Abstract: A bifilar vibration absorber is provided for the main rotor of a helicopter in which the pendular mass is constrained so that the path of motion of its cg relative to the rotor hub is a cycloid.

Abstract: An improved helicopter designed to create minimum drag and turbulence in which the main rotor pylon has a top surface having a forward portion defining the rotor head well aperture so as to have a selectively curved lip on the rearward side thereof to eliminate flow separation therefrom of the air being discharged rearwardly from the rotor head well, further having a central portion curving slightly away from the direction of helicopter flight and including a laterally extending boundary layer slot a selected distance downstream of the curved lip through which fluid is expelled substantially parallel to the direction of helicopter flight to energize the surface flow along the pylon top surface, further having a rear portion at a lower elevation extending approximately in the direction of helicopter flight, and having engine and other exhaust ports positioned a selected distance downstream of the boundary layer control slot through which the exhaust fluids are directed over the rear portion in a direction subs

Abstract: A vibration absorber, which may be variable frequency, adapted to be fixedly mounted in a fixed vibration prone system. The vibration absorber is of the pendular-type with two dynamic masses suspended in pendular fashion from a base member, and with at least one coil spring acting upon the masses to establish and linearize the vibration absorber natural frequency. The absorber has a selectively constructed base member supporting two dynamic mass members on opposite sides thereof through three or more dually offset pendular connections and with mass member loads being reacted at I-shaped stations in the base member, and with one-piece, solid pin members extending through aligned holes in the base member and mass members, and with two deflected coil spring members imposing internal loads on the mass members to establish and linearize the vibration absorber natural frequency.

Abstract: A helicopter main rotor has an improved fairing enclosing the rotor hub and blade root area for drag and vibration reduction purposes. The fairing has peripheral cutouts through which the blades project provided with rounded lips on the rim of the cutouts to streamline air flowing in and out of the fairing through the cutouts. Internal partitions divide the fairing into chambers, each of which subtends one cutout, thus preventing flow of air through the fairing and attendant drag caused thereby. The rotor pylon is provided with a well through which the rotor drive shaft projects having a rounded lip adjacent the fairing to produce streamline airflow out of the well.

Abstract: An improved jam-proof control including a cylinder-piston assembly in which the piston is controllably positioned within the cylinder to perform the control function and in which the piston rod which extends through the cylinder wall is enveloped by a deformable sleeve so that when the piston rod is deformed by sharp impact, the piston rod is permitted to continue to reciprocate within the housing due to the deformation, either due to frangibility or softness, of the piston rod sleeve.

Abstract: A coupling for connecting two high speed rotating shafts and fabricated so as to have torsional and radial stiffness and angular and axial softness and to accommodate maximum misalignment variation between the axes of the shafts so joined.

Abstract: In a helicopter rotor in which the blades are supported for rotation and articulation from the hub by elastomeric bearings and including a lead-lag damper which acts to cause radially inward blade motion during rotor braking and including the improvement of utilizing members which move pivotally in response to centrifugal force and which serve blade flapping and droop stop functions both statically and dynamically and which further are programmed as a function of rotor speed to prevent or limit radial inward motion of the blade during the rotor braking operation.

Abstract: Minesweep gear is suspended from an aircraft to be a selected height above the surface of the water for deployment and the sweep gear is selectively stowed within the container so that the sweep gear is selectively sequentially deployed with the sweep equipment which is to assume a position farthest from the towing aircraft being deployed first and the sweep equipment which is to assume a position closest to the towing aircraft being deployed last. The sweep lead wire is connected to the aircraft towing cable and, by remote control from the aircraft, the sweep gear can be so selectively deployed and thereafter towed by the aircraft, the container being jettisoned once the gear is deployed and the sweeping gear being jettisoned at the end of the sweeping operation.

Abstract: A marine vessel whose hull consists of a single skin bottom plating comprising a plurality of large area membrane members supported by structural members about their outer periphery only and being of low areal density so as to deflect rapidly and substantially in response to the force of the shock wave of an underwater explosion without permanent deformation and whose personnel and machinery compartments are supported from hull structural members, such as bulkheads, solely by shock absorbing mounts.

Abstract: A flight control system utilizing pilot actuated flexible cables to selectively move a control quadrant and utilizing preloaded bungees additionally connecting each cable to the quadrant so that the quadrant can be pilot actuated despite the severance of one of the cables.

Abstract: A pivotal joint in which a first member having a wheel-shaped end is pivotally connected to a second member having a forked end enveloping the wheel-shaped end and including a primary pivot bolt arrangement extending through the first and second members at the center of the wheel-shaped end to pivotally join the parts, as the primary pivotal connection therebetween and wherein the forked end of the second member presents a circumferential array of three friction surfaces which will cooperate with the periphery of the wheel-shaped end of the first member to pivotally join the two parts as the secondary pivotal connection therebetween if the primary pivot connection fails.

Abstract: Patient litter apparatus adapted for use in an air-ambulance operable to permit elevating and lowering the litter and patient while maintaining the litter in a horizontal position at all times and with provisions for locking the apparatus with the litter at a selected position of elevation, and further with provisions for attenuating a large scale force, such as that created by a down-crash of the air-ambulance, to thereby reduce the risk of injury to the patient and preserve the structural integrity of the apparatus.

Abstract: A helicopter rotor having at least one blade projecting from the central hub and mounted for pitch change, flapping and lead-lag motion and including a lead-lag damper mounted to be pivotally movable in a selected plane and connected to the blade through a pivotal link connection to avoid the adverse effects of pitch and flap coupling.

Abstract: A flight control system utilizing pilot actuated flexible cables to selectively move a control quadrant and utilizing balanced, preloaded springs connected to the quadrant to be selectively automatically releasable in response to cable severance so that the quadrant can be pilot actuated through its full control regime despite the severance of one of the cables.

Abstract: An aircraft control system component, such as a bellcrank, having sideplate members of three-ply laminates bonded together with an elastomer-modified epoxy, with the thickness of the central ply twice the thickness of the end plies, and with the outboard end ply being of selected thickness and yield strength so that when petalling occurs therein due to the passage of a projectile therethrough, the petals are deformable under control loads when they come in contact thereafter with associated parts to thereby permit the control system to continue to perform its function due to the improved ballistic tolerance of the component.

Abstract: A fiber reinforced plastic part is fabricated by laying-up upon a properly shaped mold layers of uncured fiber reinforced plastic. The layers are cut through around the outer periphery of the part and its apertures and the waste material left in place during the curing process. The waste material so cut is thereafter pressed away from the finished part material to form a smooth finished part outer periphery and smooth aperture peripheries along the smooth lines established by the cutting process.

Abstract: A tube welding mill is shown through which titanium tube preforms are drawn and closed under a relatively stationary plasma arc welding torch. The tube preforms are drawn through a series of closing capstans, over a knife-edge guide bar and eventually under the plasma arc welding torch. The weld area and some distance down stream of the weld is shielded by inert gas containing box-like trailers including an upper trailer supported on the frame of the mill having resilient side walls which embrace the outer surface of the tube and a lower trailer supported on the mandrel within the tube which is carried by the guide bar. The lower trailer is floated on springs which allow it to move bodily in vertical planes parallel with the tube and otherwise adjust itself to maintain its top edges in sealing engagement with the inside wall of the tube beneath the weld.

Abstract: A helicopter blade of improved airfoil shape which reduces or eliminates retreating blade stall by reducing the magnitude of the upper airfoil blade surface peak pressure and distributes it over a greater chord section of the blade to thereby reduce flow separation and drag.

Abstract: An elastomeric bearing for a helicopter rotor in which the laminates of the bearing are shaped and positioned so that the center of hydrostatic pressure generated in each elastomer laminate and the cross-sectional center of gravity of each metal laminate are in alignment so that the integrated load vectors reacted through the metal and elastomer laminates of the bearing in imparting blade centrifugal loads to the hub therethrough are substantially in alignment to thereby prevent the creating of eccentric internal moments and hence avoid life reducing bending and hoop stresses in the metal laminates and unnecessarily high hydrostatic pressures in the elastomer laminates.

Abstract: A passive aircraft landing gear system in which the spring rate and damping for aircraft rolling motions about a longitudinal axis are independent of the spring rate and damping for aircraft vertical motions, thereby permitting the landing gear system to optimally accomplish both landing impact attenuation and ground resonance instability abatement.