November 30, 2005: New Acquisitions for Air Force Flight Test Center Museum

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  • Air Force Flight Test Center

The Air Force Flight Test Center Museum acquired the YF-15A, S/N 71-0287, the eighth prototype built. It was primarily used for high angle of attack testing early in the program and was later used to test the new F100-PW-220 engines for the F-15C. The -220 engine introduced single-crystal turbine airfoils, an advanced multi-zone augmentor, an increased airflow fan and a digital electronic engine control system. Later in its career, the aircraft had been assigned to NASA’s Dryden Flight Research Facility at Edwards where it was used for digital electronic flight and engine control research under the Highly Integrated Digital Electronic Control (HIDEC) program. The aircraft was also used to test and evaluate a computerized self-repairing flight control system for the USAF that detected damaged of failed flight control surfaces.

The effort to operational link engine and flight control systems was a natural outgrowth of the successful Digital Electronic Engine Control (DEEC) unit flight tested on the F-15 at NASA Dryden between 1981 and 1983. The DEEC program, using a Pratt and Whitney F-100 test engine, demonstrated significant improvements in thrust, fuel consumption, and engine life. The successful program paved the way for the U.S. Air Force and Pratt and Whitney to install operational DEEC units on all F100 engines powering F-15 and F-16 fighters.  The HIDEC project studied the integration of aircraft engine operations with air data and flight control systems to improve aircraft performance. Research efforts led to the development of several control modes that demonstrated extended engine life, increased engine thrust, and lower fuel consumption.  The major elements of HIDEC were a Digital Electronic Flight Control System (DEFCS), the engine-mounted DEECs, an on-board general-purpose computer, and an integrated architecture allowing all components to "talk to each other."  Digital systems developed on the HIDEC F-15 were the adaptive engine control system (ADECS) and performance seeking control (PSC). It became the first aircraft to demonstrate the self-repairing flight control system (SRFCS) and the propulsion-only flight control system (PCS).  The integration of digital propulsion and flight control systems on military, commercial, and general-purpose aircraft could lead to very significant savings in fuel, maintenance, and operational costs. The advantages of extended engine life and enhanced engine and flight performance also give the aircraft a greater safety margin, a factor that can be appreciated by aircrews as well as passengers. 

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