This thread is about ski flying... I have recently learnt about this event. Here is a video of the world record jump/fly of 239m, the guy spent about 7 seconds in the air: http://www.youtube.com/watch?v=Q4c4DhVVAwU Anyhow, when I was reading about Eddie, the Eagle, it was mentioned that he was 20 pounds heavier then most of the ski jumpers. Eddie was a famous loser in skijumping. There is also a saying that "fat men don't fly", a reference to the small size of most ski jumpers. But I don't really understand why. Assuming that 2 jumpers are the same heights and their surface areas are also similar, I thought the heavier would jump/fly farer. But according to this saying, it isn't so...Keep in mind that muscle is heavier than fat, so a heavier jumper can be also more muscular...>>> more powerful jump... So why being a skinny jumper is an advantage compared to being heavy in ski jumping??? I think in downhill skiing being heavier is an advantage, one reason why men are faster than women in that event....
I'm guessing that jumpers use their body and skis as a wing, gaining lift from their movement through the air. Heavier jumpers would be slowed down less by air resistance, but they would also get less help from lift. It seems that in this case (ie at these speeds, weight ranges, downslope grade, etc) the second effect outweighs the first. Think of a glider - too light, and they are unable to maintain headway through the air. But too heavy, and you might as well be flying a brick.
Not really, if you mean that they are going upward. Maybe in jumping there is a little vertical lift, but on the video of ski flying it looks like it is mostly sideways/ downward motion...
Well, you are right---typically, you would assume that the skier is a projectile, in which case his mass doesn't enter into the problem. But these equations neglect air resistance. My guess is that fat guys have a higher wind resistance, which make a big difference when the velocity is large and the distances are far.
"Lift" means an upward force. It won't result in upward motion unless it is larger than the downward gravitational force. Generally, it results in reduced downward motion, ie a better glide ratio.
Airfoil to weight ratio would be key - fat guys weigh more per airfoil loading possible. A slat-thin human with light bones and strong legs would be ideal. They can tuck on the run, and lay out in good airfoil shape once flying. The record jump on the hill now being used for the Olympics, IIRC, is by a woman.
OK, let's change the approach slightly. I am assuming that for any throw/jump/roll there is a most effective weight, where the distance is the farest, assuming everything else (size, resistance,etc.) are the same. So let's say we are rolling bowling balls down the skijump. They have all the same size but different weight. I guess too light balls don't gain enough momentum and too heavy ones have too much snow resistance before reaching the jumping off point. So there has to be a most effective weight. Probably the same for jumpers, and it is around the 150 or so pounds. So the answer to my question would be: heavier jumpers don't speed up enough due to snow resistance on the jumping ramp and too light jumpers have also disadvantage of their weight not working the snow effectively enough. Bottomline is that it has to do more with the time spent on the ramp and not in the air, again, assuming that air resistance is similar for the jumpers.
What are the rules regarding the aerodynamics of the skier? Can he have webbing between his legs? How wide can his skis be? Can be wear webbed ski-gloves to 'plane' through the air?
Slightly off-topic... I've always been somewhat confused about how things like random wind gusts, slight temperature variations that affect the friction of the ramp, etc. are accounted for in competitive ski jumping. It always seems to be lots of people jumping over 100 m, with the winners and losers determined by only a meter or less. With such small variations and long flight times, it seems like the winner or loser could easily be determined by relatively trivial things that don't have anything to do with the skier's skill or athleticism.
The aerodynamics during flight make a lot of difference. You don't need to call it lift, if you don't want to, but the flight position is a lot of the skill. They are "sailing". re the rules etc: http://en.wikipedia.org/wiki/Ski_jumping
Judging from those rules, one is penalized for going too far in flight, beyond the "K-Line". So why don't they try to maximize the distance of the flight? I would expect that a good 50% increase in distance would be obtainable with a more aerodynamic planing surface as the skier went through the air.
You guys mixing up jumping and flying. In jumping they are supposed to land on K-line and if they do they get 60 points another 60 coming from 3 judges (20-20) for style and such. There are actually 5 judges but highest and lowest don't count. Anyhow, it is more precision and style then distance. In flying it is distance, but there is still a maximum, the end of the field, hello? Seriously, after a certain point it is considered dangerous to land, and you definiately don't want to land on the flat part... So they call it flying because it is extra distance jumping and no, extra webbing isn't allowed. Anyhow, it is offtopic... Personally I don't think much of "jumping" is involved, when I analized they just let it go, I didn't see any extra effort of gaining extra at the end of ramp, but I am no expert...
The Wikipedia page says: Skiers are awarded 60 points if they land on the K Line. Skiers not landing on the K Line receive or lose points for every metre (3 ft) they miss the mark by, depending on if they surpass it or fall short, respectively.I.e. penalized for falling short, rewarded for going beyond.
Thanks Pete. My misreading of the Wikipedia article. That makes a lot more sense! Is that a real picture from cosmictraveler? It's gotta be fake, but it sure makes a statement!
