Research on the F/A-18E/F Using a 22%-Dynamically-Scaled Drop Model

Mr. Mark A. Croom, Ms. Holly M. Kenney, and Mr. Daniel G. MurriNASA Langley Research CenterandMr. Kenneth P. Lawson*Naval Air Systems CommandABSTRACTResearch on the F/A-I 8E/F configuration wasconducted using a 22%-dynamically-scaled drop modelto study flight dynamics in the subsonic regime.Several topics were investigated includinglongitudinal response, departure/spin resistance,developed spins and recoveries, and the falling leafmode. Comparisons to lull-scale flight test resultswere made and show the drop model stronglycorrelates to the airplane even under very dynamicconditions. The capability to use the drop model toexpand on the information gained from full-scaleflight testing is also discussed. Finally, apreliminary analysis of an unusual inclined spinningmotion, dubbed the "cartwheel", is presented here forthe first time.INTRODUCTIONFlight dynamic issues can significantly impactthe safety and effectiveness of high-performancevehicles such as the Navy's latest strike aircraft, theF/A-18E/F Super Hornet shown in figure 1.Dynamic aspects often dominate the aerodynamics andcan strongly influence the flight mechanics,particularly during the large-amplitude, high-ratemaneuvering that is required of this class of aircraft.The typical challenge to the designer is to maximizemaneuvering performance while maintaining goodlevels of departure resistance throughout the intendedoperational envelope and beyond (for margin).A time-honored approach to achieve thisbalance between stability and maneuverability is togain a comprehensive understanding of the aircraftflight dynamic properties by subjecting theconfiguration to a battery of tests.Figure 1.-The F/A-I 8E/F Super HornetIn the subsonic flight regime these tests (see figure 2)typically include captive and free-flying wind-tunneltests (static force and moment, forced-oscillation, free-flight, free-spin, and rotary-balance, among others),outdoor drop model tests, numerical based analyses(e.g., piloted simulation studies), and culminate withfull-scale flight testing. All of these tests wereperformed during the F/A-18E/F development;however, this paper concentrates on the drop modeleffort.Statics Free-Flight SimulationRotaryBalance Free-Spin DropModelFigure 2.- Ground-based test methods.* Member AIAACopyright © 2000 by the American Institute ofAeronautics And Astronautics, Inc. No copyright is asserted in the United States underTitle 17, I.I.S.Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein forGovernmental Purposes. All other rights are reserved by the copyright owner.