Lockheed Martin [LMT] is suggesting that its F-35 fighter will need an Advanced Engine Transition Program powerplant or something akin to it for Block 5 and above of the F-35.
“AETP technologies deliver more power and greater cooling capability, which is required as we modernize the F-35 beyond Block 4,” the company said on June 21st.
That contention received push back from
Raytheon Technologies‘ [RTX] Pratt & Whitney unit, which makes the F-35’s F135 engine and is embarking upon an F135 Engine Core Upgrade (ECU) for Block 4 and beyond.
“AETP is a technology program that will feed into 6th gen fighter platforms,” Jill Albertelli, president of Pratt & Whitney’s military engine business, said in a statement.
“Lockheed Martin wants to put an unproven adaptive engine on a single engine fighter jet, regardless of the hefty price tag and the significant delay in delivering critical capabilities to the warfighter at a time of urgent need,” she said. “This undermines the DoD’s decision to move forward with the F135 Engine Core Upgrade, a decision that was studied, validated, submitted, and fully funded in the administration’s budget. Despite recent public comments, Block 5 does not exist as a defined set of capabilities at this time, but regardless of which Block we’re discussing, the F135 ECU paired with an upgraded PTMS [Power and Thermal Management System] can provide 80KW [kilowatts] or more of cooling power for the F-35, which will exceed all power and cooling needs for the F-35 through the life of the program.”
Pratt & Whitney is gearing up to finish the preliminary design review (PDR) of the F135 ECU and is planning to enter the detailed design phase for the F135 ECU early next year. P&W said this week that it has more than doubled the number of F135 ECU workers from 200 to 500 to satisfy that goal.
As the U.S. Air Force awaits congressional action on the requested $245 million in fiscal 2024 to begin the F135 ECU, Pratt & Whitney is highlighting not only the goals for improved F135 ECU engine performance and cooling compared to the baseline F135, but also the number of jobs involved (Defense Daily, June 15).
Albertelli said this month that the F135 employs 55,000 workers in more than 420 suppliers in the United States.
Pratt & Whitney wants to field the F135 ECU by 2028 to enable weapon and sensor upgrades in Block 4 of the F-35.
The Air Force’s fiscal 2024 budget funds F135 ECU and ends the service’s AETP to develop a new engine for the F-35 (Defense Daily, March 13).
Air Force Secretary Frank Kendall has said that the service decided on F135 ECU as the more affordable option. He said that AETP promised significant performance improvements for the F-35 and that the service may have decided to continue AETP, “if the cost had been lower.”
As part of AETP, General Electric [GE] proposed its XA100 engine to accommodate the envisioned Block 4 weapons and other upgrades for the Lockheed Martin F-35.
Last October, 48 representatives urged DoD to invest in next generation, adaptive propulsion, such as the XA100, for fighters in a letter co-sponsored by Sens. Rob Portman (R-Ohio) and Sherrod Brown (D-Ohio) and Rep. Brad Wenstrup (R-Ohio).
The F-35 Joint Program Office (JPO) considers the F135 ECU and a new or upgraded PTMS) as a single effort (Defense Daily, May 31).
Honeywell [HON] builds the PTMS as a subcontractor to Lockheed Martin. The PTMS uses air pressure from the engine to cool aircraft subsystems and enables main engine start, emergency power, cockpit conditioning, equipment cooling, and some electrical power.
Last month, a Government Accountability Office (GAO) report said that the F135 will need a new or improved PTMS to accommodate future weapons and sensors on the aircraft (Defense Daily, May 30). The question appears to be when.
The GAO report said that the F135’s cooling system “is overtasked, requiring the engine to operate beyond its design parameters” and that “the extra heat is increasing the wear on the engine, reducing its life, and adding $38 billion in maintenance costs.”
While the F-35 Joint Program Office (JPO) has said that it is “very confident we can minimize the $38 billion impact simply with ECU,” the GAO report called into question whether the F135 ECU will provide enough cooling to accommodate Block 4 or whether the F135 ECU will need a new or upgraded PTMS as well to allow Block 4.
If Congress decides to continue AETP in fiscal 2024, AETP integration on the F-35 would require further analysis before proceeding, the F-35 JPO has said (Defense Daily, May 11).
The weight of the F135 for the F-35A and C is 6,400 pounds, while the F-35B has a lift fan system, which means the engine weight for that variant is about 10,400 pounds. The AETP requirement weight is 6,600 pounds.
“Size, weight, power and cooling (SWaP-C) are fundamental considerations for aircraft performance,” the F-35 program said last month in response to written questions on AETP. “It is understood that an increase in the weight of the aircraft will have a negative impact on its performance. AETP with its higher thrust, higher weight and further aft center of gravity present additional integration risk compared to ECU, and further structural analysis is required to quantify short-term and long-term impacts on the airframe and overall performance.”
Launched in 2016, AETP followed Air Force engine developments in the Adaptive Versatile Engine Technology program, begun in 2007, and the Adaptive Engine Technology Development program, started in 2012. In June 2016, Pratt & Whitney and GE each received contracts worth more than $1 billion for AETP–GE for its XA100 and Pratt & Whitney for its XA101.
David Tweedie, vice president and general manager for advanced products at GE Edison Works, has said that “GE Aerospace developed the XA100 to meet F-35 performance, reliability and single-engine safety needs” and that “for more than a decade, GE Aerospace has been working with Lockheed Martin in concert with the U.S. Air Force to assess the engine’s performance and integration, understand the challenges, and de-risk putting an adaptive engine in the F-35, efforts that are continuing during the Design and Manufacturing Advancement.”
The XA100 has been above the 6,600-pound AETP specification, but GE said that its engineers have reduced weight, and the company believes the XA100 will meet the weight specification.
GE said that the additional thrust provided by the XA100 would offset additional engine weight and still provide more than a 10 percent increase in overall thrust across all parts of the flight envelope.
GE says that 500 GE Aerospace employees, including 400 engineers, continue their work on the company’s XA100 in Evendale, Ohio.
The F-35 JPO said that it considered ECU, the XA100, and the XA101 adaptive cycle engine offerings in a business case analysis that informed the Air Force’s decision on AETP and ECU.