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.
Similar to the T-38 merged with features of Northrop’s long-abandoned F-20 Tigershark, the design also incorporates area ruling aft of the inlets for transonic capability and a notably tall vertical fin, as well as a distinct dorsal spine. The fuselage incorporates a semi-chined forebody and is mounted on a simple tricycle gear arrangement with an extended wheelbase between the nose and main gear legs.
From initial images released on Aug 19, the aircraft also appears to have simple trailing edge flaps and horizontal stabilizers mounted at a slightly negative dihedral (or anhedral) angle. The images also appear to indicate a baseline, non-afterburning engine – at least for the initial demonstrator. Northrop first revealed a brief glimpse of the concept to reporters in December 2015 and specified at the time the design was tailored to meeting the Air Force’s requirements for sustained G, instantaneous G, angle-of-attack maneuvering and turn rate/ turn radius – without being too expensive.
According to FAA registration details, the demonstrator is designated the Model 400 according, to its Scaled Composites design number. It is powered by a single General Electric F404-102D engine. The aircraft was registered with the FAA in mid-June 2015. 
Northrop, which is teamed on T-X with BAE Systems and L-3, is expected to make the first flight of the demonstrator before year end. Competition for the T-X program is intense with Lockheed Martin and KAI offering a variant of the T-50A, while Boeing andSaab are working together on a clean-sheet design. Raytheon has partnered with Leonardo to offer the T-100, an upgraded version of the Leonardo (Alenia Aermacchi)M-346 advanced jet trainer.
The Air Force is planning to release a request for proposals for T-X in December, with a contract award expected by early 2018. The T-X is now expected to have operational capability in 2034 with initial operational capability in 2024.