Saturday, November 5, 2011 5:15:44 PM
But that envelope is initially theoretical - it's based on calculations by the designers. If you fly at the limits of the envelope, you can determine how accurate it is. If you can fly the plane at the calculated safe limits, you are testing the boundary of the safe limits in one or more factors - you are pushing the envelope in that sense. If you exceed any safe factor and don`t crash as a result, you have moved the envelope outwards - you are pushing the envelope in that sense.
Saturday, November 5, 2011 5:10:36 PM
The phrase still doesn't make any sense. Maybe if it was an envelope filled with thousands of pounds of lead or something I would get it, but it`s pretty stupid.
It makes perfect sense once you know that strictly speaking an envelope is *anything* that envelops *anything*. In maths, it`s a well-defined term.
The origin of the phrase "pushing the envelope" comes from the combination of maths and engineering required in aircraft design. It describes the range of combinations of factors that the aircraft designers have calculated as being the safe parameters for flight. For example, flying speed and rate of turn. Below a certain speed, you`ll stall. At any given speed, there`s a limit to how fast you can safely turn without blacking out, losing control surfaces and/or over-stressing some key part of the aircraft. Plot that on a graph and you get a line surrounding the safe area - an envelope.