FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1963
1963 - 0715.PDF
TO. 142,000 lb, STD*4I*F STD DAY^. —l I 500 IPOO l52,OOOIb 1,000 1500 2000 RANGE (miles) !S2,OOOIb- TYPiCAL MIXED CLASS 142.0001b- 688 The upper curves are for s.l. take-off with 20,0001b pay- load, operating weight empty of 83,5001b, reserves of 10,0001b and cruise at Mach 0.82 at 30,000ft (no wind); this approximates to a mini mum-cost operation. The lower curves show payload against range, with assump tions similar except for the use of maximum cruise thrust at 25,000ft; this is a high-speed operation for com petitive routes 7500 US gal-| ^OOOUSqal 500 l,000 RANGE (miles) ISOO 2000 BOEI NG 727 .. . 114 cu ft cylinders. Passenger oxygen becomes operative at a cabin pressure altitude of 14,000ft, or upon manual command. There are typically four drop-out masks in each passenger service unit. A noteworthy feature of the oxygen system is the employ ment of modular units which combine pressure reduction, automatic actuation of the passenger oxygen, continuous flow regulation, and other functions in two parallel modules, either of which will alone perform the essential oxygen functions. The 727 Programme Milestones in the development, sales and manufacturing pro gramme are indicated graphically on page 677. In the lower part of this diagram is plotted a curve showing the design manpower applied to the 727. From the summer of 1960 this force grew at the rate of 115 engineers per month for a whole year, drawing upon a design staff of some 17,000 in the Seattle area. Such figures FLIGHT International, 9 May 1963 underline the importance of the regrouping of the British industry into units able to operate on the same scale. Manufacture of the 727 takes place almost wholly at Renton, components of the new aircraft being interspersed among 707s and 720s and often being superficially almost identical. Boeing have built separate airframes for fatigue and static-strength tests—a philosophy differing from that evolved by de Havilland. The first flight 727, N7001U, was rolled out in its company chocolate and lemon livery last February 5, and flew four days later. Boeing's flight test department is so strong in personnel and computation equipment that the first 727 carries over 16,0001b of test equipment in the passenger cabin and freight holds, with 500 channels of instrumentation. By February 18 nine flights totalling 16hr 21min had sufficed for the following tests: checkout of all systems; full stalls at every flap setting, with power off, power on and full asymmetric power; complete low-speed tests of all flight controls, including operation on A and B systems, either system alone and with both systems off; stick force per g at forward e.g.; Dutch roll stabilities at various altitudes, speeds and con figurations, with yaw damper on and off; .partical airspeed cali bration; use of speed brakes, reversers and manual tailplane trim; in-flight engine starts and engine stability experiments; wet-runway decelerations; trim checks at up to 142,0001b with e.g. from 17per cent to 39 per cent; partial drag polar; IFR flight clearance (FAA); and CAR stall speeds with full flap using the trailing-bomb a.s.i. In the heading picture on page 675 N7001U is seen taking off with a flutter-inducer attached to the tips of the starboard wing and tailplane. This series of tests took place early in March, when Mach development reached 0.87 and take-off weight the design limit of 152,0001b. At the time of writing, the second (N72700) and third 727 (N7002, in United colours) have flown, and the fourth and last flight-test machine was rolled out on April 2. Orders so far announced for the 727 are as follow: United, 40; Eastern, 40; Lufthansa, 12; American, 25; TWA, 10; TAA, 2; and Ansett-ANA, 2. This is a sound basis on which to plan production big enough to absorb Boeing's vast capacity. It could be argued that Boeing have unduly penalized themselves in striving for so short a field length, and in making the 727 so much like the 707 and 720 instead of producing an uninhibited design. But these are two of the chief reasons why 131 of these aircraft have already been sold. Boeing appear to have achieved a good compromise with the smallest member of their airline family. PRATT & WHITNEY JT8D-1 IN the foregoing description of the Boeing 727 the point is made that, for the first time ever in the USA, this aircraft was designed around an engine designed not for military but for airline service. In Britain there have been many such engines since the advent of the gas turbine, the most widely known being the Dart, Proteus, Conway, Tyne, Medway (the original RB.141 for the de Havilland 121) and Spey. The Conway and Spsy are both now in production for bombers, and the Tyne for an RAF transport, but these engines were all originally designed primarily for airline use. But in the USA the Pratt & Whitney JT8D is unique in having no military appli cation, apart from the propulsion of the Swedish J37 Viggen. The JT8D-1 was the first engine outside Britain planned as a turbofan from the outset, and not converted from an existing turbojet. At the same time, Pratt & Whitney Aircraft went to great lengths to incorporate into the JT8D the maximum "carry across" from their earlier jet and fan commercial engines, and to choose conservative design points to facilitate the attainment of durability and reliability. In fact, part of the design was based on the existing J52 turbojet, though the JT8D is no mere fan conversion. Compared with its only real rival, the Rolls-Royce Spey, the JT8D-1 operates at reduced pressures and temperatures—and thus is proportionately larger and heavier; but it employs solid turbine blades of relatively cheaper design and is claimed by Pratt & Whitney to incur lower parts-costs in the course of each year. Engineering features may be clearly seen in the cutaway drawing of the No 1 engine of the 727 on pages 681 -682. Pratt & Whitney draw attention to the following points:— Fan inlet case (item 2 in the drawing) of new design, reflecting experience gained with the JT3D. Fan blades of titanium—dovetailed into their discs and incorporating mid-span shrouds in the first stage (3) and pinned to the discs there after. Labyrinth seals (14) at the front and rear of both compressor sections to prevent bleed-air contamination. Low-pressure blading of titanium (7). Heat shields (17) protect against oil coking. Double ball-bearings (10, 16), either race of which can carry the thrust of one complete rotating assembly. High-pressure compressor blading (12) of steel. Double fuel manifold (90) in what Pratt & Whitney call a "relatively cool" location, although it is tucked away inside the by-pass duct. Simple bullet-nose flame tubes (25), each with a single burner and offering minimum pressure-drop. This is a departure from previous P&W practice, and an unusual feature is that the ten tubes discharge into a common annular nozzle. Turbine blades and guide vanes (22, 23, 26) are solid. "Piggyback" mounting of fuel control (84) to fuel pump (83) and oil tank (101) to accessory gearbox (123), eliminating much exterior plumbing. Accessories are conveniently located in a cool environment. Deposits in the oil strainer (117) are detectable by means of pressure taps. Each accessory may be removed without disturbing neighbouring accessories and piping (apart from the fuel pump, which requires removal of the fuel control). Fan discharge case (27) and main fan duct casing are split into upper and lower halves to facilitate removal. JT8D-1 drawings were released to experimental fabrication in November 1960, the first engine ran in April 1961, the first proto type engine was delivered to Boeing (for tests on the Dash 80) in May 1962, and the first production JT8D-1 was shipped to Renton in February of this year. Total development running time is now approximately 6,000hr. By the end of 1965 it is expected that the JT8D-1 will have flown a total of l,350,000hr in the Boeing 727 and Caravelle 10B, and time between overhauls is expected by then to have reached 2,500hr.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
