Showing papers on "Blade pitch published in 1969"

Variable pitch propeller or rotor

Abstract: The invention is concerned with a root for the blade of a variable pitch rotor, usually the drive torque compensating rotor for a helicopter. The root has a cylindrical portion slidable and rotatable in a plastic sleeve partially embedded in a hub.

Pitch control mechanism for bladed rotor

Abstract: Two Z-crank mechanisms connect at different stations to a rotor swashplate so that translation of the mechanisms causes collective pitch variation of the blades and so that rotation of the mechanisms either together or separately causes cyclic pitch variations of the blades.

Method of and apparatus for controlling a variable pitch steering propeller

Abstract: A variable pitch steering propeller for a ship is controlled by continuously monitoring the power supplied to the propeller to drive it and producing a signal indicative thereof, generating a reference signal indicative of a desired propeller power output, comparing the two signals and producing a control signal representative of the difference between the actual power signal and the reference signal and adjusting the pitch of the propeller in accordance with the control signal.

Ram-air turbines

Abstract: A ram-air turbine comprises a variable-pitch bladed rotor, a hydraulic actuator for effecting pitch variation of the blading of the rotor, and a pump driven by the rotor to supply fluid for operation of the actuator. A rotary speed-sensitive flyweight governor is provided to control the supply of fluid to the actuator whereby to cause the rotor automatically to rotate at constant speed, and the arrangement includes a machine driven by the rotor. The rotor, hydraulic actuator, pump, governor and driven machine are all coaxially arranged.

Variable geometry rotor system

Abstract: This rotor system is designed to control the nonuniform wake shed from a given rotor blade impinging upon the other blades of the rotor system. The rotor system utilizes blade sets which are of a different diameter than another blade set in the system. The azimuth spacing between the blade sets can be varied while the aircraft is in flight. The vertical spacing between the blade sets can also be changed. Mechanism is provided for collective pitch control of the blade sets. The plan form of blade sets, as well as the configuration of their tips, are varied.

Rotor blade pitch control by mechanical hydraulic system sensing blade deflection

Abstract: A system of mechanisms for automatically controlling, at relatively low speed, rotation of a helicopter rotor blade responsive to gust conditions or flapping loads or to reverse flow of air on the rear or trailing edge of a rotor blade. The system comprises novel blade sensor means, amplifying means coupled thereto, converting means, pitch azimuth sensing means, means for locking out gyroscopic control, and automatic low-speed pitch control means.

On the optimum one-bladed cycloidal ship propeller

Abstract: The optimal motion of a one-bladed cycloidal propeller is investigated by minimizing the kinetic energy, left behind in the wake The propeller blade is assumed to perform a, fish tail like, trochoidal motion and to provide a prescribed thrust The theory is two-dimensional The efficiency of the propeller is calculated and its quality is discussed

Tail rotor of a helicopter

Abstract: A tail rotor of a helicopter comprising a hub with at least two blades hinged to it, each blade having a sweep angle selected in combination with transverse displacement, and a rod controlling the collective pitch of the rotor, said rod carrying an articulated blade-pitch control means.

Control system for a dozer blade

Abstract: A control system for a dozer blade or the like incorporating valving for combining with a tilt control for the blade tilt motors and hydraulic circuitry for the lift motors to additionally provide blade pitch control. Also disclosed is a ball and socket connection for connecting the dozer blade to the dozer frame.

Propeller synchrophaser system

Abstract: A combined system for synchronizing engine speed and propeller blade phase on multiengine craft with hydraulic blade pitch adjustment wherein each engine has a speed sensor and propeller blade position sensor. Electronic signal comparator and error signal generating circuits effect adjustment of speed governors and propeller blade pitch actuators to first secure engine speed synchronization and propeller blade synchrophasing, the latter being performed without affecting the former.

Fluid-driven mass flowmeter

Abstract: A fluid-driven mass flowmeter comprising two identical impellers or rotors, having the same blade pitch design, arranged in tandem, back to back, and coupled by an intermediate linear torsion spring such that the upstream rotor is driven as a compressor by the downstream rotor which acts as a turbine. Energy input and flow turbulence are minimized and increased torque on the rotors is derived by the use of a compound blade shape and close rotor positioning so that the annular momentum which the upstream or compressor rotor puts into the passing stream, in the form of a swirl, is removed by the downstream or turbine rotor. The differing torques acting on the two rotors cause an angular displacement between them and an indication of the mass flow is obtained by measuring the time displacement of suitable markers on each rotor, which markers are axially aligned at zero angular displacement.

Flying rotorcraft toy

Abstract: A flying toy having a driven propeller mounted in a duct, with lifting rotor blades extending from the top of the duct, the outer ends of the blades being interconnected by a protective annular ring. The duct and blade assembly rotates in the opposite direction to the propeller, due to torque, the lift of the blades adding to that of the propeller for vertical propulsion. When power is shut off, the toy descends gently in autorotation. The airframe structure is a simple unitary molding and the rotor blades are partially adjustable in pitch to vary the effective lift and thus control the flight.

Rotor blade heavy core tuning weight

Abstract: A helicopter rotor blade includes a honeycomb core within the airfoil contour forming a composite-type rotor blade having the required mass for dynamically tuning the structure. The location and mass of the tuning weight is variable and the composite rotor blade is attachable to the hub in the conventional manner.

Tandem Propeller in Review

Abstract: The tandem propeller system (TPS) for submersible propulsion and control was conceived by the author in 1961. This paper traces its theoretical and experimental development through the most recent tests conducted at Cornell Aeronautical Laboratory. Although the initial configuration was for high-speed nuclear submarines, the emphasis in recent years has been for application to the slower, more maneuverable deep-submergence vehicles. Both configurations are discussed in detail in this paper.

Method and apparatus for variable pitch propellers

Abstract: THE LOAD ON THE ENGINE OF A SHIP IS MAINTAINED WITHIN PRESCRIBED LIMITS BY MAKING AN ADJUSTMENT OF THE PROPELLER OF THE SHIP TO COMPENSATE FOR CHANGES IN WIND AND SEA CONDITIONS AND THE LIKE. THIS IS ACCOMPLISHED BY GENERATING A CORRECTIVE SIGNAL, DEPENDING ON THE DISCREPANCY THAT MAY EXIST BETWEEN ACTUAL AND DESIRED ENGINE LOAD. THE CORRECTIVE SIGNAL, IN THE FORM OF A TRAIN OF PULSES, CONTROLS A SERVOMECHANISM THAT ADJUSTS PROPELLER PITCH.

Pitch adjustment in screw-bladed devices, such as propellers

Abstract: A propeller having a boss to which are bolted fixed blades which can be located at the required pitch by means of dowels engaging in pairs of registering holes in the boss and the blade root, a number of different sets of holes being provided to give different pitch settings.

Suppression of Transmitted Harmonic Vertical and Inplane Rotor Loads by Blade Pitch Control

Abstract: : A method was developed to study the possibility of using higher harmonic pitch-angle inputs to eliminate the transmission of oscillatory vertical and inplane forces from a helicopter rotor to its driving shaft. The aerodynamic loads are computed by using a realistic model which represents the rotor blades by bound vorticity distributions and the wake by a mesh of segmented vortex filaments. Computed results are presented for a two-bladed teetering rotor which was approximately the same as that of the UH-1A configuration except for the assumed differences in pitch control. The required pitch-angle inputs were determined for eliminating various combinations of harmonic root shears for three flight conditions.

Air-cushion vehicles and rotary compressors therefor

Abstract: 1,140,563 Air cushion vehicles DOWTY ROTOL Ltd 4 April, 1966 [14 April, 1965], No 16054/65 Heading B7K [Also in Divisions F1 and G3] An air cushion vehicle has at least one compressor of rotodynamic type suitable for providing the air cushion and/or propulsive thrust for the vehicle, and the rotor of the or each compressor includes adjustable blading, adjustment of which during operation affords variation in delivery pressure and mass flow without the need to change the rotational speed The air cushion vehicle shown in Fig 1 has at least one centrifugal or axial-flow compressor 14 to provide the air cushion and driven through a bevel gear-box 20 by a gas turbine engine 15 which also drives a propeller 16 The compressor 14 has variable-pitch impeller blading (see Division F1) and the propeller 16 may also be of variablepitch type, whereby the thrust of the compressor and of the propeller can be varied independently without alteration of rotational speed Two or more compressors may be provided so that slight changes of attitude of the vehicle can be made by differential adjustment of their blade pitch The propeller may be replaced by a further ducted compressor or by using the aircushion compressor for propulsion also

Helicopter rotor construction

Abstract: A paired blade helicopter rotor having a strut connecting the blades and a tie rod connecting each blade with the rotor hub, provision being made to pretension the tie rods.

Pitch control for rotary wing aircraft

Abstract: A rotary wing aircraft includes a central fuselage and a rotor consisting of an inner annular hub rotatably supported on and encircling the fuselage, radially extending radial blades and an outer supporting ring. The rotor is adapted to be driven by a turbine device associated with the rotor outer ring and an outer track nonrotatably attached to the fuselage. Each rotor blade is attached to a radially disposed, rotatable spindle in the hub structure; and pitch control arms are fixed to these spindles for controlling the rotation of the spindles and, therefore, the pitch of the attached rotor blades. An annular, pneumatically controlled bellows system, mounted on the fuselage concentric with the hub selectively controls the oscillation of the pitch control arms and thereby provides collective and cyclic pitch control for the rotor blades. In a rotary wing aircraft, such as a helicopter, it is conventional to provide means for changing the pitch of the rotor blades for control of the aircraft. The changing of the pitch of each of the rotor blades simultaneously and uniformly is referred to as ''''collective pitch control,'''' this control being used to increase or decrease the lift of the rotor. The variable changing of the pitch of a rotor blade in relation to its angular position relative to the aircraft fuselage is referred to as cyclic pitch control. This control is used, during forward motion of the aircraft, to compensate for the fact that the rotor blades moving in the direction of flight should have a different pitch than the retreating blades. This cyclic pitch control may also be used for directional control of the aircraft and for trimming of the aircraft. The use of a cyclic pitch control of a directional control is particularly important in aircraft which does not have any tail structure for directional and attitude control, as do conventional helicopters.

Ship{3 s propeller and method of changing the pitch thereof

Abstract: The forces necessary to change the pitch of a ship''s propeller of variable pitch are reduced by reducing the hydrodynamic torque during the pitch change. This is done by passing fluid comprising a gas or a liquid through the propeller blade and emitting it from the propeller blade on the suction side of the blade at a distance of 3 to 15 percent of the width of the suction side of the blade measured from the leading edge.

Helicopter rotor noise generation.

Abstract: Distributive loading rotational theory for helicopter rotor noise generation, considering steady and fluctuating force radiation and impulsive blade slap

People{3 s helicopter

Abstract: The rotor consists of several groups of blades fixed to a slanting carrier in parallel position with a certain distance between them like the wing of a bird diminishing the rotor diameter, and the effect of torque and the unsymmetry, giving greater stability, and enabling higher peripheral speed whereby the flow at the backward-turning blade does not cease. The carrier of each blade group is connected by flapping hinges to the outside ring of the hub relatively large in relation to blade length. By turning the blade group the angle of incidence of blades is changed. The blade groups are periodically and collectively controlled by y control device based on a hydraulic system which is installed along the rotor shaft. A control wheel allows radial turning of the whole control device making it possible to control the helicopter in longitudinal and lateral sense. Compensation of torque and of the unsymmetry of rotor during forward flight is brought about by a long and largesurface rotor airfoil with counterweight which is installed variably and with opposite direction of rotation on top of main rotor through a differential gear in the rotor head. This airfoil is stopped during forward flight by the flow of drive wind, so that the helicopter shows an unsymmetric airfoil giving a lift by which the unsymmetry of the stream of rotor is eliminated. Compensation of torque and of the unsymmetry of rotor works automatically without special control. The blade group rotor, blade control and torque compensation are a compact unit propelled by an engine which is installed in the fuselage before the pilot.

Improvements in or relating to Overload Protection Apparatus for the Propulsive Engines of Ships having Variable Pitch Blade Screws.

Abstract: 1,172,766. Marine variable pitch propeller propulsion. SOC. FINANCIERE ET INDUSTRIELLE DES ATELIERS ET CHANTIERS DE BRETAGNE. 20 April, 1967 [7 June, 1966], No. 18269/67. Heading B7V. Overloading of an engine driving a ships variable (reversible) pitch propeller is prevented by a cam A connected to a controller or the engine fuel pump actuating a contactor 1 which de-energizes a solenoid operated valve E1, thereby stopping flow to and from the hydraulic ram V of the pitch changing mechanism, thus arresting change of pitch, further movement of the cam A resulting in further overload actuating a second contactor 2 which causes energization of the valve E1 resulting in supply to the hydraulic ram V in a direction to bring about a change of pitch in the reverse direction, i.e. if blade pitch is being increased actuation of contactor 1 arrests the increase and subsequent actuation of contactor 2 will then reduce the pitch. Hydraulic supply is through a valve E2 which is closed on operation of the contactor 1 so that the supply is through a restricted by-pass RD, the ram V thus operating slowly in the overload range. Reversers I1-I4, normally open when the ram V is in the zero pitch position, are closed one way or the other by a cam B whose movement corresponds to the movement of the ram V when the latter is in a position corresponding to ahead or astern pitch.