Since the first Wright Flyer airplane, aircraft have been controlled using modified wing surfaces and a rudder in the tail. The system used is more modern but still requires a moving mechanical system. DARPA has started the Control of Revolutionary Aircraft with Novel Effectors (CRANE) Program which aims to produce an aircraft without a physical steering system.
Instead the aircraft is controlled using a high pressure air system called Active Flow Control (AFC). Air nozzles are placed in several parts of the aircraft with air being ejected at high pressure to change direction. For phase two of CRANE, DARPA awarded a contract to produce the prototype to Aurora Flight Science who conducted the first phase of testing using a small-scale model in a wind tunnel.
The prototype will have the ability to fly at a speed of almost 900 km/h, with a wingspan of 9 meters and have the ability to test different types of AFC systems. If the second phase test is successful, the third phase test will start as early as 2025.
An aircraft without a physical steering system has several advantages especially to avoid being detected by radar. Later, the ailerons and flaperons that are now used reflect radar reducing effectiveness designed to be difficult to detect. It also allows thicker wing designs to be used for fueling.