F/A-18 External Configuration Effects on High Angle of Attack Departure Resistance

One of the challenges in defining tactical aircraft handling qualities is establishing flight envelopes for multiple external configurations. In the case of the F/A-18A/B/C/D Hornet, there are single seat and two seat variants, a wide variety of stores carriage options, and other outer moldline additions to the basic airframe that can affect aerodynamics. The F/A-18 aircraft has excellent maneuverability and departure resistance throughout the existing flight envelope, however, changes in external configuration affect departure resistance, particularly at high angle-of-attack (AOA). Various configuration effects have been studied throughout the long life of the Hornet, however this work attempts to collect that knowledge with respect to departure resistance in one document, provide insight into the reasons behind current aircraft operating limitations and overview the latest flight control system upgrade designed to improve the aircraft’s departure resistance. The basic Hornet high AOA flying qualities, flight test history, and the current departure training program are reviewed. A review of documented Hornet out-of-control (OCF) mishaps and incidents is included with a correlation to configuration effects and Navy fleet concerns about aircraft configuration. Throughout, a variety of configuration effects on high AOA flying qualities are detailed based on early development and more recent follow-on data, including wind tunnel, simulation, flight test and fleet events. Finally the latest flight control software upgrade designed to improve departure resistance and the preliminary results relating to configuration effects will be briefly discussed.