Investment by GE Aviation in next-generation military engines will increase by 50% next year even as military budgets decline in the U.S. and around the world.

The goal: to develop a sixth-generation fighter engine for the U.S. Air Force and Navy, and an advanced engine for helicopters. They will all incorporate ceramic matrix composites (CMCs) in the hot section, and 3-D printing (additive manufacturing) for difficult-to-make parts.

“We haven’t had this much activity going on in next-gen military engines for a couple of decades,” says Jean Lydon-Rodgers, vice president and general manager of GE Aviation’s military systems. “Most people would be surprised to hear that, in the middle of sequestration. I couldn’t be more excited.”

She won’t say specifically what these engines are for, except to bring more power for less weight and extended range though significant reductions in fuel burn. Applications could include future bombers and strike aircraft (and UAVs), the re-engining of fighters such as the F-35, and helicopters such as Black Hawks and Apaches. The engines could also be used for a turboprop for future regional airliners based on the GE38 turboshaft that powers the Sikorsky CH-53K, while versions of the GE38 could also re-engine Chinooks and V-22 Ospreys.

“Our R&D is at the highest level since the F136 [GE’s alternative engine for the F-35]. It is important right now to renew the technology in our portfolio because there will be a demand for new-tech engines. We’re not going to be able to rest on our laurels or continuously upgrade our legacy fleets; we simply cannot add new technologies into today’s engines and expect them to have the capabilities the Air Force and Navy need.

“Do we simply take CMCs and put them into the F110 or F414? We could, and we might get a benefit from that. But not on the order of 25% improvement in fuel efficiency.”

The improvements will come from combining the adaptive cycle, CMCs and 3-D printing to enable engines to burn hotter than ever before.

And cost will be an important factor, too. Unprecedented cooperation between GE Aviation’s commercial and military businesses and the parent company’s research labs is spreading the cost of investment not only into new materials but also how to manufacture them efficiently. For example, the results of $600 million that GE invested into R&D in CMCs for commercial engines will be applied to the military ones, too.

The military side will then take those technologies and develop them further, testing them in increasingly harsh environments. One result: GE holds the world record for the hottest engine core (the combined temperature of the compressor and turbine), as validated by the U.S. Air Force Research Lab, and now plans to raise that by another 200F.

A full engine will be run 80-100 hours before late fall to validate the adaptive cycle features as GE heads towards a preliminary design review for the next phase beyond the U.S. Air Force's AETD (Adaptive Engine Technology Development) program, leading to a sixth-generation fighter engine in 2016 for future fighters and bombers.

Lydon-Rodgers says the goal is to deliver this performance in production engines, using proven technologies to reduce the risk, at or below the cost of fifth-generation engines.

“It's a combination of lower cost and lower risk that will drive the competition for Department of Defense programs in the future,” she says.

AATE AND FATE
Meanwhile, GE is working on the future drop-in replacement for the T700 as the U.S. military seeks more power and less maintenance in its Black Hawk and Apache helicopters. It has completed two full engine tests in the U.S. Army’s AATE program (Advanced Affordable Turbine Engine) and a request-for-proposals for the follow-on ITEP (Improved Turbine Engine Program) could follow, though timing is uncertain.

AATE called for a 25% reduction in SFC, 65% higher power-to-weight ratio, 35% lower production and maintenance costs, and 20% longer design life relative to the T700, in the same size envelope. The program is expected to lead to a production turboshaft by 2023.

GE was the sole source winner of the U.S. Army’s FATE (Future Affordable Turbine Engine) program to reach the next level: a 35% increase in fuel efficiency and 85% improvement in power-to-weight ratio for a 6,000-7,000 shp engine. Combustor tests are now underway with full engine tests planned for 2015. Lessons from this are being plowed back into AATE, Lydon-Rodgers says.

FATE technologies can also be instilled in the GE38 turboshaft as it can be scaled up or down from its current 7,500 shp, or developed into a turboprop. “We can build CMCs into that, too,” she says.