JSF’s F135 Engine Meeting Milestones
September 20/17: Pratt & Whitney has successfully finished tests of an adaptive three-stream fan paired with a F135 core engine. The fan includes an adaptive bypass airflow that aims to improve fuel efficient and cooling capacity, andis part of a $1 billion program to develop a full-scale, 45,000lb-thrust-class prototype engine under the Adaptive Engine Transition Program (AETP) that could be used to re-engine the F-35 and power a future combat aircraft. At present, most military turbofan engines have only two airstreams, but including an additional, adaptive airstream will give the engine the option to increase its thrust on demand or lower its fuel consumption.
Lockheed Martin and Pratt & Whitney have successfully performed the first start of an F-35 Joint Strike Fighter aircraft test engine, using an integrated power package (IPP) that the functions traditionally performed by the auxiliary power system, emergency power system, and environmental control into a single system. The system was used to start a Pratt & Whitney F135 short-takeoff/vertical-landing (STOVL) engine at the company’s advanced test facility in West Palm Beach, FL. The IPP is a subsystem of the F-35 Power and Thermal Management System (PTMS).
The JSF program has targeted the successful IPP engine start as a major milestone since the beginning of the System Development and Demonstration phase of the program in 2001. The achievement paves the way for additional development testing in preparation for the F-35’s first flight in 2006, and comes about a month after the Pratt & Whitney F135 System Development and Demonstration (SDD) program successfully completed the post test Critical Design Review (CDR) by the Joint Strike Fighter (JSF) Joint Program Office (JPO). The JPO review found that the F135 propulsion system has met all review objectives and is on track to deliver the first flight test engine later this year.
Unlike current-generation fighters, the F-35 will rely on “more-electric” systems to operate the aircraft that are tightly integrated to save weight, add reliability and improve packaging efficiency. Performing engine starts with the integrated systems demonstrates the maturity of their designs and reduces risk for first flight.
At the heart of the IPP is a small gas-turbine engine “turbomachine” that provides power to the engine-mounted starter/generator, bringing the engine to its threshold starting speed. The engine then increases to idle speed and the electrical system, which includes the engine-mounted starter/generator (ES/G), transitions from operating as a motor to operating as a generator. The IPP is also available for in-flight emergency power.
In 2001, Pratt & Whitney was awarded a 10-year $4.8 billion contract for System Development and Demonstration to develop the F135 propulsion system through flight clearance, flight test, and qualification for Low Rate Initial Production.
To date, the Pratt & Whitney led F135 propulsion team has delivered three Conventional Take-Off and Landing (CTOL)/Carrier Variant (CV) configuration and four Short Take-Off and Vertical Landing (STOVL) configuration F135 engines to test for a total of seven engines delivered on or ahead of schedule. In December, the team will deliver the first flight test engine in preparation for Initial Flight Release in January 2006 and first flight in August 2006. Production deliveries of the F135 are scheduled to begin in early 2009.
The F135 is an evolution of the highly successful F119 engine for the F/A-22 Raptor. Together the F135 and F119 engines will have logged more than one million flight hours in support of the F-35’s introduction to operational service in 2012.
The F135 will be competing with the GE/ Rolls-Royce F136 engine, designed to be completely interchangeable with the F135 in any JSF plane.
The F135 propulsion system team consists of Pratt & Whitney, the prime contractor with responsibility for the main engine and system integration; Rolls-Royce, supplying lift components for the STOVL F-35B; Honeywell International, supplying the integrated power package; and Hamilton Sundstrand, provider of the F135’s control system, engine start system, external accessories and gearbox.
September 20/17: Pratt & Whitney has successfully finished tests of an adaptive three-stream fan paired with a F135 core engine. The fan includes an adaptive bypass airflow that aims to improve fuel efficient and cooling capacity, and is part of a $1 billion program to develop a full-scale, 45,000lb-thrust-class prototype engine under the Adaptive Engine Transition Program (AETP) that could be used to re-engine the F-35 and power a future combat aircraft. At present, most military turbofan engines have only two airstreams, but including an additional, adaptive airstream will give the engine the option to increase its thrust on demand or lower its fuel consumption.
January 17/17: Ethical conflicts at Pratt & Whitney have resulted in the ousting of the head of the company’s F135 engine program alongside nine other employees. The dismissals come after the completion of an internal audit which uncovered an ethics issue linked to a visit by South Korean military officials several years ago. During the trip, the Korean delegation paid a visit to the company’s West Palm Beach facility in Florida, and Pratt & Whitney paid for a rental van to fetch them there. While certainly not the most outrageous form of graft in the industry’s history, causing no violation of US export control or anti-bribery laws, the engine company deemed the move as a breach of their strict ethics laws, amounting to “inappropriate entertainment.”
May 3/16: Following 15 years of work, Pratt & Whitney announced that they are coming to the end of the development of the F-35 Joint Strike Fighter‘s F135 propulsion system. The F135 team is also about 85% of the way through correcting an engine fault inherent in 180 early-model units which caused one aircraft to catch fire on the runway at Eglin AFB, Florida in June 2014. Derived from the F119-100 turbofan that powers the F-22 Raptor, the F135 was selected for both Lockheed X-35 and Boeing X-32 JSF prototypes.
Additional Readings & Sources:
- News Release: Unique Integrated System Starts F-35 Engine in Joint Test By Lockheed Martin, Pratt & Whitney
- News Release: Pratt & Whitney F135 SDD Program Successfully Completes Post Test Critical Design Review
- DID March 11, 2005 – F136 Engine Reaching Test Milestones
- DID March 7, 2005 – GAO Releases Study of F-22, F-35 Programs