part power. In the mid tandem fan concept, a high specific flow single stage fan is located between the high pressure (HP) and low pressure (LP) compressors of a turbojet core. Only bypass air is allowed to pass through the fan, the LP compressor exit flow passing through special passages within the fan disc, directly underneath the fan rotor blades. Some of the bypass air enters the engine via an auxiliary intake. During take-off and approach the engine behaves much like a normal civil turbofan, with an acceptable jet noise level (i.e., low specific thrust). However, for supersonic cruise, the fan variable inlet guide vanes and auxiliary intake close-off to minimize bypass flow and increase specific thrust. In this mode the engine acts more like a 'leaky' turbojet (e.g. the F404). In the mixed-flow turbofan with ejector concept, a low bypass ratio engine is mounted in front of a long tube, called an ejector. This silencer device is deployed during take-off and approach. Turbofan exhaust gases induce additional air into the ejector via an auxiliary air intake, thereby reducing the specific thrust/mean jet velocity of the final exhaust. The mixed-flow design does not have the advantages of the mid-tandem fan design in terms of low-speed efficiency, but is considerably simpler. In fighter aircraft engines, an emerging concept is the three-stream architecture, where a third bypass stream can be used to increase bypass ratio when fuel efficiency is required, or have additional airflow directed to the core for greater power. Under the Versatile Affordable Advanced Turbine Engines (VAATE) program, the U.S Air Force and industry partners developed this concept under the Adaptive Versatile Engine Technology (ADVENT) and the follow-on Adaptive Engine Technology Demonstrator (AETD) and Adaptive Engine Transition Program (AETP). Examples of three-stream engines include the General Electric XA100 and the Pratt & Whitney XA101, as well as the propulsion system for the Next Generation Air Dominance (NGAD) being developed under the Next Generation Adaptive Propulsion (NGAP) program. Other applications Another application that could benefit from the VCE approach is combat aircraft. Designers normally have to make a compromise on specific thrust of the engine. If they choose a high specific thrust, the reheat specific fuel consumption (SFC) will be very good, but the dry SFC poor. A high specific thrust implies a high fan pressure ratio, which indicates a high nozzle temperature in dry power. Consequently, the thrust boost in