Abstract: A rotor blade includes a root, tip, leading edge, trailing edge, forward surface, and aft surface, and a pitch section disposed equidistantly between the root and tip. The blade has a forward sweep from at least the pitch section to the blade tip relative to incoming streamsurfaces of a fluid flowable over the blade.

Abstract: A quiet tail rotor (QTR) blade for helicopters that provides reduced noise levels and increased thrust efficiency. The QTR blade includes a first segment for connecting the QTR blade to a helicopter tail rotor hub and an outboard segment, integral with the first segment, having a configuration that reduces high speed impulsive noise and blade vortex interaction noise and provides increased thrust efficiency. The outboard segment includes an inboard segment integral with the first segment and a swept, tapered tip segment integral with the inboard segment. The inboard segment has a constant chord and a predetermined constant airfoil section profile defined by constant upper and lower surface contours. The predetermined constant airfoil section profile has a t/c ratio greater than about twelve percent of the chord at any station. The swept, tapered tip segment has a variable chord and a predetermined airfoil section profile defined by constant upper and lower surface contours.

Abstract: A ducted fan antitorque device for a helicopter having an empennage structure including a shroud configured for internal mounting of the ducted fan antitorque device. The ducted fan antitorque device has a configuration optimized to provide the antitorque thrust required for helicopter yaw stability and maneuverability and to minimize the operating noise levels of the ducted fan antitorque device. The ducted fan antitorque device includes an airflow duct and a fan assembly coaxially mounted within the airflow duct. The airflow duct includes an inlet having a curved lip configuration of constant radius, a divergent duct portion downstream of and contiguous with the inlet having a predetermined divergence angle, and an outlet terminating the divergent duct portion having a curved lip configuration of variable radius.

Abstract: In a turbomolecular pump, the blade angle of each of rotor blades relative to the plane of a rotor gradually decreases from its base toward its outer most periphery, and the opening ratio and relative blade interval of said rotor blades are made substantially constant from the base of the rotor blade to the outer most periphery of said rotor blade.

Abstract: An axial flow air impeller for automotive radiator fan use and the like comprising a hub carrying a plurality of integrally formed similar circumaxially spaced and generally radially outwardly projecting air moving blades. Each blade has a root end portion integral with the hub and a radially outwardly disposed tip end portion with smoothly curving leading and trailing edges extending therebetween. The leading edge curves substantially forwardly while the trailing edge extends substantially radially to provide for a blade projected width at the tip end portion approximately 40% greater than at the root end portion. The thickness of each blade varies from a maximum at the root end portion to a minimum at the tip end portion with the latter being at least three times the thickness at the blade edge. An integral orifice ring circumscribes the plurality of blades and has a bell mouth at its upstream or downstream end.

Abstract: To reduce the noise levels of open rotor devices rotating at supersonic tip speeds, a combination of blade sweep and aerofoil profile is employed. The sweep of the blade extends through the sonic radius, and in the region of the sonic radius the section comprises a leading edge profile with a rounded nose conforming essentially to the formulaT.about.x.sub.L.sup.a Lwhere T is the blade thicknessx.sub.L is the distance from the front of the leading edgea.sub.L is an algebraic power greater than 3/4 and less than 1.The leading edge profile extends 2-15% of the aerofoil chord and has a nose radius not greater than 2% of the chord. It can be shown that, by these measures, it is possible to moderate the perceived noise levels from a device such as an aircraft propeller rotating at supersonic tip speeds.

Abstract: A clutch fan has a new and unique blade design that results in quieter and more efficient operation. The blade design involves the leading edge having inner, intermediate, and outer regions such that the intermediate region is of increasing skew in the direction of rotation and the outer region is of decreasing skew. The pitch ratio increases as a function of increasing blade radius. Along the outer region, the blade increases in pitch on a defined curvature as a function of blade radius and angle to form a tip curl.

Abstract: This invention relates to a blade for shrouded propeller, wherein: in plan, its aerodynamically active part presents a rectangular shape; and the maximum relative camber of the successive profiles constituting the aerodynamically active part of the blade increases from a value close to 0 to a value close to 0.04; the twist of the aerodynamically active part of the blade decreases from a first value close to 12.degree. to a second value close to 4.degree., then increases to a third value close to 4.5.degree.; and the maximum relative thickness of said successive profiles decreases from a value close to 13.5% to a value close to 9.5%.

Abstract: An adjustable diameter screw propeller includes a hub having a plurality of spindles, each mounted in the hub for rotation about an axis disposed radially of the hub axis and a mechanism for synchronously turning the spindles in a common direction. A plurality of propeller blades having a fixed pitch contour and a skew in the range of 60.degree. to 90.degree. are attached to respective ones of the spindles, such that as the spindles are turned, the blades rotate between a first disposition in which the diameter of the propeller is maximum and a second disposition in which the diameter of the propeller is reduced. In addition, the pitch of the propeller increases as the propeller diameter decreases to compensate for the loss of power that would otherwise occur as the propeller diameter is decreased.

Abstract: Compact fan and shroud package for radiators with fan blades curved rearwardly to position rotating shroud at optimized distance from radiator for improved air flow through radiator.

Abstract: An axial fan in which the median line (B) of each blade (3) has a first radially-innermost, rearwardly-directed curved portion (B.sub.1) and a second radially-outermost, forwardly-directed curved portion (B.sub.2), the former portion being between 25% and 50% of the full radial extent of the blade. The profile of the blade is characterized in that its circular thickness (S) increases progressively from the interior to the exterior, and the pitch setting angle (W) of the profile decreases progressively from the interior to the exterior.

Abstract: A fan in which the root-to-tip net blade skew angle (A.sub.b) (either forward or rearward) is less than 1/2 of the blade spacing; in a first radially inward region of the blade, the blade is rearwardly skewed as indicated by the leading edge skew angle (A.sub.e); in a second region radially outward of the first region, the leading edge skew angle indicates a forward skew.

Abstract: A compact, efficient axial flow fan with blades that are rearwardly (i.e., away from the direction of fan rotation) skewed and which are oriented at a pitch ratio which continuously decreases as a function of increasing blade radius along the radially outermost 30% of the blade.

Abstract: An improved air delivery system is provided for an impingement food preparation oven including a plurality of air ducts disposed in a cooking chamber, a plenum connected to the air ducts, and a scoop-type fan disposed in a backwall opening of the plenum to provide a flow of heated air smoothly and uniformly through the plenum into the air ducts. The fan device includes a plurality of tear-drop shaped blades, wherein each blade has a leading edge portion that tapers to a point in the direction of rotation and a trailing row portion at a given pitch angle for forcibly moving the flow of air in an axial direction toward the plenum front wall. The plenum front wall has a plurality of openings connected to the duct members, and a centrally disposed conical surface projecting outwardly toward the fan so that the axially directed flow of heated air from the fan is smoothly and uniformly directed by the conical surface the plurality of air ducts so as to provide a uniform cooking temperature in the cooking chamber.

Abstract: In a propeller for use in a ship of the type comprising 4 or more even number blades, at least one of two adjacent blades is inclined forwardly or rearwardly or one inclined forwardly and the other rearwardly so as to make different the rake angles of the two blades. The pitch angle of the rearwardly inclined blade is made larger than that of the forwardly inclined blade. With this construction the mutual interference between adjacent blades is efficiently utilized to prevent decrease in the efficiency even when operating conditions and the diameter of the propeller vary.

Abstract: A fluid driven turbine includes a central rotor having a plurality of wind blades mounted circumferentially around the axis of the rotor and arranged to define a general spiral configuration extending along the axis of the rotor in a predominant fluid flow direction. The hub is spherically shaped to force the fluid outward with an increase in velocity into engagement with the blades.

Abstract: A flexible fan device includes a power driven boss and a plurality of fan blades, each secured on the boss at an attached angle. The fan blade has a root portion secured to the boss and a tip portion offset with respect to the root portion in the downstream direction so that the blade angle is decreased under the influence of centrifugal force in response to an increase in the rotating speed. The fan blade is formed to have an angle inclined in the direction of rotation of the boss.

Abstract: This invention is directed to an improved tandem marine propeller having sets of radially extending blades which are connected at their roots to a hub in tandem arrangement for minimizing drag adjacent the hub and having the blades configured by skewing one set forward and the other set backward and raking the blades of the two sets toward each other so that outer portions of the blades are equispaced radially about the hub and lie substantially in a common plane of rotation whereby loading on the blades of both sets is substantially equalized for increased efficiency.

Abstract: Impulsive noise reduction is provided in a rotor blade by "acoustically sweeping" the chord line from root to tip so that the acoustic radiation resulting from the summation of potential singularities used to model the flow about the blade tend to cancel for all times at an observation point in the acoustic far field.

Abstract: A conical shaped rotor is described for rotation about a horizontal shaft axis for responding to or creating a moving airstream. The rotor is elongated and conical shaped along the rotor axis with elongated blades extending longitudinally and radially inward from an enlarged end to a reduced end. The blades are angularly offset between 1.degree. and 15.degree. from the rotor axis to cause an inner side edge of each blade to be closer to the rotor axis than an outer side edge without the blades being twisted about their longitudinal axis. In one form an electrical generator is operatively attached to the rotor shaft for generating electrical energy in response to the rotation of the rotor by wind passing therethrough. In a second form the rotor is driven by a motor to create an air flow therethrough to serve as a fan.

Abstract: A propeller blade is rotatable about an axis of rotation and has a leading edge and a trailing edge. The blade has a configuration such that for any fixed point on the leading edge of the blade .gamma. has a maximum value of 90.degree., and for any fixed point on the trailing edge .gamma. has a maximum value of Arc cotg[(tg .beta.).sup.3 ] wherein .gamma. is the angle between a radius extending from the axis of rotation to the fixed point and a vector from the fixed point in the direction of rotation of the blade, the vector lying in a plane which is perpendicular to the axis of rotation and which passes through the fixed point. The vector is normal to a section outline formed by the plane passing through the blade. .beta. is the angle between the plane and the chord of a cylindrical profile or corss-section of the blade formed by an imaginary cylinder concentric to the axis of rotation and passing through the fixed point.

Abstract: A propeller hub rotatable about an axis is provided with a plurality of airfoil surfaces peripherally arranged about the axis and defining a first pitch angle that is acute and adjustable with respect to the tangent on the circular arc described by rotation of the airfoil surface as seen in a plane perpendicular to the axis, and further by a second pitch angle being acute and ajustable and measured with respect to the axis of rotation within a plane containing the axis of rotation. Peripherally adjacent airfoil surfaces may have their first pitch angles oppositely oriented and second pitch angles oppositely oriented to respectively propel fluid inwardly and outwardly with respect to the axis of rotation. The air foil surfaces may be directly connected to the hub and extend conically outward or connected to the hub by means of arms that may be angled airfoil surfaces functioning as conventional screw propellers. The hub may be mounted coaxially adjacent a counter rotating screw.

Abstract: A propeller having a specified combination of blade sweep, camber and rake which provides distinct operating advantages when utilized on pleasure boats; and further including weed cutting and protection features which make the prop particularly suitable for use on outboard motors and stern drives employing underwater exhaust through the lower gear case housing. Propeller blade rake and camber are adjusted as described to improve performance of light to moderately loaded, medium to high speed pleasure boats. The blades are swept aft and weed cutting blade-like fingers extend forwardly of the propeller blades to prevent weeds from accumulating forward of the prop and blocking the exhaust passageway.