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> keep wondering, what is the origin of the recently-popular "pushing the
> envelope"?  Mental pictures of legal-sized envelopes getting shoved around a
> table do not help. (Except to get me giggling).
>
Johanna,
  "Pushing the envelope" comes from aviation. Every aircraft type
manufactured (from Cessna 150s to Boeing 767) has to undergo tests
(usually by the manufacturer) to determine it's safe operating parameters.
Things like how fast it can go, and much more important, how slow can it
go and remain in flight?  Then you add things like how many degrees of
flaps does it take to let me fly x-amount slower. And 'what happens if I put
another 100 lbs behind the rear seats'. All these things make up the
safe OPERATING ENVELOPE. You can actually see a part of that illustrated
in the Pilots Operating Handbook (POH) for any manufactured aircraft type
by looking at the _Center of Gravity Moment Envelope_ graph.

The manufacturer comes up with what they _think_ those parameters should be
during the design phase. Once the test aircraft is completed someone has
to go out and actually fly the thing to see if the designers were right
<-g->. Part of the testing procedure includes the test pilot deliberately
exceeding (either doing too much or too little of whatever is being
tested) the design envelope - thus he is "pushing the envelope".

Pilots who regularly push the envelope without being part of an official
test program generally don't get to be "old pilots". There is a saying
among aviators: "There are old pilots, and bold pilots. But there aren't
many old, bold pilots."  (except Chuck Yeager!)

        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        Melissa Davis                   Librarian       & Private Pilot
        Splendora Middle School         Splendora I.S.D.
        P O Box 168                     Splendora, TX 77372
        Internet: mbdavis@tenet.edu     PHONE: (713)689-2853
        CompuServe: 75146,771           FAX: (713)689-8702
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