PALMDALE - Northrop Grumman Corp. will build three unmanned X-47B aircraft and their associated systems under a $1 billion contract awarded Wednesday. The contract with the Defense Advanced Research Projects Agency is part of the Joint Unmanned Combat Air Systems demonstration program, intended to produce the technologies for unmanned aerial vehicles capable of delivering munitions. The three vehicles will be assembled at Northrop's facility at Air Force Plant 42 in Palmdale. Company officials, however, do not foresee a large increase in employment at the site due to this contract, said Jim Hart, Northrop spokesman. The X-47B is expected to begin...