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If you finish a block without control and continue to the next point you will get an OC and zero point for that block. You got to show control to the judges even though technically there is a freeze frame where everything looks neat.

I guess that the problem here is that the rest of the load will have trouble seeing which one of you that is going to land first (since they are just watching your landing pattern and tries to follow it) And by the time the first jumper hits the grounds, a few other have probably started their pattern. So even if you land upwind to show them which way to go, they will have to abort their pattern and find a new approach. Which unfortunately isn't the most obvious thing to do for people with moderate experience. So, whenever I see 2 people setting up for landing in different directions, I get the hell out of the regular landing area and land somewhere else since I know that a few moments later it will be filled with jumpers landing in every direction. And everyone is going to be wondering who picked the right direction. rgds, Stefan

Obviously the best desicion. But for the other 9 jumpers that are trying to hug each other during landing I'd like to have them going in the same direction

Hi! A couple of days ago at a local dropzone we had some pretty light winds that were channing direction all the time (not very common here in sweden) And one of the loads ended up landing in all kinds of directions. All of a sudden I find myself discussing this with the jumpleader (I wasn't on the load). He was saying that out of 10 people only 3 people were landing in the correct direction. (Into the very light wind that was observed, no T was put out) So I asked him how the first jumper was landing. Downwind he said. Then, I asked him why he thought those 3 jumpers were landing in the correct direction when they obviously didn't land according the first jumpers (There were at least 2 jumpers landing together, downwind) What's your opinion on this subject? I was trying to tell him that I'd rather see the full load land in 3m/s downwind that see 2 canopies collide 5 meters above ground but he wasn't listening. Comments, suggestions anyone? regards, Stefan

Hello! Oops I forgot to tell. We are a 4 way team. And yes, I am from Skane. I jump both at Syd and Skydive Skane. regards, Stefan

Hello! Where is the best place to look for a camera flyer? (Here perhaps? :) We are a team that is going to be jumping at Skydive Space Center,FL 27/2-14/3 this spring and plan to do about 75 jumps. Anyone who is interested or knows someone that might be interested? Please email me at sb@anoto.com Blue skies from Sweden! Stefan Burstrom

Hello! Where is the best place to look for a camera flyer? (Here perhaps? :) We are a team that is going to be jumping at Skydive Space Center,FL 27/2-14/3 this spring and plan to do about 75 jumps. Anyone who is interested or knows someone that might be interested? Please email me at sb@anoto.com Blue skies from Sweden! Stefan Burstrom

Ah, now we are getting somewhere ;) I wasn't assuming that this is the case everytime, everywhere. I was merely assuming that this was the case when you will experience the effect that I was talking about. By definition turbulence is curl in the windmass. Curl is created when the sheer gets larger than a certain point. Which means that sheer can occur without curl up to a certain point. Just look at a floating river. When the river is wide, you will see the sheer very easy by looking at the water with different speed in the middle and close to the edges. When the same river gets narrow (and transporting the same water but with a different speed) you will clearly see when the sheer forces gets too large and curl is created. You should have joined us today then ;) Most of us got quite a few bumpy rides just becase of the wind. But of course this was caused by the fact that it wasn't a stable air mass, due to both the nature of the wind and obstacles on the way. (Quite far away, but still enough to create turbulence.) However, I have to disagree that the air mass is always stable. If you study fluid dynamics of a pipe, you'll be able to see that the speed of the fluid is different in the middle of the pipe compared to the speed at the edges. Air flowing past a surface (ie the ground) is subject to the same phenomena. One important factor here is the friction between the air and the ground so I guess that in some places, you hardly notice any sheer (or turbulence which happens when the sheer gets too large). In other places this effect will be very obvious and then you need to take care. The bottom point I was trying to make is that if you don't believe what I say, go ahead and hook like you always do, but be prepared to hurt yourself! The wind will not be equal everywhere and even if you feel the wind is free of turbulence, it can still contain sheer. Be safe, have fun! regards, Stefan

What is it that doesn't work like this? You fail to tell us why you disagree. That the wind speed is different at different levels? Or that the physics behind this is wrong? I didn't earn a degree in engineering physics for nothing... Let me know and I'll redo the maths for you. regards, Stefan

>A wing is a wing and they both interact with aerodynamic >forces in the same way. Of course, but only if they are manuvered the same way. I said that it was wrong to compare a diving parachute with a plane turning with constant altitude. >As far as wind shear and turbulence goes (you had given an >example of the wind near a building), those are other topics >entirely and are not what is being discussed here. Maybe not. BUT the point I (and others) are trying to make is that you can hurt yourself badly if you are not aware of the wind when you are doing hook turns. Personally it has never been anything worse than I couldn't walk away by myself, but still bad enough that I had trouble sitting for 2 weeks! Even though the initial question was about a proof that I and others are 'wrong' I don't want other people to hurt themselves when obviosly people have made this misstake before. What is said about turning etc. in a constant air mass is of course right. What I am trying to explain is what happens close to the ground where the air mass is not constant in most cases. Btw, how did you include the stuff from my post the way you did instead of having to resort to the old usenet way that I am using ;-) (2nd reply) >Then you need to go back to the top of this thread and reread it from the beginning. We have been talking simply about the wind in general and not turbulance or wind shear. What is wrong changing the subject just a little. Some of us are trying to tell people how to not get hurt ;) Let me try to explain a little better what I mean by this example: You are traveling downwind at 100 m above the ground where the wind speed is 15 m/s with a relative forward speed of 10 m/s. Your relative ground speed is then 25m/s. Then you make an aggressive upwind (180) turn and you start to dive. Lets say that at 25 m above the ground you have forward speed of 15 m/s relative to the ground (in the other direction). This speed has been created by changing your potential energy into inertial energy (chaning your speed from 25 m/s into -15m/s). The physics behind this does not take the wind into account, only your initial position and speed (which was of course created by the wind) The problem however is now if the speed of the wind is lets say 5m/s at this altitude. This could be due to turbulence from the ground or windsheer or something else) This means that the relative speed in the wind is 20 m/s which creates a certain amount of lift. Now, lets assume that we are doing the same thing without the wind. Then the numbers would be 10 m/s ground speed at 100m, at 25 m it would be (10-40) = 30m/s in the other direction. Since there was no wind, this would be 30 m/s relative to the air. 30 m/s creates more lifting power than 20 m/s which means that the recovery arc of the parachute (or plane if you tried the same stunt with a plane ;) will be smaller. Of course you can change the numbers into anything because I didn't make more thorough calculations other than assuming that the speed is different at 100 and 25 m and thus proving the different lifting force experienced with or without the wind. A funny side effect of this is of course then that if you actually turn downwind, your lifting force would actually be greater. Hoverer I wouldn't recomend anyone doing a downwind hook if the air speed at 100m is about 15 m/s :-) regards, Stefan

>As a flight instructor, I can tell you that when a new pilot turns an airplane, it dives. I don't doubt that, but when I talk about turn, I mean a _turn_, not a turn and then dive. What I was trying to say is that when you are doing a frontriser turn, you are also diving even if you call it a turn, but when you talk about a plane turning downwind, you mean turning and compensating for the loss of airspeed to maintain altitude. That's why you cannot really compare the effect of a turning airplane and a turning (and diving) parachute regards, Stefan

The iPilot thing is not really applicable since a parachute dives when you turn it, a plane does not (unless you make it dive) And when the parachute dives, it experiences different windspeeds at different altitudes. That said, I think that we can agree that there is no such thing as a downwind stall, however I think you'd all agree that if the wind suddenly dies, everything will stall. Anyone tried landing towards a building knows what I mean ;) regards, Stefan

I would say that theoretically, there is no difference between a down wind swoop and an up wind swoop. But my back tells me otherwise ;) When I am doing 180 turns in windy conditions I tend to do them higher and I guess it is because of the different air speeds at different altitudes. When the parachute is recovering, it depends on some air to fly on. If it decends quickly it looses cell preasure since the relative speed to the air is decreasing simply because you are moving down. I have once hit the ground pretty hard when my parachute didn't recover as it normally does and this was in very windy (>10 m/s) condition. The second time it happened to me I immediately felt it and had time to flare higher than I usually do and then all was fine. Stefan