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Aviation History
1962
1962 - 2128.PDF
FLIGHT International 20 September 1962 487 outer skins form a portion of the nacelle when the reverser is in the stowed position. An auxiliary power unit by AiResearch is located in the forward end of the left main-gear pod. Designed to operate only on the ground, it is started by a hydraulic motor and is used to provide air for engine starting, ground air-conditioning, and power to the electrical system via a 40/50kVA generator. Turbine-blade con tainment is provided, together with an overspeed cut-off, and the intake and exhaust door actuators are interlocked to prevent operation with doors closed. A high-rate fire-extinguishing system feeds dibromo-difluoro- methane into Zones 1 and 2 of the nacelle from two bottles in the trailing-edge of the outboard pylons. Following a fire warning, the pilot pulls the appropriate "panic" handle, which shuts-off the engine and its fuel supply and arms the extinguishing system. When it is determined other than by signal that a fire exists, the agent can be discharged. Both sets of pilot flight controls are interconnected through cranks and push-rods under the flight-station floor, and dual cables are provided in the aileron, elevator and rudder systems. Irreversible hydraulic power units are used in each system, with artificial feel. The servo unit consists of side-by-side actuators, one in No ] system and the other in No 2, each providing half the required power. The actuators are designed into a trunnion-mounted manifold containing filters, tandem control valves with dampers, and shut-off and by-pass valves. No probable single failure can cause loss of control. Adequate manual capability is available in the event of loss of both No 1 and No 2 hydraulic systems. Secondary systems comprise three trim axes, wing flap, and wing spoiler systems. The design of the trim flight controls permits only those forces and rates to be applied which will not compromise the primary controls or result in unsafe flight conditions. The tailplane can be trimmed by either of two methods. A hydraulically powered fast rate system is used by manipulating either of the two control levers on the pilots' pedestal. This provides a rate up to 0.4°/sec, the rate being controlled by varying the displacement of the lever from neutral. Trim is also attained by electro-mechanical means through switches on the pilot's and copilot's control wheel, with a rate of 0.8°/sec. Aileron and rudder trim is accomplished by positioning the servo-unit control valve with electric trim actuators. Fowler flaps are operated by a ball-screw and carriage system interconnected by torque tubes and powered by hydraulic motors. A conventional servo positioning lever is used, and safety brakes are actuated by a synchro-type asymmetry system. In flight, the maximum upper-surface spoiler deflection under no load is 21° and the lower spoiler 51°. On the ground the upper spoiler deflects 90° and the lower 0° to achieve maximum drag as well as lift spoiling. The control lever is on the side of the console. The pilot may select any spoiler position from fully closed to maximum, up to 250kt. The spoilers may be operated up to 350kt, but will be blown down below the maximum in-flight position. The control may be operated manually on the ground, or armed so that, when the nose gear strut compresses, the spoilers automatically extend. During take-off the control may be armed to the throttles, so that if reverse thrust is selected for a rejected take-off the spoilers are automatically extended. The PB-60 autopilot system, being developed and produced by Eclipse-Pioneer Division of Bendix, is a direct outgrowth of the PB-20 in use by 45 airlines and MATS. Every mechanical device and electronic circuit has been service-proven, and the PB-60 has benefited from Eclipse-Pioneer's recent product-improvement programme. The control panel is installed on the console between the pilot and copilot, and the three-axis trim and function indicator is located on the main instrument panel. Roll, yaw, and pitch computers are installed in the electronics compartment, as are the three-axis rate sensor and dynamic vertical sensor. The aileron servo is located on the wing rear beam, and the rudder and elevator servos in the empennage. The control-wheel force sensor is in the pilot's wheel hub. The C-141A is unique in that all lateral navigation mode selec tion has been integrated into a single control panel external to the autopilot panels. The navigation selector panel serves both the pilot's flight director and the autopilot, and provides for selection of VOR/localizer, TACAN, heading hold, heading select, Doppler navigation, and ASN-24 navigation. Glide-slope selection is retained on the autopilot controller. The trim indicator provides the pilot with information on the servo effect in yaw, pitch, and roll, and also indication of autopilot-off. power-off, glide-slope armed. TF33-7 turbofan engine installation and glide-slope engaged. Separate pitch and lateral disengagement switches are provided on the autopilot controller, for flexibility in adapting the system to future procedures for utilizing lower minimums. Provisions are also being made for Mach/altitude -hold through use of throttle servos, for a jet penetration, or let-down, computer for vertical navigation, and for de-crab and flareout computers when fully automatic landings become feasible. The Mach trim compensator provides up-elevator signals to the pitch trim actuator when the aircraft enters the "tuck" region. •The C-141A contains three independent 3,0001b/sq in hydraulic systems, designed to insure adequate flow under single faults or two-engine-cutout conditions. System 1 is powered by paralleled outputs of two variable-volume pumps on engines 3 and 4; the only function of these pumps is to supply one-half of the dual elevator, rudder and aileron actuators. System 2 is powered by variable-volume pumps on engines 1 and 2; No 2 system supplies power for the landing gear, brakes, steering, flaps, spoilers, hori zontal trim, emergency generator, and one-half of the dual elevator, rudder and aileron actuators. System 3 serves as a standby and supplemental system for the flaps and spoilers, and as an emergency system for the brakes. The pressure door, ramp, petal doors, tailplane actuator and APU starter are supplied only by No 3. The system receives its power from a pair of variable-volume pumps connected in parallel. The power for these pumps is taken from a bus supplied by the four engine-driven alternators; on the ground ii is supplied by the APU generator. The environmental system includes pressurization, air-condition ing, windshield rain removal, and surface anti-icing. The cabin is pressurized by direct engine bleed air, introduced through the air- conditioning units. Conventional outflow and emergency valves are used, and the system is designed to maintain an 8,000ft cabin altitude at 40,000ft. Cabin heating and cooling is accomplished by two air-cycle units, which condition the bleed air. Automatic temperature control is basic, and an underfloor heating system is provided in the cargo compartment. Rain removal for the pilot's and copilot's forward windows is of the bleed-air jet blast type. Hot-air surface anti-icing systems are designed for the leading edges of the wing and engine air inlets. The tailplane is electrically de-iced by 16 chordwise parting strips heated—for 15sec, or until a predetermined temperature is reached—by cycled, stainless-steel clad elements. A liquid-oxygen storage and supply system is permanently installed for eight crew members. The 25-litre converter is located on the left side of the nosewheel well in an unpressurized area, and is protected from wheel-thrown objects by a glass-fibre shield. Servicing valves are accessible from outside for filling or draining the converter, and the manual shut-off valve is operated from a knob on the pilot's side console. Nine pressure demand regulators and provisions for stowing oxygen masks are installed at the stations for the pilot, copilot, check pilot, flight engineer, navigator, two lower bunk seats, and two extra crew seats. Stowage provision is made for smoke goggles at each duty station. Portable cylinder rechargers are located aft of the pilot's and copilot's stations, in the crew toilet and on each side of the forward end of the cargo com partment. Two portable cyclinders are aft of the copilot, two at the outboard extra seat, and one in the crew toilet. A quantity indicator and press-to-test switch are on the copilot's panel and a low-quantity warning light is on the annunciator panel. Cargo-compartment oxygen is a continuous-flow system com prised of three major sections: the permanently installed distribu tion system, the removable liquid-oxygen supply kit, and the oxygen distribution kit. The distribution system consists primarily of two Continued on page 504
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