Abstract: The loading, firing and ejection of beltless, cased ammunition is facilitated by the use of an oscillating breech having two breech chambers defined therethrough, which breech is disposed between two parallel ammunition chutes. Unfired rounds are provided to a load position in a first ammunition chute and the oscillating breech rotated to align one chamber with the load position. The unfired round is rammed into the aligned chamber, thereby forcing the spent cartridge just fired from the opposing end of the chamber into an eject position in a second opposing ammunition chute. Meanwhile, a second chamber within the oscillating breech is simultaneously aligned with a corresponding one of two barrel bores and fired.

Abstract: A universal joint for use in a pitch cone rotor system in a helicopter is comprised of crossed lift beams, one beam of which is coupled to the rotor hub and the other beam of which is coupled to the driven rotor shaft. The two crossed lift beams are coupled to each other through a cruciform case. The cruciform case in turn is coupled to each of the crossed lift beams by means of a plurality of flexures. The flexures and cruciform case are made of composite fiber materials and the flexures are soft enough to permit angular and translational deflections of the crossbeams with respect to each other thereby tending to smooth out and reduce sudden changes in rotor speed between the shaft and rotor system and thereby tending to make rotor speeds more uniform. The crossed lift beams are further coupled together at the center of their crossing by a flexible elastomeric tension link which conducts rotor loads between the two beams when the rotor develops negative lift loads on the ground and in flight.

Abstract: An improvement is made in an externally driven gun having an ammunition feeder capable of providing at least two types of ammunition to the gun by incorporating a gear transmission into the driving mechanism coupled to the ammunition feeder to appropriately control an in-feed sprocket within the ammunition feeder so that the ammunition type can be changed prior to commitment of the previously selected type of ammunition to the firing mechanism of the gun. The gear transmission which is coupled to the in-feed sprocket provides acceleration to the sprocket at the last possible moment prior to handing-off the round to the firing mechanism. In one embodiment the gear transmission includes a cam follower rotatably coupled about an offset axis to the input shaft and coupled to the output shaft through a radial slot. The cam follower is rotated by means of a stationary cam race as the follower itself is rotated as a whole by the input shaft.

Abstract: The side stripping of ammunition from linked ammunition belts in an automatic weapon system is improved by providing a stripping mechanism including a link sprocket for engaging the link belt and rounds and including a synchronously rotating follower guide. A plurality of followers are disposed and slidable within a corresponding plurality of radial slots defined in the follower guide. Two followers are provided for each round which could be accommodated by the link sprocket. The follower slides radially along the slot in the following guide toward and away from its corresponding round as controlled by a cam pin extending from the follower and engaging a cam raceway in an adjacent fixed cam plate. By this means a purely radially force is symmetrically applied to each round through the longitudinal axis of the round and perpendicular to the axis of the sprocket so that no net torque is applied to the round or its corresponding link.

Abstract: A fast forward flight helicopter is provided with a multiple speed helicopter rotor transmission. The transmission allows a variation in main rotor RPM or tail rotor RPM or both, dependent upon the desired flight conditions, while maintaining satisfactory lift and performance. With this means, noise is controlled without loss of aerodynamic performance. In one embodiment a helicopter is provided with a transmission for interconnecting the power input shaft through the main rotor shaft and tail rotor shaft in common. The transmission employed is a planetary gear transmission. A brake means is provided for clutching the planetary gear transmission from a first and second transmission speed so that power is continuously delivered, and shifting is accomplished in a smooth manner, thereby allowing the helicopter to remain in smooth flight. In another embodiment the main rotor is driven through the planetary gear transmission and the tail rotor is directly driven.

Abstract: Autorotation in helicopters at low altitudes can be achieved even when the inherent design of the helicopter would prohibit successful entry into the autorotation mode. Angular kinetic energy from the main propulsion engine is stored in a flywheel which automatically transfers this energy to the main drive shaft in the event of engine failure. During normal operation, the flywheel is driven through the main drive shaft by coupling to a secondary drive shaft. The main drive shaft in turn is driven by the engine through an overrunning clutch assembly. The flywheel is maintained within an evacuated housing whereby air drag is substantially eliminated. In the event of engine failure, the overrunning clutch disengages the engine from the main drive shaft and flywheel will continue to apply energy to the main drive shaft through the secondary drive shaft to permit autorotation and a no-damage landing even at low altitude flight levels.

Abstract: A compact, rugged, streamline, stiff, pitch control system is devised in a helicopter by concentrically nesting a cyclic pitch control tube and collective pitch control tube within the drive shaft and stationary mast of a helicopter rotor system. The collective pitch control tube terminates in an upper inclined flange which engages a stationary swashplate by means of a bearing member disposed in an inclined bearing raceway in the stationary swashplate. The stationary swashplate in turn is rotatably coupled through a universal joint to the cyclic pitch control tube. Relative rotation of the cyclic pitch control tube with respect to the collective pitch control tube adjusts the stationary swashplate to a selected inclination with respect to the longitudinal axis of the control tubes and of the helicopter mast. A rotating swashplate is rotatably coupled to the stationary swashplate and transmits the angular orientation of the stationary swashplate to the pitch case of each rotor blade as appropriate.

Abstract: An improvement is made in an externally driven gun having an ammunition feeder capable of providing at least two types of ammunition to the gun by incorporating a gear transmission into the driving mechanism coupled to the ammunition feeder to appropriately control an in-feed sprocket within the ammunition feeder so that the ammunition type can be changed prior to commitment of the previously selected type of ammunition to the firing mechanism of the gun. The gear transmission which is coupled to the in-feed sprocket provides acceleration to the sprocket at the last possible moment prior to handing-off the round to the firing mechanism. In one embodiment the gear transmission includes a cam follower rotatably coupled about an offset axis to the input shaft and coupled to the output shaft through a radial slot. The cam follower is rotated by means of a stationary cam race as the follower itself is rotated as a whole by the input shaft.

Abstract: A low drag, bearingless coupling is provided between a blade and hub of a helicopter rotor system by coupling the hub and blade together by means of a planar, elastic flexure or element which extends between the blade and the hub in a generally azimuthal direction in the rotor plane. The thickness of the flexure is such so that it is smaller than the adjacent blade or hub thicknesses so that the aerodynamic cross section presented by the flexure to air flow is negligible. The flexure is particularly characterized by having a bend in the coupling between the hub and blade. In the illustrated embodiment the flexure is integral and "W"-shaped with a "U"-shaped segment of the "W"-shaped flexure extending between each side of the adjacent blade and hub arms. The flexure may be made of rod having a circular cross section or of flat plate formed in a shape to have the desired elastic and resilient characteristics.

Abstract: A fail-safe flexible coupling is provided for coupling shafts, typically in an aircraft, wherein the coupling includes a plug coupled to the first shaft and a socket coupled to the first shaft and a socket coupled to the second shaft. The plug is arranged and configured to loosely mate with the socket when the shafts are being rotated together by virtue of their primary coupling. When the primary coupling fails, the socket and plug engage each other notwithstanding the failure of the primary coupling between them. The plug is particularly characterized by a screw portion and head portion. The screw portion is threaded into the first shaft. The coupling is secured to the first shaft by the head portion of the plug.

Abstract: A low drag, bearingless coupling is provided between a blade and hub of a helicopter rotor system by coupling the hub and blade together by means of a planar, elastic flexure or element which extends between the blade and the hub in a generally azimuthal direction in the rotor plane. The thickness of the flexure is such so that it is smaller than the adjacent blade or hub thicknesses so that the aerodynamic cross section presented by the flexure to air flow is negligible. The flexure is particularly characterized by having a bend in the coupling between the hub and blade. In the illustrated embodiment the flexure is integral and "W"-shaped with a "U"-shaped segment of the "W"-shaped flexure extending between each side of the adjacent blade and hub arms. The flexure may be made of rod having a circular cross section or of flat plate formed in a shape to have the desired elastic and resilient characteristics.

Abstract: An improved drill bit for drilling Kevlar laminates or the like, has a pair of helical edges each terminating in an outer cutting point; a center point; and concavely curved cutting edges extending between the center point and each of the outer cutting point. The cutting edges curve back sharply from the cutting points in a plane transverse to the longitudinal drill bit axis and in a direction opposite to normal rotation of said drill bit so as to draw material served by the cutting points radially inwardly from the edge of a bore. A method is disclosed for modifying a conventional drill point to the novel configuration by grinding on a grinding wheel.

Abstract: The apparatus comprises one or more acoustical transducers associated with a particular interchangeable rotor blade for monitoring acoustic emissions emitted by the rotor blade under operating stress. The output of the transducers is connected to a computer associated with the particular aircraft. The transducer output signals are processed by the computer and filtered to allow real time stress return level readings so as to accumulate a count of critical acoustic emissions which are indicative of progressive irreversible structural fatigue or damage to the interchangeable rotor blade.

Abstract: Each landing gear of the undercarriage of an aircraft includes an hydraulic cylinder, and the hydraulic cylinders are interconnected through hydraulic restoring devices. The hydraulic restoring devices yieldably urge the pistons in each of the hydraulic cylinders to an equilibrium position, thereby restoring the length of each landing gear to an equilibrium length following a disturbance. In non-level landings, the hydraulically interconnected system causes the landing gear that strikes the ground first to be compressed and the other landing gears to be extended; this absorbs some of the energy of the impact. Extension of the other landing gears tends to limit the extent to which landing energy is converted to angular velocity of the aircraft caused by pivoting of the center of gravity of the aircraft about the first landing gear to contact the ground.

Abstract: A single barrel externally powered gun includes a feed mechanism, a bolt assembly, a bolt control assembly and a power transmission system. The bolt control assembly is in the form of a chain drive unit driven continuously along a predetermined path of travel which defines the timing and sequence of loading, ramming, firing and ejecting. The chain drive assembly controls the reciprocating motion of the bolt assembly relative to a fixed non-rotating and non-reciprocating barrel, the bolt being stationary in the firing and loading sequences. The feed mechanism which continuously advances rounds is integrated to the intermittent motion of the bolt by a Geneva wheel mechanism, as the bolt assembly reaches the proper position in its rearward movement. Bolt locking, firing and unlocking are all controlled, and carried on while the chain drive assembly is continuously moving.

Abstract: A fail-safe flexible coupling is provided for coupling shafts, typically in an aircraft, wherein the coupling includes a plug coupled to the first shaft and a socket coupled to the first shaft and a socket coupled to the second shaft. The plug is arranged and configured to loosely mate with the socket when the shafts are being rotated together by virtue of their primary coupling. When the primary coupling fails, the socket and plug engage each other securely though the shafts continue to be driven notwithstanding the failure of the primary coupling between them. The plug is particularly characterized by a screw portion and head portion. The screw portion is threaded into the first shaft. The coupling is secured to the first shaft by the head portion of the plug.

Abstract: The lead-lag angle or phasing of a rotor blade system for helicopter can be adjusted by using a method and apparatus which positions the blade tip at a spatial location and angular orientation approximating a no-lift, full centrifugal load condition. An optical means is used to form a line-of-sight from the blade tip to a first and second target. The first target is mounted on the lead-lag hinge pin and the second target is mounted on or near the rotor drive hub. Both the optical means and either one or both of the targets may be offset so that, when the optical means, first target and second target will lie along a linear line-of-sight, the designed lead-lag angle of the corresponding blade to which the apparatus is coupled, will be achieved. The apparatus comprises a frame member through or on which the blade tip slips and includes levels to ensure the proper spatial and angular orientation of the blade given the specific rotor blade system.

Abstract: A single barrel externally powered gun includes a feed mechanism, a bolt assembly, a bolt control assembly and a power transmission system. The bolt control assembly is in the form of a chain drive unit driven continuously along a predetermined path of travel which defines the timing and sequence of loading, ramming, firing and ejecting. The chain drive assembly controls the reciprocating motion of the bolt assembly relative to a fixed non-rotating and non-reciprocating barrel, the bolt being stationary in the firing and loading sequences. The feed mechanism which continuously advances rounds is integrated to the intermittent motion of the bolt by a Geneva wheel mechanism, as the bolt assembly reaches the proper position in its rearward movement. Bolt locking, firing and unlocking are all controlled, and carried on while the chain drive assembly is continuously moving.

Abstract: A tactical wire-cutting system for helicopters includes a forwardly extending probe having a plurality of explosive cutting charges disposed along the probe. The probe is inclined with respect to the vertical as defined by the normal helicopter trim during flight such that a suspended cable will come into successive contact with the explosive cutting charges. The charges are designed to catch and hold the cable until detonation and thereafter to allow the cable to proceed to the next successfully positioned charge if unsevered.

Abstract: A fiberglass-epoxy flexbeam extends from tip to tip of each opposed blade pair, carrying the blade centrifugal forces so that none of the centrifugal loading is carried by the hub. The primary load-carrying connector between the flexbeam and the hub is a set of elastomeric pads. These provide a soft mount between the flexbeam and the hub to keep the primary bending moments within the flexbeams where the filaments are designed to accommodate them. The elastomeric pads are also effective in isolating the hub from chordwise loads which include the steady driving torque and the "C" mode and "S" modes of coriolis vibration. The elastomeric hub mount damps these vibrations and tunes their frequencies to values well separated from the rotor frequency.