Pratt says it submitted its proposal for the next two lots of F135 engines Sept. 24. (Pratt & Whitney)
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WASHINGTON — Pratt & Whitney has submitted its proposal for the next two lots of F-35 joint strike fighter engines to the Pentagon, and the engine manufacturer expects to reach an agreement in the first quarter of 2014, according to a top executive.
The proposal for low-rate initial production (LRIP) lots 7 and 8 of the F135 engine was submitted to the F-35 Joint Program Office (JPO) on Sept. 24, less than a month after the company announced a tentative agreement with the JPO on engine lot 6, said Bennett Croswell, Pratt’s president of military engines.
“We really want to work with the JPO to negotiate those two concurrently and get an agreement on that by the end of the first quarter,” Croswell said. “Then we’ll be positioned to have a more regular tempo of the LRIP proposals.”
While the final agreement on LRIP-6 has not been announced, the costs per engine for the conventional-takeoff-and-landing engines used in the F-35A and F-35C models dropped 2.5 percent between LRIP-5 and LRIP-6, according to Croswell. He said costs for the short-takeoff-and-vertical-landing (STOVL) F-35B model dropped by 9.6 percent.
The company expects to see a similar cost reduction when it negotiates the next batch of engines, although Croswell cautioned that estimating reductions for the STOVL engine is difficult due to the small quantities being purchased.
“From a tempo standpoint, in terms of contracting, [both] the JPO and Pratt feel like it would be a good thing for us to close [LRIPs] 7 and 8 together,” Croswell said. “It’s also consistent with Lockheed. We’ll kind of be synched up.”
Lockheed Martin, which negotiates the purchases of the fifth-generation fighters independently of Pratt, announced Friday it had reached final agreement with the JPO on LRIP-6 and LRIP-7 as part of a joint package. Final agreement on Pratt’s LRIP-6 will likely come in the next few weeks.
With negotiations of the F135 ongoing, the company is focusing on what the next generation of engines will look like.
“If you look further down the road, we have a great deal of stuff going on,” Croswell said, much of it built around the Adaptive Engine Technology Demonstration (AETD) engine the company has been developing.
“AETD will be the foundation of our sixth-generation fighter engine,” he said. “It will also provide us an opportunity to spin technologies off and back into the F135, to continue to improve it over time.”
The key to that configuration is a three-stream fan, which the company bills as the first in a military engine. Current military engines rely on a two-stream design, with one stream of air moving through the core of the engine and a second bypassing it. Adding a third stream should lead to increased fuel efficiency, as well as a cool stream of air for thermal management.
For the F-35, putting in this new design could give pilots flexibility on how to operate the fighter. The engine could provide capability for extra thrust, or it could reduce the flow to get better fuel economy.
The Air Force Research Laboratory (AFRL) began doing tests on the three-stream technology at its Dayton, Ohio, facility this month.
The company is keeping an eye on what requirements could be to power future “sixth-generation” platforms, including eventual replacements for the Navy’s F/A-18 and the Air Force’s F-22.
The Pentagon has “a real desire to reduce fuel consumption,” Croswell said. He highlighted thermal management and the ability to generate extra power as two other priorities for the sixth-generation engine.
The latter is particularly interesting, given the likelihood that a next-generation fighter would contain some form of directed energy weaponry.
“They’re going to need more power for that,” Croswell said.
While developing new engine technologies, Pratt will also deliver the first KC-46 engine, a slightly modified commercial 767 engine, for the tanker replacement program in November.