MIAMI – Today in Aviation, the United States Federal Aviation Administration (FAA) certifies the Boeing 747SP in 1976.
After a difficult start for the Boeing 747, caused by a series of problems with the Pratt And Whitney PW JT9D engines, the Jumbo Jet developed by Boeing and designed by Joe Sutter has achieved considerable commercial success. Many airlines around the globe order the type to offer travelers the opportunity to travel to every continent with maximum comfort.
The aircraft is made as a transitional version to answer the Douglas DC-10 and the Lockheed L-1011 Tristar. The Boeing 747 was too big for some routes and Boeing did not have enough capital to design and build a new model, thus deciding to create a smaller one, with greater autonomy and optimizing speed at the expense of capacity.
The construction of the Boeing 747SP came from a request from PanAm. It asked Boeing for a variant of the Jumbo jet capable of carrying out the New York-Tokyo route without technical stops. Before making the SP variant, Boeing had considered two possibilities: a twin-engine variant or a three-engine variant.
History, Orders and Costs
Production of the Boeing 747SP began in 1973 at the Everett factories and on May 19, 1975 the first model left the facilities. On July 4, it made its first flight. On August 14, the second example made its maiden flight and on October 10, it was the third’s turn to take to the sky. On October 8, 1975, the fourth model was rolled out and flew for the first time on November 3.
With this aircraft Boeing decided to go around the world to promote the 747SP. The type, painted in Boeing colors and set up in Pan Am configuration and registration N40135, took off on November 11 from Seattle to New York. The next day, with 200 passengers on board, the type made a non-stop flight from New York to Tokyo, flying 12,999km in 13 hrs and 33 min, reaching a cruising altitude of 46,000 feet (14,020 meters) at a speed of 0.86 mach.
Once the Boeing 747SP landed, it still had 13,000 kg of fuel in the tanks. After the stop in Tokyo, the tour continued through Asia, passing by Taipei, Singapore, Kabul and Bombay before heading to Sydney.
The test program for the Boeing 747SP ended on December 22, 1975, two weeks ahead of schedule, with the three test aircraft flying a total of 544 hrs and 27 min, to which were added the 140 hours of the fourth tour. exemplary.
Pan Am signed an initial order for 10 units with an option for another 15 for approximately US$280m. Each unit cost just over US$27m, or US$3m less than the Boeing 747-200B, but US$1.5m more than the competing DC-10 and L-1011.
In addition to having a shorter fuselage of 14 meters, the Boeing 747SP had a larger rudder and tailplane, obtaining the following benefits: it could fly over 11,000km at a maximum speed of 981km/h, a higher rate of climb and the to operate at higher altitudes. The main deck entrance doors were 8 (4 per side) instead of 10 (5 per side).
The maximum capacity of the 747SP, in two classes was 331 seats, while in the three-class configuration 297 seats, while in a single class, 440 seats. The plane is 56.31 meters long, with a wingspan of 59.64 meters. With a top speed of 1095 km / h, the 747 special performance had a range of 11,500km.
There were two engines available: it was the P&W JT9D-7A/7AH/7AW/7F/7FW/7J and the Rolls Royce RB211-524B2/B4/C2/D4. The P&W JT9D was an engine that over time has had to undergo significant improvements, as it presented some problems not just. In addition to being under-sized in terms of thrust, it had overheating problems. This led to delays in the certification of the 747-100.
P&W moving forward in time, to overcome the problem of overheating, inserted a nozzle into the engine that sprayed water in large quantities to lower the operating temperature of the engine. To improve the air flow, 12 flaps were subsequently installed which closed and opened with special flaps or flaps by means of a vacuum drive.
With entry into service in 1970, P&W continued to improve the JT9D by using new materials, and above all by creating the EEC electronic engine control which was later replaced by the FADEC on the PW4000 series. The engine had a thrust between 21,000kg and 23,000kg.
The Rolls Royce RB211, developed in 1966, originally intended to equip the Lockhedd L-1011, had a troubled development. To have a significant advantage in terms of weight and performance, an innovative Hyfil front fan was introduced, a plastic reinforced with carbon fiber that guaranteed enormous weight savings. But, in foreign body ingestion tests, this innovative material proved very fragile.
Featured image: Las Vegas Sands VP-BLK Boeing 747SP-31. Photo: Misael Ocasio Hernandez/Airways