Now this is funny ... or sad?
In 1990, the U.S. AirForce unveiled its newest long range bomber:
The B2 "Stealth" bomber had cost billions to develop.
It was characterized by its allwing design:
The aerodynamic analysis included a ritual for finding the volume distribution that maximized the range.
The ritual involved taking a derivative and setting it equal to zero.
In general, to find the maximum of f(V), one sets the derivative equal to 0: f '(V) = 0
... then solve for the value of V. It'll be a "candidate" for the maximizing value.
To guarantee that it IS a maximum, one checks to see if the second derivative is negative: f ''(V) < 0
Conclusion? The volume should be "almost all in the wing".
Hence the B2.
 
Alas, the engineers who recommended the allwing design neglected to test the second derivative ... to see if'n it was a maximum or a minimum.
It turned out (as discovered subsequently), that the allwing design MINIMIZED the range of the aircraft.
Indeed, the flying wing was the aerodynamically worst possible choice of configuration.
Now, if'n I only had that story at my finger tips when I taught introductory calculus!
