Boeing 747SP - Development

Development

The idea for the 747SP came from a request by Pan Am for a 747 variant capable of carrying a full payload non-stop on its longest route between New York and Tokyo. Joined with Pan Am's request was Iran Air; their joint interest was for a high capacity airliner capable of covering Pan Am's New York–Middle Eastern routes and Iran Air's planned New York-Tehran route. (New York to Tehran may have been the longest non-stop commercial flight in the world for a short time, until Pan Am started Tokyo to New York in mid-1976.) The aircraft was launched with Pan Am's first order in 1973 and the first example delivered in 1976.

A shorter derivative of the 747-100, the SP was developed to target two market requirements. The first was a need to compete with the DC-10 and L-1011 while maintaining commonality with the 747, which in its standard form was too large for many routes. Boeing lacked a mid-sized wide-body to compete in this segment. The second market requirement was an aircraft suitable for the ultra-long-range routes emerging in the mid-1970s following the joint request. These routes needed not only longer range, but also higher cruising speeds. Boeing could not afford to develop an all-new design, instead opting to shorten the 747 and optimize it for speed and range, at the expense of capacity. Production of the 747SP ran from 1976 to 1983. However a VIP order for the Royal Flight of Abu Dhabi led Boeing to produce one last SP in 1987.

A special 747SP is the Stratospheric Observatory for Infrared Astronomy (SOFIA) astronomical observatory, which has its airframe modified to carry a 2.5-meter-diameter reflecting telescope to high altitude, above 99.9% of the light-absorbing water vapor in the atmosphere. The telescope and its detectors cover a wide wavelength range from the near infrared to the sub-milimeter region; no window material is transparent over this whole range, so the observations are made through a 13 ft (3.96 m) square hole in the port upper quarter of the rear fuselage, aft of a new pressure bulkhead. A sliding door covers the aperture when the telescope is not in use. Astronomers take data and control the instrument from within the normally pressurised cabin. Originally delivered to Pan Am and titled "Clipper Lindbergh", NASA has the name displayed in Pan Am script on the plane.