Boeing 747SP

The Boeing 747SP (for "Special Performance") is a shortened version of the Boeing 747 widebody airliner, designed for a longer range.
Boeing needed a smaller aircraft to compete with the McDonnell Douglas DC-10 and Lockheed L-1011 TriStar trijet widebodies, introduced in 1971/1972. Pan Am requested a 747-100 derivative to fly between New York and the Middle East, a request also shared by Iran Air, and the first order came from Pan Am in 1973.
The variant first flew on July 4, 1975, was approved by the Federal Aviation Administration on February 4, 1976, and entered service that year with Pan Am.
The SP is shorter than all other 747 variants. Its main deck doors are reduced to four on each side to compensate for its lower capacity. The vertical and horizontal tailplane are larger and its wing flaps have been simplified. With a MTOW, it can fly 276 passengers in three classes over .
One 747SP was modified into the Stratospheric Observatory for Infrared Astronomy (SOFIA).
The last airliner was delivered in 1987; some were converted to transports of heads of state.
Sales did not meet the expected 200 units, and only 45 aircraft were ultimately produced.
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 Tehran. 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 was the longest non-stop commercial flight in the world for a short time). The aircraft was launched with Pan Am's first order in 1973 and the first example delivered in 1976.
A shorter derivative of the a 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. Until the arrival of the 767, 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.
Originally designated "747SB" for "short body", it later was nicknamed "Sutter's balloon" by employees after 747 chief engineer Joe Sutter. Boeing later changed the production designation to 747SP for "special performance", reflecting the aircraft's greater range and higher cruising speed. 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. Pan Am was the launch customer for the 747SP, taking the first delivery, "Clipper Freedom", on March 5, 1976.
The 747SP was the longest-range airliner available until the 747-400 entered service in 1989. Despite its technical achievements, the SP never sold as well as Boeing hoped. Increased fuel prices in the mid-1970s to early 1980s, the SP's heavy wings, high cost, and reduced capacity, and the increased ranges of forthcoming airliners were some of the many factors that contributed to its low sales. Only 45 were built and of those remaining, most are used by operators in the Middle East. However, some of the engineering work on the 747SP was reused with the development of the 747-300. In the 747SP, the upper deck begins over the section of fuselage that contains the wingbox, not ahead of the wingbox (as is the case with the 747-100 and 747-200). This same design was used in the 747-300 and newer 747-400, resulting in a stretched upper deck.
Design.
Apart from having a significantly shorter fuselage and one fewer cabin door per side, the 747SP differs from other 747 variants in having simplified flaps and a taller vertical tail to counteract the decrease in yaw moment-arm from the shortened fuselage. The 747SP uses single-piece flaps on the trailing edges, rather than the smaller triple-slotted flaps of standard 747s.
The SP could accommodate 230 passengers in a 3-class cabin or 331 in a (303 economy, 28 business) 2-class cabin, and a maximum of 400 passengers in one class.
Variants.
A special 747SP is the Stratospheric Observatory for Infrared Astronomy (SOFIA) astronomical observatory, which had 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-millimeter region; no window material is transparent over this whole range, so the observations are made through a 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 script on the port side of the aircraft.
Operators.
Deliveries.
Forty-five 747SP aircraft were built between 1974 and 1987 with two more planned but never constructed. The production line was ended in 1982 but reopened in 1987 to fulfill an order for the United Arab Emirates.
Current operators.
As of October 2020, there were six Boeing 747SPs still in active service with 18 more stored and one preserved. The remaining 19 were either scrapped, otherwise destroyed or abandoned. In 2016, the last 747SP in commercial service was withdrawn from service after 40 years by Iran Air. , the majority of the six aircraft still in service are used for governmental or VIP transport.
Former operators.
This list also includes organizations that used the aircraft temporarily, besides main operators.
Records.
There were three significant commercial around-the-world record-setting flights flown by 747SP: two operated by Pan Am and the other operated by United Airlines with the aircraft being "loaned" to Friendship Foundation, in order to raise money for the foundation. Those flights are:
Specifications.
"Note"