I know we have the cruise speed for altitude graphs and climb rates, but what I would like to see is a performance envelope for all of the aircraft in the game. Heck, if I was give the raw data (min/max speeds for given altitude in 1000 foot increments), I would put it together myself. It would be great to have one chart to show me minimum airspeed at a given alt and maximum for a given alt as well as displaying the ceiling for a given airspeed.
For those that are unfamiliar with the flight (performance) envelope,
here is a basic overview of it from Wikipedia. As stated, it is just a graph where the X axis if for airspeed and the Y axis is altitude. Each plotted point represents the minimum or maximum speed for a given altitude. The area inbetween all of the points represents the "envelope". Taking your aircraft outside of that envelope equates to departing controlled flight (and in the case of Vmax, usually loosing vital aircraft components).