Sikorsky Aircraft Corporation

United Technologies Corporation

US Government As Represented by the Secretary of the Army

David G Matuska

Donald L Ferris

Evan A Fradenburgh

Donald S Anttila

Edward W Gronenthal

Timothy Fred Lauder

Vineet Sahasrabudhe

Robert C Moffitt

Evan A Fredenburgh

W Donald Jepson

Brad J Kronauer

A method of obstacle avoidance for a rotary wing aircraft includes detecting an obstacle proximate to the aircraft and commanding a servo to generate a force to an input control device in a direction that tends to preclude the aircraft from contacting the detected obstacle, the command having lesser authority than a pilot input command.

Rotary wing aircraft flight control system with a proximity cueing and avoidance system

A safety enhancement warning system includes an avoidance system which communicates with a multiple of geographical positional systems. A geographic algorithm of the avoidance system utilizes a recursive algorithmic to determine if the aircraft will enter a sensitive area. If the aircraft distance to a sensitive area decreases below a predefined minimum threshold, then an audible and/or visual warning is issued. For certain sensitive areas, aircraft RF emissions are silenced or reduced in power when the predetermined minimum threshold breaches the sensitive area. The use of the avoidance system enables usage of relatively inexpensive UWB radar for the proximity sensor suite to assure avoidance of interference with particular delicate instruments and thereby meet regulations such as those propagated by the FCC.

Rotary wing aircraft proximity warning system with a geographically based avoidance system

Variable diameter tilt rotor aircraft

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.b), a stop surface (64s) formed internally of each internal chamber (64), and an actuation means (90) operative for transpositioning the centrifugal restraint assemblies (80) within the internal chambers (64) such that, in one operating mode, the centrifugal restraint assemblies (80) are disposed in abutting engagement with the stop surfaces (64s) and, in another operating mode, the actuation means (90) is disposed in abutting engagement with the centrifugal restraint assemblies (80) of at least one of the blade assemblies (O.sub.b, E.sub.b).

Rotor system having alternating length rotor blades and positioning

A retraction/extension mechanism (70) for a Variable Diameter Rotor system (10), the Variable Diameter Rotor system (10) having a plurality of rotor blade assemblies (16) mounted to and rotating with a rotor hub assembly (18) about an axis of rotation (20), each rotor blade assembly (16) having inboard and outboard blade sections (24, 22) wherein the outboard blade section (22) telescopically mounts to the inboard blade section (24). The retraction/extension mechanism (70) includes a reeling assembly (80) disposed in combination with the outboard blade section (22) of each rotor blade assembly (16) and an epicyclic gear train (100) disposed in combination 7ith the rotor hub assembly (18) and the reeling assembly (80). The epicylic gea2 train is, furthermore, operative for driving the reeling assembly (80) so as to effect telescopic transition of the outboard blade sections (22) with respect to the inboard blade sections (24).

Retraction/extension mechanism for variable diameter rotors

A torque tube/spar assembly (100) for transferring operational loads of a Variable Diameter Rotor blade assembly (16) to a rotor hub assembly (18) and includes a torque tube member (24), a spar member (30) and a bearing assembly (40a, 40b) for telescopically mounting the spar member (30) to the torque tube member (24) and furthermore defines an internal channel (62) for housing a retraction/extension mechanism (64) which mounts to an internally formed restraint surface (86) of the spar member (30) and is operative to vary the length of the rotor blade assembly (18). The torque tube member (30) has a substantially constant external geometry along the length of bearing assembly engagement and defines a root end region (102), a tip end region (106) and an intermediate transition region (104) disposed therebetween. The spar member (30) has a substantially constant internal geometry and defines a root end region (110), a first transition (112), an intermediate region (114), a second transition region (116), a restraint region (118) and a tip end region (120). Each of the various regions of the torque tube and spar members (24, 30) have a characteristic stiffness value wherein the characteristic values (104m, 106m) of the intermediate transition and tip end regions (104,106) of the torque tube member (24) are less than the characteristic stiffness value (102m) of the root end region (102) thereof, and wherein the characteristic stiffness value (118m) of the restraint region (118) of the spar member (30) is greater than said characteristic stiffness values (114m, 120m) of the intermediate and tip end regions (114, 120) thereof, and wherein the characteristic stiffness value (114m) of the intermediate region (114) is less than the characteristic stiffness values (110m, 112m, 116m, 118m) of the root end, first transition, second transition and restraint regions (110, 112, 116, 118).

Torque tube/spar assembly for variable diameter helicopter rotors

A major design consideration in helicopters is that of compensating for ssses on blades resulting from air forces during blade revolutions. Spinning rotor blades are severely stressed. To some degree conventional articulated helicopter rotor hubs overcome vibration difficulties, but high maintenance is a problem. Hingeless helicopter rotor assemblies, generally employing composite materials, were developed to overcome these obstacles. Such hingeless helicopter rotor assemblies usually include a rigid central hub member, and radial flexbeams rigidly attached to the hub member. Flexbeam rotors do not completely eliminate the dynamic instability difficulty. Even using these designs energy must be absorbed by damping means. The shear principle of damping is utilized in this invention.

Apparatus for damping helicopter rotor blade oscillations

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 surround 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. The structure is cured by molding with sufficient heat and temperature in a controlled cure cycle. The structure does not exhibit 'oil-canning' in that the flat diaphragm or diaphragm sides do not displace from the substantially flat uniplanar mode when subjected to varying temperatures. The spring characteristics of the structure when constrained as a torque drive remain approximately linear and buckling and snap-through are eliminated during operation.

Filament wound structure for use as a torque drive

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, a rim, rim reinforcement fibers and at least one fiber reinforcement ring. The diaphragm has a central attachment means for receiving a shaft and the rim has an attachment means. An alternative embodiment of the structure is a hollow disc having first and second substantially flat diaphragm sides with a connecting rim, rim reinforcement fibers and at least one fiber reinforcing ring for each diaphragm side. The sides have centrally located attachment means. The structure comprises a resin matrix, fibers wound substantially tangentially to the central attachment means with sufficient tension in a multiple circuit pattern to form the structure, fibers wound with sufficient tension in an essentially circumferential manner to reinforce the rim of the structure and fibers wound substantially circularly to form rings for reinforcing the diaphragm. The structure is cured by molding with sufficient heat and temperature in a controlled cure cycle. The structure does not exhibit 'oil-canning' in that the flat diaphragm or diaphragm sides do not displace from the substantially flat uniplanar mode when subjected to varying temperatures. In addition, the structure does not buckle under heavy torque loading. The spring characteristics of the structure when constrained as a torque drive remain approximately linear and buckling and snap-through are eliminated during operation.

Filament wound structure having filament wound reinforcing rings for use

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. The structure is cured by molding with sufficient heat and temperature in a controlled cure cycle. The structure does not exhibit 'oil-canning' in that the flat diaphragm or diaphragm sides do not displace from the substantially flat uniplanar mode when subjected to varying temperatures. The spring characteristics of the structure when constrained as a torque drive remain approximately linear and buckling and snap-through are eliminated during operation.

Apparatus for damping blade lead/lag motion on a hingeless helicopter rotor assembly, including a hub, blades and flexbeam(s) interposed between the root end of the blades and the hub. Rigid, radial links extend the length of the flexbeams for attachment to the outboard ends thereof. Lead/lag motion at the outboard end of the flexbeam causes flexbeam bending, which is converted to radial translation of the links. This radial translation of the links and likewise the blade lead/lag motion is damped by damper means connected between the inboard ends of the links and the hub.

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Huntington, CT, United States of America

David G Matuska