Abstract: A rotor blade (1) is disclosed which recenters itself in relation to the retention member (10) in which it is installed. Imposition of an external force (A) upon the rotor blade (1) creates a moment (M) which acts about the rotor blade's root (3). Recentering is accomplished by centrifugal forces acting through an offset distance (C") resulting from an off-center rotation of the blade and its captivated shaped retaining pin (6) within a plurality of retention member tenons (12), achieving an enhanced opposing restorative moment (M'.sub.R) on the rotor blade (1). The retention member tenons (12) contain arcuate bearing surfaces (8) which bear against a corresponding arcuate surface (9) with a smaller radius of curvature lengthwise disposed on the shaped retaining pin (6).

Abstract: A lightweight propulsor blade (10) is constructed 10 of a hollow internal spar (30) and an exterior airfoil shell (20) which defines and encompasses a hollow interior cavity (26). The internal spar (30) is disposed within the cavity 26 and extends spanwisely from its tip portion to terminate in a spar root portion (40). The spar has at least forward and aft spanwisely extending, chordwisely spaced, hollow box-like cavities (52A, 52B), a leading edge shear web (53) projecting chordwisely forward from the forward cavity (52A), a trailing edge shear web (55) projecting chordwisely rearward from the aft cavity (52B), and an intermediate chordwise shear web (57) spanning the space between and interconnecting the forward and aft cavities (52A, 52B). An additional intermediate box-like cavity (52C) may be incorporated in the intermediate chordwise shear web (57) in spaced relationship between the forward and aft cavities (52A, 52B).

Abstract: A composite axial flow rotary machine blade (10) and method of blade construction is disclosed. A substantially full length composite spar (30) is spanwisely disposed within an airfoil planform (18) which supports an airfoil surface (11a). A pad of reinforcing fibers (40) is sandwiched between the spar's periphery and the airfoil surfaces' proximate inner surfaces (24a, b) corresponding to the pressure (22) and suction (24) sides of the airfoil planform in a spanwise distribution. A quantity of structural foam filler (50) is disposed through the balance of the blade's cavity (16).

Abstract: Preloading and retention of a variable-pitch, light-weight propeller blade (10) are achieved through a retention assembly wherein the blade shank (20) is retained within a hub arm (24) with an inboard angular contact pitch change bearing (30) and an outboard angular contact anti-rocking bearing (50) which is elastomerically preloaded. The outboard bearing (50) is disposed intermediate a bearing race (34) on the shank (20) and an annular frusto-conical rigid support member (62) which is biased outboardly against the anti-rocking bearing (50) by an annular frusto-conical body (72) of elastomeric material selected to impart a desired stiffness and/or damping effect to the retention assembly.

Abstract: A propeller or fan blade is rotatably mounted to a blade retention pitch member by a pin radially outside of a spinner. By mounting the propeller blade for rotation about the axis of the pin, the blade response to a vibratory excitation in a first mode of vibration is modified such that the twisting motion of the blade is minimized. High speed stability of the blade is enhanced thereby. Moreover a damaged blade may be easily replaced.

Abstract: A retention system for a rotor blade (10) utilizes the combinatioin of a fixed retention flange (13) and a removable retention plate (16) with a closed-sided retention member (12). This system enables the rapid replacement or removal of the rotor blade (10) for inspection, maintenance, or replacement purposes without requiring removal of surrounding major engine components or structural members. The rotor blade (10) is installed in a retention member (12) contained in a rotatable hub (not shown) by inserting an outwardly extending portion (20) of a shaped blade root (22) of the rotor blade (10) below a radially-inwardly projecting shaped flange (13) peripherally disposed within the interior of the retention member's structure. A removable shaped retention plate (16), which is releasably secured to, and adapted to mate with, the retention member (12), then captures and secures another outwardly extending portion (21) of the shaped root of the rotor blade (10) with a releasable fastener (18).

Abstract: A pitch retention member rotatably mounts a propeller or fan hereto radially outwardly from a spinner or a hub. The member attaches to the blade of a pair of tenons, each tenon having a hole passing therethrough for receiving a pin about which the blade may rotate. The pitch retention member cooperates with a motion limiter provided at the base of the blade to: damp rotational movement of the blade about the pin to minimize blade angular excursions when centrifugal loads are low; improve high speed blade stability; moderate blade vibratory motion and tune out undesirable blade resonant frequencies; and, absorb force created by impact with foreign objects. Such impact is adsorbed at a desired threshold level of bending load of a crushable material disposed within the blade retention pitch member.

Abstract: An essentially composite propeller or fan blade is provided which is rotatably mounted to a blade retention pitch member by a pin radially outside of a propeller spinner or hub. The blade has a plurality of composite layers wrapped directly around a root fairing which engages the pin. The propeller blade has a motion limiter provided at the base thereof which cooperates with the blade retention pitch member to damp rotational movement of the blade about the pin to minimize blade angular excursions when centrifugal loads are low, to moderate blade vibratory motion, to help tune out undesirable blade resonant frequencies and to transmit force created by impact with foreign objects to the pitch member. By cooperating with the pitch retention member, the root of the blade may be more aerodynamically shaped than other composite blades which must absorb the force of impact in their root portions.

Abstract: A rotor blade (1) is disclosed which recenters itself in relation to the rotatable hub in which it is installed. Imposition of an external force (A) upon the rotor blade (1) creates a moment (M) which acts about the rotor blade's root (2). Recentering is accomplished by centrifugal forces acting through an offset distance (C) resulting from rotation of the blade root (2) about a shaped retaining pin (6), achieving an enhanced opposing restorative moment (M') on the rotor blade (1). The rotor blade (1) contains an arcuate bearing suface (8) within a chordwisely disposed slot (7) in the rotor blade's root (2). This arcuate surface (8) bears against a mating arcuate surface (9) with a smaller radius of curvature lengthwise disposed on the shaped retaining pin (6).

Abstract: Improved prop-fan stability is achieved by providing each blade of the prop-fan with a leading edge which, outwardly, from a location thereon at the mid-span of the blade, occupy generally a single plane.

Abstract: A pitch-change apparatus for a ducted thrust fan having a plurality of variable pitch blades employs a rotatable ring bearing a plurality of camming members, and each of the plurality of blades is connected with a pitch-change horn engaged by one of the camming members. The ring and camming members rotate coaxially about a hub axis with the blades and rotate about the hub axis relative to the blades to collectively change blade pitch. The rotatable ring, the camming members and the pitch-change horns develop a variable mechanical advantage, and the pitch horns are connected with their respective blades so that the minimum mechanical advantage corresponds with the low-load, feathered pitch position of the blades and greater mechanical advantages correspond with the higher load, forward and reverse pitch positions of the blades.