Northrop Grumman has moved a step closer to achieving autonomous in-flight refuelling, which remains one of the major technology barriers facing unmanned aircraft systems.

A series of 10 test flights in March proved that a software algorithm based on relative navigation technology works inside an existing Northrop navigation system.

The software package allowed LN-251, a global positioning system/fibre-optic inertial navigation system, to guide a Learjet acting as a surrogate UAS within approximately 1m (3.28ft) of a refuelling boom on a US Air Force Boeing KC-135 tanker, says Simona Kelley, programme manager for Northrop's autonomous aerial refuelling system.

Learjet UAS test - Northrop Grumman 
© Northrop Grumman

The flight tests, sponsored by the Air Force Research Laboratory, followed a series performed in 2007 using the same software package on a US Navy-owned processing system, she says.

Northrop's system requires the tanker and receiver to exchange navigational data, allowing the LN-251 to establish their position in relation to each other in space within centimetres.

Source: Flight International