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Using Engine Thrust for Emergency Flight Control: MD-11 and B-747 Results

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Using Engine Thrust for Emergency Flight Control: MD-11 and B-747 Results NASA/TM-1998-206552 Using Engine Thrust for Emergency Flight Control: MD-11 and B-747 Results Frank W. Burcham, Jr., Trindel A. Maine, and John J. Burken Dryden Flight Research Center Edwards, California John Bull CAELUM Research Corporation NASA Ames Research Center Moffett Field, California May 1998 The NASA STI Program Office . in Profile Since its founding, NASA has been dedicated • CONFERENCE PUBLICATION. to the advancement of aeronautics and space Collected papers from scientific and science. The NASA Scientific and Technical technical conferences, symposia, seminars, Information (STI) Program Office plays a key or other meetings sponsored or cosponsored part in helping NASA maintain this by NASA. important role. • SPECIAL PUBLICATION. Scientific, The NASA STI Program Office is operated by technical, or historical information from Langley Research Center, the lead center for NASA programs, projects, and mission, NASA’s scientific and technical information. often concerned with subjects having The NASA STI Program Office provides access substantial public interest. to the NASA STI Database, the largest collection of aeronautical and space science STI in the • TECHNICAL TRANSLATION. English- world. The Program Office is also NASA’s language translations of foreign scientific institutional mechanism for disseminating the and technical material pertinent to results of its research and development activities. NASA’s mission. These results are published by NASA in the NASA STI Report Series, which includes the Specialized services that complement the STI following report types: Program Office’s diverse offerings include creating custom thesauri, building customized databases, organizing and publishing research • TECHNICAL PUBLICATION. Reports of results . even providing videos. completed research or a major significant phase of research that present the results of For more information about the NASA STI NASA programs and include extensive data Program Office, see the following: or theoretical analysis. Includes compilations of significant scientific and technical data • Access the NASA STI Program Home Page and information deemed to be of continuing at http://www.sti.nasa.gov reference value. NASA’s counterpart of peer-reviewed formal professional papers but • E-mail your question via the Internet to has less stringent limitations on manuscript [email protected] length and extent of graphic presentations. • Fax your question to the NASA Access Help • TECHNICAL MEMORANDUM. Scientific Desk at (301) 621-0134 and technical findings that are preliminary or of specialized interest, e.g., quick release • Telephone the NASA Access Help Desk at reports, working papers, and bibliographies (301) 621-0390 that contain minimal annotation. Does not contain extensive analysis. • Write to: NASA Access Help Desk • CONTRACTOR REPORT. Scientific and NASA Center for AeroSpace Information technical findings by NASA-sponsored 7121 Standard Drive contractors and grantees. Hanover, MD 21076-1320 NASA/TM-1998-206552 Using Engine Thrust for Emergency Flight Control: MD-11 and B-747 Results Frank W. Burcham, Jr., Trindel A. Maine, and John J. Burken Dryden Flight Research Center Edwards, California John Bull CAELUM Research Corporation NASA Ames Research Center Moffett Field, California National Aeronautics and Space Administration Dryden Flight Research Center Edwards, California 93523-0273 May 1998 NOTICE Use of trade names or names of manufacturers in this document does not constitute an official endorsement of such products or manufacturers, either expressed or implied, by the National Aeronautics and Space Administration. Available from the following: NASA Center for AeroSpace Information (CASI) National Technical Information Service (NTIS) 7121 Standard Drive 5285 Port Royal Road Hanover, MD 21076-1320 Springfield, VA 22161-2171 (301) 621-0390 (703) 487-4650 ABSTRACT PCA propulsion-controlled aircraft TOC thrust-only control With modern digital control systems, using engine thrust for emergency flight control to supplement or replace failed aircraft normal flight controls has INTRODUCTION become a practical consideration. The NASA Dryden Flight Research Center has developed a propulsion- In the past 25 years, more than 10 aircraft, including controlled aircraft (PCA) system in which computer- B-747, L-1011, DC-10, B-52, and C-5A aircraft, expe- controlled engine thrust provides emergency flight rienced major flight control system failures, and the control. An F-15 and an MD-11 airplane have been crews tried to use engine thrust for emergency flight landed without using any flight control surfaces. Pre- control. In most cases, a crash resulted; the B-747, liminary studies have also been conducted that show DC-10, and C-5A crashes claimed more than 1200 lives. A summary of these accidents has previ- that engines on only one wing can provide some flight ously been published.1 control capability if the lateral center of gravity can be shifted toward the side of the airplane that has the oper- With the advent of digital engine control systems, ating engine(s). Simulator tests of several airplanes considering the use of engine thrust for emergency with no flight control surfaces operating and all engines flight control became feasible. To investigate this possi- out on the left wing have all shown positive control bility, NASA, the United States Department of capability within the available range of lateral center- Defense, industry, and university researchers have been of-gravity offset. Propulsion-controlled aircraft sys- conducting flight, ground simulator, and analytical tems that can operate without modifications to engine studies. One objective is to determine the degree of control systems, thus allowing PCA technology to be control available with manual manipulation of engine installed on less capable airplanes or at low cost, are throttles for various classes of airplanes. Simulation also desirable. Further studies have examined simpli- tests have included B-720, B-747-400, B-727, MD-11, fied “PCA Lite” and “PCA Ultralite” concepts in which MD-90, C-402, C-17, SR-71, F-18, and F-15 airplanes. thrust control is provided by existing systems such as Flight tests have included B-747-100, B-777, MD-11, autothrottles or a combination of existing systems and T-39, Lear 24, F-18, F-15, T-38, and PA-30 airplanes. manual pilot control. The pilots use differential throttle control to generate sideslip that, through the dihedral effect, results in roll. Symmetric throttle inputs are also used to control NOMENCLATURE flightpath. For all tested airplanes, these tests have shown sufficient control capability to maintain gross AGL above ground level (radar altitude) control; both flightpath and track angle may be con- CG center of gravity trolled to within 2° to 4°. These studies have also shown that making a safe runway landing is exceed- CGX longitudinal center of gravity, percent of ingly difficult using only manual thrust-only control mean aerodynamic chord (TOC)2 because of the difficulty in controlling the CGY lateral center of gravity, distance from phugoid and dutch roll modes, slow engine response, fuselage centerline, in. and weak control moments. CGZ vertical center of gravity, distance from To provide safe landing capability, NASA Dryden fuselage centerline, in. Flight Research Center (Edwards, California) engi- neers and pilots have conceived and developed a EPR engine pressure ratio system, called propulsion-controlled aircraft (PCA), FADEC full-authority digital engine control that uses only augmented engine thrust for flight con- trol. The PCA system uses pilot flightpath inputs and FPA flightpath angle, deg airplane sensor feedback parameters to provide appro- FDS Flight Deck Simulator priate engine thrust commands for emergency flight control. The concept was first evaluated on a piloted ILS instrument landing system B-720 simulation.3 This augmented system was evaluated in simulation lateral control could be provided using the limited- and flight tests on the F-15 airplane,1, 4 and actual land- authority engine trim system installed on some aircraft. ings were made using PCA control. The PCA technol- For airplanes without digital engine controls, a still ogy was also successfully evaluated using a simulation simpler system called “PCA Ultralite” would use the of a conceptual megatransport.5 Another major PCA autothrottles to provide pitch control, and the flight simulation study has been conducted at NASA Ames crew would provide lateral control by differential throt- Research Center (Moffett Field, California) using the tle manipulation. 6 advanced concepts flight simulator, an airplane that Studies on the B-720, MD-11, and B-747-400 simu- closely resembles a B-757 twin-jet airplane. More lations show the feasibility of emergency control using recently, a PCA system was designed and tested on the engine thrust and other systems, such as lateral fuel B-747-400 simulator at NASA Ames. Approaches and transfer, with all engines out on one side of a two-, landings using the PCA system have been flown by three-, or four-engine airplane.13 In preliminary simu- more than 30 government, industry, and commercial 7 lation tests, open-loop manual throttle control and airline pilots. closed-loop PCA control have been tested with the With the success of the F-15 PCA flight program and lateral center of gravity, CGY, offset. the other simulation studies, The Boeing Company This paper presents the principles of throttles-only (formerly McDonnell Douglas Aerospace, Long flight control and summarizes
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