Abstract: An active control system for reducing blade-vortex-interaction (BVI) noise generated by a rotor blade. The active control system includes a pressure sensor assembly, a device for changing a lift generated by the rotor blade, and a controller for activating the device upon a detected change in air pressure by the sensor assembly. The sensor assembly is disposed in close proximity to the rotor blade, and is adapted to detect a change in air pressure on a surface of the rotor blade near a leading edge of the rotor blade. The device is adapted to be activated by the controller, to thereby change a lift of the rotor blade. The controller activates the device to change a lift of the rotor blade in order to introduce a compensating pressure onto the surface of the rotor blade. This compensating pressure attenuates the magnitude of the change of air pressure.

Abstract: An active control device for use on an aerodynamic structure is provided. The aerodynamic structure includes an outer aerodynamic skin and an interior volume, wherein the outer aerodynamic skin surrounds the interior volume. The active control device includes at least one aperture disposed on the outer aerodynamic skin and a diaphragm disposed in the interior volume of the aerodynamic structure. The at least one aperture connects the outer aerodynamic skin to the interior volume, and the diaphragm in the interior volume is movable between a first position and a second position. Movement of the diaphragm from the first position to the second position pushes air through the at least one aperture and out of the interior volume. Movement of the diaphragm from the second position to the first position draws air through the at least one aperture and into the interior volume. The diaphragm may be circular, or may be oval-shaped.

Abstract: A pressurized porous surface near the leading edge of a rotorcraft blade, is designed to be used as an active control device which alleviates the aerodynamics of blade vortex interactions (BVI) and thus the impulsive BVI noise levels and signature. The pressurized porous surface can be actuated on an azimuth-dependent deployment schedule or actuated continuously. The pressurized porous surface is supplied with either positively pressurized air, negatively pressurized air, or a combination of both, when actuated. The pressurized porous surface targets the local blade aerodynamics, rather than the vortex strength or blade/vortex separation distance.

Abstract: An active control device is disclosed for modifying a tip vortex on a lifting body. The lifting body includes a positive-pressure generating structure and a negative-pressure generating structure, and is adapted for providing lift when a first fluid pressure adjacent to the positive-pressure generating structure is greater than a second fluid pressure adjacent to the negative-pressure generating structure. The active control device includes a fluid source adapted for providing a positive pressure of fluid, such as air, to an interior of the lifting body. The active control device further includes a fluid router, which is disposed on the lifting body and which is adapted for directing a portion of the positive pressure of fluid out of the interior of the lifting body and in a general direction from the fluid router toward the positive-pressure generating structure of the lifting body. The lifting body may be either a rotorcraft blade, an aircraft foil, or a marine foil such as a marine propeller.

Abstract: A noise deduction for a rotorcraft includes a unit to produce compressed air, a drive shaft provided with a first air supply passage in which the compressed air from the air-producing unit flows, and rotor blades provided with second air supply passages in which the air from the first air supply passage flows. In order to eject the compressed air supplied from the rotor blades, ejection nozzles having an ejection adjusting mechanism therein are arranged at respective blade tips of the rotor blades and respective trailing edges thereof in the rotational direction. In operation, the ejection nozzles eject the compressed air to the radial direction of the rotor blades, so that, since the blade tip vortex in the vicinity of the blade tip of the preceding rotor blade is relocated outside the blade tip of the following rotor blade, a direct collision thereof on the vortex can be avoided.

Abstract: An air encircled marine thruster cowling includes a cowling that surrounds a propeller and provides an annular blanket of air around the slipstream from the propeller. The cowling includes an inner conical section around the propeller and an outer tubular section around the conical section to form an annular space around the conical section. A duct leads exhaust gas from the engine into the annular space, and an additional duct leads moving ambient air into the annular space, as when a boat is in motion.

Abstract: A turbine airfoil having a cut-back trailing edge and a plurality of diffusing flow dividers upstream of the cut-back trailing edge is disclosed. Various construction details are developed which provide ejection of a diffusing film of cooling fluid over a cut-back trailing edge. In one particular embodiment, a turbine airfoil includes a plurality of radially spaced flow dividers extending between a pressure wall and a suction wall. Each flow divider includes a rounded leading edge, a pair of parallel sidewalls downstream of the leading edge, and a pair of converging sidewalls downstream of the parallel sidewalls. Adjacent sidewalls of adjacent flow dividers form flow channels having a constant area channel and a diffusing section. The diffusing section includes a covered portion upstream of the cut-back trailing edge and an uncovered portion extending over the cut-back trailing edge.

Abstract: A propeller vane or blade construction wherein cavitation is precluded at the base of the blade where they join the hub on their leading side by introducing a source of pressurized fluid in this area. The fluid may be pressurized either from the dynamic flow through the unit or by the static flow generated by the operation of the unit.

Abstract: A rotary wing aircraft with rotor blades mounted on a rotor head and with reaction drive. The rotor blades have hollow interiors and are provided on their trailing edge with at least one outlet opening for compressed air supplied via the rotor head. Such rotor head may include an air suction region in which there is mounted a suction device having a pressure side connected to the hollow interiors of the rotor blades.

Abstract: Control law system for the collective axis, as well as pitch and roll axes, of an X-Wing aircraft and for the pneumatic valving controlling circulation control blowing for the rotor. As to the collective axis, the system gives the pilot single-lever direct lift control and insures that maximum cyclic blowing control power is available in transition. Angle-of-attach de-coupling is provided in rotary wing flight, and mechanical collective is used to augment pneumatic roll control when appropriate. Automatic gain variations with airspeed and rotor speed are provided, so a unitary set of control laws works in all three X-Wing flight modes. As to pitch and roll axes, the system produces essentially the same aircraft response regardless of flight mode or condition. Undesirable cross-couplings are compensated for in a manner unnoticeable to the pilot without requiring pilot action, as flight mode or condition is changed.

Abstract: Method and arrangement for the reduction of the resistance to rotation of the propeller (3) of a ship (1) going in ice when the ice increases the resistance to rotation of the propeller to a level higher than when sailing in open water. When the resistance to rotation increases, gas is passed to the propeller (3), and the supply of gas is adjusted when the resistance to rotation is changed. The supply of gas may be continual, but as a rule it is used only for short periods in order to correct the speed of rotation of the propeller to the appropriate level.

Abstract: A circulation control rotor system for aircraft in which compressed air is directly supplied at generally constant pressure to plenums in the rotor blades and discharged through area controlled slots, the area controlling means involving camming surfaces and being actuated by cyclic, collective, aircraft vibration and flight stability inputs.

Abstract: The present invention relates to a circulation flow control rotor system for an aircraft which includes rotor blades provided with slit shaped blower nozzles further comprising control devices for obtaining a cyclic or multicyclic or collective rotor blade angle control under utilization of individual pressure gas flow from a pressure chamber to the nozzle slits; further including deformable control members which are going to be deformed in accordance with certain rules underlying the requisite control.

Abstract: A circulation control aircraft rotor blade of advanced composite material having a spanwise Coanda surface 16 and a plurality of spanwise extending flexible panels 18 cooperating with the Coanda surface to define slots for the discharge of compressed air from a duct 14 within the blade with each panel having flexure means 34 associated with attaching means 24 and limiting means 38 for establishing a slot opening preload and a slot maximum opening and with limiting means 38 providing structural equilibrium and reduced bending moments in the inboard corners of the air duct.

Abstract: An apparatus for a ship's propeller, whose fins, which may be pitch-controlled, are provided in the vicinity of the leading edges with air openings. These air openings are fed via air ducts in each propeller fin by a compressed air source located in the ship. The compressed air is fed from the ship's compressor to the propeller by an air coupling which is protected by a split covering sleeve. The coupling is fed by an air feed line laid outside the ship's hull along the stern post or propeller strut. The air feed line penetrates the covering sleeve between the propeller strut and the propeller. The air line is connected to a two-piece inlet feed fitting. Air is fed from the inlet fitting through a two-piece bypass ring which rotates with the propeller shaft, to a two-piece air discharge fitting connected to the propeller hub.

Abstract: A helicopter main rotor blade having built-in twist for improved hover performance is provided with a trailing-edge, short span slot near the tip end of the blade for upwardly directing a stream of pressurized air therefrom. The upward ejection of air from the slot untwists the blade, which will enhance the forward flight performance of the blade. A method of modulating the ejection of air from the slot is disclosed for antivibratory control.

Abstract: A multi-bladed propeller and shaft assembly is provided in which air can be fed to the propeller blades to reduce the effects of cavitation. A shaft leads to a multi-bladed propeller and carries a sleeve formed with inlet passages and axial and radial passages leading to the respective blades. A slip ring supported in an anti-rotation device allows the shaft sleeve to rotate within axially spaced bearings of the slip ring. Axially spaced air seals together define with the body of the slip ring an annulus within which inlet passages rotate. Each seal is formed as a multiplicity of arcuate segments resiliently biased towards the sleeve and having movably sealed end face portions to maintain pressure tightness. The body further has a radial flow passage for admission of air under pressure to the annular space and a flexible fluid connector connects the radial flow passage to an air supply line leading from the hull structure.

Abstract: A device for producing a force when in a moving fluid, such as air or water, and a method for using said device. The device may be placed in a fluid moving in a first direction for producing a force in a second direction, which is substantially transverse with respect to the first direction. The device avoids the use of large sail areas needed where the force derived from wind is proportional to said area. The device according to the invention comprises an elongated body having in cross-section a rounded symmetrical profile, which defines an elongated and rounded leading portion whose thickness increases from the front to the rear and a rounded trailing portion whose thickness decreases from the front to the rear, the leading portion being longer than the trailing portion. The device according to the invention is also provided with at least one flap, which projects from the body and which is located on the trailing portion of the profile.

Abstract: A circulation control aircraft rotor blade having a spanwise Coanda surface 16 and a plurality of spanwise extending flexible composite material panels 18 cooperating with the surface to define slots for the discharge of compressed air from within the blade with each panel having first flexure means 60 associated with screw adjustments 36 for establishing a slot opening preload and second flexure means 62 associated with screw adjustments 38 for establishing a slot maximum opening.

Abstract: Inadvertent slot opening in a circulation controlled rotor due to plenum valve leakage is averted by venting duct pressure below a control minimum. A vent valve is disclosed.

Abstract: A plenum for a circulation control rotor aircraft which surrounds the rotor drive shaft (18) and is so constructed that the top (32), outer (38) and bottom (36) walls through compressed air is admitted are fixed to aircraft structure and the inner wall (34) through which air passes to rotor blades (14) rotates with the drive shaft and rotor blades.

Abstract: X-wing aircraft employ a rigid rotor-wing utilizing symmetrical circulation irfoils. The rotor is driven mechanically, and lift is achieved by modulation of air circulation about the base airfoils. This is accomplished by blowing compressed air through trailing edge openings in the rotor blades, and controlling the amount of air being ejected through those openings. By cyclically modulating the amount of ejected airflow, cyclic lift control is obtained. Likewise, by collectively controlling the ejected airflow collective lift control is obtained. One reason for the lack of popularity of circulation control rotor systems is concern over a loss or air pressure resulting from a damaged rotor blade. The damage to a rotor blade, such as ballistic damage, can cause the entire plenum pressure to be vented through that damaged blade. The result is a loss of pneumatic control, not only of that blade, but control of all rotor blades.

Abstract: Quad-redundant signal processors in a flight control computer control valves to modulate airflow in a circulation control rotor system. The valves are arranged in a series and each valve is responsive to two signal processors. Loss of a valve occurs when both signal processors for that valve fail. A first valve, and every fourth valve in the series thereafter is responsive to a first signal processor and a third signal processor. The next valve in the series, and every fourth valve in the series thereafter is responsive to a second signal processor and a fourth signal processor. The third valve in the series, and every fourth valve in the series thereafter is responsive to the first signal processor and the fourth signal processor. The next valve in the series, and every fourth valve in the series thereafter is responsive to the second signal processor and the third signal processor.

Abstract: A circulation control rotor system in which butterfly valves (44, 46) control the flow of compressed air from a plenum chamber (40) to the rotor blades (14). Each has an actuator (48, 52) positioning the valve in accordance with a control input and in which a spring loaded averaging linkage (120) between adjacent valves around a plenum chamber circumference acts to position the valve at an average position of the two adjacent valves if a fault in the actuator or within its control or power system should develop. Should such a fault develop, as determined by a comparison of actual valve position with command position, the faulty valve's actuator is shut down.

Abstract: Mechanical collective pitch control system for a circulation control rotor system aircraft utilizing an axially moveable pneumatic system plenum 32 in the collective pitch control system.

Abstract: A non-moving fluid thrust deflector and force augmentor is disclosed for aerodynamic and hydrodynamic vehicles and devices. When the deflector is utilized in an aerodynamic application and in conjunction with a thrust producer and a plenum, upon pressure initiation within the plenum, a jet sheet issues and remains attached to a specially designed wing having a rounded trailing edge by balancing reduced static pressure with centrifugal force, and thus provides a controlled resultant force or thrust in some direction other than that corresponding to the original flow. Upon application to hydrodynamic vehicles, the deflector is placed in the propulsor stream and provides turning or pitching forces to the vehicle without any deflection of itself. These applications require no mechanical moving components to deflect or augment the thrust or force, and thus yield considerable reductions in weight and complexity.

Abstract: A multi-purpose mono-element airfoil is disclosed for aerodynamic vehicles and devices. The multi-purpose mono-element highlift airfoil when utilized in an aerodynamic application provides a combined no-moving-parts high lift and cruise airfoil which in conjunction with a plenum, upon pressure initiation, causes pressurized air to issue from a slot tanget to the airfoil surface and remains attached to the airfoil's shaped trailing edge, providing a controlled resultant force or thrust. Upon application to hydrodynamic vehicles, the multi-purpose mono-elements airfoil is placed in the freestream and provides turning or pitching forces to the vehicle without any deflection of itself or any mechanical components.

Abstract: A propulsion system for an underwater vehicle includes a solid propellant gas generator producing gas which drives a gas turbine. The turbine drives one, or alternately two, centrifugal pumps which induct sea water from intake ports and supply it under pressure through a passage to passages leading to tip nozzles in the blades of a propeller which drives the vehicle, thereby using the reaction force from the tip nozzles to drive the propeller. Exhaust gas, after driving the turbine, is conducted through a conduit and to an annular chamber where it is cooled by means of a spray of sea water, thus condensing the steam present and reducing the volume of exhaust gas.

Abstract: A non-moving fluid thrust deflector and force augmentor is disclosed for aerodynamic and hydrodynamic vehicles and devices. When the deflector is utilized in an aerodynamic application and in conjunction with a thrust producer and a plenum, upon pressure initiation within the plenum, a jet sheet issues and remains attached to a specially designed wing having a rounded trailing edge by balancing reduced static pressure with centrifugal force, and thus provides a controlled resultant force or thrust in some direction other than that corresponding to the original flow. Upon application to hydrodynamic vehicles, the deflector is placed in the propulsor stream and provides turning or pitching forces to the vehicle without any deflection of itself. These applications require no mechanical moving components to deflect or augment the thrust or force, and thus yield considerable reductions in weight and complexity.

Abstract: A multi-purpose mono-element airfoil is disclosed for aerodynamic and hydrodynamic vehicles and devices. The multipurpose mono-element highlift airfoil when utilized in an aerodynamic application provides a combined no-moving-parts high lift and cruise airfoil which in conjunction with a plenum, upon pressure initiation, causes pressurized air to issue from a slot tangent to the airfoil surface and remains attached to the airfoil's shaped trailing edge, providing a controlled resultant force of thrust. Upon application to hydrodynamic vehicles, the multi-purpose mono-element airfoil is placed in the freestream and provides turning or pitching forces to the vehicle without any deflection of itself or any mechanical components.

Abstract: A method of raising the propulsion efficiency of a propeller by reducing viscous drag. Basically, a fluid polymer solution is injected along the leading edge of the power face of the propeller blade to form a boundry layer solution adjacent the power face, thereby suppressing turbulence. A propeller suitable for practicing the above method is also disclosed.

Abstract: Structure for minimizing gap changes in a circulation control pneumatic ve. A flat, flexible ring is located below and adjacent to the plane of the nozzle of blade ducts. The flat, flexible ring is supported from beneath by an array of actuators. In one embodiment, the nozzles are immobilized relative to hub-induced displacements and thus eliminate any feedback due to hub flexing. In another embodiment, the nozzle is pivotally attached to a rotating carrier and feedback is reversed so that feedback becomes negative.

Abstract: Aircraft engine exhaust is mixed with air and fuel and recombusted. Air is drawn into the secondary combustion chamber from suction surfaces on wings. Exhaust of the secondary combustion chamber is blown over wing and fuselage surfaces.

Abstract: 1. A method of decreasing the deleterious effects of cavitation on a ship propeller comprising providing a propeller having supercavitating blade sections, rotating said propeller to drive said ship, and ejecting air from the suction side of each said blade when said ship speed and propeller speed reach a predetermined point to thereby produce a cavity which extends from the leading edge to a point in the water beyond the trailing edge of said blade and envelops the entire suction side of said blade.

Abstract: A circulation control airfoil having an edge slot formed by upper and lower uct panels. A plurality of struts are spaced along the length of the edge slot and are adjustably attached to the upper and lower duct to maintain the edge slot height. A reinforcing saddle is provided at each attachment position on the panels for distributing load applied to the struts over a large area of the duct panels. Each strut is provided with a differential lead thread system which provides high resolution adjustment capability for the edge slot.

Abstract: This fluid valve is mounted in the hub of a circulation control helicopter otor to modulate the flow of air through the hub to the blowing slots on the leading and trailing edges of the blades. The valve independently controls the air pressure to the leading edge slots and trailing edge slots so as to vary the lift produced by each rotor blade as a function of its azimuth angle. The periodic waveforms of the air pressure provided to the leading edge slots and trailing edge slots in the blades are controlled by a combination of flow regulating cams and programming rings.

Abstract: A circulation controlled rotor blade which reduces rotor flutter by introing a laminar flow over the trailing edge. A trailing edge structure has a deformable tube to control a spanwise slot formed by the juxtaposition of an upper trailing edge lip over the deformable tube. The laminar flow is created by compressed fluid directed through the rotor blade and through the slot.

Abstract: This invention is for rotating machines of all types such as helicopters, propellers, compressors, to be equipped with slotted tube or a tube with series of holes extending outwardly in the spanwise direction near the trailing edge of a jet-circulation-control rotor-blade tip for blowing jets of fluid in the direction opposite to the lift of the blade. Thereby achieving flow in the form of a jet sheet to abate, diffuse the undesirable blade-tip vortices and to increase the overall efficiency of the machine.

Abstract: A control system for rotary wing aircraft having a circulation controlled tor is provided. Two axial flow air compressors driven from the engine input shaft provide an air flow which is ducted to the rotor blades through a bifurcated duct and a non-rotating air plenum and released through spanwise slots in the blades. Damping is accomplished by a conically shaped diverter valve in the air plenum and a butterfly valve adjacent the air compressors. Aircraft stability is achieved through a gyro coupled to the rotor shaft which integrates pilot controlled input with rotor cyclic flap moment input.

Abstract: An airflow control valve for a circulation control rotor helicopter blade wherein the airflow path is equally distributed about the closure element so as to prevent the generation of unbalanced pressure forces.

Abstract: This invention is for wings of all types, such as fixed wings for aircraft and hydrofoil boats, and rotary blades (or wings) for helicopters and turbines, to be equipped with a slotted tube, or a tube with series of holes extending outwardly in the spanwise direction near the trailing edge of the wing tip for blowing jets of fluid (such as air or water) in the direction opposite to the lift of the wing, thereby achieving flow in the form of a jet sheet to abate, diffuse and break up the undesirable wing-tip or blade-tip vortices.