Abstract: A helicopter rotor head mounting assembly includes a rotor drive shaft and rotor hub splined to the shaft for rotation therewith. The rotor hub includes a central bore having an internal tapered portion which is forced downwardly upon a mating tapered portion of the rotor drive shaft. An annular split cone is mounted between the rotor shaft and the hub at a bottom portion of the hub bore and the split cone is forced upwardly into firm engagement with the hub and drive shaft by means of a plurality of individual loading means which are carried by an annular plate affixed to the bottom of the hub. The loading means are individually adjustable and apply loading force directly onto the split cone to thereby assure a secure, non-vibrational rotation of the hub with the rotor shaft.

Abstract: A stop device limits rods, such as control rods, used in helicopter flight control systems, from roll-over in selected directions, while allowing substantially unrestricted motion in other directions.

Abstract: During flight, helicopter landing gears are suspended by a tuning spring m the helicopter airframe to provide limited relative movement between the landing gear masses and the airframe. As the aircraft vibrates due to vertical or in-plane forces at the rotor head, the landing gear masses react oppositely thereto, thus generating balancing forces which are applied to the airframe to balance the rotor excitations.

Abstract: The need for crash-resistant fuel tanks to eliminate or minimize post-crash fires is well known. An equally well known fact is that such tanks, when ruptured ballistically or by impact, are very difficult to repair. Many materials have been tried, but without success. The variety of materials such as metal, plastic and nylon, which must be bonded to make a satisfactory repair renders the repair problem particularly challenging. A combination of bonding matrixes has been found which has resulted in a desirable fuel cell repair system.

Abstract: Helicopter rotor blades require tip weights for spanwise and chordwise bace to assure that all of the blades rotate in the same track. The improved rotor blade tip weight assembly of the present invention comprises an elongated spar, preferably formed of a reinforced plastic, adapted to be connected at one end thereof to a rotor hub. An aft fairing structure is carried by the spar and a balancing weight assembly is bonded and/or cured in place within the spar, proximate the free end thereof. The balancing weight assembly includes, in the preferred form thereof, a fiberglass weight tube housing having a pair of internally threaded weight tubes positioned therewithin. The weight tubes form bores having longitudinal axes in a common, substantially horizontal plane, and the axes each extend in a direction parallel to the axis of the spar. One or a plurality of externally threaded cylindrical weights are locked in each weight tube during balancing of the rotor blade.

Abstract: Daily engine checks or health tests are being developed for determining the ondition of an engine by relating significant performance parameters. One such health test, termed "HIT," utilizes exhaust gas temperature along with compressor speed. Since results of this test vary with outside air temperature conversions must be made by maintenance personnel and pilots. A calculating device is provided for this use.

Abstract: Microwave absorbers reduce radar cross-sections of airborne objects by attenuating reflectivity values. In Jaumann absorbers laminated layers are placed on the reflecting surfaces, the laminated layers being lossy layers separated by dielectric spacing layers. From the point of view of accuracy and reproducibility Jaumann absorbers have been difficult to construct. A mode of fabrication overcoming these difficulties is provided herein.

Abstract: Microwave absorbers reduce radar cross-sections of airborne objects by attenuating reflectivity values. In Jaumann absorbers laminated layers are placed on the reflecting surfaces, the laminated layers being lossy layers separated by dielectric spacing layers. From the point of view of accuracy and reproducibility Jaumann absorbers have been difficult to construct. A mode of fabrication overcoming these difficulties is provided herein.

Abstract: Structural cores are quasi-isotropic load-carrying constructional elements n the form of parallel rows of polyhedrons disposed in alternating sequence. These have been made from interwoven fibrous filaments, coated with plastic. Such structural cores are made herein from a continuous ribbon.

Abstract: Sand and dust erosion of turbine engines by ingested particulate matter is major problem facing both airframe and engine manufacturers. Various types of particle separators are used to keep sand and dust out of the engine. In these separators the particles are diverted by swirl vanes and similar devices to keep them out of the engine. An inlet scroll separator herein permits the particles to continue their course of travel and diverts the air stream, reducing power requirements and eliminating swirl and deswirl vanes.

Abstract: Successful flight of high altitude military aircraft is dependant, in part, pon the ability of the aircraft to remain undetected during flight. However, the hot gas plume is a prime source of infrared radiation, and highly sophisticated infrared sensors have been developed in recent years. A particularly effective infrared radiation suppressor is the plug-type exhaust system. This invention increases heat exchange relationships in the plug-type infrared radiation suppressor without significantly penalizing engine power during suppressor operation.

Abstract: Compound helicopters, those having a rotor blade and a small wing, possess rear propulsion propeller adjacent to the tail rotor. The tail gearbox is driven through a drive train coupled to the main rotor drive shaft. In such aircraft the tail rotor is in operation when the propulsion propeller is turning, and vice versa. A mechanism is provided herein for stopping or feathering the tail rotor when driving the propulsion propeller, or for stopping the propulsion propeller when the tail rotor is in operation.