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Boeing 747

The Boeing 747 was first of the wide-body turbo fan-powered transports to enter airline service. The 747 jumbo jet, first produced in the mid-1960s, is still selling. Design work on the aircraft was initiated in the 1960's, and the first details were announced in April 1966. Simultaneously, Pan American World Airways announced orders for 25 [441] of the new aircraft. First flight Look place in February 1969, and certification was completed by December of that year. The first passenger were carried on a flight from New York to London on January 22, 1970. The 747 aircraft is utilized by 32 operators throughout the world. Over 595 units had been ordered by mid-1982, and the type remained in production for years thereafter.

The appearance of the four-engine 747 is very similar to that of its well-known ancestor, the Boeing 707. In addition to its large size, however, the 747 has two distinguishing features. First, the passenger cabin extends all the way to the forward end of the fuselage. The flight deck, with a small cabin behind it, is mounted on a second level and is reached by a circular stairway from the main cabin. This interior arrangement results in a distinctive hump in the external appearance of the top, forward end of the fuselage.

A second distinguishing feature of the 747 is the main landing gear, which is unique for a passenger-carrying aircraft. The main gear consists of four struts, or posts, to which are attached four-wheel bogies. The two rear struts are mounted on the fuselage near the trailing edge of the wing and retract forward into the fuselage. The other two struts are mounted in the wing, farther forward, and retract inward into the wing. The four-post main gear is required in order to property distribute the massive weight of the aircraft on the runway.

The engines first offered on the 747 were the Pratt & Whitney JT9D turbofans. In addition to these engines, the aircraft is now certified with the General Electric CF6 and the Rolls-Royce RB.211 turbofans. The 747-200B, for which data are given in table VII, is powered with four JT9D-7R4G2 engines of 54,750 pounds thrust each.

The aerodynamic configuration of the 747 is very similar to that of the 707. The 747 wing has slightly more sweepback than that of the 707 and is of about the same aspect ratio. An improved airfoil design is also incorporated in the wing of the 747. The maximum lift-drag ratio of the aircraft, (L/D)max, is estimated to be about 18, as compared with a value somewhat over 19 for the 707, The lower value of (L/D)max, results from a higher value of ratio of wetted area to wing area on the 747 than on the 707.

The high-lift system employed on the 747 is typical of Boeing practice and consists of trailing-edge triple-slotted flaps, similar to those employed on the 727, and leading-edge flaps. The lateral control system utilizes a combination of spoilers together with inboard and outboard ailerons. The spoilers are also used for lift and drag control when deployed symmetrically. The horizontal tail is located in the conventional low position at the rear of the fuselage. Longitudinal control is provided by an elevator and adjustable stabilizer trim system. No trim tabs are employed. All controls are fully powered.

The very large size of the Boeing 747 is the most striking feature of the aircraft. The gross weight of the 747-200B is 836 000 pounds, for many years more than that of any other aircraft ever built. The Lockheed C-5A military cargo transport is the next largest aircraft at a weight of 769 000 pounds. The 747-200B can carry a maximum payload of 144 520 pounds for a distance of 6854 miles and has a cost-economical cruising speed of 564 miles per hour (Mach number of 0.85) at an altitude of approximately 35 000 feet. With a maximum fuel load and a reduced payload of 87 800 pounds, the range is 8706 miles. In a maximum capacity configuration, the aircraft can carry 550 passengers with 10-abreast seating. In this arrangement, four seats are placed in the middle of the aircraft, between the two aisles, and three seats are located against either side of the cabin. Many other seating arrangements for a smaller passenger load are used in the aircraft. The particular seating arrangement utilized is dictated by the airline using, the aircraft and is based on the passenger density anticipated on the various routes served by the aircraft.

The 747-100 entered commercial service in 1970. Initially, engines only were available from Pratt & Whitney, but by 1975 engines also were available from General Electric and Rolls-Royce. Boeing delivered 250 of the 747-100s, the last in 1986. Boeing built two versions of the 747-100 passenger airplane, one of which had a higher payload capacity and was known as the -100B. The 747-100 also was available as a short-range airplane, which had a modified body structure to accommodate a greater number of takeoffs and landings. This model typically was used by airlines on short flights with a high-passenger capacity, as many as 550. 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.

Although the 747-200 was developed after the 747-100, it was built during roughly the same time frame. The first -200 went into commercial service in 1971, and Boeing delivered a total of 393, the last in 1991. Although its external appearance is nearly identical to the 747-100, it was designed to carry more payload. In addition to being offered as a passenger airplane, the -200 was the first 747 to be configured as a freighter, a combination passenger-freighter and a convertible.

From the beginning, the 747 was designed to serve as an all-cargo transport. The first 747 Freighter could easily carry 100 tons (90,000 kg) across the Atlantic Ocean or across the United States. Its operating cost was 35 percent less per ton mile than the 707 Freighter. The 747 Freighter has a hinged nose to allow cargo loading through front of the airplane, with the option of a large side-cargo door.

The 747-200 Convertible was configured to serve as a passenger airplane, a freighter or a combination of both. This airplane responded to airlines' needs to carry different payloads at different times of the years, such as higher passenger capacities during the summer and more cargo during the winter. Similar to the convertible is the -200 Combi, which was designed to serve as a passenger-only airplane or as a passenger-freighter mix. The combi has a large side-cargo door on the main deck, and is used by airlines to make better use of their routes during different times of the year. The convertible has a nose cargo door similar to the freighter.

The 747-300 entered commercial service in 1983, and was the first to integrate the most significant changes of the 747 Classics. These changes included an extended upper deck and improved engines with a reduced fuel burn of 25 percent per passenger. In addition, passenger capacity increased 10 percent by extending the upper deck and relocating the new straight stairway to the rear of the upper deck (prior models had a spiral-shaped staircase in the center of the upper deck). The 747-300 had an upper deck extended by nearly 24 feet. Sixty-nine passengers can be carried in a six-abreast configuration in the upper deck of this aircraft and total capacity is 624. Overall size and gross weight are not altered by the extended upper deck. Boeing delivered 81 747-300s in passenger, combi and short-range configurations, the last in 1990.

Boeing has designed or modified 15 747s for special purposes. Among them are two 747-200s delivered as U.S. presidential Air Force One airplanes, and four 747-200s, designated E-4s, delivered to the U.S. Air Force as airborne emergency command and control posts. Another 747 was modified to ferry the U.S. space shuttle between California and Florida. Other 747s have been demonstrated as tankers capable of refueling other airplanes in flight.

In addition, Boeing completed modifications to 19 existing 747-100s to Civil Reserve Air Fleet (CRAF) configurations in 1990. If called into service by the U.S. Air Force, these passenger planes can be converted to freighters in less than 48 hours. Boeing donated the original 747, line No. 1, to Seattle's Museum of Flight. On lease to Boeing, it occasionally is used as a flying testbed for aeronautical developments.

The Boeing 747 is available in 10 versions adapted to various airline needs. One major variant of the 747 is the 747SP (Special Performance), which is lighter and has a smaller fuselage and lower passenger capacity but has a longer range than any other version of the aircraft.

In developing the 747, Boeing designers understood that in order for the airplane to be successful, it would have to be a long-term program. It would have to achieve gains in capacity, range and efficiency, so the basic design had to absorb the march of technology. In the late 1980's, Boeing thoroughly redesigned the 747 with the -400 model, making major aerodynamic improvements, adding winglets to improve fuel efficiency, incorporating new avionics, installing a new flight deck and providing the latest in-flight entertainment systems. The 747-400 remains the world's fastest subsonic commercial jetliner, allowing passengers to arrive at their destinations nearly an hour sooner than passengers flying on competitor's airplanes. The 747-400 flight deck replaced the analog systems of the 747-100, -200 and -300 with digital avionics. This reduced the number of lights, gauges and switches from 971 to 365. Programmable displays and simpler cockpit procedures also reduced crew workload in the flight deck, allowing the number of crew members to decrease from three to two.




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