dangerous than relying on horizontal separation. If you open 300 feet away from me to my left, we have lots of time not to collide. If you open 300 feet away from me directly over my head and cut away, things could get exciting. If you plan to open 300 feet above me and snivel longer than you thought you would, things could get interesting. If you plan to open 300 feet above me and I have a premature, things could get interesting. All of these concerns go away if you are off to the side. Brent Yeh, I agree... vertical collisions are the worst nightmare, but horizontal separation is what prevents them! If you're in your own column of air you can't be hit from above or below.www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
The111 1 #12 December 3, 2003 QuoteBut the high opening FF does matter...If he is opening high he is not if freefall as long . And that reduces his horizontal seperation (Now if he is after the flat group this just ADDS seperation.) And he is open earlier than normal. So if the FF guy is opening high then you would need to add even more exit time to be safe. True, but assuming he's smart enough to turn crosswind upon opening (which can be a considerable assumption, depending who we're talking about), his horizontal separation from the other groups *at his deployment altitude* will be the same as if he had stayed in freefall through that altitude. And horizontal separation below his deployment altitude is not critical since there will be great vertical separation created by those freefalling past him. Again, this is assuming he turns crosswind on deployment. Basically by stopping his freefall earlier than the other guys he has "ceased to exist"... it's like looking at Kallend's trajectory and assuming the curve ended halfway through. Sure his overall horizontal distance covered in freefall will be different, but his horizontal separation from the other groups at his deployment altitude will be the same.www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
tombuch 0 #13 December 3, 2003 Quote I'm curious about two things. 1) Why do they do this? Are there any benefits? I'm aware of all the benefits of RW before FF, but I'm not aware of any for the opposite, save vertical separation, which again is not too important and very hard to control. 2) What should I do? I think they do it because of politics. My hunch is that most of the assertive jumpers at those DZ's are freeflyers, and they just want to be near the door where it is cooler and there is more space. Your best bet is to tell them you plan to open high and would rather be out after the lower opening flatflyers. Hopefully they will understand that, but of course you are then obligated to actually open where you say you will. At my home DZ we want our flat flyers out first but allow freeflyers to get out first as long as they negotiate the issue with the flatflyers and everybody is OK with it. I generally open at 2,000 feet, so no matter what I'm doing I want to be out first (unless I'm playing with a higher opening partner), and most people at the DZ know I have the experience to stay out of their airspace, so it usually isn't a problem. So, talk it up with the others as best you can. Tom Buchanan S&TA Instructor (AFF, SL, IAD, Tandem) Author JUMP! Skydiving Made Fun and EasyTom Buchanan Instructor Emeritus Comm Pilot MSEL,G Author: JUMP! Skydiving Made Fun and Easy Quote Share this post Link to post Share on other sites
DBCOOPER 1 #14 December 3, 2003 Tell them your a belly solo.A real unstable belly solo.Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon If the plane is unrecoverable then exiting is a very very good idea. Quote Share this post Link to post Share on other sites
bmcd308 0 #15 December 3, 2003 >>If you're in your own column of air you can't be hit from above or below. << Even the freeflyers will have to admit that all the top FF teams track away from the center of the formation at breakoff. Why? Horizontal separation. If vertical separation was really so great, they would have one guy fall fast, one guy fall medium, and one guy fall slow from breakoff to pull time, then rely on the vertical separation to keep them from colliding. You don't hear very often about teams doing that, though. ---------------------------------- www.jumpelvis.com Quote Share this post Link to post Share on other sites
DanG 1 #16 December 3, 2003 Is it possible that these DZ's are using a crosswind or downwind jumprun? That might explain it, too. - Dan G - Dan G Quote Share this post Link to post Share on other sites
The111 1 #17 December 3, 2003 QuoteIs it possible that these DZ's are using a crosswind or downwind jumprun? That might explain it, too. - Dan G You know, I think one of them actually was crosswind. Not sure about the other. Good point. I overlooked the basics. www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
bch7773 0 #18 December 4, 2003 QuoteTell them your a belly solo.A real unstable belly solo. MB 3528, RB 1182 Quote Share this post Link to post Share on other sites
kallend 1,672 #19 December 4, 2003 Quote As a solo FFer, I'm often forced to go right before a big RW group (in windy conditions), knowing they'll give me 6-7 seconds MAX (no matter what I ask for, try debating physics on jumprun) and I'll almost certainly drift into their airspace.... If it's a big RW group like a 12 way or 16 way they'll probably take 10 - 15 seconds on the climb-out alone. Add that to the 6 - 7 seconds delay and you've got 20 or so seconds before they actually leave the plane. This will be plenty enough in light winds but marginal if the uppers are strong. I'd be more concerned about a 3-way RW right behind you. At one FL DZ I know where they put FF out first, the S&TA runs the FF school and likes to sit by the door. That may have something to do with the exit order.... 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
turnlow 0 #20 December 4, 2003 I saw this at a large FL DZ and did ask the S&TA about it. This may not be the same DZ, but what he told me was, "We used to put RW out first, but we found that it lead to more problems with canopy traffic on landing. The RW folks generally fly larger, slower canopies then the FF jumpers. As a result, even thought the FF's open later, they get down about the same time." While I still do not agree with it, all of the canopy collisions of late give me pause. _________________________________________________ ________________________________________________It matters not how strait the gate, How charged with punishments the scroll, I am the master of my fate: I am the captain of my soul. Quote Share this post Link to post Share on other sites
Ron 7 #21 December 4, 2003 QuoteTrue, but assuming he's smart enough to turn crosswind upon opening (which can be a considerable assumption, depending who we're talking about), his horizontal separation from the other groups *at his deployment altitude* will be the same as if he had stayed in freefall through that altitude. You can't rely on that. Most folks I know turn right to the DZ and head there. Assuming that the FF would do that its is a really bad way to be safe."No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334 Quote Share this post Link to post Share on other sites
Ron 7 #22 December 4, 2003 QuoteI saw this at a large FL DZ and did ask the S&TA about it. This may not be the same DZ, but what he told me was, "We used to put RW out first, but we found that it lead to more problems with canopy traffic on landing. The RW folks generally fly larger, slower canopies then the FF jumpers. As a result, even thought the FF's open later, they get down about the same time." My group has a V90, a ST107 a V79, and and Veng 107. These are much smaller than most FF peoples canopies. The only time that they are right is when there is a Muff load. And you can land a 100 way there safe, and we land formation loads safe there all the time.....So the FF have smaller canopies argument is not a very good one."No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334 Quote Share this post Link to post Share on other sites
Aviatrr 0 #23 December 5, 2003 QuoteQuoteIs it possible that these DZ's are using a crosswind or downwind jumprun? That might explain it, too. - Dan G You know, I think one of them actually was crosswind. Not sure about the other. Good point. I overlooked the basics. One of the DZ's in question(the one we were at over the weekend) runs jumprun one of two directions - right along the main runway. They do not fly into the wind - just whichever direction is closer to into the wind than the other. Jumprun is always either due North or due South - therefore, jumprun is almost always crosswind based on the typical prevailing winds aloft in that part of FL. Mike Quote Share this post Link to post Share on other sites
The111 1 #24 December 8, 2003 Yeh, it seemed pretty crosswind to me when I thought about it in retrospect. At the time I was not paying that much attention to it, something which I've recently changed... now I *always* know which way the wind is going relative to jumprun and I *always* do a good job of spotting... ask me about my off landing this Friday and you'll know why. www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
kelel01 1 #25 December 8, 2003 Ok, so question: This past weekend, we had a 2-way belly go out in front of our 4-way, because we were going to pull at 3500, and they were pulling at 3000. How significant is the drift difference acheived by a 2-way and a 4-way? Should we have done this? Also, I was told that if you are in a 4-way, 3-way, whatever, the "turn 180 degrees and track your ass off" rule applies moreso than the "don't track up the line of flight" rule. Is that correct? I had a couple of problems with me and another jumper trying to track in roughly the same direction, and I'm not sure what to believe. Kelly Quote Share this post Link to post Share on other sites
