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Bungee jumping but...

...from two aircraft with a non-stretchy rope and completely different.
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As my esteemed colleague [MaxwellBuchanan] pointed out otherwhere on this site, a system was devised in the 1920s for lowering a person or object from an aeroplane by means of a rope. It involved the plane flying in circles while the lowered person remained relatively still at the centre.

Howevertheless, this is relatively little fun, and involves only one aeroplane which has to fly in circles.

So.

Instead, we have two aircraft, flying one behind the other and, say, 1000ft apart at an altitude of 1000ft.

The person to be lowered (and I would like to volunteer, personally, that [8th] be that person in the first instance) sits in the back of the front 'plane, which (and this is important) has a tailgate opening.

A non-stretchy rope is attached to this person's harness, and runs from there to a second attachment point on the rearmost aeroplane.

At an appropriate moment, said person steps off the tail ramp of the frontmost aeroplane.

Viewed from the perspective of the second aeroplane, the person will swing, pendulum-like, underneath the aeroplane.

With some careful control of flying speed, the person will reach the bottom of the arc and be:

(a) At exactly zero feet above the ground
(b) Travelling backwards, with respect to the second aeroplane, at a certain speed V which will
(c) exactly match the groundspeed of the aeroplane.

Assuming that all of these criteria have been met, the person has merely to press the quick-release button on the rope, to be left standing calmly after the experience of a lifetime (potentially).

MaxwellBuchanan, Jul 06 2014

Skyhook https://www.youtube...watch?v=u4xlYpKrCnU
hard to believe but totally true [xenzag, Jul 07 2014]

[link]






       You really need to see someone about this split personality problem your experiencing [Max].
Skewed, Jul 06 2014
  

       //I would like to volunteer, personally, that [8th] be that person//   

       Makes sense, as a borg collective he's got plenty of spare bodies after all.
Skewed, Jul 06 2014
  

       //the person has merely to press the quick-release button on the rope, to be left standing calmly after the experience of a lifetime (potentially)//   

       Or if it all goes horribly wrong ends up as rather a lot of geography, as a consolation prize he (or she) gets a touching eulogy from their nearest & dearest, I find it slightly disturbing that I'd actually like to try this (after 8th).
Skewed, Jul 06 2014
  

       Well, I'm afraid that I'm going to agree and disagree.   

       First, I agree about the test pilot part.   

       Second, the rope is going to immediately go slack as the downward acceleration will pale into insignificance compared to the deceleration caused by the wind.   

       And don't think you can go changing the rope to a pole, either. How you gonna get a 1000ft pole as carry on?
Ling, Jul 06 2014
  

       [Ling] the behindermost aeroplane should be at a somewhat higher altitude so the initial drop angle is not vertical.
pocmloc, Jul 07 2014
  

       This is clever, and has a certain surface patina of logic to it. However, like [Ling], I worry that air resistance will cock the whole thing up and lead to the deaths of legions of your test subjects.
hippo, Jul 07 2014
  

       //the rope is going to immediately go slack//   

       I rather thought there'd be something like an extendible dog leash mechanism to prevent slack as the rope pays out, was sure I'd seen such in use as an alternative to landing or a parachute for fast yet controlled drops from helicopters & the like.   

       The friction / grip applied by these as it pays out also keeps the speed of decent to non-terminal velocities.   

       Or have I misunderstood your concern [Ling]?
Skewed, Jul 07 2014
  

       [Skewed] "friction / grip" -> "gription" (q.v)
hippo, Jul 07 2014
  

       Well, at a pinch we could always have the rearmost aeroplane in front, and the foremost one behind.
MaxwellBuchanan, Jul 07 2014
  

       Well, that does make a lot more sense.   

       // careful control of flying speed //   

       We wish to point out that for fixed-wing aircraft, there is a well- defined range of velocity within which flying is possible.
8th of 7, Jul 07 2014
  

       Actually, there may be a way to test this without terminal deceleration (isn't suddenly stopping from more than 20mph, terminal?).   

       If you hung from a plane, and then powered forwards in ever more increasing arcs*, just like a swing but from the moving plane, there may be an optimum point where air resistance and the swing downwards combine to cancel out the planes velocity. If the rope starts to get slack during the increasing arc phase of the experiment, then stop and find someone else to carry on the experinent.   

       *The plane could accelerate/decelerate
Ling, Jul 07 2014
  

       Do you actually need a second plane? I think you could have one big plane which could pay out a sort of gliding drogue. You'd need 2 pieces of rope - one to pull the drogue and one to dangle the minion.
Then when you've deployed your volunteer you can winch it back in and attach another.
Loris, Jul 07 2014
  

       //for fixed-wing aircraft, there is a well- defined range of velocity within which flying is possible.//   

       Quite so. This might work best from a pair of biplanes, many of which have stall speeds in the few-tens of mph. It might also require the droppee to be very dense. [8th]?
MaxwellBuchanan, Jul 07 2014
  

       <Shuffles behind [Skewed], points meaningfully>   

       // "I find it slightly disturbing that I'd actually like to try this " //   

       Hey, we're not going to stand in your way !   

       Ohh, look ! There, on the ground ! Money !   

       <Tries to surreptitiously attach large carabiner on a long rope to the back of [Skewed]'s belt>
8th of 7, Jul 07 2014
  

       [8th] I'll buy you a ticket to the National Railway Museum if you go guinea-pig on this one.
MaxwellBuchanan, Jul 07 2014
  

       [Skewed], if it ends badly the ticket's yours.
MaxwellBuchanan, Jul 07 2014
  

       Check out the link. Skyhook rescue system.
xenzag, Jul 07 2014
  

       The link is cool (though not as cool, clearly, as the present invention).   

       However, I'm unhappy about the way they tested it on a sheep first. Sheep are expensive, sentient beings.   

       [8th] have you got that harness on yet?
MaxwellBuchanan, Jul 07 2014
  

       I remember reading about a helicopter based people deployment system that's similar to this. The people hang from the heli at the end of long ropes, and the chopper does a brief flaring maneuver, timed so the people swing forward, come to a complete stop exactly where they want to get off (whereupon they unclip), by which time the chopper is moving off at a smart pace. The idea being, say, to drop people off onto a rooftop without people in the building knowing it was being done. The heli pauses so briefly in the maneuver that there's a good chance no one realises what's been done. anyhow, it's similar in that it uses pendular motion.
Custardguts, Jul 07 2014
  

       // National Railway Museum //   

       Ohhhhh ... <dribbles>   

       <picks up parachute harness>
8th of 7, Jul 08 2014
  

       +1: The sound of the sheep in the skyhook video
Ling, Jul 08 2014
  

       //<picks up parachute harness>//   

       Ah - we thought a full parachute harness would be a bit over the top for the first tests. If you just slip your arms into the two loops in the string, and hold very tightly, it'll probably be alright.
MaxwellBuchanan, Jul 08 2014
  

       OK, done that. So what happens noTWOINGGGGGGG EEEeeeeeeeaaaaaahhhhhh .....
.
.
.
.
<distant thud>
8th of 7, Jul 08 2014
  

       No sheep baaaaaaaaaaaa sound?
xenzag, Jul 08 2014
  

       <faint groans and whimpering>
8th of 7, Jul 08 2014
  

       //gription//   

       [hippo], it only just occurred to me to Google gription, I didn't know it was a real word, thanks.   

       <looks round>   

       Where's [8th] gone I thought I heard him here a minute ago?... is that his National Railway Museum ticket on the floor there?, oh well, if he doesn't want it.
Skewed, Jul 08 2014
  

       That's spoken for.   

       Well, the dummy run with [8th] went about as well as expected. It's been very useful to be able to find the weak points in the arrangement.   

       Admittedly, trying to drop [8th] directly into the National Railway Museum was a bit overambitious. Who knew they'd built that new shed? Still, [8th] seemed to enjoy it. At least, when I said "Did you enjoy it?", his left eye blinked once. Unless it was a twitch. It was hard to tell while he was wearing all that corrugated iron.
MaxwellBuchanan, Jul 08 2014
  

       With respect to the rear plane, this person would be travelling at a maximum of terminal velocity for a falling person I think, presuming they conserved their speed. That's about 200 km/hr, seemingly feasible for a near-zero groundspeed.   

       I'll be sure and look for it in the next Bond film.
RayfordSteele, Jul 08 2014
  

       <twitch>
8th of 7, Jul 08 2014
  

       Presumably this could also operate in reverse for picking up a person from the ground.
pocmloc, Jul 08 2014
  

       Hey! Did you see that?! [8th] twitched! I told you he'd be fine.
MaxwellBuchanan, Jul 08 2014
  

       There he is!   

       Well duh!, he's got nanites, could take them a while to repair all that damage though, not sure how good they are at repairing brain damage, do you think he hit his head?
Skewed, Jul 09 2014
  

       I'm not sure. I thought I saw a lot of bruising and puffiness around the face and nose, until I realized I was looking at the wrong end.
MaxwellBuchanan, Jul 09 2014
  

       <bzzt> .... <fsssszt> ....
8th of 7, Jul 09 2014
  
      
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