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WBraun
climber
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Hahahahaha, yeah
These number guys, ..... and then this guy flies thru the air and lands on his head and "breaks" all the real world rules.
They sit there scratching their heads, compiling their math trying to figure it out. Mean while, the magician waves his wand and all the rules go to hell.
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Ed Hartouni
Trad climber
Livermore, CA
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I should be resting my brain...
...ok lots of weird stuff can happen. Obviously those ski jumpers get big air and land without breaking anything. This guy, who knows.
Falling 245' = 74.7m
g=9.806 m/s/s
 = 0.5*g*t^2
gives the time t = sqrt(2*x/g) = 3.903 s
velocity would be v = gt = 38.28 m/s = 85.6 mph
the acceleration is hard to calculate. I'd do it by using the change of the momentum divided by the time to come to a stop.
The time to come to a stop can be estimated by the sum of the height of the guy and the depth of the hole, say a total of 4 meters.
Then the time to stop would be like 4m/38.28m/s = 0.104 s
The momentum would be just mv, what is his mass? guess equivalent to 160 lbs maybe? 75 kg?
the Force F = mv/t and the acceleration would be: ma = F = mv/t
a = v/t and in g's this would be a' = v/(gt) = 38.28/(9.806*.1) = 39 g's
he's dead.
Terminal velocity for a person without skis is some where around 50m/s, greater than the velocity above.
How does he live? my guess is that the snow prolonged his stop, it gets crushed, heats up and all that good stuff disepating the energy, making the time to stop longer and the acceleration smaller.
If the drag force goes like the velocity, and a skier has about 20% more resistance than a normal human (so a 40m/s terminal velocity), this guy takes about 4.9 s to hit and is going 25m/s by my calculations.
He's still hurting.
I'd guess that the snow has to stretch out his stop by at least a factor of 3, so to .3 seconds, which would get him down to about 7 g's...
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BASE104
climber
An Oil Field
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I'm not surprised he landed on his head.
When you BASE jump, the first three seconds you are moving so slow that you can't fly your body...turn, flop over if you are on your back...start the track, etc.
At about three seconds you are falling fast enough to recover from a screwed up exit or something. You are now able to "fly;" you have control. You can turn, turn over if on your back, start a track (which takes about six seconds to start cranking.)
With two skis on your feet, they would catch a ton of air and tend to turn you upside down. Simple aerodynamics. Well, maybe not simple...but you get it.
Watch Sylvester ski off Asgard. He is pretty much out of control until he cuts loose the skis. Then he turns over, gets stable, and dumps. Pretty cool.
Ski jumpers are the most beautiful to watch. They pull those skis up next to their body, camber their torso, catch all the wind with their hands.....perfect track. I used to try to track like a ski jumper without the skis.
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BASE104
climber
An Oil Field
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Sorry to post twice. You couldn't pay me to do a four second free fall with skis on. That is the realm of ski jumpers who have a big ass ramp and know how to do it.
If I BASE jumped with skis on for a four second free fall, I would have ended up....on my head.
Now, I would have done it off something big like El Cap, where you have plenty of time to cut the skis loose and get your act back together.
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Ed Hartouni
Trad climber
Livermore, CA
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these simple mechanics questions are never simple, I should write a book -
"Dealing with gravity - a sportsman's guide to physics"
anyway, we'll see the video at some point. My guess on the landing? he hits the sloped snow field and skids then post holes in.
Ski jump hills are shaped "parabolically" to parallel the trajectory of the jumper. The jumper is never more than 4 or 5 meters away from the slope. So most of the hurt is in the skid, which is usually slick.
This guy may be courageous, and be faithful, but he is one lucky idiot. I would encourage more of this behavior BEFORE he decides to breed.
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the Fet
Trad climber
Loomis, CA
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High Divers know the deal, he should have thrown a backflip or two. You can control how fast you spin, so you can spot the landing and get your feet under you. It's actually safer than no rotation.
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Peter
climber
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Ed
Looks like you ended up with the same deceleration as me. If he reached 40m/s at the end of his fall and came to a stop at the bottom of a 2m hole, then (a = v2/2d) he experienced about 40g (400m/s2) average deceleration.
That might sound bad but is actually completely survivable without serious injury. I conducted vehicle crash tests for a few years, then did accident reconstructions for a few years more. Crash tests are designed to simulate a 30mph or so front collision (ie: one vehicle into an immovable concrete block at 30mph, or two vehicles into each other both at 30 mph, or one vehicle at 60 mph driving into a stopped vehicle). In a modern vehicle with a crush zone and seatbelts, but no air bags, the peak force seen by belted occupants is about ... 40g. Drivers and passengers can be expected to sustain no serious injuries.
If you whack your head on something hard you'll see a lot more than 40g peak, and it is guaranteed to hurt. Go ahead and try! Think about bike helmets. They're designed to decelerate your head gradually over about 1/2 an inch of crush zone in order to reduce the impact when you whack the pavement. The guy who landed the jump had 6 feet of crush zone in which to decelerate - luxury!
Russ - if a rope has 35% elongation under a factor 2 fall, then I feel a lot better about my anchors - thanks!
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Hootervillian
climber
Zak's Cabin
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screwed up the landing...lol
seems i've seen video of this cat superman into a headstand a couple of times before...one off the dead tree cliff outta Brighton ~120' iirc?
now if'n he was free-heelin, it would be art, of course.
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Russ Walling
Social climber
This space for rent
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Peter says Russ - if a rope has 35% elongation under a factor 2 fall, then I feel a lot better about my anchors - thanks!
I'm not really saying that for other scenarios. To get that elongation you need a giant amount of rope out, like your 200ft fall on 100ft of rope, or even better, a 300ft fall on 150ft of rope. If you have like 10ft of rope out and take a 20 ft fall, you will have nowhere near that 35% soft catch figure.
Oh Ed..... could you do up some of these for us??? Pretty please???
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artifact
Trad climber
San Francisco, CA
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Topic Author's Reply - Feb 2, 2006 - 12:39pm PT
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I met this guy last year in AK who wanted to jump out of a heli in his flying squirrel suit at 10,000 ft (no parachute), freefall to 6,000 and land on a 50 degree Chugach peak w/ 3-5 feet of pow.
He claimed that in his suit he can (regardless of the acceleration or freefall), slow decent to about 70 mph upon impact, he seemed more concerned about nailing the landing zone. His idea was to "pill bug" upon impact.
This guy's perfect powday never came, but he's more determined for this year. Super calculated, but super crazy!
I think the distance record (nordic) is ~780ft
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JuanDeFuca
Big Wall climber
Stoney Point
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How many feet of packing peanuts to stop a person that jumps of a 100ft cliff.
That would be fun.
Juanito
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Ed Hartouni
Trad climber
Livermore, CA
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ugh, there doesn't seem to be much agreement out there.
The rope elongates under load; this is a physical constant of the rope, the Young's Modulus, Y. This is given by:
Y = (F/A)/(dL/L)
where F is the applied force, A is the area of the rope, L is the length of the rope and dL is the amount of elongation.
The work done on the rope in the fall is F'*dL, where F' is the "impact" force, and dL is the elongation of the rope which stops the climber. This is equal to the energy of the fall, if a free fall this is:
F'*dL = mgh
where m is the mass of the climber, g is the gravitational acceleration (9.81 m/s^2) and h is the height through which the climber falls.
So the force on the rope is:
F = F' + mg
= mgh/dL + mg
= mg*(1 + h/dL)
roughly the weight of the climber multiplied by the ratio of the height to the rope elongation.
This works out well, if the elongation is large (dL is large) the force on the rope becomes small. If dL -> infinity, then F -> mg, just the weight of the climber.
from the Young's modulus equation we can write the elongation as:
dL = FL/K
where we define K = YA, the Young's modulus multiplied by the rope area.
substituting into the above equation for force gets us:
F = mg * (1 + (hK/LF))
which is the same as the quadratic equation:
F^2 - F*mg -mg*f*K = 0
f = h/L, the fall factor.
Solving for F:
F = (mg + mg*sqrt( 1 + 4*f*K/(mg)))/2
not the Beal ropes equation... but this one makes sense. Once again, if f -> 0, then F -> mg the weight of the climber. This is good.
Does this ever happen? Yes, Jaybro reported it when he was simulclimbing Keeler Needle and his second fell off onto a very soft catch. My guess is that the loading was gradual (with a lot of friction too) and Jaybro didn't have any problem holding the partner.
But the other thing this equation tells us is that for a fall of a fixed fall factor, the force will be the same, independent of the amount of rope out.
Working backward now,
dL/L = F/K,
the elongation percent only depends on the force divided by the Young's Modulus multiplied by the rope area. In this model, it doesn't depend on the length of rope out.
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Jerry Dodrill
climber
Bodega, CA
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``It wasn't some yahoo stunt,'' Pierre said. ``I chose to do it so it would open up doors so I could witness my faith in Christianity.''
I read that and had a flash back to a story I read years ago in Bible class. Jesus had the brains not to jump. Check it out:
"Then the devil took him to the holy city and set him on the pinnacle of the temple and said to him, “If you are the Son of God, throw yourself down, for it is written,“‘He will command his angels concerning you,’and “‘On their hands they will bear you up, lest you strike your foot against a stone.’”Jesus said to him, “Again it is written, ‘You shall not put the Lord your God to the test.’” (Matthew 4:5-7)
I'm not sure doing a stupid/courageous stunt, yahoo or not, is the right way to witness your faith. Powder snow is good, but angel hands it is not. Mr. Pierre is lucky to walk away without being a darwin award recipient.
I'll solve for F...
(powpow!)skis+cliff*faith - brains + balls - angels= F--ked
Luckily his angels kicked in at the last second!
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Rock!...oopsie.
Trad climber
pitch above you
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Congrats to Jerry for the best formula to describe the event so far.
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Ed Hartouni
Trad climber
Livermore, CA
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T*R - thanks for the offer, I think Debbie's got me occupied next week with putting in the gravel pathways around the house... but I am an always available "coping mechanism" for math (I do have my limits though... just a simple physicist).
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ß Î Ø T Ç H
Boulder climber
ne'er–do–well
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Sep 11, 2015 - 11:02pm PT
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... "Werners Chute" at Mammoth makes that jump look like 'nuthin....
Werner is too modest to say it, but he was a bad-ass skier. What was that one of legend... LeConte Gulley, lost a ski, plenty of rock, no falls?? I climbed LeConte gulley one time (used single point of aid), but
Werner's chute is for real - it drops from the absolute summit of Mammoth Mountain - nobody really hikes the few steps up, past the gondola drop-off it takes.
I used to walk up there in the summer with binocs to look at anything rock-worthy to the south.
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