Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: A fan includes blades and a side plate. The side plate includes a fan ring portion having a cylindrical shape centered on a fan axis. A guide part that is annular is arranged on one side of the fan ring portion in the axial direction and forms a suction port through which the air sucked into the fan passes. A communication path that allows an upstream space located on the one side in the axial direction with respect to the guide part to communicate with a gap between the fan ring portion and the guide part is formed outside the guide part in a radial direction of the fan axis. The fan ring portion is located outside in the radial direction with respect to an innermost peripheral portion of the guide part located on an innermost side in the radial direction.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: An arrangement for influencing a liquid flow includes a first section selectively configurable to provide a vortex generator surface, the vortex generator surface comprising a series of laterally aligned projections, to induce vortices in the liquid flow.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: According to the present disclosure there is provided a liquid flow influencing duct arrangement comprising: a first duct section arranged to receive a liquid flow therethrough, the first duct section defining a first direction through the first duct section from a liquid inlet end to a liquid outlet end; a second duct section defining a second direction through the second duct section from a liquid inlet end to a liquid outlet end, the second duct section comprising a vortex generator surface, wherein the vortex generator surface is arranged to induce vortices in the liquid flow through the first duct section, wherein the duct arrangement further comprises a rotor housed in one of the duct sections.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: A fan includes an impeller including a boss and a plurality of blades; an air guide portion through which an airflow moves from one end to the other end of the air guide portion; and a bell mouth defining a first suction passage inside the bell mouth and defining, together with an inner surface of the air guide portion, a second suction passage outside the bell mouth. Between an upstream end point located in an inlet of the first suction passage and a downstream end point located in an outlet of the first suction passage of the bell mouth, the bell mouth includes a minimum possible radius point to which a distance, in a radial direction, from a rotation axis of the boss is smaller than a distance, in the radial direction, from the rotation axis to the downstream end point.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: A section of a gas turbine engine includes a ceramic component and a metallic component situated adjacent the ceramic component. The ceramic component and the metallic component are situated outside of a core flow path of the gas turbine engine. The section of a gas turbine engine also includes an interface between the ceramic component and a metallic component and a mullite-based coating disposed at the interface. The coating provides thermal protection to the ceramic component and the metallic component, and provides thermochemical protection against interaction between the ceramic component and the metallic component. A gas turbine engine and a method of protecting components in a gas turbine engine are also disclosed.

Abstract: A rotor for use in a turbomachine includes a hub centered on a central axis and having a disk portion and a shaft portion and a blade extending outward from the hub. The hub and the blade together include a plastic substrate and metal plating disposed on at least apportion of an outer surface of the plastic substrate. The plastic substrate has a matrix material and fibers embedded in the matrix material. The fibers have a first coefficient of thermal expansion. The metal plating has a second coefficient of thermal expansion. The fibers are selected such that a bulk coefficient of thermal expansion of the plastic substrate at the outer surface of the plastic substrate substantially matches the second coefficient of thermal expansion of the metal plating.

Abstract: Propeller for an airplane or boat includes a rotatable hub attachable to a power axle, a ring structure including an inner ring spaced apart from and connected to the hub, and shovel blades fixed to the inner ring. Each shovel blade is connected at an inner lateral edge to an outer surface of the inner ring and is angled rearward. The shovel blades are spaced apart from one another such that a leading edge of each shovel blade does not overlie a trailing edge of an immediately adjacent shovel blade and the trailing edge of each shovel blade does not underlie the leading edge of an immediately adjacent shovel blade. There may be an outer ring around the shovel blades, or separated blade guides on an opposite side of the shovel blades from the inner ring with each blade guide being associated with a respective shovel blade.

Abstract: A fan assembly includes a fan cover. The fan cover is provided with a vane assembly and is fixed by a rotating shaft, which includes blades and magnetic vanes arranged along its outer contour. The coils are evenly arranged along the fan cover. The magnetic rotor blade and the alternating magnetic field generated by the coils can drive the blades to rotate, and the rotation speed can be adjusted by changing the speed of the alternating magnetic field. The coils are fixedly installed in the outer cover of the fan, and the vane assembly is only installed by the rotating shaft, which can easily disassemble from the vane assembly. The structure is simple and has higher reliability. So, it is not easily damaged, and has a longer service life. The fan assembly can be completely waterproof, so that the product can be used in high humidity and even water.

Abstract: A combined fixed fan for a disc-type motor includes a front fixing sheet (1), a fan (2) and a rear fixing sheet (3) in sequence in an axial direction, wherein the front fixing sheet and the rear fixing sheet are both circular sheets with a central hole (10), and are provided with magnet fixing holes (4) evenly arranged in a circle, the fan (2) is integrally provided with an annular column-shaped spacing frame (11), a center of the fan (2) is axially provided with a shaft hole (15) for a motor rotating shaft to pass through, and a plurality of fan blades (13) arranged around the shaft hole (15) are arranged in the spacing frame (11); and a side surface of the spacing frame is provided with a plurality of air outlet channels (16) evenly arranged in a circle.

Abstract: A convertible ducted fan engine and mounting system. The convertible ducted fan engine has a shroud encircling a mechanical fan. The convertible ducted fan engine includes a fluid-propulsion configuration in which the mechanical fan rotates freely with respect to the shroud to produce thrust through fluid flow, and a drive-wheel configuration in which the shroud rotates about the rotational axis.

Abstract: Particular embodiments described herein provide for an electronic device that includes a fan. The fan can include a center shaft, fan blades that extend from the center shaft, and a plurality of magnets on an outside portion of at least two of the fan blades, where stator coils interact with the magnets to drive the blades around the center shaft. The center shaft and fan blades are a single component from the same material. In some examples, the center shaft and fan blades were created using a metal injection molding process.

Abstract: A rim-rotor assembly has an annular structure including a composite rim and a hub. Blades project from the hub, tips of the blades contacting the annular structure, the blades configured to be loaded in compression against the annular structure. A thermal barrier is in the annular structure, the thermal barrier defining at least part of a radially inward surface of the annular structure. The tips of the blades contact the thermal barrier, the thermal barrier being a thermal barrier coating.

Abstract: A fan including a frame and an impeller is disclosed. The frame has an air inlet and an air outlet. The impeller is disposed in the frame and includes a hub and multiple blades. Each blade has a negative pressure surface facing the air inlet, a positive pressure surface facing the air outlet, a blade root, and a blade tip opposite to the blade root. In a first region extending from the blade root to the blade tip by a first length, the negative pressure surface and the positive pressure surface are respectively a convex arc surface and a plane. In a second region extending from the blade tip to the blade root by a second length smaller than the first length, the negative pressure surface and the positive pressure surface are respectively a convex arc surface and a concave arc surface or both are convex arc surfaces.

Abstract: Described are computer-related techniques for determining rotation direction of an axial fan for use in fluid flow simulations. The techniques involve receiving by a computer processing system digital data of a three dimensional representation of an axial fan having plural fan blade, determining by the computer processing system from the data of three dimensional representation of the axial fan, at least a single centerline of a single blade of the axial fan from a two dimensional projection of the axial fan, and calculating by the computer processing system based on the initial valve of fan rotation, an actual value of fan rotational direction.

Abstract: Systems and methods are provided for a digital beamformed phased array feed. The system may include a radome configured to allow electromagnetic waves to propagate; a multi-band software defined antenna array tile; a power and clock management subsystem configured to manage power and time of operation; a thermal management subsystem configured to dissipate heat generated by the multi-band software defined antenna array tile; and an enclosure assembly. The multi-band software defined antenna array tile may include a plurality of coupled dipole array antenna elements; a plurality of frequency converters; and a plurality of digital beamformers.

Abstract: A tip shroud includes a pair of opposed, axially extending wings configured to couple to an airfoil at a radially outer end thereof. The tip shroud also includes a tip rail extending radially from the pair of opposed, axially extending wings. Tip shroud surface profiles may be of the downstream and/or upstream side of the tip rail, a leading Z-notch of the tip shroud, and/or downstream radially inner surface of a wing. The surface profiles may have a nominal profile substantially in accordance with at least part of Cartesian coordinate values of X and Y, and perhaps Z and a thickness, set forth in a respective table. The radially inner surface of the wing may define a protrusion extending along the radially outer end of the airfoil, the suction side fillet, and a radial inner surface of the wing to an axial edge of the wing.

Abstract: The invention is directed to a propeller hubcap and method for installing a propeller hubcap which includes attaching a propeller hubcap to main propeller where the main propeller has at least two blades and a shaft and where the shaft has a diameter of from 2.5 inches to 6 inches. The propeller hubcap includes a central body and propeller blades, where the propeller blades are timed with the blades of the main propeller. A thick and thin nut are provided on the main propeller shaft where the thick or thin nut which is positioned further from the main propeller is tapped by multiple holes which have received a fastener. The fasteners attach the propeller hubcap to the main propeller shaft via complementary holes in the central body of the propeller hubcap.

Abstract: A diagonal fan includes an electric motor, a housing, and a diagonal impeller received inside the housing and drivable via the motor. The diagonal flow during operation is deflected in an axial flow direction. The diagonal impeller includes impeller blades distributed in the circumferential direction and a slinger ring encloses said blades. The diagonal fan includes an inlet nozzle on the suction side accommodating a main flow for the diagonal fan. The inlet nozzle extends overlapping at least in sections relative to the radial section of the slinger ring forming a nozzle gap therewith. A bypass channel on the housing forms a flow connection from a pressure-side surrounding region (U) of the diagonal fan to an inflow side of the nozzle gap. During operation of the diagonal fan, a swirl-free secondary flow (NS) is guided at the inflow side of the nozzle gap via the bypass channel.

Abstract: A centrifugal fan includes a main plate, a blade connected to the main plate, and a shroud having an annular shape and connected to a shroud-side end of the blade that is an end opposite a main-plate-side end of the blade connected to the main plate. The centrifugal fan rotates about a rotation axis to suction a fluid through an opening of the shroud and discharge the fluid through the blade in a radial direction. A leading edge of the blade includes a recess located next to a point at which a shroud inner surface of the shroud that faces the main plate is connected to the leading edge and curving inwardly from the point toward a trailing edge and a projection located closer to the main plate than is the recess and projecting in the rotation direction.

Abstract: A method of forming a gas turbine engine component including an airfoil and at least one shroud includes the steps of (1) machining a gas path surface of the at least one shroud utilizing a non-electrochemical machining (ECM) process, and (2) then utilizing ECM on at least the airfoil.

Abstract: A fan blade device includes a plurality of main fan blades and extension fan blades. Each main fan blade includes a main fan blade body arranged obliquely, a plurality of first protrusions, and at least one engaging groove. Each extension fan blade includes an extension fan blade body arranged obliquely and having a top surface that is contiguously flush with a top surface of the main fan blade body of a respective main fan blade, a plurality of second protrusions respectively abutting against the first protrusions of the respective main fan blade, and at least one engaging piece engaging the at least one engaging groove of the respective main fan blade.

Abstract: An electric fan for producing thrust to propel an aircraft is disclosed. The electric fan comprises a stator, a fan rotor rotatably mounted relative to the stator and an electric motor mounted to the stator and drivingly engaged with the fan rotor to cause rotation of the fan rotor relative to the stator. The fan rotor comprises an annular body defining a flow passage therethrough and a plurality of fan blades disposed in the flow passage and mounted for common rotation with the annular body about a fan rotation axis. The electric motor has a motor rotation axis that differs from the fan rotation axis.

Abstract: A centrifugal fan includes first blades and second blades connected via a separation plate. A side plate supports the first blades located on one side in an axial direction, and a main plate supports the second blades on the other side in the axial direction. The separation plate has an inner diameter larger than or equal to an outer diameter of the main plate and larger than or equal to a largest inner diameter of the second blade. The separation plate has an outer diameter smaller than or equal to an inner diameter of the side plate and smaller than or equal to a smallest outer diameter of the first blade.

Abstract: A duct for a ducted-rotor aircraft includes a hub, a duct ring, and a plurality of stators that extend outward from the hub. The hub may be configured to support a motor. The duct ring defines a trailing edge. The duct ring is coupled to each of the plurality of stators such that all or substantially all of each of the plurality of stators is located aft of the trailing edge of the duct ring.

Abstract: A system and method for improving the flight control and efficiency of an aerial vehicle. Many embodiments are directed to a rotor-shroud assembly system where a plurality of rotor blades are connected to the internal side of a shroud and are set up to pivot through the use of a pitching mechanism. The entire assembly is configured to rotate when attached to a motor.

Abstract: An aircraft impeller (001) and an aircraft, relating to the field of aircraft drive components, the aircraft impeller (001) including a frame body (100) and a rotating wheel part (200); the frame body (100) includes a mounting groove (130), the rotating wheel part (200) being fixedly arranged in the mounting groove (130); the mounting groove (130) has an axial centre line (105); the mounting groove (130) also has an open face and a bottom face (131) arranged opposite to one another; the rotating wheel part (200) includes at least one vane (210) distributed around the axial centre line (105), the vane (210) including a windward face (211); at the connecting point of the windward face (211) and the open face, the angle of the tangent plane of the windward face (211) and the open face is an acute angle.

Abstract: The invention concerns an impeller (1a, 1b, 1c, 1d, 1e, 1f) of a motor vehicle fan comprising: a cylindrical ring (2) having a center (P), blades (3) extending from the cylindrical ring (2) and toward the center (P), each blade (3) having two radially opposite ends (4, 5), referred to as the blade root end (4) and the blade tip end (5), the blade root end (4) being directed toward the center (P) and the blade tip end (5) being secured to the cylindrical ring (2), characterized in that all the blade root ends (4) are free or linked together by a central hub (20) of reduced diameter.

Abstract: A turbine rotor blade includes: a blade body including a pressure surface and a suction surface; and a tip shroud on a tip portion of the blade body, the tip shroud being inclined outward in a radial direction from the pressure surface to the suction surface in an axial direction. The tip shroud includes a fin at a center portion in a circumferential direction, the fin extending radially outward, a pressure-side tip shroud on the pressure surface side, and a suction-side tip shroud. The suction-side tip shroud includes a suction-side contact block at a front edge end of the tip shroud. The pressure-side tip shroud includes a pressure-side contact block at a rear edge end of the tip shroud, the suction-side contact block includes a first surface facing in the circumferential direction, and the pressure-side contact block includes a second surface facing in a direction opposite to the circumferential direction.

Abstract: A fan module includes a hub, a first body and a second body. The hub is configured to rotate along a central axis. The first body is connected to an outer wall of the hub. The second body is sleeved on the outer wall of the hub. The second body includes a plurality of ribs. The ribs are disposed on an inner wall of the second body and abut against the outer wall of the hub.

Abstract: A blade includes an airfoil that extends from a root end to a tip end. The airfoil includes a cooling channel defined therein. The blade further includes a tip shroud extending from the tip end, and at least one fillet coupled between the tip end and the tip shroud. The at least one fillet includes an interior wall. The interior wall at least partially defines a cavity in downstream flow communication with the cooling channel.

Abstract: A blade for a turbomachine, a tip for a blade of a turbomachine and a related method are disclosed. The blade may include a tip body having a shape at least partially configured for coupling to an airfoil body of the blade; at least one coolant passage in the tip body configured for fluid communication with at least one coolant passage in the airfoil body; and a retention member extending from the tip body for coupling to a tip retention member seat in the airfoil body. The tip can be replaced, allowing for changes in the coolant passages in the tip of a blade.

Abstract: A rotor blade includes a blade body which has an airfoil shape and a shroud 57 which is formed in an end portion of the blade body. The shroud includes a shroud cover and a seal fin which protrudes from the shroud cover toward a radial outside and extends in a direction having a direction component in a circumferential direction. A front end of the seal fin extends in the circumferential direction and a base end of the seal fin extends in a direction having a direction component in the circumferential direction. A part of the seal fin in the circumferential direction forms a shift portion. An axial center position of a base end of the shift portion is different from an axial center position of a front end of the shift portion in the axial direction.

Abstract: Embodiments are provided for a fluid pump having a hollow shaft centrifugal impeller capable of using suction or pressure to move large volume flows of fluids including liquids and gasses. In one or more non-limiting embodiments, the pump has an impeller assembly that is capable of being attached to the inner circumference of a housing tube and said housing tube is connected to a magnetic rotary. The magnetic rotary is capable of spinning the hollow shaft and the impeller assembly inside the hollow shaft and moving the fluid through the hollow shaft.

Abstract: A fan system includes a rotor having plurality of blades and a ring airfoil, the plurality of blades being rotatably joined to a hub and the ring airfoil. The fan system may include a second contra-rotationally disposed rotor having a plurality of blades and a ring airfoil. The first and second ring airfoils having a cambered shape and an angle of attack between about ?5 degrees and about 45 degrees. Passive leading edge slats are attached to the ring airfoil and are configured to open and close using springs.

Abstract: A vane ring assembly capable of preventing vibration of a vane, and wear damage caused thereby, by fixing the vane to a ring through a strong contact therebetween. The vane ring assembly includes a retaining ring having an inner peripheral surface in which a dovetail groove is formed; a vane including a dovetail inserted into the dovetail groove and an airfoil protruding from the dovetail in a radial direction of the retaining ring; and a locking key disposed between the dovetail and the dovetail groove and configured to press the dovetail into the dovetail groove. A method of assembling the vane ring assembly includes steps of inserting the dovetail into the dovetail groove; and forcibly pushing the locking key between the dovetail groove and the bottom surface of the dovetail.

Abstract: A gas turbine having a turbine casing, an outer and inner casing part between which a hot gas flows. An annular duct is formed between the outer casing part and the turbine casing to accommodate a cooling fluid. An exhaust gas casing is positioned downstream in the flow direction of the hot gas. A bearing system for a rotor has bearing struts arranged around the circumference which extend from a shaft bearing to an outer casing and, in the hot gas path of an exhaust gas diffuser arranged in the exhaust gas casing are shielded by another strut set which surrounds the bearing struts and is hollow to support the diffuser, wherein, to center the turbine and the exhaust gas casing, these are connected to one another via a fit wherein the turbine and the exhaust gas casing can be supplied with cooling air independently of one another.

Abstract: An exhaust diffuser includes: an internal cylinder; an external cylinder that forms an exhaust passage between the internal cylinder and the external cylinder, the exhaust passage expanding from front to rear; and at least one tubular strut that couples the internal cylinder and the external cylinder together. The external cylinder includes: a front conical portion that is positioned forward of the tubular strut; and an outer flaring portion that starts flaring at a positon forward of the tubular strut at an inclination angle that is greater than an inclination angle of the front conical portion. The internal cylinder includes: a front straight portion that faces the front conical portion and the outer flaring portion; and an inner flaring portion that starts flaring at a position between a maximum width portion and a trailing edge of the tubular strut.

Abstract: A cooling fan module is provided. The cooling fan module may include a frame, a fan assembly, a number of guide vanes, and a cylindrical deflector. The frame may include a sidewall that defines an opening and an outer periphery. The fan assembly may be disposed within the opening and include fan blades extending from a hub and terminating at a fan ring. The fan ring may have a curved profile. The number of guide vanes may be disposed radially around the opening. The cylindrical deflector may extend axially from the sidewall and radially surround the number of guide vanes. The cylindrical deflector may be disposed radially between the number of guide vanes and the outer periphery.

Abstract: A gas turbine engine blade root shim for use between a composite blade root and a wall of a slot in a rotor includes a longitudinally extending base having distal first and second transversely spaced apart ends, first and second longitudinally extending legs acutely angled inwardly towards the base from the first and second ends, and one or more apertures disposed through each of the longitudinally extending first and second legs. Apertures may include rectangular slots having rounded edges along the first and second outwardly facing surfaces of the first and second legs respectively and/or rounded corners between the first and second outwardly facing surfaces and the first and second inwardly facing surfaces of the first and second legs. Low coefficient of friction coatings may be disposed on outwardly facing surfaces, of the legs. Coatings may include polytetrafluoroethylene powder dispersed in a resin binder and other coatings having polytetrafluoroethylene.