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From: dappel@grafted.UUCP (Dave Appel)
Newsgroups: rec.skydiving
Subject: bungee jump from plane
Message-ID: <38P3w3w161w@grafted.UUCP>
Date: 9 Feb 91 00:39:13 GMT
Sender: bbs@grafted.UUCP
Organization: Grafted Branch, Indianapolis, IN
Lines: 41

to: the genius who wants to bungee jump from a plane.
 
Uh, excuse me, but where did you leave your BRAIN?
 
Do you have any idea of the effects that vector forces have
on an airplane?  Lift, drag, thrust, etc?  Have you ever
noticed the pilot trying his darnedest to maintain straight
and level flight with 4 or more skydivers hanging on the
outside?  Usually causing the CG (center of gravity) to
be outside of normal limits?
 
First off, connecting the bungee cord to any point other than
the center of gravity is going to cause the plane to be unstable
at best, or tumble out of the sky at worst.

SECOND, as each person leaves the plane, the center of gravity
changes.  Thus the connecting point is going to move.
 
THIRD, it would be impossible to connect the bungee to the
"true" CG, but it would have to be connected to the frame
or fuselage at the nearest point. Thus, when a force is
applied on the connecting point, it will cause the plane
to rotate. Initially in a direction perpendicular to the
line segment between the connecting point and the true CG.
 
FOURTH, the pendulum effect of a mass hanging at the end
of a long elastic cord is going to cause it to bounce around.
What effect do you think this will have on the pilot's efforts
to keep the plane stable?
 
How big a plane did you plan to do this from? I've noticed that
even when a skydiver shifts his position from sitting on his
(or her, excuse me) butt to a kneeling position in the back of
a Twin Beech, that the pilot immediately feels it and has
to make small adjustments.  Now imagine the torque applied
by a 200 pound object at the end of a 300 foot elastic cord.
 
Maybe, just MAYBE, such a stunt would be possible from a C-130
hercules, where the weight of one jumper would make only
a very small difference in the CG.   But anything the size
of a DC-3 or smaller would be courting disaster.