Abstract: Large Contra-Rotating Wind Turbine used to generate mechanical torque by extracting wind energy efficiently. Large scale innovative rotor designs include swept blades to utilize a tension hoop, which supports the outside end of the blades instead of having cantilevered rotor blades. Actual size and configuration of the rotors or blades, including swept area, number of blades, curvature of blades, airfoil shape, or other bends of the blades are not relevant or specific to this invention, however this innovation does allow the size and capacity of the wind turbine to achieve capacities of 3.0 Mw or greater. This new wind turbine configuration places the electric generator at grade where it is easy to access and maintain, and is not supported by the tower. The capacity of this new wind turbine configuration type can be larger than 3.0 Mw.

Abstract: An embodiment of a ceiling fan assembly has a motor rotatably mounted to a shaft and adapted to be mounted to an extent of a substantially planar support surface. A first set of fan blades are connected to the motor and a second set of fan blades are connected to the shaft a predetermined distance below the extent of the substantially planar support surface, the motor, and the first set of fan blades. A method of circulating air comprises driving the motor to drive the first set of blades in a first rotational direction about the shaft. Simultaneously, responsive to the air flow generated by the rotation of the first set of blades in a first rotational direction, the second set of blades rotates in a second rotational direction about the shaft, opposite the first rotational direction.

Abstract: A system of counter-rotating propellers for an aircraft turbine engine including a first and a second propeller, each including a stalling control system for the blades, a rotating actuating mechanism for sliding an element to move the angle of attack of the blades, and a disengaging mechanism for rigidly fixing in rotation the rotating actuating mechanism. The system is designed so that when the disengaging mechanism is engaged, a relative rotation speed is created between the elements and the associated rotating actuating mechanism thereof, bringing the blades into a neutral position thereof for feathering.

Abstract: A turboprop propulsion unit includes at least one pusher propeller 5, 6 driven by an aircraft gas-turbine engine, with the aircraft gas-turbine engine being arranged in front of the pusher propeller 5, 6 in a direction of flight. A turbine outlet area 9 is arranged at the front in the direction of flight and a compressor area 14 faces towards the pusher propeller 5, 6.

Abstract: A method for reducing the vibration levels capable of occurring, in a turbine engine including at least one propeller and one coupling structure of the turbine engine, because of the turbulence of aerodynamic origin generated by the coupling structure on the propeller. The method includes: defining an initial configuration of the aerodynamic profiles, calculating the synchronous forced response on the propeller as a function of the force of harmonic excitation generated by the coupling structure expressed in the form of a linear function of the generalized aerodynamic force for the mode in question, and determining a tangential geometric offset value ? of the individual aerodynamic profiles for stacked sections of one of the propeller or of the coupling structure in order to reduce the term corresponding to the generalized aerodynamic force. The combination of the sections with the tangential offsets therefore defines a new configuration of the aerodynamic profiles.

Abstract: A drive device (D) for driving first and second lift rotors (2, 3) of a twin-rotor rotorcraft, includes link elements provided with first and second transmission shafts (5, 6) for synchronizing the first and second transmission members (74, 84) of first and second main gearboxes (7, 8), the first main gearbox (7) being provided with first power combiner element (73) firstly meshing with the first transmission member (74) and secondly mechanically linked with the first transmission shaft (5) and with the second transmission shaft (6), and the second main gearbox (8) being provided with second power combiner element (83) firstly meshing with the second transmission member (84), and secondly mechanically linked with the first transmission shaft (5) and with the second transmission shaft (6).

Abstract: A pitch control mechanism for an open rotor gas turbine engine is provided, the engine having a first rotor assembly and a second rotor assembly, with a plurality of airfoil blades circumferentially mounted on each rotor assembly, and arranged in contra-rotational relationship to each other. The pitch control mechanism includes an actuator assembly configured to be secured to a non-rotating frame of the engine, the actuator assembly having a first actuator and a second actuator, with the actuator assembly being rotationally isolatable from and couplable to the first and second rotor assemblies such that, in use, an actuation signal from the first or second actuator induces a corresponding desired change in pitch of the airfoil blades of the respective first or second rotor assembly independently of the pitch of the airfoil blades of the second or first rotor assembly.

Abstract: A method of operating a contra-rotating propeller engine that preferably comprises a 12 bladed front and a 9 bladed rear propeller. As is conventional, the engine is operated during at least a take-off phase, a cruise phase and an approach phase; during the cruise phase the engine operates with a generally constant propeller tip speed. The method is characterized by the step of operating the engine such that the tip speed of either or both of the propellers, during at least one of take-off, climb or approach, at least 10% greater than cruise tip speed. With a specific front to rear propeller spacing, increasing the tip speed reduces overall noise generated by the propellers.

Abstract: A hydrokinetic water turbine system includes a frame structure, first and second shafts rotatably supported by the frame structure, and first and second rotors secured to the first and second shafts respectively and each having a plurality of spaced-apart blades so that the flowing stream of water revolves the first and second rotors about a central axis of the first and second shafts respectively. The first and second shafts are horizontally-disposed and coaxial and the first and second rotors are adapted to rotate in opposite directions. The blades are hollow and filled with a foam material to reduce weight and increase buoyancy. The frame structure is a substantially rectangular and open frame structure and includes frame members adapted to reduce a coefficient of drag of the frame structure. The frame members can be hollow and filled with a foam material to reduce weight and increase buoyancy.

Abstract: A mechanism for adjusting pitch of blades of a propeller of a system of contra-rotating propellers for a turbomachine, wherein each blade moves around a radial axis. The mechanism includes a linear actuator, a structure to transform movement imparted by the linear actuator into rotation of each of the blades in a synchronized manner around their radial axis, the structure including a bracket of longitudinal axis formed of a central ring, an outer ring, and multiple radial arms rigidly connected to the central ring and to the outer ring. The central ring can be subject to actuation of the linear actuator, and the central ring and the outer ring are positioned in two separate planes, orthogonal to the longitudinal axis, such that the bracket is shaped as a truncated cone.

Abstract: A serial axial fan includes first and second axial fans. The first axial fan preferably includes a first motor portion, a first impeller, and a first housing. The second axial fan preferably includes a second motor portion, a second impeller, and a second housing. In the first impeller, an angle defined by a rotational plane of the first impeller with a chord of each blade of the first impeller on an imaginary cylindrical surface centered about a central axis increases as the radius of the imaginary cylindrical surface increases.

Abstract: According to the invention, in order to eliminate or at least to reduce a possible unbalance of the propulsive system (1), counterweights (40, 50, 60, 70) are brought in locations that are provides on the hub envelope (22, 32), near the ends (22A, 22B, 32A, 32B) of the latter away from the planes od the propellers (B-B?, C-C?).

Abstract: A bidirectional water turbine including: an upstream rotor and a downstream rotor, wherein the upstream rotor and downstream rotor are contra-rotating and each rotor includes a plurality of blade, the blades of the upstream and downstream rotors having substantially the same profile.

Abstract: A fan includes a first motor having a first rotor and a second motor having a second rotor which is rotationally connected to the first rotor. The fan further comprises a first impeller which, when driven by the first motor, rotates along a first direction and creates a main flow along a direction perpendicular to the periphery thereof and a tangential flow along the tangent thereof. The fan also includes a second impeller which, when driven by the second motor, rotates along the reverse direction of the first direction and impel the tangential flow to the direction perpendicular to the periphery of the first impeller.

Abstract: A blade for a windmill disposed around a rotation center (M) in a vertical direction so as to receive wind force, comprising a front surface (26) including; a front nose surface (26F) being disposed at front of a traveling direction, also having a greatest average curvature a low speed airflow passing surface (26L) disposed on a closer side to the rotation center, and formed continuously from the front nose surface to rearward of the traveling direction, and a high speed airflow passing surface (26H) disposed a distant side from the rotation center, formed continuously from the front nose surface to rearward of the traveling direction with a curved surface swollen greater than the low speed airflow passing surface, and having length as viewed from the vertical direction greater than the low speed airflow passing surface.

Abstract: A counter-rotatable low pressure turbine includes counter-rotatable outer and inner drum rotors. The outer drum rotor is connected to a sole shaft for transmitting torque and power out of the low pressure turbine. Low pressure outer drum turbine blade rows extend radially inwardly from an outer shell of the outer drum rotor. Low pressure inner drum turbine blade rows extend radially outwardly from the low pressure inner drum rotor. The outer drum turbine blade rows are interdigitated with the inner drum turbine blade rows. The drum rotors are geared together through an epicyclic gearbox for transmitting all the torque and power produced by the drum rotors to the shaft. The gearbox may be located aft of the drum rotors. A differential thrust bearing is disposed between the drum rotors. A single stage fan section of an engine is connected to the turbine by the shaft.

Abstract: A hub for a propeller having variable pitch blades for a turbine engine, for example for a propfan turbine engine. The propeller hub includes: a polygonal ring having substantially radial cylindrical housings distributed about a central axis of the ring for receiving the blades; a rotor element for the turbine of the turbine engine; a supporting flange attached to the ring so as to connect the ring to the rotor element; and a plurality of backup retaining members linked to the rotor element, and each of which includes at least one bearing surface opposite an outer surface of the ring with a radial spacing.

Abstract: According to some embodiments, a method and system are provided to receive an airflow at a blower fan via an axial fan, and expel the airflow via a blower fan. The blower fan comprises a hub associated with an axis of rotation, and the axial fan comprises the hub.

Abstract: A support frame portion is divided into a first support-frame half-portion and a second support-frame half-portion along a virtual reference dividing plane. A raised portion is integrally formed with each of side walls in a pair of the first web half-portion, projecting toward the second web half-portion beyond the virtual reference dividing plane. A raised portion is integrally formed with each of side walls in a pair of the second web half-portion, projecting toward the first web half-portion beyond the virtual reference dividing plane. A recessed portion is formed in each of the side walls in the pair of the first web half-portion, and is fitted with the raised portion corresponding thereto of the second web half-portion. A recessed portion is formed in each of the side walls in the pair of the second web half-portion, and is fitted with the raised portion corresponding thereto of the first web half-portion.

Abstract: A system for adjusting the pitch of a counter-rotating propeller has a propeller shaft, a forward propeller driven by the propeller shaft, and an aft propeller connected with the forward propeller. The forward propeller has a hub, blades mounted within the hub, and an actuator connected with an end of the blades. The aft propeller has a hub, blades mounted within the hub, and a cam assembly connected with an end of the blades. The actuator of the forward propeller has a forward end and an aft end, wherein the aft end is connected with the cam assembly of the aft propeller. Thus, when the actuator moves in an axial direction, the cam assembly moves relative to the actuator and the pitch of the forward propeller blades and the pitch of the aft propeller blades are simultaneously adjusted.

Abstract: According to the invention, a system for generating electricity from wind is disclosed. The system may include a vertical mounting pole, a generator, a first vertical axis wind turbine (“VAWT”), and a second VAWT. The generator may include a rotor, stator, and frame, fixedly coupled with the stator, and rotatably coupled with the vertical mounting pole such that the generator can rotate around a substantially vertical axis. The first VAWT may be fixedly coupled with the frame and configured to rotate in a first rotational direction around the vertical axis, and at least partially about the vertical mounting pole, when a wind is received. The second VAWT may be fixedly coupled with the rotor and configured to rotate in a second rotational direction around the vertical axis, and at least partially about the generator, when the wind is received, where the second rotational direction is opposite the first rotational direction.

Abstract: A device is described for generating energy. The device includes at least two ultralight airfoils rotating along their own axis, which functionally reproduce the characteristics of a propeller. The ultralight airfoils which characterize such aerodynamic configuration use pulling members (such as cables or tie-rods) to keep their shape when operating. An important weight reduction of the structure is thus obtained, which allows different applications in the aeolian generation field.

Abstract: A propeller for an aircraft is disclosed. The propeller has an odd number of unequally circumferentially spaced blades. The propeller may be provided as part of a contra-rotating propeller arrangement and/or aft of a pylon on an aircraft. The propeller has been found to reduce noise levels and to be efficient.

Abstract: Disclosed is a gearbox with two driver gears that are phase shifted 180 degrees with respect to a driven gear so that counter-rotation of the driver gears combine to rotate the driven gear together. The gearbox can be used to couple a counter-rotating, coaxial wind turbine rotors by coupling the driver gears to the counter-rotating rotors and the driven gear to a generator so that the counter-rotating rotors on the wind turbine rotate the driven gear in the same direction. The driven gear can be coupled to a generator to produce electricity.

Abstract: A turbine (5) having at least two sets of co-axially mounted, rotatable blades (10, 15) arranged so that one set cannot eclipse another. Preferably, the sets of blades (10, 15) are contra-rotatable. Each set of blades (10, 15) may be operable to extract similar amounts of energy, thereby to minimise the net reactive torque.

Abstract: A rotor blade comprising a core blade section; and a trailing edge section, the trailing edge section being attached to the core blade section along a join interface. The trailing edge section comprises a shape memory material which is actuable so as to cause selective deformation of the trailing edge section between a first condition in which a trailing edge of the trailing edge section follows a substantially smooth profile and a second condition in which the trailing edge is perturbed. The direction of the perturbation may be oblique or perpendicular to the direction of flow over the blade in use. The rotor blade may be a fan or propeller for a gas turbine engine.

Abstract: An embodiment of a ceiling fan assembly has a motor rotatably mounted to a shaft and adapted to be mounted to an extent of a substantially planar support surface. A first set of fan blades are connected to the motor and a second set of fan blades are connected to the shaft a predetermined distance below the extent of the substantially planar support surface, the motor, and the first set of fan blades. A method of circulating air comprises driving the motor to drive the first set of blades in a first rotational direction about the shaft. Simultaneously, responsive to the air flow generated by the rotation of the first set of blades in a first rotational direction, the second set of blades rotates in a second rotational direction about the shaft, opposite the first rotational direction.

Abstract: A counter-rotating axial flow fan in which the shape of stationary blades of a middle stationary portion is optimized to reduce noise is provided. Defining the maximum axial chord length of front blades as Lf, the maximum axial chord length of rear blades as Lr, and the maximum axial chord length of stationary blades as Lm, a relationship of Lm/(Lf+Lr)<0.14 is satisfied. Defining the maximum dimension between the blade chord for lower surfaces of the stationary blades and the lower surfaces as K1, the maximum axial chord length Lm of the stationary blades satisfies a relationship of Lm/K1>5.8.

Abstract: A counter-rotating axial flow fan with improved characteristics and reduced noise compared to the related art can be provided. Defining the number of front blades as N, the number of stationary blades as M, and the number of rear blades as P, and defining the maximum axial chord length of the front blades as Lf, the maximum axial chord length of the rear blades as Lr, the outside diameter of the front blades as Rf, and the outside diameter of the rear blades as Rr, the counter-rotating axial flow fan satisfies the following two relationships: N?P>M; and Lf/(Rf×?/N)?1.25 and/or Lr/(Rr×?/P)?0.83.

Abstract: An axial fan unit includes two or more impellers which rotate about a center axis in opposite directions relative to each other to create an axial airflow. Each impeller includes a hub and a plurality of blades disposed around the hub. The impellers are surrounded by a housing in a radial direction that is perpendicular or substantially perpendicular to the center axis. On a cross-sectional plane of the axial fan unit including the center axis, a distance between the hubs of the impellers and the housing decreases from an upstream side to a downstream side in a direction of the axial airflow.

Abstract: An improved coaxial rotor assembly for a helicopter includes an upper rotor system having a multiple of upper rotor blades each having outer tips and mounted on and extending outwards from a central rotor shaft and a lower rotor system having a multiple of lower rotor blades each having outer tips and mounted on and extending outwards from the central rotor shaft with the upper rotor system spaced an axial distance from the lower rotor system on the central rotor shaft. A rotor blade support ring extends circumferentially around each of the upper and lower rotor systems which movably engages and supports the outer tips of the upper and lower rotor blades in spaced apart relation such that the upper and lower rotor systems rotate in opposite directions and the rotor blade support ring means prevents contact between the upper and lower rotor systems during operation thereof.

Abstract: A first motor rotates, in one of two rotating directions, the first impeller including a plurality of front blades in a suction opening portion of a housing. The second motor rotates, in the other rotating direction opposite to the one rotating direction, the second impeller including a plurality of rear blades in a discharge opening portion of the housing. A plurality of stationary blades are arranged between the first impeller and the second impeller in the housing. When the number of the front blades is N, that of the stationary blades is M, and that of the rear blades is P, their relationship is defined as N>P>M. A length L1 of the front blades measured in an axial direction is set longer than a length L2 of the rear blades measured in the axial direction.

Abstract: A variable blade pitch wind turbine and method of passively varying the blade pitch is presented. Each blade of the turbine rotor can individually and passively rotate about a respective blade axis to continuously vary the pitch of the blades to adjust to the ever changing wind speed and direction without active controls or other mechanical or electrical induced inputs to force rotational movement of the blades. Sections of each blade can respectively rotate to change the blade twist. In one example, a second rotor is used to increase the electrical generation and efficiency of the blade turbine.

Abstract: In a contra rotating propeller engine propeller blade assemblies are provided which rotate in opposite directions as a result of association with an epicyclic gear assembly acting as a differential gearbox. A carrier is provided to drive one propeller blade assembly. Actuators are provided to cause pitch angle adjustment of the respective propeller blades of the assemblies. These actuators, are secured upon a stationary structure and act through actuator rods and appropriate mechanisms to cause such angular pitch adjustment. Rotational de-couplers are provided to rotationally isolate the actuators while an actuator rod part acts across the assemblies and a rotational de-coupler to de-couple contra rotation between the assemblies while still allowing axial displacement for adjustment of the other propeller blade assembly.

Abstract: A wind turbine comprises a tubular casing having an inlet opening, an outlet opening, an outer surface generating a pressure decrease, an inner surface presenting a convergent section joined to the inlet opening, a divergent section joined to the outlet opening and to the convergent section by a throat, and a propeller mounted rotating with respect to the tubular casing in proximity to the throat. It is coupled to a first generating machine. It comprises another propeller mounted rotating with respect to the tubular casing, placed upstream from the first propeller in the convergent section.

Abstract: The object is to facilitate the installation of a contra-rotating propeller on a mother ship. Disclosed is a contra-rotating propeller unit in which a predetermined part on the rear side of an inner shaft (12) is supported by a contra-rotating rear bearing (36) provided in a boss (13a) of a front propeller (13), and which includes an inner fixing tool (50) detachably attached to a tip of an outer shaft (11) to temporarily support a predetermined part on the front side of the inner shaft (12), and a contra-rotating thrust bearing (40) provided in the boss (13a) of the front propeller (13) to receive the thrust load from the outer shaft (11) to transmit the thrust load to the inner shaft (12).

Abstract: A magnetic de-rotation system includes an inner ring which supports an eddy current ring and at least one inner ring magnet and an outer ring which supports at least one outer ring magnet, attraction between the at least one inner ring magnet and the at least one outer ring magnet produces a stable rotational position for a fairing.

Abstract: The invention relates to a hydroelectric machine. According to the invention, the machine includes: at least two pipes (10, 11) connected to a ballast (8) and to a horizontal bar (14), bearing a vertical axis (15) driving a first gear manipulation box (25) and then the rotor of a first generator (27); blades (16) opposite the openings (12, 13) of the pipes (10, 11), carried by bearings (17) and beams (18), and by a second structure (24) via rolling bearings (22), the beams (18) leading to a hollow cylinder (31) driving, via two sprockets (28, 29) and an axis (30), a second gear manipulation box (31) and then the rotor of a second generator (33); cylindrical steel frames (38, 40, 42, 44, 47, 49) bearing shoulders and rolling bearings (39, 41, 43, 45, 46, 48, 50); a power supply for powering two needle latches (59, 60) via two concentric metal hoops (55, 56) and two brushes (57, 58).

Abstract: A fan for an aircraft engine, particularly a gas turbine aircraft engine, is disclosed. The fan has a fan rotor with fan blades, which extend radially outwardly from a hub to an outer flow path wall of a fan flow path. The fan has an auxiliary rotor that is positioned upstream of the fan rotor and has auxiliary blades that extend radially outwardly from a hub and end at a distance from the outer flow path wall of the fan flow path. The auxiliary rotor and the fan rotor are designed as separate rotors, such that the auxiliary rotor can be operated at a higher speed than the fan rotor.

Abstract: A wind turbine for generating energy includes a first rotor having a first set of blades and a first shaft, and a second rotor having a second set of blades and a second shaft, wherein the first rotor is configured to rotate in a first direction, and the second rotor is configured to rotate in a second direction that is opposite to the first direction. A wind turbine for generating energy includes a first rotor having a first set of blades and a first shaft, and a second rotor having a second set of blades and a second shaft, wherein one of the first set of blades is oriented to receive wind for turning the first rotor, and wherein one of the second set of blades is oriented an at angle to receive wind that is deflected from one of the first set of blades for turning the second rotor.

Abstract: A method for assembling a gas turbine engine includes coupling a low-pressure turbine to a core turbine engine, and coupling a counter-rotating fan assembly including a first fan assembly and a second fan assembly to the low-pressure turbine such that the first fan assembly rotates in a first direction and the second fan assembly rotates in an opposite second direction.

Abstract: A wind turbine for generating energy includes a first rotor having a first set of blades and a first shaft, and a second rotor having a second set of blades and a second shaft, wherein the first rotor is configured to rotate in a first direction, and the second rotor is configured to rotate in a second direction that is opposite to the first direction. A wind turbine for generating energy includes a first rotor having a first set of blades and a first shaft, and a second rotor having a second set of blades and a second shaft, wherein one of the first set of blades is oriented to receive wind for turning the first rotor, and wherein one of the second set of blades is oriented an at angle to receive wind that is deflected from one of the first set of blades for turning the second rotor.

Abstract: A turbomachine having two unducted external fans mounted to contrarotate about a common axis, the fans constituting respectively an upstream fan and a downstream fan, wherein at least some of the blades of the upstream fan carry air guide means on their radially outer end portions, the air guide means being outwardly oriented on going from upstream to downstream and serving to deflect the vortices that are formed in the vicinity of the blade tips of the upstream fan radially to outside the blades of the downstream fan.

Abstract: Wind turbine devices are presented that use counter rotating rotor assemblies in a horizontal axis wind turbine (HAWT) arrangement. This reduces the torque applied to the HAWT thereby reducing the structural requirements of a wind energy generation system. Additionally, the counter rotating rotor assemblies cooperatively rotate an output shaft. In one arrangement, this shaft is a vertical shaft which allows removing power generation equipment from the axis of rotation of a HAWT to a position below the wind turbine and/or located on the ground.

Abstract: The invention relates to a device for controlling the pitch of fan blades of a turboprop. The device includes at least at least one set of adjustable pitch fan blades secured to rotate with a rotary ring centered on a longitudinal axis and mechanically connected to a turbine rotor. Each blade of the set is coupled for pitch-adjustment purposes with a synchronization ring centered on the longitudinal axis, the synchronization ring being suitable for pivoting about the longitudinal axis relative to the rotary ring under drive from actuators carried by the rotary ring and each having a respective axis extending in a direction that is substantially tangential to the synchronization ring.

Abstract: An improved power unit placed in a fluid stream, comprises a common stationary hollow axle, two coaxially mounted orthogonal turbines, having hollow shafts oppositely rotatable around the axle, inner and outer rings, adjustable blades attached to the rings, an electro-generator located between the turbines including two annular rotors formed on the inner rings with flat electro-conductive rings attached thereto, circumferentially immovable bilateral inductors having a core fixed to an arm half-hingedly coupled with a frame mounted to the axle enabling axial displacement of core relatively to the rotor, a winding having a first and third coils cross-wisely wound up on the core, and a second coil transversely wound up between the first and the third coils, forming two magnetic fluxes running in the opposite directions on the opposite sides of inductor facing the rotors, and electric cables for power takeoff mounted on the frame and passed through the axle.

Abstract: A turbo pneumatic cylinder of a pneumatic tool, including a front turbine, a one-way rotatable inverse turbine and a rear turbine. The front and rear turbines are mounted on the rotary shaft of the pneumatic cylinder. The inverse turbine is one-way rotatably fitted on the rotary shaft between the front and rear turbines. Multiple blades are arranged on the circumferences of the front and rear turbine and the inverse turbines. The blades of the inverse turbine are directed in a direction reverse to the direction of the blades of the front and rear turbines. The front and rear turbines and the rotary shaft rotate in the same direction, while the inverse turbine rotates in a direction reverse to the direction of the front and rear turbines. As a result, the efficiency of the pneumatic cylinder is enhanced and the twisting of the pneumatic cylinder is avoided when it is in operation.

Abstract: A blade for a windmill disposed around a rotation center (M) in a vertical direction so as to receive wind force, comprising a front surface (26) including; a front nose surface (26F) being disposed at front of a traveling direction, also having a greatest average curvature a low speed airflow passing surface (26L) disposed on a closer side to the rotation center, and formed continuously from the front nose surface to rearward of the traveling direction, and a high speed airflow passing surface (26H) disposed a distant side from the rotation center, formed continuously from the front nose surface to rearward of the traveling direction with a curved surface swollen greater than the low speed airflow passing surface, and having length as viewed from the vertical direction greater than the low speed airflow passing surface.

Abstract: A rotor hub fairing system includes an upper hub fairing, a lower hub fairing and a shaft fairing therebetween. The rotor hub fairing system reduces the total drag on a dual, counter-rotating, coaxial rotor system. Other aerodynamic structures may be mounted to the shaft fairing, hub fairings and airframe to facilitate flow around the upper and lower hub fairings to reduce flow separation and drag.

Abstract: A first motor 25 rotates, in one of two rotating directions, the first impeller 7 including a plurality of front blades 28 in a suction opening portion 15 of a housing 59. The second motor 49 rotates, in the other rotating direction opposite to the one rotating direction, the second impeller 35 including a plurality of rear blades 51 in a discharge opening portion 57 of the housing 59. A plurality of stationary blades 61 are arranged between the first impeller 7 and the second impeller 35 in the housing 59. When the number of the front blades 28 is N, that of the stationary blades 61 is M, and that of the rear blades 51 is P, their relationship is defined as N>P>M. A length L1 of the front blades 28 measured in an axial direction is set longer than a length L2 of the rear blades 51 measured in the axial direction.