ABSTRACT
That rule of thumb can be applied across 90 years of aviation during which successful airplane designs have eventually succumbed to techno logical obsolescence, such as the Curtiss Jenny, Douglas DC-3, and the Boeing 707. The best military aircraft designs-such as the DeHaviland DH4, Chance Vought F4U Corsair, McDonnell F4 Phantom, and Boeing B-52 Stratofortress-have all had somewhat shorter useful lives, but have followed the same trend.
