A four-way competition to build the US Navy's next carrier-based unmanned air system (UAS) expect to begin revising year-old, preliminary designs that were submitted before the mission changed.

Lockheed Martin and Boeing each received $43 million risk reduction contracts on 23 September from the US Navy. Two more bidders, Northrop Grumman and General Atomics Aeronautical Systems, are waiting for their awards.

The new round of contracts pays the contractors to convert their preliminary designs, which were tuned to support the navy's original requirement for a stealthy, carrier-launched surveillance and strike aircraft (UCLASS).

The navy has since converted the MQ-25 programme into the carrier-based airborne refueling system (CBARS). Rather than penetrating into defended airspace to detect and attack targets, the MQ-25s will mostly serve as an escort or "buddy" tanker for manned strike aircraft. The MQ-25 also would be equipped with a 19-23in-diameter forward looking infrared sensor turret for a surveillance mission in permissive airspace.

Industry sources say the navy is expected to release a draft request for proposals in Fiscal 2017, launching the bidding process for the development phase of the programme.

Source: FlightGlobal.com