Pratt & Whitney F117

Pratt & Whitney F117
Name	Pratt & Whitney F117
Type	Turbofan engine (experimental)
Manufacturer	Pratt & Whitney
Status	Prototype/derivative

Pratt & Whitney F117 The Pratt & Whitney F117 is an experimental low-bypass turbofan powerplant developed in the late 20th century for stealth aircraft propulsion and quiet performance. Conceived within United States Air Force and National Aeronautics and Space Administration influenced programs, the F117 program intersected with projects at Lockheed Martin, Northrop Grumman, and McDonnell Douglas and informed later production engines used on aircraft like the Lockheed F-22 Raptor and F-35 Lightning II. The program brought together personnel from Hamilton Standard, General Electric Aviation, and academic partners including Massachusetts Institute of Technology and Stanford University.

Development

Development traces to Cold War era initiatives driven by requirements from Secretary of Defense offices and specific procurement efforts such as the Advanced Tactical Fighter competition. Funding sources included the Defense Advanced Research Projects Agency and industrial research programs tied to United States Department of Defense laboratories and the Air Force Research Laboratory. Initial concepts incorporated lessons from the Pratt & Whitney F100 program, collaborative studies with Rolls-Royce teams, and acoustic research formerly pursued at NASA Lewis Research Center and Langley Research Center. Engineers drew on computational fluid dynamics advances from Courant Institute of Mathematical Sciences collaborations and wind tunnel data from the Arnold Engineering Development Complex. Testbeds were planned at Edwards Air Force Base and Wright-Patterson Air Force Base with oversight from program offices in Tinker Air Force Base.

Design and Features

The F117 design emphasized reduced thermal and radar signatures and low infrared output to meet requirements shaped by lessons from operations like Operation Desert Storm and intelligence assessments from Central Intelligence Agency briefings. Core features included a single-rotor low-pressure turbine derived from studies at Pratt & Whitney Aircraft laboratories, contra-rotating fan concepts influenced by work at Snecma and MTU Aero Engines, and a mixer-ejector exhaust geometry similar to proposals evaluated by Rockwell International. Materials technology leveraged superalloy research at Oak Ridge National Laboratory and composite fan cases from Hexcel Corporation and DuPont programs. Control systems integrated digital engine controls developed in partnership with Honeywell International and software verification methods pioneered at Carnegie Mellon University. Noise reduction strategies traced to the Quiet Short-Haul Research Aircraft and civil research involving Federal Aviation Administration standards.

Variants and Derivatives

Proposed variants for the F117 family included an afterburning derivative for air superiority concepts evaluated by Boeing and a non-afterburning maritime variant for carriers like those of the United States Navy. Derivative powerplants informed engines in the Pratt & Whitney F119 lineage and cross-pollinated with work on the General Electric F110 through industrial advisory panels including representatives from Airbus and Eurofighter GmbH. Experimental modules tested thrust-vectoring hardware comparable to systems on the Sukhoi Su-35 and adaptive cycle elements later visible in programs supported by United States Navy Advanced Technology Initiatives. Collaborative spin-offs supported civil turbofan research in cooperation with International Civil Aviation Organization guidelines and manufacturers such as Rolls-Royce Holdings plc.

Operational History

Although not fielded as a production engine, the F117 served as a technology demonstrator in flight test programs at facilities like Palmdale, California and flight envelopes exercised near Area 51 and other restricted ranges. Test campaigns coordinated with airframe partners such as Lockheed Corporation and Northrop supplied critical data used in engine selection for the F-22 program and influenced procurement discussions within the Office of the Secretary of Defense. Components from F117 trials were validated under stress conditions defined by standards from Society of Automotive Engineers committees and maintenance practices shaped by work at Subcommittee for Propulsion panels. Data from F117 experiments also informed lifecycle cost models used by analysts at Congressional Budget Office reviews.

Applications

Intended applications ranged from stealthy tactical fighters to reconnaissance platforms and unmanned aerial vehicles evaluated by Defense Advanced Research Projects Agency initiatives and programs overseen by National Reconnaissance Office. Although the F117 itself was not retrofitted to front-line fleets like the McDonnell Douglas F-15 or General Dynamics F-16 Fighting Falcon, its technologies were referenced in upgrade paths and industrial proposals to aerospace primes including Saab AB and Mitsubishi Heavy Industries. Civil adaptation studies considered regional jet installations discussed at symposiums hosted by American Institute of Aeronautics and Astronautics and international air shows such as the Paris Air Show.

Specifications

General characteristics - Type: Low-bypass turbofan (experimental) - Manufacturer: Pratt & Whitney - Configuration: Single-spool/dual-spool concepts evaluated; mixed-flow exhaust with noise-reduction features - Materials: Superalloys, advanced composites, thermal barrier coatings from Ceramic Coatings research

Performance (demonstrator estimates) - Thrust: Program estimates varied by configuration; development aimed for comparable output to contemporaneous engines such as the Pratt & Whitney F100 and General Electric F110 - Specific fuel consumption: Targeted improvements based on Fuel Efficiency studies and Aerodynamic Research Laboratory findings - Features: Reduced infrared signature, reduced radar cross-section contribution, digital control integration

Category:Pratt & Whitney engines Category:Experimental jet engines