New funding accelerates the design phase of the F135 Core Update

Pratt & Whitney received an additional $66 million for the F135 Engine Core Upgrade design. This increases the total budget for this engine modernization project to $180 million, covering design, program management, risk reduction, procurement, and weapons system integration. 

Fuel line may have damaged F135, deliveries stopped, no acceptance flights
Photo credit: Twitter

VP for the F135 program, Jen Latka, expressed gratitude for the increased funding, which will expedite the design phase and keep the project on track for the 2028 deadline. The decision to upgrade the F135 engine was made by the U.S. Air Force, Marine Corps, and Navy in 2023, as part of President Biden’s 2024 budget proposal. 

Rep. Rosa DeLauro highlighted the importance of the modernized engine for a modernized F-35. She assured ongoing support and funding for the program to meet national defense priorities and support the defense industrial base. 

The F135 ECU, optimized for all three F-35 variants, offers the fastest, most cost-effective, and lowest-risk solution for F-35 operators worldwide, yielding $40 billion in lifecycle cost savings. Lockheed Martin expressed their support for the F135 ECU on June 30, 2023.

What is the F135 engine?

The F135 engine is a turbofan engine designed for the F-35 Lightning II fighter jet. It is the result of a collaboration between Pratt & Whitney and Rolls-Royce and is considered one of the most advanced fighter jet engines in the world.

The F135 engine is a two-spool engine, meaning it has two sets of rotating blades, or spools, that compress air and mix it with fuel to create thrust. It also features advanced technologies such as a three-stage fan, a low-pressure compressor, and a high-pressure turbine.

The F135 engine is capable of producing up to 43,000 pounds of thrust, allowing the F-35 to reach a top speed of Mach 1.6 and a maximum altitude of 50,000 feet. It also has a high level of reliability and maintainability, with a mean time between unscheduled removals [MTBUR] of over 3,000 hours.

Cutting-edge engine: third stream of air may power US F-35-F135 engine
Photo credit: Pratt&Whitney

The F135 engine has undergone extensive testing and development since its inception, with over 500,000 hours of testing and 20,000 hours of flight time accumulated as of 2021. It is also designed to be modular, allowing for easy maintenance and upgrades as technology advances.

GE is still in the game

Lockheed Martin recently expressed support for a new generation engine for the F-35 fighter jet, contrary to the Pentagon’s plan to upgrade the existing Pratt & Whitney engines. Lockheed’s executive vice president for aeronautics, Greg Ulmer, unveiled the company’s support for the Adaptive Engine Transition Program [AETP] for the F-35 at the Paris Air Show. 

Ulmer advocated for a new engine and expressed support for the AETP, criticizing current strategies as short-sighted. Lockheed Martin detailed the benefits of an AETP engine, including its power and cooling capabilities, which could advance the F-35 beyond anticipated upgrades. 

They also stated their readiness to meet the U.S. government’s F-35 requirements, including an engine upgrade. However, Pratt & Whitney felt these remarks undermined the Pentagon’s support for the Engine Core Upgrade. Jill Albertelli, head of Pratt & Whitney’s military engines, warned against using an untested adaptive engine for a single-engine fighter jet, advocating for Pratt’s F135 engine upgrade instead. 

Cutting-edge engine: third stream of air may power US F-35 - XA100 engine
Photo credit: GE Aviations

The F-35, a Lockheed project, is set to remain operational for another 50 years, necessitating an engine upgrade. Both General Electric Aerospace and Pratt & Whitney are competing to develop the AETP engines. While GE plans to incorporate its adaptive engine into the F-35, Pratt views the adaptive engine as suitable for a sixth-generation aircraft. 

Despite initial excitement for a new engine for the Air Force’s F-35As, it wasn’t suitable for other F-35 variants. The Pentagon chose to upgrade the existing F135 engine due to cost-effectiveness. Interestingly, the House Armed Services Committee proposed additional funding for the new engine while still funding the Engine Core Upgrade. Ulmer has recently solidified his stance on the F-35’s future propulsion system, a shift from his previously undecided position in a 2022 Defense News interview.


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