The Northrop/McDonnell Douglas YF-23 was a prototype fighter aircraft designed for the United States Air Force. The YF-23 was a finalist in the U.S. Air Force's Advanced Tactical Fighter competition. The YF-23 lost the contest to the Lockheed YF-22, which entered production as the Lockheed Martin F-22 Raptor.
The YF-23 was designed to meet USAF requirements for survivability, supersonic cruise (supercruise), stealth, and ease of maintenance. Designed with all-aspect stealth as a high priority. The YF-23 was an unconventional-looking aircraft with trapezoidal wings, substantial area-ruling, and a V-tail. Similar to the B-2, the exhaust from the YF-23's engines flows through troughs lined with heat ablating tiles, which shields the exhaust from infrared (IR) missile detection from below. The wing flaps and ailerons deflect inversely on either side to provide roll. Pitch was provided by movement of both V-tails, and yaw was supplied by opposite movement. Deflecting the wing flaps down and ailerons up on both sides simultaneously provided for aerodynamic braking。