Abstract: A porous surface on an aircraft structure driven with oscillating positive and negative pressures is used as an active control device for attenuating negative aerodynamic interactions. The porous surfaces can be driven with positive and negative pressures either continuously or when predetermined flight conditions are present. The porous surfaces can be used on rotor blades to reduce BVI noise in descent flight conditions. The porous surfaces can be configured on rotor blades for affecting blade variable twist in accordance with various flight conditions, and can further be incorporated for reducing rotor hub vibrations as well. Porous surfaces placed on aerodynamic surfaces below the rotor blades of a tiltrotor aircraft can attenuate or eliminate download and fountain flow conditions.

Abstract: A bulk absorber has a continuous concentration gradient of particles with dielectric or magnetic altered properties. The bulk absorber may be made from foam or, ceramic. The particles may be carbon fibers, carbon black, carbon whiskers, coated hollow microspheres, or a combination thereof. A manufacturing system for fabricating a bulk absorber has two delivery devices, a controller, an intermingling device, a positioning device, and a forming device. The delivery devices produce flows of absorber precursors, with at least one of the flows having a concentration of particles having dielectric or magnetic altering properties. The ratio of the flows is controlled by the controller. The intermingling device receives and mixes the flows to produce a combined flow. The particle concentration in the combined flow is controlled by the controller. The positioning device directs the depositing of the combined flow into a cavity to build a non-solidified item.

Abstract: A composite structure is made by first furnishing a skin layer made of a composite material of quartz fibers embedded in an uncured cyanate ester-resin matrix. A transition layer of a first epoxy resin is applied to the skin layer. The skin structure including the skin layer and transition layer is cured at a first temperature and post cured at a second temperature greater than the first temperature. A bonding layer of a second epoxy resin is thereafter applied to the bonding surface of the transition layer, and a substrate is contacted to the exposed face of the bonding layer. The second epoxy resin is cured at a third temperature no greater than the first temperature.

Abstract: Porous surfaces on an aerodynamic structure driven with positive and negative pressures are used in an active control system for attenuating shock waves responsible for high-speed impulsive (HSI) noise. The control system includes an array of apertures in the outer skin of the structure providing fluid communication between the exterior flow stream and an interior volume of the structure. A movable diaphragm within the structure pushes air out of and pulls air in through the apertures under the action of a drive mechanism within the structure, thus creating oscillating air jets. The drive mechanism may be actuated by a controller based on information supplied by a sensor in the leading edge of the aerodynamic structure. The array of apertures may be spaced apart along the outer skin of the aerodynamic structure so as to span a distance of about 15% of the chord length. The oscillating airjets may be provided on multiple surfaces of the aerodynamic structure, including the upper and lower surfaces.

Abstract: A composite structure is made by first furnishing a skin layer made of a composite material of quartz fibers embedded in an uncured cyanate ester-resin matrix. A transition layer of a first epoxy resin is applied to the skin layer. The skin structure including the skin layer and transition layer is cured at a first temperature and post cured at a second temperature greater than the first temperature. A bonding layer of a second epoxy resin is thereafter applied to the bonding surface of the transition layer, and a substrate is contacted to the exposed face of the bonding layer. The second epoxy resin is cured at a third temperature no greater than the first temperature.

Abstract: A locking mechanism for locking an orientation of a weapon is disclosed. The locking mechanism includes a first movable arm adapted to contact and apply pressure onto a control surface associated with the weapon, and a second movable arm adapted to contact and apply pressure onto the control surface associated with the weapon. The locking mechanism further includes a valve for applying and removing resistance to the first movable arm and the second movable arm, to thereby control a resistance to movement of the first movable arm and the second movable arm. The valve is adapted to remove resistance from the first movable arm and the second moveable arm in order to allow the weapon to be moved freely into a desired orientation. After the weapon is moved into the desired orientation, the valve may be moved again to increase resistance to thereby allow for fine adjustments in the orientation of the weapon. Finally, the valve may be completely closed to lock the orientation of the weapon.

Abstract: A low-profile transportation and storage assembly is readily substitutable with a conventional pair of skid landing gear. The low-profile transportation and storage assembly includes a front auxiliary crosstube having low-profile wheels attached to opposing ends of the front auxiliary crosstube, and a rear auxiliary crosstube having low-profile wheels attached to opposing ends of the rear auxiliary crosstube. Both the front auxiliary crosstube and the rear auxiliary crosstube are readily substitutable with the pair of skid landing gear of a conventional helicopter. A pair of front saddle mounts and a pair of rear saddle mounts secure the front crosstube and the back crosstube of the pair of skid landing gear to the helicopter. The pair of front saddle mounts and the pair of rear saddle mounts can be quickly removed from the aft crosstube and the forward crosstube by removal of expandable bushing fittings of the saddle mounts.

Abstract: An apparatus for compensating for spatial phase angle phase errors in the flapping angle oscillations of a rotor blade is disclosed. The apparatus receives a measured aircraft roll and a measured aircraft pitch. Gyroscopic moments resulting from these measured rolls and pitches are determined, and compensating gyroscopic moments are then generated and summed with commanded pitch and roll accelerations. Flapping angle phase lags of the rotor blade swashplate are added to the summed signals to cancel any flapping angle phase leads, caused by changes in aircraft or rotor blade speed caused by installation configurations of the rotor blade swashplate.

Abstract: A conversion access gearset includes a first bevel gear, which is connected to a wing cross shaft leading from the proprotor drive train path to the second turbine engine. A second bevel gear is connected to a main transmission input shaft, which is adapted for driving the proprotor. A bevel pinion receives power from the turbine engine, and drives both the first bevel gear and the second bevel gear. An input pinion is connected between the turbine engine and the bevel pinion, and several idler gears are connected between the input pinion and the bevel pinion. A helical gear is connected between the several idler gears and the bevel pinion. The main transmission input shaft is connected to a main transmission input pinion, which is located on the main transmission input shaft opposite of the second bevel gear. The main transmission input pinion receives torque from the main transmission input shaft, and a torque-splitting device splits the torque received from the main transmission input pinion.

Abstract: A concentric face gear assembly includes a first face gear having first face gear teeth and second face gear having second face gear teeth. At least one input pinion contacts both the first face gear teeth and the second face gear teeth, and at least one idler pinion contacts both the first face gear teeth and the second face gear teeth. The first face gear is adapted for directly driving a rotor, but the second face gear is not adapted for directly driving a rotor. The load carried by the first face gear includes the force needed to drive the rotor. Since it does not drive a rotor, the second face gear does not comprise a web or spline attachment and is therefore lightweight. Both the first face gear and the second face gear include thrust bearings, which are located radially outwardly of the first face gear teeth and radially inwardly of the second face gear teeth.

Abstract: An apparatus for compensating for spatial phase angle phase errors in the flapping angle oscillations of a rotor blade is disclosed. The apparatus receives a measured aircraft roll and a measured aircraft pitch. Gyroscopic moments resulting from these measured rolls and pitches are determined, and compensating gyroscopic moments are then generated and summed with commanded pitch and roll accelerations. Flapping angle phase lags of the rotor blade swashplate are added to the summed signals to cancel any flapping angle phase leads, caused by changes in aircraft or rotor blade speed caused by installation configurations of the rotor blade swashplate.

Abstract: An active control device is disclosed for modifying a tip vortex on a lifting body. The lifting body includes a positive-pressure generating structure and a negative-pressure generating structure, and is adapted for providing lift when a first fluid pressure adjacent to the positive-pressure generating structure is greater than a second fluid pressure adjacent to the negative-pressure generating structure. The active control device includes a fluid source adapted for providing a positive pressure of fluid, such as air, to an interior of the lifting body. The active control device further includes a fluid router, which is disposed on the lifting body and which is adapted for directing a portion of the positive pressure of fluid out of the interior of the lifting body and in a general direction from the fluid router toward the positive-pressure generating structure of the lifting body. The lifting body may be either a rotorcraft blade, an aircraft foil, or a marine foil such as a marine propeller.

Abstract: A nozzle for use on opposing ends of the rotor of a jet powered tri-mode aircraft is disclosed. The nozzle includes two thermally-controlled doors, which are moveable between an open configuration where hot jet engine exhaust is vented therethrough to propel the rotor in a helicopter mode, and a second closed configuration where the two doors are tightly sealed to provide a stable aerodynamic surface for the rotor when the jet powered tri-mode aircraft is operating in an airplane mode. The two doors are thermally-activated by an internal surrounding temperature, such that they remain open by the hot jet engine exhaust passing thereby in the helicopter mode, and remain shut by resulting cooler air when the hot jet engine exhaust is not routed by the two nozzle doors.

Abstract: The present invention provides a slotted cam control system for controlling pitch angles of fan blades of a relatively low-pressure-ratio fan within a fuselage of a helicopter. The stream of air generated by the fan is directed into the tailboom of the helicopter, and is selectively discharged through the circulation control tailboom and left and right openings of a direct jet thruster. A force-receiving arm of a slotted cam control system receives left and right forces from corresponding left and right foot rudder pedals. An end of the force-receiving arm fits into a V-shaped cam. When the pilot depressed a left foot rudder pedal and releases a right foot rudder pedal, for example, the end of the force receiving-arm is first moved along a first predetermined distance of the V-shaped cam in order to decrease the pitch angles of the fan blades while the opening of the direct jet thruster corresponding to the released foot rudder pedal is closed.

Abstract: A failure of any one of three swashplate actuators of a helicopter rotor blade is detected. Once such a detection is made, the position of this nonfunctional swashplate is locked and measured. The inputted commanded swashplate collective position, commanded swashplate x-axis rotational position, and commanded swashplate y-axis rotational position are then passed to a failure-mode control matrix. The failure-mode control matrix computes swashplate actuator commanded positions for the two operable swashplate actuators so that aircraft attitude control is maintained. These two swashplate actuator commanded positions instruct positional movement of the rotor blade swashplate to thereby meet the commanded swashplate x-axis rotational position and the commanded swashplate y-axis rotational position which will control attitude. A quasi-swashplate-collective-position corrector computes the quasi-swashplate collective position that will occur because of the successful control of the aircraft's attitude.

Abstract: The present invention provides a desired design approach for retuning a rotorcraft airframe by utilizing resilient connections between major airframe components. In the preferred embodiment, the design employs resilient material, preferably elastomeric material, in the mounting system between the vertical tail and the tailboom of a helicopter as a method of providing dynamic detuning of the tailboom torsion/lateral mode. Other possibilities include similarly mounting the horizontal stabilator and the wing onto the airframe. Using elastomeric or similar devices to soft mount the vertical tail of a helicopter on the tailboom can efficiently and effectively alter the natural frequencies of the entire aircraft. By choosing the spring constant of this connection, the designer can place fuselage frequency at a desired value.

Abstract: A method for making helicopter rotor blades includes wrapping a prepreg strap around the conical or cylindrical outboard end of each weight segment. The weight segment is then placed in the rotor blade spar and goes through the spar cure cycle with it. Primary retention is provided by adhesive bonding between the weight and the spar. Secondary retention is by hoop tension in the strap, acting through interlaminar shears at the co-cured interface with the spar.

Abstract: An active control device for reducing blade-vortex interactions (BVI) noise generated by a rotorcraft, such as a helicopter, comprises a trailing edge flap located near the tip of each of the rotorcraft's rotor blades. The flap may be actuated in any conventional way, and is scheduled to be actuated to a deflected position during rotation of the rotor blade through predetermined regions of the rotor azimuth, and is further scheduled to be actuated to a retracted position through the remaining regions of the rotor azimuth. Through the careful azimuth-dependent deployment and retraction of the flap over the rotor disk, blade tip vortices which are the primary source for BVI noise are (a) made weaker and (b) pushed farther away from the rotor disk (that is, larger blade-vortex separation distances are achieved).

Abstract: A cable assembly is described, which includes a bundle of wires (14, FIG. 1) and a shield structure (24) around them which is of light weight for aircraft applications, and which provides effective shielding especially against electromagnetic interference. The shield structure includes a metal braiding (32) sandwiched between radially outer and inner shrink tubes (34, 30), with each shrink tube having an electrically conductive coating (42, 40) in contact with the metal braiding. The inner shrink tube, which has a conductive coating on its outside surface, is initially shrunk around the bundle of wires to stabilize their positions. The tubular wire braiding is installed around the inner shrink tube and the outer shrink tube which has a conductive coating on its radially inner surface, is placed around the braiding. Then, the outer shrink is tube is heat shrunk in place. Sandwiching the wire braiding between two metal coatings provides enhanced interference protection.

Abstract: Leading edge weights for helicopter rotor blades are required to provide blade chordwise balance and maintain rotor inertia. Provision for retention of the leading edge weights in a high centrifugal force field, after failure of the primary adhesive bond, is necessary. The invention discloses wrapping a prepreg strap around the conical or cylindrical outboard end of each weight segment. The weight segment is then placed in the rotor blade spar and goes through the spar cure cycle with it. Primary retention is provided by adhesive bonding between the weight and the spar. Secondary retention is by hoop tension in the strap, acting through interlaminar shears at the co-cured interface with the spar.