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Prosepiparachute

I *knew* I'd forgotten something.
  (+14)(+14)
(+14)
  [vote for,
against]

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.

pertinax, Jun 16 2013

US Standard Atmosphere http://www.engineer...mosphere-d_604.html
It's cold outside, there's no kind of atmosphere... [Wrongfellow, Jun 17 2013]

[link]






       Brilliant! [+]
Grogster, Jun 16 2013
  

       Could also be fired from the ground. Like an aerial life ring.
pocmloc, Jun 16 2013
  

       Just might work!
blissmiss, Jun 16 2013
  

       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.   

       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.
MaxwellBuchanan, Jun 16 2013
  

       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.
  

       I have always wondered why the airlines just didn't supply parachutes instead of oxygen masks! [+]
xandram, Jun 17 2013
  

       //why the airlines just didn't supply parachutes instead of oxygen masks!//   

       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.
MaxwellBuchanan, Jun 17 2013
  

       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.
MechE, Jun 17 2013
  

       //why the airlines just didn't supply parachutes instead of oxygen masks!//   

       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.
MechE, Jun 17 2013
  

       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.
Wrongfellow, Jun 17 2013
  

       "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.   

       "Sergeant?"
"SPEAK UP, SOLDIER!"
"Was this packed by a pre-modern etymologist? I'm just asking, 'cause..."
pertinax, Jun 17 2013
  

       [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.
pertinax, Jun 17 2013
  

       Better than being packed by an entomologist I would think.
pocmloc, Jun 17 2013
  

       //-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.//   

       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.
MaxwellBuchanan, Jun 17 2013
  

       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).   

       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.   

       And that ignores the probably lethal case of the bends the person will have, but that's another story.
MechE, Jun 17 2013
  

       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?
cudgel, Jun 17 2013
  

       //Better than being packed by an entomologist//   

       [marked-for-tagline]
Wrongfellow, Jun 17 2013
  

       ^ seconded.
FlyingToaster, Jun 17 2013
  

       // "Prosepi-" means something like "furthermore" //   

       Thanks! I wasn't sure which language to translate and search engines weren't popping anything up on their own.   

       Is it Latin? Greek? Cheyenne?
Closest I could come up with on my own was "precip".
  

       Sounds Greek. Like Persephone.   

       Packed by an etymologist.
lurch, Jun 18 2013
  

       Surviving a jump without a parachute is easy. All you have to do is fall asymptotically to the ground.
ytk, Jun 18 2013
  

       "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.   

       I'm sorry to say I don't know any Cheyenne.   

       "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.
pertinax, Jun 18 2013
  

       Thank you for the numbers, [MechE].   

       Wait - I can feel a half-bakery Abba knock-off coming on - no, some other time.   

       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.   

       The other end is more of a challenge.   

       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.
pertinax, Jun 18 2013
  

       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.   

       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.
MechE, Jun 18 2013
  

       // 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.
MaxwellBuchanan, Jun 18 2013
  

       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.   

       You might quote cost extras as the reason but I bet people would pay more money per ticket for the peace of mind alone.   

       [cudgel] asks a fair question.   

       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.]"   

       Also, absent-minded armies could deploy prosepiparatroops to mystify their enemies. "What are they *doing* up there?"
pertinax, Jun 19 2013
  

       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...   

       Also meanwhile, I quite like the idea of a net full of angry, live bar-headed geese.
pertinax, Jun 19 2013
  

       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.
pertinax, Jun 19 2013
  

       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.   

       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.
MechE, Jun 19 2013
  

       //[...] but how quickly it can accelerate, turn over, decelerate, and intercept [...]//   

       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.
pertinax, Jun 19 2013
  

       Fascinating. Thanks [pertinax], I've never studied languages but most of them seem to make a lot more sense than English.   

       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.
MaxwellBuchanan, Jun 20 2013
  
      
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