Boeing 707 lb (57.8 kN) with water injection. Maximum takeoff weight was 247,000 lb and first flight was on December 20, 1957. Major orders were the launch order for 20 707-121 aircraft by Pan Am and an American Airlines order for 30 707-123 aircraft. The first revenue flight was on October 26, 1958; 56 were built, plus seven short-bodied −138s; the last −120 was delivered to Western in May 1960. The 707-138 was a −120 with a fuselage 10 ft shorter than the others, with 5 ft (three frames) removed ahead and behind the wing, giving increased range. Maximum takeoff weight was
Boeing 707 During 1949–1950, Boeing embarked on studies for a new jet transport, realizing that any design must be aimed at both the military and civilian markets. At the time, aerial refueling was becoming a standard technique for military aircraft, with over 800 KC-97 Stratofreighters on order. With the advent of the Jet Age, a new tanker was required to meet the USAF's fleet of jet-powered bombers; this was where Boeing's new design would potentially win military orders. Boeing studied numerous wing and engine layouts for its new transport/tanker, some of which were based on the B-47 and C-97, before settling on