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Aviation History
1953
1953 - 1487.PDF
FLIGHT, 13 November 1953 641 Mfffll ""*- ' """vC" WESTINGHOUSE TURBOJETS Some Notes on the U.S. Navy's Principal Aircraft Gas Turbines DURING the past year we have made several refer ences to the difficulties being experienced by the Westinghouse Electric Corporation of America with their more recent aircraft power units. Very little has been published in this country about the engines themselves, and this is a short account of their development and characteristics. Westinghouse have long been famous as manufacturers of heavy electrical equipment and, in particular, of the main propul sion machinery for warships. The U.S. Navy Department have always held the company in high esteem and, in December, 1941, the Bureau of Aeronautics asked them to design a turbojet for future Navy fighters. From the start, the axial type of compressor was chosen. When the first engine appeared in 1943, it was hailed as the first American gas turbine free from foreign (i.e., British) influence. Whether this was an advantage or not, Westinghouse did an excellent job in those early years in laying the foundations for an entirely original line of small-diameter turbojets quite unlike any others. The first production engine was the 19XB-2B, 261 of which were built (130 by Pratt and Whitney) for the McDonnell Phantom. In service, this engine was known as the J30-WE-20, and it passed its 150-hour test in November, 1946. It had a ten-stage compressor and gave 1,550 lb sea-level static thrust. Two notable features of the engine were the annular combustion chamber — consisting of two tapering stainless-steel tubes mounted concentrically, with a large number of downstream burners injecting into the annular space between them—and an oil cooler which was fabricated from rectangular-section aluminium tubing wrapped around a mandrel of the same diameter as the engine intake and then attached to the front of the engine to be cooled by the intake air. The second, and most widely-used Westinghouse engine so far is the Model 24 (U.S. Navy designation J34), large numbers of which have been built for such aircraft as the Douglas Sky- night and McDonnell Banshee. Apart from being the largest of the original Westinghouse range of three engines, the J34 employs an extra stage of compression and an additional turbine. But indicative of the poor state of the art at the time the engine was designed (about 1945) is the fact that even with 11 stages the pressure ratio is only 3.85:1, raised to 4.35 in the latest version. As a direct result, the specific fuel consumption is no better than can be obtained with a centrifugal compressor. The J34 has worked quite well during the past five years, and has also been supplied to the U.S. Air Force, both with and without an after burner. It is gradually passing out of major production, but remains the most rewarding engine the company has produced. The direct descendant of the J34 is the J46, which is about half as big again in linear dimensions. The J46 was to have powered several Navy fighters, including the swept-wing F3D-3 Skynight, which was cancelled. Now, however, only two aircraft are scheduled to receive the engine: the Chance-Vought F7U-3 Cutlass and Convair F2Y Sea Dart. Westinghouse have ex perienced much trouble with the J46, notwithstanding its similarity to the J34. The engine is already months, or years, behind in its type-test programme and deliveries of cleared engines have been no more than a trickle. The speedy, but frightening, Cutlass has been held up seriously as a consequence, and much of the test flying has been carried out with two Allison J35s. The Sea Dart has not, we believe, been retarded greatly, and the prototype now flying is fitted with two afterburning J34s. But, if the J46 continues to give trouble, a serious bottle neck could develop, because no replacement engine has the same geometry. Far more important than the J46 is the J40, which passed its type-test in 1951. At that time, several fine, supersonic Navy prototypes were about to fly, and the J40 was scheduled as the power unit of every one. The engine is a completely new design, able to pass about three times the airflow of the J34 to give nearly three times the thrust. As with almost all other engine manufacturers, Westinghouse turned to the lengthy, small- diameter, low-revving axial layout in an effort to obtain increased power. The J40 is quite different in detail from almost any other engine, and marks a notable advance on previous Westinghouse practice. The quite good compression ratio, achieved with only ten stages, is reflected in the reasonable specific fuel consumption (see table, p. 642). Most J40s have bifurcated intakes with a number of fuel and control accessories mounted below and forward of the ducts, as shown in the photograph. From the front, notable features of the engine are as follows: There are twin oval intakes separated by a wheel-case upon which can be mounted pads for accessories. The intakes them selves are de-iced by air bled from the delivery end of the com pressor. The compressor casing consists of two forward halves of aluminium alloy and two rear (high-pressure) halves of steel. The rotor contains ten steel discs and all the fixed and moving blading is also of steel. The annular combustor is of the "step- TheJ40-WE-8atthehead of the page is reminiscent of a turbo-alternator set for a power station; its appearance suggests that installation must raise some acute problems. The smaller engine on the right is a typical J34, as used in the Skynight and Banshee. The cylin drical oil-cooler around the intake is visible and is referred to in the text.
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