In 1943, Theodor Von Karman, in response to a request by US Air Force headquarters, claimed that the realization of a supersonic aircraft would have been doable using the right technology and tools. The fear of breaking the "sound barrier" was finally removed in 1947, when the Captain Yaeger flew the Bell X-1 at a speed slightly above Mach 1 for few seconds, producing the famous and long-awaited sonic boom (caused by an impulsive pressure change created by the sonic waves detaching from the aircraft), music for the scientists attending that historical moment, but current nightmare for the 21st Century supersonic vehicles' designers .
Since the first wind tunnel investigations on high speed flow over a stationary airfoil (1918), it was clear that when the free stream velocity approached a certain value, a major increase in drag coefficient occurred at exactly what later was characterized as the drag-divergence Mach number. Thanks to the introduction of Shclieren optical system, in 1933, it was possible to state that this aerodynamic phenomenon was mainly due to the presence of regions of supersonic flow over the airfoil consequently terminating in a shock wave, which is the cause of the drag-increasing flow separation downstream the shock .
The presence of the wave drag represented the main technical obstacle for the design of supersonic aircraft and, to the same extent, for the improvement of their cruise efficiency. Indeed, the need of source of thrust powerful enough to overcome the increased drag force, embodies a major second technical challenge.
From the 1947 four rocket engines solution of the X-1, to the 1960's state of the art B-58's GE J79 jet engines, the power issue was addressed with increasing sophistication. It focused only on the pure performances, neglecting the big problem of emission control that would eventually contribute to the failure of the most recent supersonic transport programs (SST).
The B-58 itself showed to the world that the possibility of a civilian SST was at least worthy of accurate investigation and capital investments. Although the large bomber implemented the supersonic efficient area-ruling design first introduced by Whitcomb (mid 1950s ) and therefore it could deliver a nuclear payload cruising at Mach 2 for about two hours, the light and thin wings, designed for high altitude flight and inefficient close to the ground at subsonic speed, highlighted a new set of primary technical challenges to be addressed by a commercial SST: the realization satisfactory structural design, the optimization of the wing aerodynamics for subsonic flow, and related to the last point, the improvement of takeoff and landing performance. A deadly crash at 1961 Paris air show summed up all the concerns about safety issues related to a not optimal overall design .
Three civilian SST programs started in the 1960s: the successful Anglo-French Concorde, the somewhat failed Russian TU-144 and the short ten year long...