The U.S. Navy is planning to demonstrate an armed, sensor-equipped, carrier-based unmanned combat aircraft system (UCAS) by 2018, as a follow-on to carrier-suitability and autonomous aerial-refueling demonstrations planned for completion in 2013.

A request for information (RFI) will be released this year, according to Rear Adm. William Shannon, program executive officer for unmanned aviation and strike weapons, speaking Feb. 17 at Aviation Week’s Defense Technology and Requirements conference in Washington.

The program could be worth as much as $2 billion, with major funding starting in Fiscal 2013. The RFI will be open to all manufacturers, and not automatically an extension of Northrop Grumman’s work with the X-47B UCAS-D demonstrator, now undergoing ground tests.

The X-47B is intended to demonstrate the carrier suitability of a stealthy, tailless unmanned aircraft. The follow-on armed demonstrator is expected to lead to a joint Navy/Air Force UCAS program, but the winning team will have to compete for the in-service system, which is a possible replacement for the F/A-18E/F from 2025.

This would represent a second run at a joint UCAS program for the services: the previous J-UCAS effort was split in late 2005, with the Air Force pursuing a larger aircraft and the Navy heading along the path to UCAS-D.

But the Air Force is noncommittal. Lt. Gen. Mark Shackelford, Air Force military deputy for acquisition, said at the same conference that the service is watching the program but "does not want to do the Air Force version of the Navy platform."

Shannon, meanwhile, says first flight of the X-47B, originally expected last fall, will not take place until the summer. Issues include software to control the brakes, and overstress in the exhaust system caused by vortex-induced resonance in the curved tailpipe.

Integration of aircraft and ship systems has begun on the USS Lincoln, using a King Air as a surrogate for the X-47B, performing the same procedures and communicating via digital messages. That will be followed this year with tests using an F/A-18 to emulate the X-47B, which is scheduled to make its first carrier landing in late 2011.

Northrop Grumman concept