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From: pvf@ESD.3Com.COM (Paul Fries)
Newsgroups: rec.skydiving
Subject: Re: bungee jump from plane
Message-ID: <3044@bridge2.ESD.3Com.COM>
Date: 13 Feb 91 20:03:19 GMT
References: <40BXw1w163w@ireta.cynic.wimsey.bc.ca> <1991Feb13.172511.6896@murdoch.acc.Virginia.EDU> <1991Feb13.191314.13568@cbnewsh.att.com>
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Organization: 3Com Corporation
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In article <1991Feb13.191314.13568@cbnewsh.att.com> msb@hos1cad.ATT.COM (Mike Balenger) writes:
>
>>>>>> On 13 Feb 91 17:25:11 GMT, ds4a@dalton.acc.Virginia.EDU (Dale Southard) said:
>
>ds4a> 1) Can the jumper really bounce back up and hit the plane? (I
>ds4a> think this violates some enery conversion law somewhere)
>
>Finally, a good question!!!
>
>Bungee jumpers never make it back to the jump altitude!!!  (I think
>they make it back to about 70%, but I'd rather hear the real number
>from a real jumper.)  Energy is lost in stretching the cord and
>overcoming air drag.  My guess is that the air drag on a plane bungee
>jumper would so dominate the equations that there'd be little or no
>rebound.  Boo hiss!!!  I'd like lots of rebounds.

I can't comment on this particular thing.  In a very early reply
to the original post, I asked what was going to happen to the bungee
when the jumper released.  It would, I think, be able to get back to
the plane.  Could it get into the prop? control surfaces? what else?

Re: the magnitude of the force acting on the plane when you have a
jumper in tow vs the bungee jumper:

Nobody seems to account for the different relative velocities of the
two situations.  A jumper in tow hits the end of the static line in
about 10 feet or so.  His relative velocity with respect to the plane
is not great.  The bungee jumper on a 300 foot elastic is going to
have a lot more relative velocity.  Is this going to be distributed
adequately by the elastic, or is it going to be transmitted as a jolt
to the airframe?  If a jolt is involved, I fear it would be well in
excess of the jolt presented by the jumper in tow situation, even
though the jumper in tow does not have an elastic static line.

Comments?

pvf