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Bun, but tried throwing things while skydiving at
terminal
velocity? I suspect its more difficult than you think. |
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It needs autodeployment, human reflexes and strength just aren't up to it. |
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Have the cannister attached to you by a long string (length
predetermined by various factors...) and suitably streamlined
so its terminal velocity is greater than yours. So it will hit the
water before you & do its bubbling. |
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Personally at this depth... I'm going to have to charge you double. |
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Get it? 'cause depth charge and, stuff.
Hello.
Is this thing on? Turn off those lights so I can see if everyone is at lunch and I need to get a rain-cheque on the audition. |
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Someone check these calculations, but if a person if going
120mph (terminal velocity) and decelerate at a constant 5 G's
(adjust for max short term acceleration without blacking out
or having the air forced from your lungs), it will take 1.1
seconds to stop, during which time the user will travel 190
feet. I recommend designing this explosion to make a column
of bubbly water 190 feet tall so that the user stops near sea
level rather than 190 feet underwater. |
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From the title I thought this might be the idea of a
type of super polymer based chewing gum that you
blow out into a bubble when needed which
becomes parachute sized on the way down. |
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// I suspect its more difficult than you think.// |
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Meh, you have the rest of your life to figure it out and get it
right. |
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//decelerate at a constant 5 G's// |
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I know physicists that spew sentences like this while
rapidly calculating stuff on paper. It gets my goat, you
can't start feeding demonstrably wrong stuff into a
calculation without being sure of getting wrong stuff out
of it. If you fire a bullet into water it won't make 190ft
down, well, maybe the fragments will sink that far. |
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Nothing in fluid like this is linear. I suspect the graph
curves hard at both axes, where very low velocities will
decelerate at almost 0, and high velocities at almost
infinity. Calculations with 0 & infinity in them are hard. |
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I imagine falling from any kind of aircraft-normal height
into water is going to be lethal. Especially since you're
going to need to be conscious and in reasonable physical
shape to stay afloat. |
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Thanks for that. I find some of the most nuts/interesting
stuff comes out of peak cold war era military studies. |
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Heh, take it as a compliment. I'm more than a little
jealous of some of those who lived through the period. It
seems things happened, fast. If you were in
science/technology, it was "here's the money, have at it".
I read a study a while ago, I was trying to get some kind
of handle on what fraction of human energy is lost as
heat through breathing. I found one source from a late
50's/early 60's Air Force study. Essentially it went: "We
don't know how much heat humans loose while breathing
in harsh conditions, so, we took 25 volunteers and made
them dig trenches in Greenland to find out". |
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There's tons like it: "We don't know what g-forces do to
people, so we strapped this guy to this thing we invented
called a rocket sled, to find out". "We don't know how
nuclear reactors behave in the air, so we took this B-36..." |
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In my area, things were the same, 80% of the drugs in use
today were developed 1940-1970. |
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Having met people, it's the stories created by living in a
fast-moving era that my generation can't compete with.
My ex-girlfriend's dad: "I cut through the boot floor &
through the top of the fuel tank, she managed to curl up
in there under the boot carpet and spare wheel and I just
drove us out of Poland. Problem was, I had to rig up the
windscreen washer bottle as a makeshift fuel tank, I had
to stop every 10-15 miles to top it up all the way through
Europe". |
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We need to learn how to do science again. It's not about papers, acronyms after names, and peer review. Our dearly departed knew that and served as excellent examples of how science should be done. |
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A missile that deploys a series of weapons could do it. Throw out thirty or so explosive devices timed to foam the water and for the shockwaves to mostly disperse before the user hits. She can sink into a progressively lower series of foamed water and dead fish. |
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Maybe a sizable depth charge, such that the
waterspout would rise up to meet the falling flyer,
would do the trick, and would generate many bubbles. |
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As [bs0] pointed out directly hitting a waterspout would be a rather unpleasant experience. But maybe if the waterspout were timed to start falling before the user, such that it would be falling when met, but somewhat slower...? |
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//Flying over ocean in a rickety aircraft// Solving the rickety part might be the best solution. |
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// I know physicists that spew sentences like this while
rapidly calculating stuff on paper. It gets my goat, you can't
start feeding demonstrably wrong stuff into a calculation
without being sure of getting wrong stuff out of it. If you
fire a bullet into water it won't make 190ft down ... // |
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Sorry for stealing your goat, but while a bullet obviously
won't go through 190 feet of water, and a person traveling
at 120mph will go though even less un-aerated water, my
point is that if the water was aerated enough to slow
down a person at a reasonable rate of deceleration, they
would end up that deep. |
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//they would end up that deep.// |
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Would they? Even aerated water would be strongly velocity
sensitive. How far down is the aeration? Making bubbles at
190ft down would need a lot of pressure & therefore air.
Those bubbles would represent a fraction of the water by
volume, but that fraction would be heavily dependent on
the depth related pressure. My point is, it's a very tricky
calculation full of non-linearities and unknowns. I suspect it
would be easier to do the experiment. |
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Of course it's nonlinear. To have a constant 5G
deceleration you'd need a nonlinear distribution of
bubbles. If you couldn't control the bubbles that precisely
and you wanted to keep deceleration less than 5G, then
you'd need to design it to have deceleration of 5G or less,
so the user would have to go even deeper than 190 feet.
190 feet is the best case with max 5G deceleration. Now
we may find that deceleration greater than 5G for less than
a second won't cause black out, or it will be a short enough
black out that the person will wake before inhaling water.
But still even if we can cut the distance by half, 95 feet
under water is an issue that needs addressing. I threw out
the idea of a 190 foot tall column of aerated water. It's not
a trivial problem... |
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Side note: This idea is completely worthless in the real
world and it seems that only a very remotely related
variant of this idea could ever have a practical use. This is
the half-bakery, so I'm suspending disbelief and attempting
to point out an issue that hadn't been addressed yet, and
proposing a possible work-around. I think the fundamental
core of this idea (aerating water to soften the impact) is
true to some extent, and interesting, which is why I
bothered to
comment. When I first read the idea (// let you settle
into the ocean as if it was a fluffy bed //), I pictured a 10
foot deep pillow of aerated water. But then I decided to
do a reality check on that and discovered it would have to
be a lot deeper. I figured I'd share my results. Are my
results useful? Absolutely not. As you implied, there's no
known way to generate a 190 foot column of aerated water
(either above or below the water surface) by dropping any
sort of bomb on the surface, let alone a column that has
the proper gradient of aeration to provide constant
deceleration. That seems fairly obvious to me. |
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//the fundamental core of this idea (aerating water to soften
the impact) is true to some extent//
It's absolutely true. See linky for diving aeration systems. |
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Interesting. I didn't realize this was commonly used for diving
training. |
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A skydiving school could feature a large pool of aerated water for this purpose. Or a small one if you're feeling lucky. |
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Yes, this idea came up while watching diving
practice. The coach would press a button to release
bubbles just before the dive. |
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Yes, this idea came up while watching diving
practice. The coach would press a button to release
bubbles just before the dive. |
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Yes, this idea came up while watching diving
practice. The coach would press a button to release
bubbles just before the dive. |
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A triple back-flip jack-knife with a two-and-a-half twist! |
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Actually a density gradient will arise naturally in
the bubble/water column with the bubbles
expanding as they rise - but it’s going to be linear
density/depth, you might prefer it to be non-linear
proportional to d^2.
All the same- propelling your depth-charge 190
feet under water, as you fall, is going to be a
challenge.
Having the capacity to do anything at all in free-
fall takes a lot of training! |
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