Westinghouse J40
The Westinghouse J40 was an early high-performance afterburning turbojet engine designed by Westinghouse Aviation Gas Turbine Division starting in 1946 to a US Navy Bureau of Aeronautics (BuAer) request. BuAer intended to use the design in several fighter aircraft and a bomber. However, while an early low-power design was successful, attempts to scale it up to its full design power failed, and the design was finally abandoned, deemed a "fiasco" and a "flop".
The design originally called for an engine of 7,500 lbf (33 kN) thrust at sea level static conditions without afterburner and 10,900 lbf thrust with afterburner. A more powerful model 9,500/13,700 lbf thrust version was intended to replace the earlier engines in the various airframes. In total, thirteen different variations were planned. The projected need for the higher-power engines led BuAer to place a second source production contract with Ford Motor Company, Lincoln Mercury Division for both J40-WE-10 and J40-WE-12 engines.
The higher-powered versions proved to have a flawed compressor design and lacked a suitable control system. This left the Navy with only the earlier, lower-power engines. These were eventually used for early flight testing, but proved to be largely unusable. A particularly notorious use was in the McDonnell F3H-1N Demon, which proved to be dangerously underpowered with the smaller engines. The design was quickly grounded after repeated incidents caused by flying the now overweight airframe and a number of engine failures that led to the loss of the aircraft. A government investigation of the F3H-1N program issue failed to determine if pilots had been lost due solely to the engine issues. The grounded airframes were either scrapped or used for ground training. The F3H-2N used the Allison J71 engine.
The J40 program was terminated in 1955, by which time all the aircraft it was to power were either grounded, cancelled or redesigned to use alternative engines. The J40's failure was among those that affected the most military programs. The program failure was primarily due to lack of investment in research and experimental resources by Westinghouse, leaving them unable to resolve the issues with the various models of the engines. In 1953 Westinghouse worked with Rolls-Royce to offer engines based on the Avon, which had similar performance but matured into an excellent design of even higher output. Westinghouse was out of the aircraft engine business by 1965 when their 6,200 lbf (28 kN) thrust, scaled-down version of the 12,000 lbf (53 kN) Avon 300-series engine, the XJ54, also failed to find a United States market.[1]
Decommission[edit]
Development of the big engine was protracted. The all-important 150-hour qualification test that was to have been accomplished in December 1949 was not completed until January 1951, a year behind schedule. The afterburner was particularly troublesome – the afterburning version of the engine, the J40-WE-8, did not pass its 150-hour qualification until August 1952. As a result, J40-WE-6 engines without afterburners had to be used for initial testing, causing delays in flight test programs.
Early on even the low-powered versions of the engine were considered unusable because of reliability problems. The A3D would prove successful with alternate engines, but the F3H-1 was relegated to subsonic performance using the lower-powered engine and continued to be subsonic even after substitution of the higher-power Allison J71. It has been stated, that although considered failures, the F3H-1 could have been competitive with early supersonic Air Force's Century Series fighters had the original engines delivered on their design specifications.[2] In fact, the Demon that emerged from development was a missile-armed all-weather fighter over 8,000 lb (3,600 kg) heavier than the XF3H-1 had been, and even the high-powered J71 could not restore its performance.
The F3H-1N Demon single-engine jet fighter was initially a severe disappointment, due to the unreliability of the J40 and the difficulties of flying the much heavier airframe with the lower-powered J40-WE-22A engines. The airframe design had assumed the higher-powered J40-WE-10 would be the power plant. These first production Demons were grounded for a redesign to accept the J71 engine after the loss of six aircraft and four pilots.[3] The decision to move the Demon to the J71 had occurred long before the initial production batch emerged and with the development of a suitable afterburner for the J71 being protracted, BuAer decided to accept the early aircraft with Westinghouse J40-WE-22A and -22 engines. This decision came under Congressional review in 1955 and drew sharp criticism from Congress. Time Magazine called the Navy's grounding of all Westinghouse-powered F3H-1 Demons a "fiasco", with 21 unflyable planes, that could be used only for Navy ground training at a loss of $200 million.[4] One high point of the J40 was the 1955 setting of an unofficial time-to-climb record, in a Demon, of 10,000 feet (3,000 m) in 71 seconds.[3]
A replacement engine could not be easily fitted into the grounded Demons, as the fuselage had to be redesigned and enlarged. When this redesign was done to accommodate the J71, the wing area was also enlarged to counter the increased weight of the all-weather aircraft. The F4D Skyray that had been designed to more easily accept different engines emerged in production powered by the Pratt & Whitney J57.
The A3D emerged with non-afterburning J57 engines as well. The F10F-1 program was cancelled primarily due to unsolvable aerodynamic issues with the variable-sweep wing and the control systems. The J40 engine issues were of secondary importance during the prototype flight trials.
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