A Fire Scout unmanned helicopter hovers above a U.S. Navy ship in an undated photo. The Navy wants to put weapons on the Fire Scout, and has tapped Northrop Grumman Corp.’s Rancho Bernardo workforce to help it.

A Fire Scout unmanned helicopter hovers above a U.S. Navy ship in an undated photo. The Navy wants to put weapons on the Fire Scout, and has tapped Northrop Grumman Corp.’s Rancho Bernardo workforce to help it.

This fall, the Pentagon decided to extend the time the aircraft will spend backing up troops in northern Afghanistan...