Rather than an ICBM test silo, the U.S. Air Force is to use a launch pad at Vandenberg Space Force Base, Calif., for the first flight test of an unarmed LGM-35A Sentinel ICBM by Northrop Grumman [NOC]. "The first flight test was moved to a pad launch to allow for a more incremental approach to flight testing," the Air Force said on Wednesday in response to email questions. "The flight test dates will be confirmed as the Air Force restructures…