h a l f b a k e r yThis is what happens when one confuses "random" with "profound."
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If someone falls out of a plane at 30 000 ft without a
parachute, we ought to be able to throw one after them
which is equipped to catch up with them before they land.
This supplementary-afterthought chute is packed inside a
tear-drop shape, so as to achieve a higher terminal
velocity than
the candidate-cadaver which it pursues. It
has fins, a small engine and a congeries of sensors
including sonic (listens for scream), optical (looks for
tumbling black dot) and IR (hoping that the distressed sky-
diver is the largest warm-blooded entity between it and
the vicinity of the ground).
Once in proximity, it casts a net in the right general
direction, allows a little time for a startled person to
fasten themselves into said net, then jettisons its hard,
heavy components and opens.
Whump. .... Bump.
US Standard Atmosphere
http://www.engineer...mosphere-d_604.html
It's cold outside, there's no kind of atmosphere... [Wrongfellow, Jun 17 2013]
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Annotation:
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Could also be fired from the ground. Like an aerial life ring. |
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I have to admit, this is way better than my
proseccoparachute, which was intended to give
the doomed person a relaxing chilled beverage on
the way down. |
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Incidentally, there is a famous incident of a
skydiver who was acting as jump camera. He
videoed the entire skydive nicely, then realized
that he had concentrated so much on setting up
his helmet-mounted camera that he had forgotten
to put his rig on. The last 10 seconds or so of the
video (which survived; the skydiver not so much)
are interesting. |
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I need another (+) to give for the summary.
But... I don't really get the title. What does the prefix Prosepi mean?
Whatever it is, it is far better than the procrastiparachute I might have gotten around to posting someday. |
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I have always wondered why the airlines just didn't supply parachutes instead of oxygen masks! [+] |
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//why the airlines just didn't supply parachutes
instead of oxygen masks!// |
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Well, partly because people will inconveniently pass
out as they queue for the exit; partly because most
airliners spend much of their time flying over water,
and 200 passengers will be spread out along a 200
mile line; and partly because in most exits from
most aircraft, passengers will have an argument with
either a wing or a tailplane very shortly after exiting. |
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Unless it's set up to auto launch after a falling object,
I have a suspicion that by the time a crew member
grabbed the chute and tossed it out the hole, the
person is A) several miles behind the point of
ejection of the chute (9.5 miles/minute at 747 cruise
speed, and B) a large smear on the ground. |
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//why the airlines just didn't supply parachutes
instead of oxygen masks!// |
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Also, I suspect, because the airlines see some
benefit in keeping the panicking idiots (I'm not
excluding myself here) tethered in
place while the flight crew does what they can to
mitigate the problem. |
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According to the [link], at 30000 feet you can expect a temperature of -43 deg C and an air pressure of 0.3 bar. I imagine you'd have to be dressed for the occasion to survive these conditions even with a parachute. |
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"Prosepi-" means something like "furthermore", [2
fries]. "Para-" often means "beside" - so, the word
"parachute" itself might suggest, to a pre-modern
etymologist, something that falls beside you, not
necessarily attached to you. |
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"Sergeant?"
"SPEAK UP, SOLDIER!"
"Was this packed by a pre-modern etymologist? I'm
just asking, 'cause..." |
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[MechE], you make a good point, and that's the main
reason why this thing needs an engine - to make up
that deficit in horizontal distance. Without the
engine, it would be, essentially, a smart bomb, but
with a more benign payload. As it is, it has to be
more like an air-to-air missile, but with a more benign
payload. |
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Better than being packed by an entomologist I would think. |
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//-43 deg C and an air pressure of 0.3 bar. I imagine
you'd have to be dressed for the occasion to survive
these conditions even with a parachute.// |
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Yes, but in about 50 seconds you'll be at 20,000ft,
which isn't so bad. And 50 seconds later you'll be at
10,000ft. 50 seconds after that is the most
dangerous part of the operation. |
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By calculator, a fall from 30,000 feet results in an
airborne time of 197 seconds. That may be a little
long if the person isn't in free fall position. Let's
say a minimum of 1500 feet for the chute to work
once it reaches the person (that's probably
optimistic, since you're going to need a larger
chute since the person will be landing in an
uncontrolled position, but whatever). That
knocks off 10 seconds. Let's say it takes 20
seconds for the flight attendant to toss out the
chute (definitely optimistic, when someone
unexpectedly exits a plane, there's usually a panic
inducing environment on the plane). That leaves
us with 167 seconds for the chute to catch the
falling person, and match velocity closely enough
that the netting doesn't snap the person's neck.
It also leaves us with 2600 vertical feet and 154fps
vertical velocity to make up, and maybe 10,000
horizontal feet (that's very rough, I'm not sure
how
quickly the person would decelerate with respect
to the plane, I just know it's a lot). |
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Now, assuming your device can actually identify
the person at that distance (as opposed to a flock
of bar headed geese, or another airplane), I'll
leave
it as an exercise for the reader (read as, I'm to lazy
to do the math) on how much acceleration is
required to catch the person before they splat. |
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And that ignores the probably lethal case of the
bends the person will have, but that's another
story. |
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The presumption that someone falls out of a plane at 30,000 feet in this idea would indicate that the plane, or the area of the plane from which said person falls has been depressurized. Airplane doors and hatches on planes in my personal experience have always opened inward before opening outward to prevent opening against cabin pressure. Where does this person fall from? |
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//Better than being packed by an entomologist// |
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// "Prosepi-" means something like "furthermore" // |
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Thanks! I wasn't sure which language to translate and search engines weren't popping anything up on their own. |
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Is it Latin? Greek? Cheyenne?
Closest I could come up with on my own was "precip". |
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Sounds Greek. Like Persephone. |
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Surviving a jump without a parachute is easy. All you
have to do is fall asymptotically to the ground. |
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"Prosepi-" is Greek, [2 fries], like "para", but unlike
"chute", which is French. There's a joke in there
somewhere about packing a portmanteau word,
but I don't think it fits in this thread. |
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I'm sorry to say I don't know any Cheyenne. |
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"Prosepi-" wouldn't come up in a translation
engine, because it only exists as a compound
prefix, not as a word in its own right. Its
components, "pros" and "epi" may be either
prefices or stand-alone words. |
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Thank you for the numbers, [MechE]. |
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Wait - I can feel a half-bakery Abba knock-off
coming on - no, some other time. |
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I think we could look at shaving time off the two
ends of the process. At one end, we give the
flight attendant more coffee. Or, we mount these
things outside the hull (they're looking more and
more like AAMs), and maybe we have them
autolaunch, as you suggested earlier. I like
[pocmloc]'s idea, too, though it would be hard to
site the batteries. |
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The other end is more of a challenge. |
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I had wondered about the case of an unconscious
falling body, and it occurred to me that, when the
net is cast, it would have weights around its edge,
and that these weights might be minibots with
swarming behaviour, which could save the
beneficiary the time and trouble of strapping
themselves in, provided that being swarmed over
by cybernetic cockroaches did not induce some
sort of silly panic attack. |
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I think the netting would have to be automatic. If
the falling person didn't have supplemental
oxygen, they are going to be unconscious or, at a
minimum, groggy. But a non-robotic hammock-ish
net is probably your best bet. |
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However, I was already assuming that in my 1500
feet. The minimum height for pulling an
emergency cute is apparently 700 ft, but those are
small, and land hard. Now a hard landing isn't the
end of the world if you're landing feet down,
breaking a leg is survivable. If you don't know the
position of the person, however, a hard landing
may mean head first, and that's just no good at all.
So you need a larger chute, and a primary chute
recommendation is more like 2000 (although that
includes a few seconds to pull the reserve if the
primary doesn't deploy), and even that might be to
much for a possible head down landing. |
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// The minimum height for pulling an emergency
cute is apparently 700 ft, but those are small, and
land hard.// Nope and nope. Opening time for a
reserve should be about 2 seconds tops to full
inflation, which is 400ft at terminal (maybe 500ft
if
you're tumbling, but then again there's no
guarantee
it'll open at all if you're tumbling). And they are
full-
size and land just fine, even with 15 stone of your
finest halfbaker under them - the difference from
a main canopy is mostly in the packing, not the
chute. |
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I still don't understand why there hasn't been engineered a detachable compartment that everyone on a flight can pile into in the case of an emergency at altitude which floats, has a transponder, oxygen supply and a single chute. |
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You might quote cost extras as the reason but I bet people would pay more money per ticket for the peace of mind alone. |
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[cudgel] asks a fair question. |
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I was thinking of the Extreme Sports crowd, who
might have a little smartphone app to be used as a
homing device. You know - "Base-jumping? Ha!
That's
for wimps. You know what *I* just did? [etc.]" |
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Also, absent-minded armies could deploy
prosepiparatroops to mystify their enemies.
"What are they *doing* up there?" |
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Meanwhile, back to [MechE]'s numbers: an actual
air-to-air missile can do, let's say, mach 2, which
means it can cover 30 000 ft in under 20 seconds.
Conceded, it has a smaller payload, and doesn't
have to do such delicate manoeuvres on final
approach to target, but still... |
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Also meanwhile, I quite like the idea of a net full
of angry, live bar-headed geese. |
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For "epi", [2 Fries], compare the proper name
"Epimetheus", sometimes translated "wise after
the event". For "pros", there's a sense of
movement towards something. Both prepositions
can convey the idea of additionality, but with
different connotations. This is one of the things
that makes ancient languages interesting; looking
for exact equivalents of Ancient Greek
prepositions is like looking for Belgium on a map of
Pangaea - it's probably all there in some form, but
not as we know it. |
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Okay, maybe I was confused about reserve chutes,
but I stand by statement that even a standard
parachute landing is probably inadvisable if the
person might be in a head down orientation. I'll
stand by my 1500 feet. |
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And [Pertinax], the key question is not how fast
can a missile go, but how quickly it can accelerate,
turn over, decelerate, and intercept at a non-neck
snapping speed. A net grabbing the falling person
at mach 2 relative is not going to be so much a
rescue but really more of a julienning. |
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//[...] but how quickly it can accelerate, turn over,
decelerate, and intercept [...]// |
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When it comes to actual missiles, that stuff tends to
be classified. For this particular technology, clearly,
more test subjects are needed. None of them have
complained yet. |
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Fascinating. Thanks [pertinax], I've never studied languages but most of them seem to make a lot more sense than English. |
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Slightly off-topic but interesting - people have now
landed wingsuits (the webbed jumpsuits that
convert you into a sort of massive flying squirrel)
without parachutes. |
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Undoubtedly a key market segment. |
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I thought this might be a parachute with your face
printed on it (i.e. sharing etymology with
'prosopagnosia' - the inability to recognise people,
which is from the Greek for 'face' and 'ignorance') |
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