projanska 0 #51 March 26, 2004 QuoteI've seen some video of exits of students. In some you can clearly see the jumper kicking his legs. Aparently it's a fairly common thing in the first couple of jumps. The jumper isn't conciously aware of doing it. ..and then adjust to ignore it as they get more used to jumping.IMO. As a semi-whuffo of couple of jumps, I can agree to this. It seems to be a natural response, you can see the same thing if people are jumping legs first from somewhere high, say to a swimming pool - they tread the air. I have personally noticed this with myself, especially when my last jump(S/L w/ under the wing exit) went poorly and I actually tumbled sideways off, I had to fight for my legs not to start kicking. I suspect it would be because being airborne is a new sensation and your brains don't know to handle it yet - with few more jumps, you apparently start to get the hang of it as the exiting from the plane becomes routine. I have also felt the dropping sensation when exiting, and as with kicking your legs, I assume it's something to do with being in a new situation, so you body is focused at every slight change of velocity, and with experience your brains start to learn that it's a "normal" situation and that you are perfectly fine. ___ "Ye Gods!" Quote Share this post Link to post Share on other sites
Storhemulen 0 #52 March 26, 2004 How about differences in body position? I don't feel much diving from 5m cliffs, but going feet first definitely feels!You're the driver, not a passenger in life. Quote Share this post Link to post Share on other sites
chuteless 1 #53 March 26, 2004 Take a bottle of water and watych how the water reacts to a fasty drop away. Bill Cole Quote Share this post Link to post Share on other sites
CrazyDave 0 #54 March 26, 2004 QuoteBrain is so overwhelmed by everything else going on that a falling sensation is least important sensation to be generating. even so... i still had a falling sensation for about .5 of a second. then all i felt was like i was floating.. strange because i didnt think that u go down towards the ground when floating Quote Share this post Link to post Share on other sites
bertusgeert 1 #55 March 26, 2004 HAHa, I kicked up to my 13th jump, everyone in the plane was laughin at me, I couldnt stop it. (have several hilarious exit videos!). My first jump, I had the falling sensation, as if on a roller coaster. I did my second directly after, and did not feel it. My third was several days later, where I did feel it again. After that, i focused more on the relative wind, rather than the ground below, and it stopped. My kicking, I had to keep my feet together to make sure I wasnt kicking. I finally got it under controll! --------------------------------------------- As jy dom is moet jy bloei! Quote Share this post Link to post Share on other sites
klafollette 0 #56 March 28, 2004 Okay, it's been a while since college physics, but I believe the "gravity vector" is always the same, straight down towards the center of the earth. Doesn't matter if you are on a diving board, in bed, jumping out of a plane, or on the Space Shuttle. The acceleration force from gravity is always the same. The classic example is to take a rifle 10 feet off the ground, with the barrel parallel to the ground. Fire a bullet from the gun. At the exact moment the bullet leaves the barrel, drop another bullet from 10 feet off of the ground. Both bullets will hit the ground at exactly the same moment, though the one fired from the gun will be several hundred yards away (disregarding the curvature of the earth). The horizontal acceleration of the bullet does not change the rate at which it falls due to gravity. What can affect your acceleration from gravity is how you present to the horizontal wind generated from your horizontal speed across the ground, immediately after exit. If it is at an angle in which the horizontal wind bouncing off of your body deflects downward (angle of attack), it will give you a force that opposes the acceleration from gravity. That's "tracking back up the hill". Any resistance from friction against the air while gravity is pulling you downward (which determines your terminal velocity) is independent of the horizontal speed when you jump. That resistance from the air friction opposing the force of gravity in a downward direction will always be the same regardless of your horizontal speed. The force of the friction against the air will decrease horizontally, while increasing vertically as you ride down the hill. The friction remains the same, but the force it generates increases as your speed relative to the wind increased. The horizontal speed of the plane just changes how far forward you travel. If you jump out of a jet traveling 200mph, you will take longer to transition to vertical freefall, but the time it takes to accelerate to terminal velocity downward should take the same amount of time as a Otter doing 90mph. If you jump out of a plane in a tight ball, you should accelerate downward at exactly the same rate as you would jumping off a diving board, going over the hill in a roller coaster, whatever.. I have always wondered why you don't get the falling sensation from a plane. I think it might be due to the over stimulation of the nerves in the skin from the relative wind, and very loud noise probably mask the "falling" sensation. The only time I've experienced that sensation is by walking off the back of a CASA. That first second when you are not buffeted by wind, and just falling straight down gives me that same "elevator dropping" feeling, until I hit the wind. Quote Share this post Link to post Share on other sites
billvon 2,396 #57 March 28, 2004 >If you jump out of a plane in a tight ball, you should accelerate > downward at exactly the same rate as you would jumping off a >diving board, going over the hill in a roller coaster, whatever.. Right. But you don't perceive acceleration downward, you perceive total acceleration - which is why a balloon or BASE exit feels different than an otter exit. In one case you feel zero G for a few moments, in the other you feel about .6G's. Quote Share this post Link to post Share on other sites
Erroll 49 #58 March 29, 2004 Quote The only time I've experienced that sensation is by walking off the back of a CASA. That first second when you are not buffeted by wind, and just falling straight down gives me that same "elevator dropping" feeling, until I hit the wind. Surely that has to do with the fact that you are stepping off into a virtual vacuum, or at the very least, an area of very low pressure such as you find in the burble? You are not being buffeted by wind because immediately as you leave any tailgate, there is no relative wind. Quote Share this post Link to post Share on other sites
daveb 1 #59 March 30, 2004 Quote... you don't perceive acceleration downward, you perceive total acceleration - which is why a balloon or BASE exit feels different than an otter exit. In one case you feel zero G for a few moments, in the other you feel about .6G's. I have not felt the dropping/falling sensation during any skydive: side, tailgate, or helicopter. The only time I have felt it was during a bungee jump - not the first fall towards earth, but at the apex of the first recoil. That was when my stomach tried to exit through my mouth and I was grabbing at everything (not that there was much within reach). The feeling I have exiting an aircraft when my air is blocked is quite different from that visceral memory of the bungee recoil. Quote Share this post Link to post Share on other sites
pchapman 261 #60 March 30, 2004 Long post... Whether a dropping feeling is actually noticed depends a great deal on one's mind & body, in addition to the requirement to have some sort of acceleration happening. The nature of the acceleration has been largely discussed already, with some of the bad physics having been cleared up. The "mind & body" may mask the dropping sensation in several ways: - Habituation - Skydivers get used to it and don't notice it any more. No different than wearing glasses and not noticing the pressure on the nose after some time. - Total acceleration - This one I haven't thought fully through but others have suggested it. Whether exiting from a balloon or a fast King Air, the downwards acceleration initially will always be about 1 g (before air resistance builds up, and assuming one isn't in some sort of tracking position to do anything other than a ballistic drop). However, with the strong horizontal deceleration going on, the vertical acceleration may be less noticed by the body. I don't know, however, how much that is because of stronger total acceleration, or because of the masking effect of another strong sensation -- the air blast which is higher than a skydiver might expect when jumping from another slower aircraft. - Masking effect of other external sensations - For example, the stronger than expected air pressure as mentioned above. - Masking effect of the brain - When we have something else to concentrate on, we may not notice sensations we would otherwise notice. For example, when jumping on a very cold day, we might notice the frigid air when the door opens, but have almost no memory of it during the freefall itself where we are strongly focused on the maneuvering and formation work. - Masking effect on internal body sensors - I have no idea of the physiology of all this, to what extent acceleration is sensed through the vestibular system (otoliths in the ear's canals etc) versus through proprioceptors ("nerve endings in the muscles and tendons and other organs that respond to stimuli regarding the position and movement of the body" - eg - stomach-in-the-throat feeling). If there are other strong stimuli, such as tensing the muscles or rotational accelerations, the body may not sense the downwards acceleration as readily. I'll come back to this point. My own experience as examples: - As an AFF student (well, PFF student in Canada) I noticed the falling feeling for a few seconds on the first few jumps but not later on. Largely a matter of habituation. The feeling was noticeable because it was so unusual, no matter how strongly I may have been focused on other aspects of the jump. For other people, the balance between these two factors might be different. - As a novice jumper I could get the falling feeling again by doing an exit in an unusual body position. Doing my first couple exits from a Cessna on my back, I got the falling sensation again. I wonder if "trying to fight the fall" somehow makes it more likely to get the falling feeling. On those first back to earth exits I wouldn't have had great body control on my back, and so there could be some feeling of 'I'm falling and trying to get in control'. An experiment to check this would be to compare novices doing their first jumps back to the wind, with one group trying to maintain their body orientation, versus another group being told to just relax and allow themselved to tumble. Assuming the latter group were already comfortable with regaining stability & getting back to belly to earth, then I think the first group might have more of a falling feeling as they try to tense against something but feel they have little support. They can flail their arms but can't keep themselves from a tumble. - Perhaps the most interesting observation in my whole post: Bridge Day last year was my second Bridge Day. On the first jump, flat and stable, I felt a little bit of dropping sensation. On the next two jumps I did aerials, and didn't remember the falling sensation at all. On the final jump I went off flat and stable but in in a very relaxed, non arched position, looking down at the girders just to take in all the visuals. Wow, that time I felt an intense falling sensation, that lack of support, getting sucked down by gravity. It is so hard to try to separate all the factors and determine which ones have the greatest influence in a particular situation and why. During the aerials jumps, my focus on getting the maneuvers right may have been a factor. Also, proprioceptive information on the falling may have been masked by the other accelerations happening -- the rotational acceleration going into a layout backloop for example. But are the total magnitudes of such accelerations, even at head and feet, very big compared to the initial 1g downwards acceleration? I haven't done the math. Having muscles tensed to hold a particular body position or do a maneuver might mask the body noticing acceleration. So being relaxed may allow the body to better sense the acceleration. That fits with my Bridge Day experience. But this can be opposite to what happens in some situations, where being relaxed actually equates with being comfortable with a situation, and not feeling the falling sensation. For example, a student jumper who feels good about jumping can exit the airplane and stay relaxed, and may not notice the falling sensation as much. The student who is frightened by the drop will tense up, get the sensation, kick their legs, or whatever they might do to 'fight the fall'. Muscle tension and movement doesn't fully mask the body noticing the acceleration, and the mind is primed to notice it in that case. That suggests the mind has a much greater effect than the body in this falling sensation issue. Quote Share this post Link to post Share on other sites
efs4ever 3 #61 March 31, 2004 Time for a balloon jump! Lay on your back and watch it go away. You'll feel it. Russell M. Webb D 7014 Attorney at Law 713 385 5676 https://www.tdcparole.com Quote Share this post Link to post Share on other sites
Go_Higher 0 #62 March 31, 2004 LOL... so true Lawn... so true... : Quote Share this post Link to post Share on other sites
Red_Skydiver 0 #63 March 31, 2004 If that's true then why is there no feeling of dropping when jumping from a balloon? Quote Share this post Link to post Share on other sites
efs4ever 3 #64 March 31, 2004 QuoteIf that's true then why is there no feeling of dropping when jumping from a balloon? ? That should produce the ole guts in the throat feeling more than anything. It did for me. Russell M. Webb D 7014 Attorney at Law 713 385 5676 https://www.tdcparole.com Quote Share this post Link to post Share on other sites
Red_Skydiver 0 #65 March 31, 2004 Well I've done 2 balloon jumps and didn't feel a thing, just the rush of adrenaline and wind! Quote Share this post Link to post Share on other sites
The111 0 #66 March 31, 2004 QuoteWell I've done 2 balloon jumps and didn't feel a thing, just the rush of adrenaline and wind! Get your inertial sensors fixed. www.WingsuitPhotos.com Quote Share this post Link to post Share on other sites
Fast 0 #67 March 31, 2004 QuoteWell I've done 2 balloon jumps and didn't feel a thing, just the rush of adrenaline and wind! Most people that I have talked to about it have felt that sensation~D Where troubles melt like lemon drops Away above the chimney tops That's where you'll find me. Swooping is taking one last poke at the bear before escaping it's cave - davelepka Quote Share this post Link to post Share on other sites
