Abstract: An active tuned mass damper applied to the offshore monopile wind turbine belongs to the field of marine technology. A mass block is connected to the inner wall of the tower through a spring. The two ends of the damper and the force actuator are connected to the mass block and the inner wall of the tower, respectively. When the installation of tower is finished, the spring and the damper begin to work. The movement of mass block will partly offset the movement of the tower caused by the wave force. The force actuator starts to work before the mating. The exact position of the nacelle can be obtained from the Global Positioning System (DGPS). The position of tower can be adjusted in the horizontal plane through the force actuator. So, the offshore installation time for nacelle will be saved. The whole installation time and cost will also be reduced.

Abstract: Soundness and a sign of abnormality of a pitch mechanism of a wind turbine blade is quantitatively diagnosed. A method of diagnosing a wind turbine power generation facility includes the steps of: rotating and fixing a wind turbine rotor including at least one wind turbine blade; providing, in a state where the wind turbine rotor is fixed, a pitch control command value to a pitch mechanism that changes a pitch angle of the wind turbine blade, to increase or reduce the pitch angle such that the pitch angle reaches a pitch angle target value from a reference angle; acquiring an actual pitch angular velocity or an actual pitch angle of the wind turbine blade corresponding to the pitch control command value; and diagnosing soundness of the pitch mechanism based on correlation between the acquired actual pitch angular velocity or the acquired actual pitch angle, and the pitch control command value.

Abstract: The present invention provides an efficient and cost-effective process to recover highly purified PHA homopolymers and copolymers, producing novel sequestered amorphous polyhydroxyalkanoate polymer (SAPP) materials derived from cellular biomass that are crystal competent. Such resulting materials (e.g., melt-derived solids and crystalline agglomerates), as well as methods of production of the sequestered amorphous polyhydroxyalkanoate polymer (SAPP) materials and subsequent processing, demonstrate cost-effective production of PHA polymer at commercial scale, which is heretofore not been achievable. Moreover, the methods and materials produced make feasible the long-awaited achievement in the industry for competitive commercialization of PHA homopolymers and copolymers from cellular biomass.

Abstract: There is presented a method for damping an edgewise vibration of a rotor blade of a wind turbine, wherein the method comprises measuring at the rotor blade a motion parameter of the edgewise rotor blade vibration, generating based on said motion parameter a blade pitch angle control signal, and damping the edgewise vibration of the rotor blade by pitching the rotor blade according to the blade pitch angle control signal, wherein the blade pitch angle control signal is arranged so that a resulting force on a rotor blade pitched according to the blade pitch angle control signal, in a direction of the edgewise vibration of the rotor blade in a coordinate system, which rotates with a rotor of the wind turbine, is opposite and proportional to the edgewise rotor blade vibration velocity.

Abstract: The invention relates to a wind turbine blade having a leading edge erosion shield. The erosion shield comprises an inner layer of a first thermoplastic material, the inner layer being an integral part of the shell body of the wind turbine blade. The erosion shield further comprises an outer layer of a second thermoplastic material attached to the inner layer.

Abstract: An integrated airfoil and platform cooling system (30) for a turbine rotor blade (10) includes an inlet (38, 48) located at the root (24) for receiving a supply of a coolant (K), and at least one cooling leg (32a, 32c, 42a, 42c) fluidly connected to the inlet (38, 48) and configured for conducting the coolant (K) in a radially outboard direction. The cooling leg (32a, 32c, 42a, 42c) is defined at least partially by a span-wise extending internal cavity (26) within a blade airfoil (12). An entrance of the cooling leg (32a, 32c, 42a, 42c) comprises a flow passage (92, 102) that extends radially outboard and laterally into a blade platform (50), so as to direct a radially outboard flowing coolant (K) to impinge on an inner side (60) of a radially outer surface (52) of the blade platform (50), before leading the coolant (K) into the cooling leg (32a, 32c, 42a, 42c).

Abstract: A propeller oil control system for a turboprop engine of an aircraft includes an engine control unit and a propeller oil controller. The engine control unit is operable to determine a flight phase of the aircraft and is configured to supply control commands. The propeller oil controller is coupled to receive a supply of oil and to discharge the oil at a discharge oil pressure. The propeller oil controller includes an electrohydraulic servo valve that receives the control commands moves to a plurality of positions between a first position and a mid-position, and a plurality of positions between the mid-position and a second position. The engine control unit only commands the electrohydraulic servo valve to move out of the first position when the engine control unit determines the aircraft is conducting a take-off roll or the aircraft is in flight.

Abstract: An assembled rotor shaft of asymmetrical design may comprise two rotor shaft components, a first rotor shaft component configured as a shaft segment with a tube section and a flange section, and a second rotor shaft component configured as a flange element. The tube section may include a tube outer surface with a profiling. A rotor of an electric machine, which includes the assembled rotor shaft, may further include a laminated core and a pressure disk disposed in the tube section. The laminated core can include laminated core disks, each of which has a structuring that corresponds to the profiling of the rotor shaft. The profiling and the structuring of the laminated core disks may form a positively locking connection.

Abstract: A method and apparatus for applying optimized yaw settings to wind turbines including receiving operating data from at least one wind turbine on a wind farm and sending the data to a supervisory control and data acquisition (SCADA) system on the at least one wind turbine to generate current SCADA data. The current SCADA data is sent a central processing center away from the wind farm. The central processing center includes an optimization system that can generate a new look up table (LUT) including at least one new wind turbine yaw setting calculated using information comprising wind direction, wind velocity, wind turbine location in the wind farm, information from a historic SCADA database, and yaw optimizing algorithms. The new LUT is then sent to a yaw setting selection engine (YSSE) where instructions regarding the use of the new LUT are generated.

Abstract: A method for controlling a wind power installation, to an associated wind power installation and to a wind farm with a number of wind power installations. The method comprises: providing a wind speed and a direction of incident flow, which are determined by a wind measuring device of the wind power installation, providing a correction value of the direction of incident flow in dependence on the wind speed, carrying out a process of learning the correction value of the direction of incident flow in dependence on the wind speed. The learning process comprises a number of optimizing steps, an execution of the optimizing steps depending on the optimizing steps that have already been carried out for the wind speed provided. Improved tracking of the wind is provided.

Abstract: A turbine blade of a turbine engine such as a turbojet engine, comprising: a root supporting a blade and extending in a wingspan direction, ending in a vertex, the blade comprising a leading edge and a trailing edge, with a pressure side wall and a suction side wall separated from one another and connecting the leading edge (17) to the trailing edge, the blade also comprising: cooling ducts in which air collected at the blade root circulates; first and second inner side recesses running along the pressure side wall in order to form a heat shield spaced apart from one another along the pressure side wall; and at least one duct extending from the pressure side wall to the suction side wall between the first and second side recesses.

Abstract: A wind power installation with a tower, an aerodynamic rotor, wherein the aerodynamic rotor can be operated with a variable rotor speed and has a number of rotor blades respectively with an adjustable rotor blade angle, a generator for generating an electrical output power, wherein for operating the wind power installation an operating characteristic, which indicates a relationship between the rotor speed and the output power, is specified and a controller, which sets the output power in a way corresponding to the operating characteristic in dependence on the rotor speed, is provided, wherein selectable as the operating characteristic is a reduced-tonality operating characteristic, which is designed such that an excitation of a system resonance of the wind power installation is reduced as compared with an optimum-power operating characteristic, without however excluding a speed that excites this system resonance.

Abstract: An optical element is configured to guide imaging light in projection lithography. The optical element has a main body and at least one optical surface carried by the main body. At least one compensation weight element, which is attached to the main body, serves for a weight compensation of a figure deformation of the optical surface caused by gravity. This results in an optical element with a small figure deformation at the use location.

Abstract: There is presented a method (320) for controlling a wind turbine (100), wherein said wind turbine comprises a wind turbine rotor (102) with one or more blades (103), wherein the wind turbine has a rated angular rotation speed (214) of the wind turbine rotor, said method comprising obtaining (322) information (323) on ambient conditions, determining, based on said information, if an erosion criterion is fulfilled, controlling (328) the wind turbine according to an extended mode if the erosion criterion is fulfilled, wherein in the extended mode an angular rotation speed of the wind turbine rotor is allowed to exceed the rated angular rotation speed (214).

Abstract: There is presented a method (320) for controlling a wind turbine (100), wherein said wind turbine comprises a wind turbine rotor (102) with one or more blades (103), wherein the wind turbine has a rated angular rotation speed (214) of the wind turbine rotor, said method comprising providing (322) an estimated drop size (324) of rain drops impinging on the one or more blades, determining (326) whether an entry criterion for operation according to a reduced mode is fulfilled, wherein said determining is based at least partially on the estimated drop size (324), controlling (328) the wind turbine according to the reduced mode if the entry criterion is fulfilled, wherein in the reduced mode an angular rotation speed of the wind turbine rotor is limited below an angular rotation speed threshold (216), wherein the angular rotation speed threshold is smaller than the rated angular rotation speed of the wind turbine.

Abstract: An aircraft turbine engine has a pair of rotating and non-ducted propellers. An upstream propeller has an outer diameter D1 and a downstream propeller has an outer diameter D2. The engine further includes a system for varying the diameter D2. The downstream propeller includes an annular row of blades, each of which is configured to be mounted telescopically in the radial direction (R) in an outer fan duct.

Abstract: Inner covering for wind turbine blades and method for mounting same, wherein said covering consists of a wall cover with a flexible wall which is formed based on layers of composite materials, having shapes and dimensions being approximately the same as those of the inner area of the blade structural element, said cover being mounted on a support with which it is introduced inside the blade. Between the support and the cover, an inflatable chamber is arranged, which upon being inflated causes the cover to be compacted and adhered against the inner surface of the blade structural element.

Abstract: A method for reducing loads of a wind turbine includes determining an operational state of the wind turbine. The method also includes commanding a predetermined pitch event. Further, the method includes monitoring at least one operating condition of a pitch drive mechanism of a rotor blade of the wind turbine during the predetermined pitch event. If the operational state corresponds to a predetermined operational state and the operating condition(s) follows a pitch fault pattern during the predetermined pitch event, the method also include yawing a nacelle of the wind turbine away from an incoming wind direction.

Abstract: A method of controlling the operation of a wind turbine is provided. The wind turbine includes a rotor, a generator and at least one heat generating component. The method includes obtaining a temperature of the heat generating component; determining the presence of a predetermined increase of the temperature of the heat generating component; and upon determining the presence of the predetermined temperature increase, controlling the rotational speed of the generator so as to increase the rotational speed of the generator while not increasing the electrical power output of the generator or while increasing the electrical power output of the generator at a smaller proportion than the increase in rotational speed of the generator so as to reduce the level of electrical current in the generator.

Abstract: A wind data detecting system for a wind turbine, the wind turbine including a nacelle and a rotor comprising a plurality of rotor blades separated by a predetermined angle within a rotor plane is provided. The system includes (a) a first wind sensor for providing first wind data (b) a second wind sensor for providing second wind data, (c) a support structure adapted to be mounted on the nacelle of the wind turbine and to support the first wind sensor and the second wind sensor at respective first and second positions, and (d) a processing unit for generating output wind data based on the first wind data and the second wind data wherein the processing unit is adapted to generate first filtered wind data and second filtered wind data by applying an adaptive filtering algorithm to the first wind data and the second wind data.

Abstract: A method for reducing loads of a wind turbine includes determining a wind speed at the wind turbine. Further, the method includes determining an operational state of the wind turbine. The method also includes determining whether a rotor of the wind turbine is imbalanced beyond a predetermined threshold when the operational state corresponds to a predetermined operational state as a rotor imbalance beyond the predetermined threshold is indicative of a pitch fault in one or more of the rotor blades. In addition, the method includes yawing a nacelle of the wind turbine to a predetermined angular position when the wind speed exceeds a predetermined speed threshold and the rotor is imbalanced beyond the predetermined threshold.

Abstract: A variable-pitch multi-segment blade component comprises multiple blade segments and at least one variable-pitch guiding structure placed outside of the blade segments. The variable-pitch guiding structure comprises a guide rail fixed to one of the two adjacent blade segments and one or multiple guiding elements fixed to another one of the two adjacent blade segments, wherein the guiding elements are constructed to be guided and moved on the guide rail. The guiding element comprises multiple rolling elements. The variable-pitch guiding structure provides guiding and bearing type connection. The two adjacent blade segments are capable of rotating about a pitch axis of the blade segments.

Abstract: Examples are generally directed to techniques for controlling a temperature of a blade in a wind turbine system. One example of the present disclosure is a method of controlling a temperature of a blade in a wind turbine system. The method includes setting a target temperature, inputting physical conditions of the blade and ambient conditions about the blade into a processor, outputting a minimum amount of energy to a heating element of the blade required to reach the target temperature based on the physical conditions and ambient conditions, and adjusting the energy provided to the heating element to reach the target temperature.

Abstract: Disclosed is a turbine vane having an airfoil in a cross section including a leading edge, a trailing edge, and a pressure surface and a suction surface connecting the leading edge and the trailing edge, the airfoil extending radially from a platform part to an end wall, wherein the trailing edge of the airfoil is provided with a cutback cut in a direction radially perpendicular to both the pressure surface and the suction surface.

Abstract: A turbine blade includes a base and an airfoil. The airfoil includes a skin extending from the base and defining a leading edge and a trailing edge opposite the leading edge. The trailing edge includes an inner edge disposed proximate to the base, an outer edge disposed distal the inner edge, and a tuning region edge disposed between the inner edge and the outer edge. The tuning region edge includes an upper transition edge, a middle transition edge, a lower transition edge, an upper tuning edge, and a middle tuning edge. The upper transition edge extends from the outer edge towards the inner edge. The middle transition edge is disposed between the upper transition edge and the inner edge. The lower transition edge is disposed between the middle transition edge and the inner edge. The upper tuning edge is disposed between the upper transition edge and the middle transition edge, being at least partially closer to the leading edge than the middle transition edge.

Abstract: A method of operating a wind turbine having a rotor. Sensor data is received from one or more sensors of the wind turbine and maximum load values are obtained on the basis of the sensor data. The maximum load values are indicative of maximum loads acting on a component of the wind turbine such as a rotor blade. An estimated extreme load value, such as a 50-year return load, is obtained on the basis of the maximum load values and compared with a reference value. A maximum thrust limit is set on the basis of the comparison, and the wind turbine is operated in accordance with the maximum thrust limit so that a wind thrust force acting on the rotor does not exceed the maximum thrust limit.

Abstract: A turbomachine module includes a rotor supporting variable pitch blades, and an inner annular shaft, a blade pitch control device, a device for feathering at least one blade comprising at least one gas generator placed between a body and a movable member. The control device and the feathering device are situated radially between the shaft and the blades, the movable member is coupled with the at least one blade and capable, under the action of the gas generated and/or released by the generator, of being moved into a reference position wherein it entails a feathered position to the at least one blade.

Abstract: Pitch cylinders for adjusting a pitch angle of a blade, methods of assembling pitch cylinders, and the use of pitch cylinders in wind turbines are disclosed. The pitch cylinder includes a cylinder barrel having a first thread with a first pitch, a piston arranged in and extending out of the cylinder barrel for coupling to a blade or hub, and a trunnion to couple the cylinder barrel to the other of the blade or hub. The cylinder barrel extends through the trunnion. The trunnion has a first thread with a second pitch different from the first pitch, and a sleeve arranged between the trunnion and the cylinder barrel that extends through the sleeve. The sleeve has an inner sleeve thread with the first pitch engaged with the first cylinder barrel thread and an outer sleeve thread with the second pitch engaged with the first trunnion thread.

Abstract: A method for controlling a wind turbine having rotor blades with an adjustable blade angle, comprising the steps operating the wind turbine in a partial load mode for wind velocities up to a nominal wind velocity, wherein in the partial load mode, a fixed partial load angle is provided for the blade angle, operating the wind turbine in a full load mode for wind velocities above the nominal wind velocity, wherein in the full load mode the blade angle is enlarged with increasing wind velocity and has values above the partial load angle, and wherein in the partial load mode, starting from a predetermined operating state, the blade angle is reduced as compared with the partial load angle.

Abstract: Embodiments of the invention describe a method for ascertaining a value of an ice buildup quantity on at least one rotor blade (111, 112) of a wind turbine (100) and to the use thereof.

Abstract: An embodiment rotorcraft includes a main rotor, one or more flight controls connected to the main rotor and operational to control flight characteristics of the main rotor by pitching a nose of the rotorcraft upward, and a flight control computer (FCC) operable to determine an attitude command and to generate an adjusted attitude command by adjusting a magnitude of the attitude command according to an above ground level (AGL) altitude of the rotorcraft. The FCC is further operable to control a flight characteristic of the rotorcraft by sending the adjusted attitude command to one or more flight controls.

Abstract: An energy generating system that utilizes a movement of a fluid/gas includes a plurality of floor tiles, a fluid/gas, and a power generating unit. Preferably, the plurality of floor tiles is layered across an area with high foot traffic. The fluid/gas is confined in a fluid tank positioned underneath the plurality of floor tiles such that a pressure applied on the plurality of floor tiles is transferred onto the fluid/gas, and generates movement in the fluid/gas. The movement allows the fluid/gas to flow towards a plurality of turbines of the power generating unit through a piping network and a plenum passage, and rotate the plurality of turbines. The rotational movement of the turbines is converted into electrical energy by a generator of the power generating unit. The electrical output of the generator is stored in a battery bank.

Abstract: A method for identifying a blade run-away condition in the event of a pitch system failure of a rotor blade of a wind turbine includes determining, via one or more sensors, an actual rotor loading of the wind turbine. The method also includes determining, via a turbine controller, an estimated rotor loading of the wind turbine based on at least one of one or more operating conditions of the wind turbine or one or more wind conditions of the wind turbine. Further, the method includes determining a difference between the actual rotor loading and the estimated rotor loading. The method also includes determining whether the blade run-away condition is present based on the difference. The method may also include implementing a corrective action that mitigates loads caused by the blade run-away condition.

Abstract: A rotor system is provided in one example embodiment and may include a rotor system may be provided and may include a drive link associated with a rotor hub of the rotor system, the drive link comprising an inner member and an outer member; and a sensor system mounted to the drive link, the sensor system to accommodate motions of the drive link to track rotor hub flapping. The sensor system for the rotor system may further include a sensor, the sensor comprising a sensor arm, wherein the sensor is mounted proximate to the inner member of the drive link; and a sensor link, the sensor link comprising a first end portion moveably coupled to the sensor arm, a second end portion coupled to the outer member of the drive link, and an angled portion between the first end portion and the second end portion.

Abstract: A method for reducing loads of a wind turbine includes determining an angular pitch speed parameter of the rotor blade of the wind turbine. The method also includes determining an operational state of the wind turbine. Further, the method includes comparing the angular pitch speed parameter to a predetermined parameter threshold during turbine shutdown and/or a commanded pitch event. If the operational state corresponds to a predetermined operational state, the method includes yawing a nacelle of the wind turbine away from an incoming wind direction when the angular pitch speed parameter is below the predetermined parameter threshold during the turbine shutdown and/or the commanded pitch event.

Abstract: A rotor blade uses hot-air, for example exhaust from a generator positioned inside a nacelle of a wind turbine, for de-icing and/or anti-icing. The rotor blade has an airfoil section and a cavity enclosed therein. A flow path inside the cavity, for flow of the hot-air, extends from a root section towards a tip section. Exhaust holes, fluidly connected with the flow path, at an outer surface of the airfoil section emit the hot-air from the airfoil section. The rotor blade includes a cover plate positioned at the outer surface of the airfoil section and masking the exhaust holes, thereby creating an external flow space between the exhaust holes and the cover plate's inner surface. The cover plate guides the hot-air over the outer surface of the airfoil section after the hot-air exits, via the exhaust holes, the airfoil section and before the hot-air escapes the rotor blade.

Abstract: Systems and methods for controlling a crossing threshold used in determining a rotational speed of a propeller of an aircraft engine. An initial value for the crossing threshold is set. A sensor signal is received that comprises a first series of pulses indicative of passage of position markers about a circumference of a propeller shaft. A detection signal is generated that comprises a second series of pulses indicative of within the first series of pulses that have a zero-crossing transition and a magnitude that exceeds the crossing threshold. The rotational speed of the propeller is determined from the detection signal. The crossing threshold is adjusted as a function of the rotational speed.

Abstract: The present disclosure relates to a system for determining at least one blade state parameter of a wind turbine blade, wherein the system is configured to: obtain blade data relating to the wind turbine blade from a sensor system associated with the wind turbine blade; compare at least one reference model of at least a portion of the wind turbine blade with the blade data; identify a reference model in dependence on the comparison; and determine at least one blade state parameter in dependence on the identified reference model. The blade data may take the form of an image, for example a 3-dimensional measurement such as a point cloud representing at least a portion of the blade.

Abstract: Embodiments of a frequency independent damper assembly are disclosed. In some embodiments, the damper assembly includes a damper housing, a damper plunger and a support spring. The damper plunger is disposed at least partially within the housing and movable within to define a first primary damper cavity and a second primary damper cavity. The support spring includes a plurality of flexible elements coupled to the damper housing and disposed radially outward of the first primary damper cavity and the second primary damper cavity. The support spring defines a first accumulator cavity and a second accumulator cavity. A flow-through channel couples the first accumulator cavity to the second accumulator cavity. A gas bearing including the frequency independent damper assembly is disclosed.

Abstract: A method is provided during which surface data indicative of a measured surface geometry of a component is received. The surface data is processed to provide model data indicative of a solid model of the component. The model data is processed to determine a center of gravity distance of the component. A moment weight of the component is determined based on the center of gravity distance of the component and a measured weight of the component. The moment weight is communicated with the component.

Abstract: A method for operating a first wind turbine and a second wind turbine, the second wind turbine being located in the wake of the first wind turbine. A prediction model is fed with a current wind value of the first wind turbine, in order to predict a future time point at which the area swept by the rotor of the second wind turbine becomes partially overlapped by the wake of the first wind turbine. The second wind turbine reacts to the prediction in that a control signal is generated in order to alter the pitch angle of a rotor blade of the second wind turbine relative to the pitch angle of another rotor blade of the second wind turbine. The invention additionally relates to a control system suitable for executing the method. Implementation of the disclosed method by a control system can reduce the loading of the second wind turbine.

Abstract: Aerial vehicles may be equipped with propellers having pivotable blades that are configured to rotate when the propellers are not rotating under power. A pivotable blade may rotate about an axis of a propeller with respect to a hub until the pivotable blade is coaligned with a fixed blade. When the propeller is rotating, a lifting force from the blade may cause the blade to rotate to a deployed position that is not coaligned with the fixed blade.

Abstract: A clamping apparatus for positioning a main bearing of a wind turbine includes a push component arranged between a main flange of a main shaft of the wind turbine and a cover of the main bearing. Further, the clamping apparatus includes a spacer plate located within a gap between the cover and the main bearing. As such, the push component is configured to apply a force to the cover so as to push the spacer plate against the main bearing such that the main bearing is pushed into and secured in place.

Abstract: Described is a system for monitoring deflection of turbine blades of a wind turbine comprising a tower. The system comprises a position detecting apparatus mounted to the wind turbine comprising a plurality of position detection components each collecting data regarding a field of detection through which a segment of the turbine blades passes, wherein the position detection components are monitoring distinct fields of detection to collect distances of a plurality of segments of each one of the turbine blades travelling through the fields of detection. The system further comprises a deflection controller configured to receive the collected distances and to determine deflection of the turbine blades accordingly. An associated method comprises collecting distances of a plurality of distinct segments of the turbine blades when the turbine blades travel within a plurality of fields of detections, and processing the collected distances to determine clearance between the turbine blades and the tower.

Abstract: A blade icing state identification method and apparatus for a wind generator set are disclosed. The method includes setting a preset wind speed threshold and a preset rotating speed threshold, and setting the preset rotating speed threshold as a lower limit value of a maximum limited rotating speed of the wind generator set operating under a limited power condition; comparing a current wind speed and a current rotating speed of the wind generator set with the preset thresholds respectively; progressively increasing a blade icing possibility index when the current wind speed is greater than the preset wind speed threshold and the current rotating speed of the wind generator set is smaller than the preset rotating speed threshold, and otherwise, progressively decreasing the blade icing possibility index; and determining that blades are in an icing state when the blade icing possibility index is greater than a preset index.

Abstract: The invention provides a lightning protection system for wind turbine blades with optimized injection means of lightning currents in conductive components of their shells. The injection means comprise a current receptor element (27; 47; 67) connected to the input cable of lightning currents and arranged over an area of a shell close to an electrically conductive component (22; 42; 62) and a current injection element (28; 48; 68; 69, 69?) arranged over the electrically conductive component (22; 42; 62) and connected to the current receptor element (27; 47; 67) by at least two distribution cables (31, 32; 51, 52, 53; 71, 72, 73, 74).

Abstract: A hybrid paddle for use in both a standing and a kneeling position is disclosed. The paddle has a shaft terminating in a blade at each end. At or near each throat or junction between the shaft and a blade is a handle. The handle has a grip sufficiently offset from the blade to allow a user to grip the handle without his or her hand colliding with the blade. While kneeling, the user grips the shaft with both hands, and alternates the placement of the blades in the water. While standing, the user grasps the handle with one hand and the shaft with the other hand, and a single blade is placed in the water. In this way, the same paddle is used in both the standing and kneeling positions, and the user can alternate between standing and kneeling as desired.

Abstract: An aircraft includes an airframe; an extending tail; a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; and a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe; wherein a ratio of (i) the hub separation between the hub of the upper rotor assembly and the hub of the lower rotor assembly to (ii) a radius of the upper rotor assembly is between about 0.1 and about 0.135.

Abstract: The invention is directed to a wind turbine system comprising a first pair of wind turbines mounted to a support structure by a first support arm arrangement, and a second pair of wind turbines mounted to the support structure by a second support arm arrangement. The first and second support arm arrangements are mounted to the support structure at a respective yaw unit so as to yaw about the major axis of the support structure. Moreover, the wind turbine system further includes a control system that is configured to control the yaw angle of each of the first and second support arm arrangements, wherein the control system is configured to identify the presence of a predetermined shutdown condition and, in response, the control system is operable to control the yaw angles of the first support arm arrangement and the second support arm arrangement to a predetermined safe state.

Abstract: A method for evaluating performance of a wind turbine includes operating the wind turbine in a first operational mode. The method also includes generating a first set of operational data relating to the first operational mode. More specifically, the first set of operational data includes, at least, a first parameter and a second parameter. Further, the first and second parameters of the first set are measured during different time periods during the first operational mode. The method further includes changing the first operational mode to a second operational mode. Moreover, the method includes generating a second set of operational data relating to the second operational mode. The second set of operational data also includes, at least, a first parameter and a second parameter. Thus, the method includes determining a performance characteristic of the first and second operational modes based on the first and second sets of operational data.