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 already seen on the −320C. These reduced takeoff and landing speeds and altered the lift distribution of the wing, allowing the ventral fin found on earlier 707s to be deleted. From 1965, -320Bs had the uprated −320C undercarriage allowing the same MTOW. These were often identified as 707-320BA-H. The 707-320C has a convertible passenger–freight configuration, which became the most widely produced variant of the 707. The 707-320C added a strengthened floor and a new cargo door to the −320B model. The wing was fitted with three-section leading-edge flaps which allowed the deletion of the underfin. Three hundred and thirty-five of