Boeing 737
The twin-engine Boeing 737 was developed as a direct competitor of the McDonnell Douglas DC-9 but did not fly until about 2 years after the latter's introduction. The 737 has been produced in two versions, the 737-100 and the 737-200. Except for 30 units, all the aircraft produced have been the 737-200 version, which is a stretched, higher capacity, and heavier aircraft than the 737-100. The total number of orders for the 737 was 978 by mid-1982, and the type is currently being manufactured at the rate of 8 per month.
The two engines are mounted under the wings in a manner similar to that of the 707. The proximity of the engine nacelles to the under surface of the wing highlights the problem, previously mentioned, incurred by the underwing engine location as the size of the aircraft is reduced. The desire to avoid a high-mounted horizontal tail, and its possible stability problems, apparently was largely responsible for the choice of this engine location instead of the aft-fuselage-mounted arrangement. The horizontal tail is located on the fuselage below the root of the vertical tail. The 737 uses basically the same Pratt & Whitney engines as those employed on the Boeing 727 and the McDonnell Douglas DC-9.
The 737 fuselage appears short and stubby, due to its large upper-fuselage diameter, which is the same as for the 707 and the 727, and its short length, which is less than for the 707 or the 727. The higher fineness ratio fuselage and greater length of the DC-9 results from the use of a five-abreast seating arrangement and consequent smaller fuselage diameter. The short fuselage length of the 737 along with the wide lateral separation of the underwing-mounted engines result in the large vertical tall on the aircraft.
The geometry of the 737 wing is very similar to that of the DC-9. The high-lift and control systems of the 737 are like those described for the 727. An examination of the data for the 737-200 and the DC-9-30 shows a close similarity in the size, weight, and performance of the two aircraft. This similarity Would be expected since they were designed for similar operations. The major difference in performance of the two aircraft is the longer range of the 737 with full fuel tanks.
A major new derivative of the Boeing 737 began initial deliveries late in 1984. Designated the 737-300, the new aircraft is a stretched, heavier variant of the 737-200 powered with the GE Snecma CFM turbofan engines of 20 000 pounds thrust and bypass ratio of 6.0. Lower seat-per-mile costs and reduced noise are among the advantage offered by the improved aircraft.
