LOS ANGELES – Northrop Grumman’s contender for the U.S. Air Force’s T-X next-generation trainer competition has begun taxi tests at Mojave, California. The aircraft, which was designed by Northrop’s Scaled Composites special projects company, is believed to have begun high speed taxi work this week. Northrop’s offering is a low-wing, single-engine aircraft with side-mounted inlets and a conventional horizontal and large vertical tail.