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Aviation History
1963
1963 - 0714.PDF
FLIGHT International, 9 May 1963 BOEING 727 Dimensions Span, 108ft; overall length, 134ft 4in; body length, 115ft 10m; outside body width, 148in; outside body depth, 158m forward, I68in aft; overall height to fin tip, 34ft; tailplane span, 35ft 9in; track, 18ft 9in; wheelbase, 53ft 3in; gross wing area, 1,650 sq ft; minimum radius of turn (about either main gear), 68ft 9in to opposite wing tip. 70ft 4in to opposite elevator tip; length of passenger cabin, 72ft 8in; total volume of cargo compartments, 855 cu ft; total volume of passenger cabin, 5,000 cu ft. Powerplant Three Pratt & Whitney JT8D-I turbofans, each having the following characteristics; inlet diameter, 42.5in; diameter at rear flange, 44.8in; dry weight, 3,0221b; by-pass ratio (cold/hot), 1.05; total mass flow, 305lb/sec; pressure ratio, 15.5 : I; max take-off thrust at sea level. 14,0001b static at I 1,000 r.p.m., or 12.5001b at MOkt; cruise thrust, 4,7201b at 25,000ft at Mach 0.85 with s.f.c. of 0.838, or 4,1 ISIb at 30,000ft at Mach 0.82 with s.f.c. of 0.818. Weights and capacities Basic operating weight, 82,3571b (82,8151b with alter native tankage); fuel capacity, 7,000 US gal (5,829 Imp gal), or 7,500 US gal (6,245 Imp gal) with alternative tankage; design payload, 24,0001b; typical number of passengers, 70 first-class, 94 mixed or 114 tourist; max take-off weight, 142,0001b (152,0001b with alternative tankage); max landing weight, 131,0001b; max zero-fuel weight, 109,0001b. Performance (computed to SR.422B) Take-off field length. 5,500ft at 142,0001b with 20° flap on std day, 6,600ft at same weight with 20° flap at ICAN + 4I°F, 6.300ft at 152,0001b on std day, 8,200ft at 152,0001b with 10° flap at ICAN + 4I°F; take-off distance and payload for a given range, see diagrams on page 688; second-segment climb limits are 143,0001b at I00"F and 152,0001b at 80"F, and reduction in flap angle enables weight to be increased under hot and high conditions provided there is adequate runway length; cruising-speed limits are Mach 0.88 above 20,500ft and 390kt e.a.s. below, and the high-speed cruise curves reach maxima at 589 m.p.h. at 21,000ft at 130,0001b and 597 m.p.h. at I 10,0001b at 23,000ft; approach speed with 40° flap at sea level, I20kt at 130,0001b, lOOkt at 90,0001b; CAR. landing field length at sea level, 4,950)t at 130,0001b, 3,950ft at 90,0001b; community noise levels, 109 PnDB on take-off (I n.m. from end of runway at 90° F),l 12 PnDB at 400ft on landing. gized, and three 50A transformer/rectifier units provide d.c. power. A 22A-hr Ni-Cd battery provides stand-by d.c. power and powers a 250VA stand-by inverter for essential flight instruments. 16kVA is supplied to galley units (24kVA optional). A gas-turbine auxiliary power unit equipped with a 40kVA generator can be installed. ARINC standard packaging is used for electrical control units to improve cooling, provide longer service life and simplify servicing. Complete circuit-breaker protection is provided. The installation of wiring in raceways provides mechanical protection for the wiring, allows flexibility for accommodating wire changes, permits ready replacement of wire bundles, and reduces the number of attaching parts. Where wiring is required to pass through inacces sible areas, conduit or wiring ducts are provided. Wiring in passenger areas is accessible through easily removable panels, and some ten per cent spare wire is provided. A maximum percentage of crimped-contact, removable-pin connectors, and a minimum number of special assembly tools are used as a result of plug standardization. Disconnects, provided at all major instrument panels, facilitate removal of the entire panel for bench maintenance. Electronics Most extensive electronic system is the autopilot. The Sperry SP-50 controls the pitch and roll axes, and can maintain a desired aircraft pitch attitude, heading or altitude, and provide such functions as VOR/Tacan, ILS localizer and glide slope, and Doppler heading control. The aileron and elevator channels may be engaged separately or together, and interlocks prevent simul taneous engagement of incompatible modes (such as altitude-hold and glide slope). The autopilot elevator control is coupled to the tailplane trim system to provide automatic trim as required. The Sperry yaw-damper system, which is a separate entity, consists of two independent channels operating the two rudders full-time without feedback to the rudder pedals. The SP-50 is designed for long life, with lower-minimums performance. A concerted effort has been made to simplify auto pilot circuitry; static switching is used extensively, and all com ponents are derated to extend component life. Tolerances have been tightened and high feedback circuitry installed to improve localizer and glide-slope control. Also important to the actual attainment of lower weather minimums is the newly included glidt-slope extension capability. The dual Collins flight director system is standard equipment, with the dual Sperry system optional. Communication and navigation equipment is largely a matter of customer preference. Air-conditioning The US industry has gradually accepted the use of engine-bleed systems for providing pressurization and air- conditioning, and the 727 system represents a great advance on its predecessors. The JT8D-1 engine is designed to provide physio logically pure air without filtration, and the basic source of cabin air is a bleed from the eighth stage of Nos 1 and 3 engines. When demands exceed the flow and pressure which this bleed can provide, a regulating valve automatically opens a second bleed from the 13th (final) compressor stage. The centre engine provides a stand-by source of eighth-stage air only. Initial cooling of the bleed air takes place in heat exchangers 687 within the side-engine struts supplied with an automatically con trolled airflow from the fan section of the adjacent engine. Separate ducts deliver the air to left and right conditioning units occupying a large bay ahead of and below the wing centre section. Here are installed two air-cycle cooling units—identical, except for nozzle area, to those on the 707/720—together with primary and secondary heat exchangers cooled by ram air in flight and electric fans on the ground. If either set of machinery should be shut down, the one remaining can furnish conditioned air for the entire aircraft. A proportion of the delivery from the left system goes to the flight deck, and the left mixing valve is controlled by the flight-deck temperature selector. The right mixing valve is controlled from the main cabin, which is supplied by the entire delivery from the right system together with that remaining from the left. On the ground, air-conditioning may be accomplished by ground carts or, if the customer specifies, by an APU in the main-gear compartment driven by an AiResearch GTCP-85 gas turbine. The distribution system combines the 707/720 "hot wall" with a new direct overhead distributing duct, and offers selective com binations of these. The latter discharges down the centre of the ceiling, and provides rapid cooling and heating when necessary, as well as desirable air motion on the ground. The hot-wall supply leads the conditioned air up through bifurcated pipes in each window bay to discharge beneath the hat racks. Individual cool-air outlets are provided at each crew station and in the service module above each passenger-seat unit. The pressurized volume exhausts through a pair of outflow valves, at the rear end of the aft cargo compartment. Both freight holds are heated by air from the cabin, which flows down the exterior walls to an exhaust collector tube beneath the freight floor. Pressurization control is entirely pneu matic, the limiting pressure differential of 8.61b/sq in providing a sea-level interior up to 22,500ft and a cabin altitude of 5,200ft at 35,000ft. Ice protection An unusual feature of the 727 (and 720) is that no provision is made for de-icing the tail unit, this being considered non-essential. The wing leading-edge slats, Kriiger flaps and critical portions of the inboard fixed surfaces ahead of the side engines, the lip and impingement area of the centre-engine inlet duct, and the upper VHF aerial, are all heated by a mixture of air bled from the 1-p and h-p compressors of all three engines. Mixed h-p bleed and ambient air is piped to protect the inlet cowls of the side engines. Electric heating is used for the pilots' windscreen (Nesa glass), pitot heads, static ports, and water drain masts. Water and oxygen A 40 US gal (33 Imp gal) underfloor titanium storage tank is pressurized to 251b/sq in by engine bleed air, with stand-by compressor, and serves drinking fountains, galley and lavatory supplies. Special emphasis has been placed on system drainage and reliability during cold-weather operation. Separate high-pressure gaseous oxygen systems are provided for the crew and passengers. Crew oxygen is served by a 76 cu ft (optional 114 cu ft) cylinder, and the passenger system by two Disposition of servicing vehicles at a major turnround. The pneumatic- power vehicle provides air for engine starting, and is not required if the optional APU is fitted
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