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, more than that of almost any other aircraft ever built. The Lockheed C-5A military cargo transport discussed below 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 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 shown in figure 13.24 along with a standard-size 747. The 747SP is lighter and has a smaller fuselage and lower passenger capacity but has a longer range than any other version of the aircraft. Latest version of the 747 to fly is the 747-300, which has 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.
