Abstract: A Variable Diameter Rotor (VDR) system (4) having telescoping odd and even blade assemblies (O.sub.b, E.sub.b) wherein the odd blade assemblies define a radial length R.sub.O and the even blade assemblies define a radial length R.sub.E. Each blade assembly (O.sub.b, E.sub.b) defines an internal chamber (64) for accepting a positioning means (70) operative to effect telescopic translation of the blade assemblies (O.sub.b, E.sub.b) such that the radial length R.sub.E of the even blade assemblies (E.sub.b) is equal to the radial length R.sub.O of the odd blade assemblies (O.sub.b) in a first operating mode, and such that the radial length R.sub.E is between about 70% to about 95% of the length R.sub.O in a second operating mode. The positioning means (70) includes a centrifugal restraint assembly (80) disposed within each internal chamber (64) of the rotor blade assemblies (O.sub.b, E.sub.

Abstract: A drive system for varying the diameter of a variable diameter rotor has a gear drive system associated with a single coaxial shaft lower end which includes a gear set for increasing or decreasing the speed of rotation of the coaxial shaft relative to the rotor drive shaft to change the length of two or more variable length blades. Utilizing a single shaft system allows a variable diameter rotor drive system to be adapted to gimballed rotors which require shaft flexibility. Since only a single shaft extends through the rotor drive shaft, hub complexity is reduced.

Abstract: A variable diameter rotor for a tilt rotor aircraft has an inboard section having a linear twist from a root end to an outboard end thereof, and an outboard section telescoped over the inboard section which additionally has a linear twist from a root end to an outboard end thereof. The outboard section is disposed at an offset of about 4.degree. to 15.degree. relative to the inboard section to provide a step wise change in twist angle when in the extended condition, such that the rotor when operated in the helicopter mode, can be operated at high blade pitch angles without premature stalling along the inboard airfoil surfaces This allows efficient operation at high thrust coefficient/solidarity ratios. Optionally, the trailing edge of the outboard section is rotated along the aft 30% of chord of the airfoil section to provide an equivalent twist increase in the offset at the transition between the blade sections.

Abstract: A viscous damper for a helicopter rotor blade having a stator member and a rotor member each having a plurality of flanges of different diameter defining cylindrical internal and external shear surfaces, respectfully, and a shear gap therebetween, one stator member internal shear surface having two diameters, the shear gap distances between proportional to radius, and a coaxial rotor member comprising two discs having outer cylindrical shaped shear suraces forming a shear gap with adjacent stator member shear surfaces and one rotor disc being axially movable so that a variable portion of its shear surface is opposite both of the diameters of the stator member two-diameter internal shear surface.

Abstract: Optical fibers are used for monitoring the structural integrity of space based or aircraft structures where prompt notification of damage is required to effect rapid repair and thereby maintain safety and operational reliability. A plurality of optical fibers are disposed in an X-Y relationship, with the fibers optimally placed in a pattern comprised of multiple path reversals which provides extensive area coverage with a minimum of fibers thus defining multiple zones wherein damage within a zone is determined by interruption of the light through the damaged fibers.

Abstract: A filament wound fiber reinforced resin matrix composite structure. The structure is particularly adapted for use as a torque drive diaphragm in a rotary wing aircraft hub. The structure comprises a substantially flat diaphragm and a rim. The diaphragm has a central hole therethrough for receiving a shaft and the rim has an inward turning flange for attachment. The diaphragm has an attachment means surrounding the central hole. An alternative embodiment of the structure is a hollow disc having first and second substantially flat diaphragm sides with a rim. The sides have concentric central holes therethrough and attachment means surrounding the holes. The structure comprises a resin matrix, fibers wound substantially tangentially to the central hole with sufficient tension in a multiple circuit pattern to form the structure, and fibers wound with sufficient tension in an essentially circumferential manner to reinforce the rim of the structure.

Abstract: A helicopter main rotor blade having built-in twist for improved hover performance is provided with a trailing-edge, short span slot near the tip end of the blade for upwardly directing a stream of pressurized air therefrom. The upward ejection of air from the slot untwists the blade, which will enhance the forward flight performance of the blade. A method of modulating the ejection of air from the slot is disclosed for antivibratory control.

Abstract: Air turbulence ahead of an aircraft is determined by scanning the beam of a variable focal distance laser airspeed unit close-in to the aircraft to determine aircraft airspeed and angle of attack, and scanning the beam at distances farther out from the aircraft and measuring airspeed. Discrepancies between the close-in measurement and the farther out measurement are quantifiably indicative of air turbulence.

Abstract: A fiber reinforced composite flexbeam which has torsionally stiff inboard and outboard end portions which taper down to form a torsionally soft, resilient, solid medial web portion is disclosed. Such a flexbeam may be used as a structural member in rotor connectors for a rotary wing aircraft to connect the rotor blade to the rotor hub.

Abstract: The present invention is a method of making fiber reinforced composite articles using match molds to compact a partially hollow fiber/matrix lay-up. The method comprises wrapping the matrix and fiber reinforcement about a mandrel, removing the mandrel from the lay-up or chilling the wrapped mandrel allowing for easy removal of the mandrel resulting in a relatively stiff hollow lay-up. The lay-up is then placed in a mold and compacted and cured to form the desired composite article. Such a method provides an easy method to form such complex composite article shapes as I-beam, C-beam, etc.

Abstract: A helicopter blade of high twist having an improved tip utilizing a combination of sweep, taper and anhedral to improve hover performance by unloading the blade tip and reducing the strength of the tip vortex and displacing that tip vortex away from the following blade surface.

Abstract: A hingeless helicopter rotor including an aerodynamically shaped hub having a flexible diaphragm as its bottom wall, which diaphragm is connected to the rotor drive shaft and is elastically deformable in response to blade loading to tilt in any direction with respect to the axis of rotation, and further having at least three equally spaced helicopter blades projecting from and supported from within the hub for rotation therewith and for flexing with respect thereto in response to blade loading so that the flexible hub and the blades coact to produce a low equivalent offset rotor and minimized Coriolis effect.

Abstract: A cambered helicopter blade having a swept and tapered tip, and having linear twist throughout the outer 70 percent of the blade span and nonlinear twist inboard thereof.

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 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: A plurality of variable diameter rotors with mechanism for varying the diameter of the rotors synchronously, and including mechanism to limit the diameter of the rotors.

Abstract: A locking control system and an overtravel safety top system are presented for a variable length rotor blade system. The lock system has linkage and pawl apparatus operated by a pilot actuated lock shaft to lock and unlock the blade adjustment system. A traveling nut on the lock shaft actuates the lock linkage, either directly or through the lock shaft to lock the blade adjustment system to prevent overretraction or overextension in the event of malfunction of the extension control system.

Abstract: A locking control system and an overtravel safety stop system are presented for a variable length rotor blade system. The lock system has a lock mechanism operated by a pilot actuated lock shaft to lock and unlock the blade adjustment system. A traveling nut locks the blade adjustment system to prevent overretraction or overextension.