Two San Diego County defense contractors are hustling to develop a new generation of comparatively inexpensive, unmanned aerial vehicles in the wake of Defense Secretary Robert Gates’ call for a less costly naval arsenal. Speaking in Washington, D.C., on Monday, Gates said the military needs to re-examine whether it can afford so many aircraft carriers and submarines when more money is needed to underwrite the Army and Marine Corps. Those two branches of the military are leading the wars in Iraq and Afghanistan, while the Navy is playing a supporting role. The Navy, whose second-largest home base is San Diego,...