TheBoeing 747SP (forSpecial Performance) is a shortened version of theBoeing 747 wide-body airliner, designed for a longerrange. It is the highest flying subsonicpassenger airliner, with aservice ceiling of 45,100 feet (13,700 m).Boeing needed a smaller aircraft to compete with theMcDonnell Douglas DC-10 andLockheed L-1011 TriStar tri-jet wide-bodies, introduced in 1971/1972.Pan Am requested a747-100 derivative to fly betweenNew York and theMiddle East, a request also shared byIran Air, and the first order came from Pan Am in 1973.
The variant first flew on July 4, 1975, was approved by theFederal Aviation Administration on February 4, 1976, and entered service that year with Pan Am.
The SP is 184 feet 9 inches (56.31 m) in length, 47 feet (14 m) shorter than the original 747 variants. Its main deck doors are reduced to four on each side to suit its lower capacity. The vertical and horizontaltailplanes are larger and itswing flaps have been simplified. With a 700,000-pound (320 t; 320,000 kg) maximum take-off weight, it can fly 276 passengers in three classes over 5,830nautical miles [nmi] (10,800 km; 6,710 mi).One 747SP was modified into theStratospheric Observatory for Infrared Astronomy (SOFIA).The last example was delivered in 1987; some were converted totransports of heads of state.Sales did not meet the expected 200 units, and only 45 aircraft were ultimately produced.[2]
The idea for the 747SP came from a request byPan Am for a 747 variant capable of carrying a full payload non-stop on its longest route betweenNew York andTehran.[3] Joined with Pan Am's request wasIran 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[4] (New York to Tehran was the longestnon-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 was delivered in 1976.[5][6][7]
A shorter derivative of the 747-100, the SP was developed to target two market requirements.[5] The first was a need to compete with theDC-10 andL-1011 while maintaining commonality with the 747,[5] which in its standard form was too large for many routes. Until the arrival of the767, 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 highercruising 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.[8]
Originally designated747SB for "short body", it was later nicknamed "Sutter's balloon" by employees after 747 chief engineerJoe Sutter.[9] Boeing later changed the production designation to 747SP for "special performance", reflecting the aircraft's greater range and higher cruising speed.[10] Production of the 747SP ran from 1976 to 1983. However, a VIP order[5] for UAE'sAbu Dhabi Amiri Flight 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.[10] Pan Am then made the first flight of the 747SP on April 25, 1976, making a nonstop flight from New York to Tokyo.[11][12]
The 747SP was the longest-range airliner available until the747-400 entered service in 1989. Despite its technical achievements, the SP never sold as well as Boeing hoped.[5] Increased fuel prices in the mid-1970s to early 1980s, the SP's heavy wings, high cost,[5] and reduced capacity, and the increased ranges of forthcoming airliners[5] were some of the many factors that contributed to its low sales. Only 45 were built. However, some of the engineering work on the 747SP was reused with the development of the747-300. In the 747SP, the upper deck begins over the section of fuselage that contains the wing box, not ahead of the wing box (as is the case with the 747-100 and747-200). This same design was used in the 747-300 and newer 747-400, resulting in a stretched upper deck.[citation needed] A proposed variant called Boeing 747 ASB, which based on 747SP's design with advanced improvements found on 747-400, includes new glass cockpit, new engine options, and winglets, was announced in 1986 but cancelled later year due to low interest from airlines and in favor ofBoeing 777.[13]
Iran Air 747SP from above, 47 ft (14 m) shorter than the 747, with four exit doors per side
Apart from having a significantly shorter fuselage and one fewer cabin door per side, the 747SP differs from other 747 variants in having simplifiedflaps and a tallervertical tail[5] to counteract the decrease in yaw moment-arm from the shortened fuselage. The 747SP uses single-piece flaps on thetrailing edges, rather than the smaller triple-slotted flaps of standard 747s.
The SP could accommodate 230 passengers in a 3-class cabin or 331 (303 economy, 28 business) in a 2-class cabin, and a maximum of 400 passengers in one class.[citation needed]
From 2007 until 2022, a specially modified 747SP was used as theStratospheric Observatory for Infrared Astronomy(SOFIA) astronomical observatory,[5] operated jointly byNASA and Germany'sDLR. A former Pan Am and United Airlines aircraft acquired in 1997, its airframe was modified to carry a 2.5-meter-diameterreflecting telescope to high altitude, above 99.9% of the light-absorbing water vapor in the atmosphere. The telescope and its detectors covered a wide wavelength range from the nearinfrared to the sub-millimeter region; no window material is transparent over this whole range, so the observations were made through a 13 feet (4.0 m) square hole in the port upper quarter of the rear fuselage, aft of a new pressure bulkhead. A sliding door covered the aperture when the telescope was not in use.[14] Astronomers took data and controlled the instrument from within the normally pressurized cabin. Originally delivered to Pan Am and named "Clipper Lindbergh", the name was displayed in script on the port side of the aircraft.[citation needed]
In September 2022,SOFIA ceased operations after the conclusion of its final mission. The retirement was made both on the grounds of cost and suitability for the requirements of the decade to come.[15] The aircraft was later flown to thePima Air & Space Museum inTucson,Arizona, to be put on public display.[16]
Forty-five 747SP aircraft were built between 1974 and 1987.[17] The production line was ended in 1982 but reopened in 1987 to fulfill an order for the Abu Dhabi Amiri Flight.[18]
As of June 2024[update], there are just two Boeing 747SPs remaining in active service, both operating astestbed aircraft for engine manufacturerPratt & Whitney Canada.[19][20] Eighteen more aircraft are stored or otherwise preserved. The remaining aircraft were either scrapped, otherwise destroyed, or abandoned.[17] In 2016, the last 747SP in commercial service flew from Tehran to Mumbai before being withdrawn from service after 40 years byIran Air.[21][22] In 2020, the last aircraft in governmental use was stored by the Royal Flight of Oman.[23]
There were three significant commercial around-the-world record-setting flights flown by 747SP: two operated byPan Am and the other operated byUnited Airlines with the aircraft being "loaned" to Friendship Foundation, in order to raise money for the foundation. Those flights are:
Pan Am Flight 50—to celebrate the 50th anniversary of Pan Am. Flown October 28–30, 1977 fromSan Francisco, with a time duration of 54 hours, 7 minutes, 12 seconds. 3 stopovers atHeathrow Airport,Cape Town andAuckland. Flight 50 flew over both the North Pole and the South Pole.
Friendship One[5]—Flown January 29–31, 1988 fromSeattle, to raise funds for Friendship Foundation. Two stopovers were made, atAthens andTaipei. The record lasted less than a month, as it was beaten by aGulfstream IV. The round-the-world flight took 35 hours and 54 minutes over 23,125 miles.[5]
In 1976 a Boeing 747SP (ZS-SPA) ofSouth African Airways was flown non-stop from theBoeing Company factory inSeattle to Cape Town during its delivery flight. This was a world record for an un-refueled commercial aircraft, this record was held for over a decade.[54]
On February 19, 1985,China Airlines Flight 006, a 747SP-09 (aircraft registration N4522V) with 274 passengers and crew on a flight fromChiang Kai-shek Airport toLos Angeles suffered an inflight failure onengine number four. While the flight crew attempted to restore power the aircraft rolled to the right and started a steep descent from the cruising altitude of 41,000 feet, pulling 4.8 G and 5.1 G on two occasions. The captain managed to stabilize the aircraft at 9,500 feet and the aircraft diverted toSan Francisco which was 550 km (297.0 nmi; 341.8 mi) away. Two passengers were injured and the aircraft suffered major structural damage.[55]
On October 5, 1998, aSouth African Airways Boeing 747SP-44 (ZS-SPF) operated byLAM Mozambique Airlines suffered an engine failure shortly after take-off fromMaputo International Airport, Mozambique. The no. 3 engine suffered an uncontained failure – flying debris caused damage to the no. 4 engine and the wing. A fire broke out that couldn't be extinguished immediately, forcing an emergency landing. All 66 people on board survived. As a result, the aircraft was withdrawn from service and scrapped.[27]
During theYemeni Civil War, a 747SP owned by thePresident of Yemen, 7O-YMN, was struck by gunfire on March 19, 2015. Subsequent photographs show that the aircraft was then completely destroyed by fire afterward.[citation needed]
On August 27, 2020, aLas Vegas Sands Boeing 747SP-21 (VQ-BMS) was damaged beyond repair duringHurricane Laura while undergoing maintenance. The right-hand wing fractured and the wing of another aircraft, believed to be BBJ N836BA, cut through the forward fuselage.[57]
^"The Boeing 747 Classics".Boeing Commercial Airplanes. Boeing. RetrievedJanuary 23, 2009.Boeing also built the 747-100SP (special performance), which had a shortened fuselage and was designed to fly higher, faster and farther non-stop than any 747 model of its time.
^McWhirter, Norris; McWhirter, Ross (1976).Guinness Book of World Records 1977. New York: Sterling Publishing. p. 321.ISBN0806900164.The longest scheduled non-stop commercial flight is the thrice weekly Pan Am New York City-Tokyo Flight 801 (6,754 statute miles) of 13 hours 40 minutes, inaugurated on April 26 1976.
^"Nonstop to the Orient...".Via Port of New York.28: 17. 1976.Pan Am has scheduled the first and fastest New York - Tokyo nonstop flights to begin on April 26, utilizing the Boeing 747 SP (Special Performance) jetliner in commercial aviation's version of the 'Orient Express.'
^"Boeing offers 747ASB"(PDF).Flight International. June 7, 1986.Archived(PDF) from the original on October 9, 2022. RetrievedOctober 6, 2012.
^"NAS's new airborne observatory".Sky and Telescope.120 (4):22–28. October 2010.
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