In a paper delivered before the Society in March 1960, Morgan concluded that a Mach number of about 2.0 may prove a natural “fit” for the first generation of long-range supersonic transports. Sub-sequently, at the second Congress of I.C.A.S., Kuchemann developed the theme of fitting an aircraft to a particular duty and concluded that the slender wing provides a natural basis for the layout of the supersonic transport. It is convenient to accept these two papers as a starting point for a more detailed examination of the aircraft, since, taken together, they can be taken as fixing some of the major variables—range, speed and general layout.