TRK track angle (magnetic heading of ground track)
V/S vertical speed
VFR visual .ight rules
INTRODUCTION
In the past 25 years, crews of many aircraft types, including B-747, L-1011, DC-10, B-52, and C-5A, have experienced major .ight control system failures, and have had to use throttles for emergency .ight control. In most cases, a crash has resulted; the B-747, DC-10, and C-5A crashes claimed more than 1200 lives (ref. 1).
To investigate the use of engine thrust for emergency .ight control, the National Aeronautics and Space Administration’s Dryden Flight Research Center at Edwards, California, is conducting .ight, ground simulator, and analytical studies. One objective is to determine how much control is available with manual manipulation of engine throttles for various classes of airplanes. Tests in simulation have included B-720, B-747, B-727, MD-11, C-402, C-17, F-18, and F-15 airplanes, and, in .ight, B-747, B-777, MD-11, T-39, Lear 24, F-18, F-15, T-38, and PA-30 airplanes. The pilots use differential throttle control to generate sideslip, which through the dihedral effect results in roll. Symmetric throttle inputs also are used to control .ightpath.
These tests show that suf.cient control capability exists for all tested airplanes to maintain gross control; the control of both .ightpath and track angle is possible to within a few degrees. For all airplanes tested, these studies also show the extreme dif.culty of making a safe runway landing using only manual throttles-only control (ref. 2). This dif.culty primarily results from weak control moments, slow engine response, and problems in controlling oscillatory modes in the pitch (phugoid) and lateral (dutch-roll) axes.
To provide a safe landing capability, NASA Dryden engineers and pilots conceived and developed a propulsion-controlled aircraft (PCA) system that uses only computer-controlled (augmented) engine thrust for .ight control. A PCA system uses pilot .ightpath and heading or bank-angle inputs and airplane sensor feedback parameters to provide appropriate engine thrust commands for emergency .ight control. This augmented system was .rst evaluated on a B-720 transport airplane simulation (ref. 3). Later, simulation studies and .ight tests were conducted on an F-15 airplane to investigate throttles-only control (ref. 4), and to investigate the in-.ight performance of a PCA system (ref. 1). McDonnell Douglas Aerospace (MDA) (St. Louis, Missouri) developed and implemented the PCA system .ight hardware and software. Flight testing included actual landings using PCA control (ref. 5). PCA technology was also successfully evaluated using a simulation of a conceptual megatransport (ref. 6). Another major PCA simulator study was conducted at NASA Ames using the advanced concepts .ight simulator (ref. 7) and the B-747 simulator (ref. 8). More than 700 PCA approaches and landings were .own by more than 20 government, industry, and airline pilots. Simulator studies of a PCA system on a C-17 were also successfully conducted.
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