970576
Figure 5. Flight (minimum) idle and approach idle throttle snap to full power, PW4460 engine, sea-level-static conditions.
(EPR = 0.99), 5 sec is required to reach an EPR of 1.1; while at approach idle (EPR = 1.04), the time to reach an EPR of 1.1 is less than 2 sec.
Fuel System
The MD-11 is equipped with fuel tanks in the wings, center fuselage, and horizontal tail. Maximum fuel quantity is 259,000 lb. Each wing tank holds 42,000 lb of fuel; the remaining fuel is in the center fuselage in main and auxiliary tanks and in the tail tank. The fuel management system normally controls fuel distribution. This system maintains a programmed CG schedule, but fuel may also be manually transferred among tanks. After takeoff, fuel is normally transferred to the tail tank to move the CG aft. The left- and right-wing tanks are maintained at approximately equal weights. In an emergency, fuel may be dumped overboard until a total of 40,000 lb remains. A manual fuel switch disables automatic fuel transfer and CG control, and allows fuel to be transferred manually.
Weight and Center of Gravity
The standard MD-11 with a full payload of 122,700 lb has a zero-fuel weight of 400,000 lb; maximum gross weight is 630,000 lb. Maximum landing weight is 430,000 lb.
The longitudinal CG is given in percentage of mean aerodynamic chord (.g. 1). At cruise altitude, the fuel management system transfers fuel to the tail tank that maintains the CG at an airline-selectable aft limit of approximately 32 percent. For takeoff and landing, the CG is normally in the range of 20 to 24 percent; 12 percent is the forward limit.
Figure 6 shows the weight and CG of MD-11 ship 560 for a typical .ight test. Zero fuel weight plus ballast was 303,000 lb at a CG of 19.5 percent. With 149,000 lb of fuel (both wing tanks and the center fuselage main tank full),
34
32
30
28
CG, percent 26 MAC
Full wing and center 22
24
main tank 20 18
Gross weight, lb
Figure 6. Gross weight, fuel weight, and longitudinal center of gravity (CG) for MD-11 ship 560 PCA .ight tests.
the takeoff gross weight was 452,000 lb at a CG of 23.6 percent. Lateral CG is normally maintained near zero, but if one wing tank is full and the other is empty, the lateral CG can be displaced by approximately 4 ft.
Landing Gear
The MD-11 is equipped with a steerable nosewheel and three main landing gears. The gears are normally operated with aircraft hydraulic systems. An alternate system independent of the hydraulic system can lower the gears, leaving the gear doors down and wheel wells open. Limited braking may be obtained with inoperative hydraulic systems using brake system hydraulic accumulators. Maximum-rated tire speed is 204 kn. Maximum touchdown sink rate at maximum landing weight is 10 ft/sec.
Instrumentation
The test MD-11 was equipped with a large data acquisition system capable of displaying and recording several thousand parameters from the standard aircraft digital data buses. Parameters included all air data, engine, and inertial parameters as well as .ight control system and PCA system parameters. An on-board, real-time, plotting and hardcopy capability was available. Cameras and voice recorders were installed in the cockpit to record the instrument panel view, the pilot’s out-the-window view, and communications and pilot comments. Test instrumentation data consoles in the main cabin provided engineers with the ability to change, in real time, parameters that were being displayed or printed to hardcopy. Data were sampled 20 times/sec. No telemetry system was installed.
MD-11 Simulation
The MD-11 .ight deck simulator (FDS), .gure 2(a), used for most of the MD-11 PCA research, is a high-.delity, .xed-base piloted simulator with actual .ight hardware for many of the cockpit controls, systems, and electronics. This simulator has a digital display projection system that can display southwestern U.S. visual scenes including Los Angeles International, Long Beach NAS, Edwards AFB, Yuma, and other airports. Data from simulator tests could be recorded for later analysis.
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本文链接地址：Development and Flight Test of an Emergency Flight Control System Using Only Engine Thrust on an MD-11 Transport Airplane(13)
