[1]. An early example was the innovative Focke-Wulf FW 190 fighter of World War II fame. Its landing gear and flaps were electrically controlled and actuated by small reliable high-torque electric motors. A variable incidence electrically controlled and actuated movable horizontal stabilizer maintained trim about the longitudinal (pitch) axis and was regularly used to relieve the heavy control forces encountered during steep dives (the FW 190 exceeded Mach 0.8 during testing). Another highly advanced FW 190 feature was the BMW 801 Kommandogerät (command equipment). This consisted of a mechanical-hydraulic analog computer that automatically adjusted engine fuel flow, variable pitch propeller setting, supercharger setting, fuel mixture, and ignition timing in response to pilot commands via the single throttle lever. This pioneering step in computerized integrated propulsion control systems greatly simplified engine control. See Albert C. Piccirillo, “Electric Aircraft Pioneer—The Focke-Wulf Fw 190,” Society of Automotive Engineers (SAE) Paper 965631, Oct. 1996.
[2]. Control cables were replaced with rigid pushrods in German World War II flight control systems, for example in the FW 190 and the Fiesler Fi-103 pulsejet-powered cruise missile (the V-1). Pushrods minimized effects produced by control cables stretching under load.
[3]. “NASA Dryden Flight Research Center Pilot Biographies.” http://www.nasa.gov/centers/dryden/news/Biographies/Pilots/index.html, accessed July 21, 2009. Herb Hoover was the first civilian pilot to fly faster than the speed of sound. He exceeded Mach 1 in the Bell XS-1 on Mar. 10, 1948.
[4]. Lawrence K. Loftin, “Quest for Performance: The Evolution of Modern Aircraft,” Part II, ch. 12, Science and Technology Branch, NASA SP-468 (1985).
[5]. Richard P. Hallion, “The Air Force and the Supersonic Breakthrough,” published in Technology and the Air Force: A Retrospective Assessment, Air Force History and Museums Program, Washington, DC, 1997.
[6]. Hallion, “On the Frontier: Flight Research at Dryden, 1946–1981,” NASA SP-4303 (1984).
[7]. Michael J. Neufeld, “The Rocket and the Reich; Peenemünde and the Coming of the Ballistic Missile Era,” The Smithsonian Institution, published by The Free Press, a division of Simon and Schuster, New York, 1995. James E. Tomayko, “Computers Take Flight: A History of NASA’s Pioneering Digital Fly-by Wire Project,” NASA SP-2000-4224 (2000).
[8]. Much like the Space Shuttle is carried on top of the NASA Boeing 747s when it is ferried from Edwards AFB to Cape Kennedy, FL.
[9]. Tomayko, “Blind Faith: The United States Air Force and the Development of Fly-By-Wire Technology,” Technology and the Air Force: A Retrospective Assessment, Air Force History and Museums Program, Washington, DC, 1997.
[10]. Dutch roll is a term commonly used to describe an out of phase combination of yawing and rolling. Dutch roll instability can be improved by the use of a yaw damper.
[11]. The Hs 129 was armed with a variety of cannon that could include a 75-millimeter antitank gun.
[12]. Norman C. Weingarten, “History of In-Flight Simulation & Flying Qualities Research at CALSPAN,” AIAA Journal of Aircraft, vol. 42, No. 2, March/April 2005.
[13]. Paul F. Borchers, James A. Franklin, and Jay W. Fletcher, “Flight Research at Ames, 1940–1997: Fifty-Seven Years of Development and Validation of Aeronautical Technology,” NASA SP-3300 (1998).
[14]. Rowland F. Pocock, “German Guided Missiles of the Second World War,” Arco Publishing Company, Inc., New York, 1967. These included Matador, Snark, BOMARC, Rascal, plus many others developed in a number of countries. See Gavin D. Jenny, James W. Morris, and Vernon R. Schmitt, “Fly-by-Wire, A Historical and Design Perspective,” The Society of Automotive Engineers, 1998.
[15]. An electrical side stick controller was developed in Germany during the Second World War to guide air-launched Henshel Hs 293 and Ruhrstahl Fritz X missiles against ships maneuvering at sea. Command signals were transmitted from the controller to the missiles via radio link. A similar guidance approach was used on the surface-to-air Wasserfall (Waterfall) command-guided antiaircraft missile. Examples of these weapons are on display at the National Air and Space Museum’s Udvar-Hazy Center at Dulles Airport near Washington, DC, and at the National Museum of the U.S. Air Force in Dayton, OH.
[16]. Bill Alford was killed on Oct. 12, 1959, in the crash of a British Blackburn Buccaneer during a visiting test pilot evaluation flight from the Aircraft and Armament Experimental Establishment at Boscombe Down in the United Kingdom.
[17]. Donald L. Mallick, with Peter W. Merlin, “The Smell of Kerosene: A Test Pilot’s Odyssey,” NASA SP-4108 (2003).
[18]. S.A. Sjoberg, “Some Experience With Side Controllers,” Research Airplane Committee Report on the Progress of the X-15 Project, pp. 167–174; Conference held at NACA Langley Aeronautical Laboratory, Langley Field, VA, Oct. 25–26, 1956.
[19]. “Automatic Flight Control System Sought,” Aviation Week, Aug. 6, 1956, pp. 275–284.
[20]. Duane McRuer and Dunstan Graham, “A Flight Control Century: Triumphs of the Systems Approach,” Paper 617, Journal of Guidance, Control and Dynamics, vol. 27, No. 2, pp. 161–173, AIAA, 2003.
[21]. J.K.B. Illingworth and H.W. Chinn, “Variable Stability and Control Tests on the S.C.1 Aircraft in Jet-Borne Flight, with Particular Emphasis on Reference to Desirable VTOL Flying Qualities,” Royal Aircraft Establishment, Bedford, UK, Her Majesty’s Stationary Office, London, 1969.
[22]. D. Lean and H.W. Chinn, “Review of General Operating Experience with a Jet-Lift VTOL Research Aircraft (Short S.C.1),” Aeronautical Research Council Current Paper C.P. No. 832, Her Majesty’s Stationary Office, London, 1965.
[23]. Illingworth and Chinn, “Variable Stability and Control Tests on the S.C.1 Aircraft in Jet-Borne Flight, with Particular Emphasis on Reference to Desirable VTOL Flying Qualities.”
[24]. J.C. Floyd, “The Canadian Approach to All-Weather Interceptor Development, Fourteenth British Commonwealth Lecture,” The Journal of the Royal Aeronautical Society, vol. 62, No. 576, Dec. 1958.
[25]. Thirty-one former CF-105 engineers were hired by NASA with several going on to hold important positions within the NASA Mercury, Gemini, and Apollo programs. Chris Gainor, “Arrows to the Moon: Avro’s Engineers and the Space Race,” (Burlington: Apogee Books, 2001).
[26]. “Experience with the X-15 Adaptive Flight Control System,” NASA TN-D-6208, NASA Flight Research Center, Edwards, CA (March 1971).
[27]. Hallion, “On the Frontier Flight Research at Dryden, 1946–1981.”
[28]. Allan F. Damp, “Evaluation Tests on Boulton-Paul VC-10 Aileron Integrated Flight Control Actuator,” Commercial Division, Boeing Company, Renton, WA, Mar. 10, 1970.
[29]. Molly Neal, “VC10: Vickers-Armstrongs’ Long-range Airliner,” Flight International, May 10, 1962.
[30]. Ray Sturtivant, “British Research and Development Aircraft: Seventy Years at the Leading Edge,” Haynes/Foulis, 1990; Kyrill Von Gersdorff, “Transfer of German Aeronautical Knowledge After 1945,” in Hirschel, Ernst Heinrich, Horst Prem, and Gero Madelung, “Aeronautical Research in Germany (From Lilienthal to Today),” Springer-Verlag, Berlin Heidelberg, 2004.
[31]. B.S. Wolfe, “The Concorde Automatic Flight Control System: A Description of the Automatic Flight Control System for the Anglo-French Supersonic Transport and its Development to Date,” Aircraft Engineering and Aerospace Technology, vol. 39, Issue 5, 1967.
[32]. During the war in Southeast Asia, 8,961 U.S. aircraft were lost. Of these, Air Force losses totaled 2,251, the Navy 859, the Marine Corps 463, and the Army 5,388 (mostly helicopters). The McDonnell-Douglas F-4 Phantom was the predominant fighter/attack aircraft used by the USAF, the USMC, and the Navy during the Vietnam war. A total of 765 F-4s were lost.
[33]. Robert E. Ball, “The Fundamentals of Aircraft Combat Survivability Analysis and Design,” American Institute of Aeronautics and Astronautics (AIAA), New York, 1985.
[34]. Gavin D. Jenny, “JB-47E Fly-By-Wire Flight Test Program (Phase I),” Air Force Flight Dynamics Laboratory TR-69-40, Wright-Patterson AFB, OH, Sept. 1969.
[35]. Gavin D. Jenny, James W. Morris, and Vernon R. Schmitt, “Fly-by-Wire, A Historical and Design Perspective,” The Society of Automotive Engineers (SAE), 1998.
[36]. Tomayko, “Blind Faith: The United States Air Force and the Development of Fly-By-Wire Technology,” Technology and the Air Force: A Retrospective Assessment, Air Force History and Museums Program, Washington, DC, 1997.
[37]. Michael L. Yaffee, “Survivable Controls Gain Emphasis,” Aviation Week, Feb. 2, 1970.
[38]. Jenny, “JB-47E Fly-By-Wire Flight Test Program (Phase I).”
[39]. Ibid.
[40]. Ibid.
[41]. Tomayko, “Computers Take Flight: A History of NASA’s Pioneering Digital Fly-by Wire Project.”
[42]. In a Dec. 30, 2006, e-mail, Drury Wood wrote: “I was the project test pilot on this airplane. Flew all of the test rigs and full size over 600 flights. Made the record flights, Awarded Bundesverdienstkreuz am Bande and Society of Experimental Test Pilots’ highest award, Kinchloe.”
[43]. Ulrich Butter, “Control, Navigation, Avionics, Cockpit,” in Ernest Heinrich Hirschel, Horst Prem, and Gero Madelung, Aeronautical Research in Germany (From Lilienthal to Today), Springer-Verlag, Berlin Heidelberg, 2004.
[44]. “RAE Electric Hunter,” Flight International, June 28, 1973, pp. 1010–1011.
[45]. Yefim Gordon, “An Industry of Prototypes: Sukhoi T-4, Russia’s Mach 3 Bomber,” Wings of Fame, vol. 9, Aerospace Publishing Limited, London, 1997.
[46]. In an interview published in Krylya Rodiny, No. 8, Aug. 1989, under the title “An Aircraft of the 21st Century,” the chief designer at the Sukhoi OKB (Experimental Design Bureau), Mikhail Petrovich Simonov, commented: “It is also time to talk about those for whom risk, courage, and a willingness to devote their lives to learning the unknown. . . . I am talking about the test pilots of our design bureau. . . . Back then we did not know how the frequency responses of control match the human capabilities. Zhenya [Solovyev] ended up in a resonant mode and was killed and the aircraft was destroyed.”
[47]. Gordon and Peter Davidson, “Sukhoi Su-27 Flanker,” Specialty Press, 2006.
[48]. David C. Aronstein and Albert C. Piccirillo, “The Lightweight Fighter Program: A Successful Approach to Fighter Technology Transition,” AIAA, 1996. M.J. Wendl, G.G. Grose, J.L. Porter, and V.R. Pruitt, “Flight/Propulsion Control Integration Aspects of Energy Management,” Society of Automotive Engineers, Paper No. 740480, 1974.
[49]. U.S. industry interest in “vortex lift” increased during the early 1960s as a result of NASA Langley aerodynamic studies of foreign delta wing aircraft such as the Concorde supersonic transport and the combination canard/delta wing Swedish AJ-37 Viggen fighter. Langley’s vortex lift research program was led by Edward Polhamus, with researcher Linwood McKinney studying the favorable effects of vortexes on lift produced by strong leading-edge vortex flow off slender lifting surfaces. See Chambers, Joseph R., Partners in Freedom: Contributions of the Langley Research Center to U.S. Military Aircraft of the 1990s, Monographs in Aerospace History No. 19, NASA, Washington, DC, 2000.
[50]. Aronstein and Piccirillo, “The Lightweight Fighter Program: A Successful Approach to Fighter Technology Transition.”
[51]. Robert B. Voas, “Manned Control of Mercury Spacecraft,” Astronautics, vol. 7, No. 3, Mar. 1962, p. 18.
[52]. “LLRV Fact Sheet,” FS-2002-09-026-DFRC, NASA Dryden Flight Research Center.
[53]. LLRV No. 2 is on display at the Dryden Flight Research Center.
[54]. Tomayko, “Computers Take Flight: A History of NASA’s Pioneering Digital Fly-by Wire Project.”
[55]. The DSKY had been developed for the Apollo program and enabled input and output to the digital computer system. It was used during Phase I of the DFBW F-8 program.
[56]. Tomayko, “Computers Take Flight: A History of NASA’s Pioneering Digital Fly-by Wire Project.”
[57]. These Sperry-developed analog computers were also used in the Air Force’s YF-4E fly-by-wire project, which was in progress at the same time as NASA’s DFBW F-8 effort. Ibid.
[58]. Gain is a measure of the sensitivity of the aircraft to command inputs to the flight control system.
[59]. As noted earlier, the NACA had evaluated a side stick controller as early as 1952. Side stick controllers had been successfully used in the NASA F9F-2, F-107A, and X-15, as well as the Mercury, Gemini, and Apollo space vehicles, and they were planned to be used in the upcoming Space Shuttle. The Air Force had flight-tested a side stick controller in a B-47E and a C-141 in the late 1960s and was planning on its use in the fly-by-wire project 680J YF-4E Survivable Flight Control System (SFCS) test aircraft.
[60]. Kenneth J. Szalai, telephone conversation with author, Mar. 11, 2009.
[61]. Tomayko, “Computers Take Flight: A History of NASA’s Pioneering Digital Fly-by Wire Project.”
[62]. Szalai, telephone conversation.
[63]. Szalai, Calvin R. Jarvis, Gary E. Krier, Vincent A. Megna, Larry D. Brock, and Robert N. O’Donnell, “Digital Fly-by-Wire Flight Control Validation Experience,” NASA TM-72860 (Dec. 1978). R.E. Bailey, M.F. Schaeffer, R.E. Smith, and J.F. Stewart, “Flight Test Experience With Pilot-Induced-Oscillation Suppression Filters,” NASA TM-86028, NASA Dryden Research Center (Jan. 1984).
[64]. Digital Fly-By-Wire, “The All-Electric Airplane,” NASA Dryden TF-2001-02 DFRC.
[65]. Szalai, et al., “Digital Fly-By-Wire Flight Control Validation Experience.”
[66]. Szalai, e-mail to the author, Mar. 11, 2009.
[67]. “General Dynamics and Northrop to Build Lightweight Fighter Prototypes,” Interavia, July 1972, p. 693.
[68]. C. Droste and J. Walker, “The General Dynamics Case Study on the F-16 Fly-By-Wire Flight Control System,” AIAA Professional Study Series, AIAA, New York, June 1998.
[69]. Chambers, Partners in Freedom.
[70]. Later, during high angle-of-attack flight-testing of an early production F-16, the aircraft entered a stabilized deep-stall condition following a series of rolls in a vertical climbing maneuver. The test pilot was unable to recover with normal aerodynamic controls and used the anti-spin parachute installed for high angle-of-attack testing. NASA worked with the Air Force and the contractor to develop a fix that involved a “pitch rocker” technique to force the aircraft out of the deep stall. The approach was incorporated into the production F-16 flight control system as a pilot selectable emergency recovery mode. In addition, the horizontal tail area of the production F-16 was increased by about 25 percent. Ibid.
[71]. B.R. Ashworth and William M. Kahlbaum, Jr., “Description and Performance of the Langley Differential Maneuvering Simulator,” NASA TN-D-7304, NASA Langley Research Center (June 1973).
[72]. Chambers, Partners in Freedom.
[73]. Joe Stout, “What a Wonderful Airplane: YF-16 First Flight,” Code One Magazine, General Dynamics, July 1992.
[74]. Aronstein and Piccirillo, “The Lightweight Fighter Program: A Successful Approach to Fighter Technology Transition.”
[75]. H.J. Hillaker, “The F-16: A Technology Demonstrator, a Prototype, and a Flight Demonstrator,” Proceedings of AIAA Aircraft Prototype and Technology Demonstrator Symposium, AIAA, New York, 1983, pp. 113–120.
[76]. Aronstein and Piccirillo, “The Lightweight Fighter Program: A Successful Approach to Fighter Technology Transition.”
[77]. Ibid.
[78]. Stout, “What a Wonderful Airplane: YF-16 First Flight.” Joseph F. Baugher, “General Dynamics YF-16/CCV,” American Military Aircraft, Mar. 31, 2000.
[79]. L. Martin and D. Gangsaas, “Testing the YC-14 Flight Control System Software,” AIAA Journal of Guidance and Control, July–Aug. 1978.
[80]. H.A. Rediess and E.C. Buckley, “Technology Review of Flight Crucial Flight Control Systems (Application of Optical Technology),” NASA CR-172332 (Supplement 1) (Sept. 1984).
[81]. Martin, et al., “Testing the YC-14 Flight Control System Software.”
[82]. Stephen D. Ishmael and Donald R. McMonagle, “AFTI/F-16 Flight Test Results and Lessons,” NASA TM-84920 (Oct. 1983).
[83]. Ibid.
[84]. Gary Creech, “AFTI/F-16 Retires After 22 Years,” The Dryden Express, Dryden Flight Research Center, vol. 43, Issue 2, Feb. 23, 2001.
[85]. James Blaylock, Donald Swihart, and William Urshel, “Integration of Advanced Safety Enhancements for F-16 Terrain Following,” AIAA-1987-2906.
[86]. Charles A. Baird and Franklin B. Snyder, with introduction by Lt. Mark Bierele, AFTI/F-16 Program Office, “Terrain-Aided Altitude Computations on the AFTI/F-16,” Harris Corporation, Melbourne, FL, Aug. 1990.
[87]. Finley Barfield, Duke Browning, and Judith Probert, “All Terrain Ground Collision Avoidance and Maneuver Terrain Following for Automated Low Level Night Attack,” IEEE AES Systems Magazine, Mar. 1993.
[88]. Robert Navarro, “Performance of an Electro-Hydrostatic Actuator on the F-18 Systems Research Aircraft,” NASA TM-97-206224, NASA Dryden Flight Research Center (1997).
[89]. James W. Ramsey, “Power-by-Wire,” Avionics Magazine, May 1, 2001.
[90]. Droste, et al., “The General Dynamics Case Study on the F-16 Fly-By-Wire Flight Control System.”