Northrop Grumman has installed landing gear and wings on the airframe of the first RQ-4 Global Hawk variant designed for the US Navy's requirement for broad area maritime surveillance (BAMS).

At the same time, the company has released new details of the critical new sensor invented for the BAMS mission. The sensor entered flight tests in December.

Both events indicate Northrop remains on track to complete first flight of the MQ-4C BAMS aircraft later this year, the company said.

 BAMS UAV - Northrop Grumman

© Northrop Grumman

The navy plans to buy 70 MQ-4Cs, including five test aircraft, under a nearly $12 billion acquisition programme, with entry into service scheduled in December 2015.

The first MQ-4C BAMS aircraft will scan the oceans for maritime traffic with a special radar developed by Northrop called the multi-function active sensor (MFAS).

Northrop had previously described MFAS as an electronically-scanned array. The company now adds that the array operates with a rotating sensor with electronic scanning functionality.

It can switch between various surveillance modes, including maritime surface search to track surface traffic, inverse synthetic aperture radar (ISAR) to classify ships by type and image-while-scan to interleave ISAR snapshots and high-resolution scans. The MFAS also can search over land using a spot SAR mode for stationary targets and a strip SAR mode for images along a fixed line, Northrop said.

 BAMS MFAS testbed - Northrop Grumman

© Northrop Grumman

Northrop had previously flight-tested a prototype version of the MFAS sensor (above) during the BAMS competition.

Publicly-released images of the prototype and the latest versions of the radar show minor changes to the radome colour and shape, but it was not immediately clear if Northrop had made more significant changes to the array itself.

Source: Flight International