Abstract: This invention is an improved turbofan engine having a variable geometry fan duct which reduces stator source noise emitted from the engine. Attached to the inner wall of the fan casing near the fan stators is a pneumatically actuated annular membrane having two operating positions. In the cruise position, the membrane is forced radially inward to press against the radially outermost tips of the fan stators. In the second position, used during approach and takeoff, the membrane is drawn against a recessed portion in the fan casing, thereby creating an annular passageway between the stator tips and the casing. When the membrane is in this position, turbulent flow from the rotor blade tips which would normally impinge on the stators is directed through the annular passageway.

Abstract: A self-depressurizing hydraulic control valve having a sliding-type metering valve to control the flow of hydraulic fluid through the valve and also a shutoff valve to stop the flow automatically. The shutoff valve is responsive to the rate of flow of fluid through the control valve and stops the flow when the flow rate decreases to a preselected value. When the shutoff valve closes, the control edges of the metering valve are no longer exposed directly to high pressure fluid, and quiescent leakage across the edges is practically eliminated. Thus, electrochemical erosion of the metering edges resulting from such leakage is substantially reduced.

Abstract: An aerodynamic spoiler mounted on the upper forward surface of the fuselage of an aircraft which is equipped to be refueled by another aircraft while in flight. The spoiler counteracts aerodynamic disturbances produced by the refueling boom and the resultant instabilities in pitch in the aircraft receiving fuel. Four species of the spoiler are disclosed and the device may be made retractable to eliminate drag when not in use.

Abstract: A nacelle for use with a turbofan engine for reducing both rotor and stator source noise emitting from the engine. The nacelle contains a ducted system which when in operation bypasses a portion of the flow in the fan duct around the fan stators causing unloading of the rotor, diffusion of the flow between the rotor and the stators, a reduction in the viscous flow at the rotor tips, and a substantial elimination of the rotor tip flow. Flow enters the duct system through openings in the interior walls of the nacelle located between the rotor and fan stators but downstream of the rotor at least a certain predetermined minimum distance. Flow through the system is controlled by doors or other means and it is normally operated only during approach and take-off, thus minimizing cruise penalty on engine performance.

Abstract: An interior wall and ceiling panel for use in the cabin of a passenger aircraft which includes attachment brackets, a support bracket assembly having three degees of adjustability for mounting the panels to the airframe and a gap cover extending between adjoining panels and to provide a finished appearance when viewed from the interior of the cabin.

Abstract: A self-depressurizing hydraulic control valve having a sliding-type metering valve to control the flow of hydraulic fluid through the valve and also a shutoff valve to stop the flow automatically. The shutoff valve is responsive to the rate of flow of fluid through the control valve and stops the flow when the flow rate decreases to a preselected value. When the shutoff valve closes, the control edges of the metering valve are no longer exposed directly to high pressure fluid, and quiescent leakage across the edges is practically eliminated. Thus, electrochemical erosion of the metering edges resulting from such leakage is substantially reduced.

Abstract: An integrated thermal anti-icing and environmental control system for a gas turbine powered aircraft uses hot high pressure bleed air from the turbine compressor to de-ice the wings and the engine air inlet, and supplies conditioned air for the aircraft cabin. In order to minimize total bleed air requirements and maximize heat recovery, bleed air exhausted from the inlet anti-icing system is passed sequentially through other systems. In this invention, the usual pre-cooler unit and the associated heat sink are eliminated and the pre-cooling function is performed within the inlet anti-icing system, preferably through the use of a double skin heat exchanger contained within the lip of the inlet. One embodiment of this system includes a closed-loop liquid anti-icing system for acoustic rings mounted in the inlet wherein the liquid is heated by passing the bleed air through a heat exchanger mounted immediately downstream of the inlet anti-icing system.

Abstract: A gage for measuring accumulated fatigue damage, or accumulated strain experience, and remaining fatigue life in a structure subjected to repeated loadings in relation to predictions or calibration tests. The disclosed embodiment has a thin, nominally rectangular metal base of uniform thickness which has a very narrow crack-like slit cut in one side and a teflon parting strip attached to the base underlying the slit. When the gage is attached to a structure with a suitable adhesive and the structure is subjected to repeated loading, a fatigue crack immediately begins at the inner end of the slit and increases in length as an approximately linear function of the accumulative fatigue damage strains incurred by the structure. The crack in the gage occurs in advance of and independently of any crack in the structure itself.

Abstract: A structural panel of the skin-stiffener type, commonly used in aircraft construction, having significantly reduced vibration response, noise radiation and increased acoustic fatigue life, has a skin supported by uniformly spaced stiffeners which are located such that the fundamental natural frequencies of stiffener segments are equal to the fundamental natural frequency of skin sub-panels between the stiffener segments. The physical and geometric properties of the skin and stringers and the spacing of the stringers in various disclosed embodiments depend upon the trace velocity of the excitation field, loading conditions to which the panel is subjected, and end-conditions of the sub-panels and stiffeners.