WASHINGTON — The US Air Force and the Army are moving full speed ahead toward next-generation engines the services hope will significantly increase fuel efficiency and power.

And both endeavors pit two giants in the engine-building world against each other: GE Aviation and Pratt & Whitney. -- against one another.

The Air Force is kicking off the next phase of its effort to develop adaptive engine technology, a new concept both companies have been developing for several years. Pratt and GE both submitted proposals, due Sept. 16, for the Air Force's Adaptive Engine Transition Program (AETP), which is meant to build and test the new engine model.

Industry expects the Air Force to award two separate contracts for AETP as it is known, one each to Pratt and GE in early 2016. The five-year program, which could be worth as much as $950 million to each team, will transition the existing technology out of the Air Force Research Laboratory and into the acquisition realm.

Industry does not expect a downselect to one company in the near term, but the Pentagon will likely make a decision on a single engine solution in the next few years.

If the stakes weren't high enough, some say AETP will play a role in shaping the requirements for the next-generation fighter jet. As the Air Force works to understand the needs of air power out into the 2030s, the service hopes soon to settle on a path forward for a sixth-generation plane. Under AETP, which runs parallel to the planned analysis of alternatives for sixth gen, Pratt and GE will work alongside the three major aircraft primes to test different concepts.

Meanwhile, the Army released a request for proposals for preliminary designs for the Improved Turbine Engine Program (ITEP) at the end of September. ITEP , as it’s called, will replace the engine in roughly 3,000 UH-60 Black Hawk and AH-64 Apache helicopters with a more powerful and fuel-efficient one.

It’s been a long, delayed road to get to the preliminary design phase. Army leaders stressed the engine replacement was its No. 1 priority, but after it wrapped up the science-and-technology phase, the service made little public progress toward the engine program’s inception for well over a year. 

Companies wishing to submit offers have until Nov. 9 to submit offers and be part of an full and open competition where up to two vendors will be selected to develop designs. While it’s possible a dark horse like France's Turbomeca could respond to the request, it’s expected only two engines will be submitted: from the usual suspects: one from a Honeywell-Pratt & Whitney team and one from GE.

The two teams both developed engine concepts in the Army's science and technology effort leading up to the ITEP program of record.

The service plans to make an award late next summer to up to two vendors to design engines. The Army will then choose one engine design to continue into the engineering and manufacturing development phase in 2019.

AETP Implications For Sixth-Gen Fighter

The Air Force Research Laboratory has been working with GE and P&W on adaptive, "three-stream" engine technology for several years, under a science and technology program called Adaptive Engine Technology Development (AETD).

Fixed-cycle engines powering today's military aircraft are limited to one capability: either maximum power or fuel efficiency. The adaptive engine concept enables new engines to switch between the two. Where most fighter jet engines have two "spools" of air, the adaptive engine design adds a third stream around the outside of the engine. By changing that air stream, engineers can adapt the engine to get optimal performance throughout the flight envelope, according to Jimmy Kenyon, Pratt's director of advanced programs and technology.

"It's like shifting a gear in your car, shifting a gear on your bicycle," Kenyon explained. "You change the way the machinery works together so you match the conditions you are running out."

Both companies finished up design review this year, and will continue to build and test individual components under AETD. The follow-on program, AETP, will build and test full-up engines, Kenyon said.

Pratt's AETD engine improves fuel efficiency by 25 percent, thrust by 20 percent and range by 30 percent, Kenyon said. Similarly, GE's AETD design improves fuel consumption by 25 percent, increases thrust by 20 percent, and extends aircraft operating range by 30 percent.

Pratt is still on contract to build F135 engines for Lockheed Martin's F-35 fighter jet, and the company is working on upgrades to improve the fuel efficiency and thrust for that engine. The company sees potential to incorporate some of the technology developed under AETD into the F135, Kenyon said.

GE’s proposal builds on the company’s commercial LEAP and GE9X engines, which will soon enter service with the Airbus' new A320 and Boeing’s new 737 MAX, according to Dan McCormick, who leads the company’s adaptive cycle program. In addition to the third air stream, the engine leverages ceramic matrix composites, (CMCs), a new type of material that can withstand hotter temperatures than conventional metals, and additive manufacturing. 

In the next few years, industry expects AETP to look at the application of adaptive engine technology to the next-generation fighter jet. Under AETP, the companies will contract with primes Lockheed Martin, Boeing and Northrop Grumman to conduct trade studies on fit and integration of the new engines into next-generation aircraft designs, McCormick said. This contractual effort is intended to inform the Navy and Air Force's ongoing analysis of alternatives for the FA-XX and F-X sixth-generation fighter programs, he said.

"This is definitely intended to help populate a matrix of capabilities that help both services determine what capabilities could be provided to the aircraft relative to Mach numbers and ranges and payloads, the typical characteristics," McCormick said.

AFRL declined to comment on future contractual efforts.

Army ITEP Opportunities

The Army's new engine will be designed to save 25 percent on fuel consumption at 3,000-shaft horsepower, as well as boost the horsepower-to-weight ratio by 65 percent and engine-design life by 20 percent.

The Army will spend $51 million in 2016 and anticipates a total development cost of $720 million.

Honeywell is taking its experience developing engines for a variety of Army platforms and applying it to its ITEP design that it believes could save the Army $1 billion a year in fuel and maintenance costs.

And Honeywell's partner Pratt & Whitney "has the most sophisticated and newest DoD engine going for the joint strike fighter," Craig Madden, president of the two companies' joint venture, the Advanced Turbine Engine Co., said last week at a media briefing. "If you combine those two companies, we can make a hell of an engine."

ATEC is offering the HPW3000 turboshaft engine for the ITEP competition, which uses a two-spool gas generator architecture that improves specific fuel consumption, according to Madden. The engine successfully completed performance and durability tests and its new inlet particle separator proved effective in sand testing, Madden said. An engine that can cope with dusty, sandy environments is a requirement stemming from the wars in Afghanistan and Iraq.

Much is at stake with the engine program, as the both companies are developing an engine specific to just two military helicopters and the possibility of selling the engine to the commercial market is slim.

But Madden is optimistic. "Either competitor, if you were to lose," he said, "you've still got the FVL [Future Vertical Lift] opportunity and that opportunity is either a 3,000 shaft horsepower or a growth or scaling up version, so there is some opportunity beyond ITEP if we were to lose."

The Army is concurrently planning for a Future Vertical Lift helicopter expected to reach initial fielding in the early 2030s. Both the service and industry have said the ITEP would be available for FVL, but whether it is the right engine to suit the future helicopters' requirements when they are ironed out remains to be seen.

Madden acknowledged that the commercial market for engines of this kind is limited but a gap exists in that market that could be filled.

There are also some technologies ATEC has developed that could spin into other engines. Additionally, the company has done analysis on scalable engine designs and believes it could scale its engine up to about 4,500 shaft power, Madden said.

GE Aviation, which makes the legacy engine in Black Hawks and Apaches, plans to submit its GE3000 engine to the ITEP preliminary design competition.

Since wrapping up full engine testing as part of the science and technology development phase, GE "continued maturing critical technologies" with the Army through the competitively awarded Future Affordable Turbine Engine (FATE) program, with goals even more aggressive than those in the ITEP program, according to a company statement.

The FATE program set its goals at 35 percent reduction in specific fuel consumption, 80 percent improvement in power-to-weight, 20 percent improvement in design life and a 45 percent reduction in production and maintenance costs relative to currently fielded engines.

GE also successfully tested a FATE inlet particle separator, compressor, combustor and turbines that validated advanced technologies like 3D aero designs, ceramic matrix composites and additive manufacturing, in which the company invests $1.8 billion annually to develop.

"The FATE engine is the world's most advanced turboshaft engine, incorporating technologies for the next generation of propulsion," Harry Nahatis, GE Aviation's general manager of Advanced Turboshaft Programs, said. "We're very encouraged by the test results thus far and are incorporating the lessons learned into our ITEP offering."