Westinghouse J40

J40
Type Turbojet
National origin United States
Manufacturer Westinghouse Aviation Gas Turbine Division
Major applications McDonnell F3H Demon

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]

The J57 would also replace, for the U.S. Navy, the disastrous Westinghouse J40 that never fully materialized in acceptable form

— Thomas Gardner, F-100 Super Sabre at War