Sikorsky Aircraft Corporation

United Technologies Corporation

Robert C Moffitt

Peter F Lorber

Brian Ernest Wake

Evan A Fradenburgh

Michael S Torok

Ashish Bagai

William Arthur Welsh

Robert D Beatty

Geoffrey C R Davis

Andreas P F Bernhard

Thomas Alan Egolf

Joseph A Visintainer

Justin J Thomas

David H Hunter

Steven D Weiner

Timothy A Krauss

David G Matuska

Ray-Sing Lin

Charles R Berezin

Stephen J Owen

Edward W Gronenthal

Robert H Blackwell, Jr

James E Duh

Nicholas Charles Tuozzo

John K Karpowich

Shawn Westfall

S Jon Davis

David G Matsuka

William D Jepson

Nick Tuozzo

A main rotor blade assembly for a rotary wing aircraft is provided including a main rotor blade root region, a main rotor blade inboard region arranged outboard of said main rotor blade root region, a main rotor blade main region arranged outboard of said main rotor blade inboard region, and a main rotor blade tip region arranged outboard of said main rotor blade main region. At least one of chord, twist, sweep, airfoil shape, and thickness/chord of the main rotor blade assembly has been optimized to achieve balanced high speed forward flight and hover relative to both efficiency and high thrust capability.

Dual rotor, rotary wing aircraft

A main rotor blade assembly with a high negative pitching moment airfoil section having a pitching moment coefficient beyond (more negative than) &#x2212;0.035 at Mach Numbers below 0.80 and a blade taper of 1:5 or greater.. The main rotor blade preferably limits blade torsional bending and an aft loaded tip airfoils to approximately 'no more' than that of conventional effective rotor blade designs based on conventional tip airfoil sections.

Rotor blade assembly with high pitching moment airfoil section for a rotary wing aircraft

A main rotor blade incorporating a rotor blade tip region having a tip chord and a tip taper such that the ratio of the main rotor blade chord to the tip chord is approximately 0.30. The tip taper ratio preferably providing an approximately 28% area of reduction in said outer 10% of said blade span. The tip region preferably further including a hover optimized high lift airfoil and a tip sweep that reaches a constant value of approximately 30 degrees along the quarter chord line.

Rotor blade tip planform

A main rotor blade exhibiting a unique planform shape in which the blade chord increases from the root end of the blade inboard region to the outer main region of the blade, where the blade chord achieves a maximum chord at a spanwise location within the main region, then decreases toward a distal tip end. The leading edge preferably is generally straight while the trailing edge is contoured to define the chord. Another characteristic feature of the rotor blade design is the location of the blade-feathering axis in which the feathering axis is located at a mid chord position over some inboard length of the rotor blade then transitions to a quarter chord location. Another characteristic feature is an airfoil distribution along the blade span that transitions from a blunt trailing edge to a sharp trailing edge airfoil suited for mid-range Mach number operation. The tip region preferably utilizes a transonic flow airfoil. Another characteristic feature of the rotor blade design is an unconventional combination of positive and negative twist gradients.

Rotor blade for a high speed rotary-wing aircraft

A multi-element rotor blade includes an individually controllable main element and fixed aerodynamic surface in an aerodynamically efficient location relative to the main element. The main element is controlled to locate the fixed aerodynamic surface in a position to increase lift and/or reduce drag upon the main element at various azimuthal positions during rotation.

Active control of multi-element rotor blade airfoils

A leading edge slat for multi-element rotor blade applications which provide multiple benefits and provide design direction which has heretofore been unexplored.

Leading edge slat airfoil for multi-element rotor blade airfoils

A multi-element rotor blade includes a main element and an active slat movable relative to the main element. The slat rotates and translates relative to the main element from a base position. The base position provides a compromise between minimum coefficient of drag C and maximum coefficient of lift C . In the advancing blade, since the airspeed thereof is significantly greater than the retreating blade, the slat is positively rotated from the base position to minimizes drag at low angles of attack. In the retreating blade, since the airspeed thereof is significantly lower than the advancing blade, the slat is negatively rotated and translated to maximize the coefficient of lift C .

An elastomeric coupler assembly having a helical elastomeric bearing movably supports an active slat relative to a main element. An inner elastomeric coupler assembly and an outer elastomeric coupler assembly support the slat therebetween. Centrifugal force operates to drive the slat to a first position and an actuator rod operates in tension to pull upon the inner elastomeric coupler assembly to drive the slat in opposition to the centrifugal force to a second position. The helical elastomeric bearing is layered such that it defines a section of a circular helix. The circular helix provides a coupling, which converts a linear input parallel to a virtual hinge axis into a rotary output to pitch the slat. In operation, centrifugal force operates to slide the slat outboard toward the blade tip such that the attached slat moves elastomerically along the helical arc of the helical elastomeric bearing to rotate the slat nose down. To retract the slat, the actuator operates to place the actuator rod under tension to pull upon the active member and retract the slat in opposition to centrifugal force.

Directional elastomeric coupler

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 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 mechanism (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 mechanism (70) includes a centrifugal restraint assembly (80) disposed within each internal chamber (64), a stop surface (64s) formed internally of each internal chamber (64), and an actuation mechanism (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 mechanism (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). The actuation mechanism includes a reeling assembly (110) having a cylindrical drum (112) disposed internally of the rotor assembly (8), end fixities (114) disposed internally of the chambers (64) and operative for engaging and disengaging the centrifugal restraint assembly (80), straps (116) for mechanically coupling the end fixities (114) to the cylindrical drum (112), and a drive mechanism (120) for effecting rotation of the cylindrical drum (112).

A rotor system (4) having odd and even blade assemblies (O.sub.b, E.sub.b) mounting to and rotating with a rotor hub assembly (6) wherein the odd blade assemblies (O.sub.b) define a radial length R.sub.O, and the even blade assemblies (E.sub.b) define a radial length R.sub.E and wherein the radial length R.sub.E is between about 70% to about 95% of the radial length R.sub.O. Other embodiments of the invention are directed to a Variable Diameter Rotor system (4) which may be configured for operating in various operating modes for optimizing aerodynamic and acoustic performance. The Variable Diameter Rotor system (4) includes odd and even blade assemblies (O.sub.b, E.sub.b) having inboard and outboard blade sections (10, 12) wherein the outboard blade sections (12) telescopically mount to the inboard blade sections (10). The outboard blade sections (12) are positioned with respect to the inboard blade sections (10 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.

Rotor system having alternating length rotor blades for reducing

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. When in the forward flight cruise mode, the inboard equivalent twist increment allows operation of the inboard airfoil sections at higher pitch angles to reduce negative lift regions and increase cruise propulsion efficiency.

Variable diameter rotor having an offset twist

An unmanned aerial vehicle having a toroidal fuselage that surrounds a pair of coaxial, multi-bladed, counter-rotating rotors. The toroidal fuselage has an airfoil profile that is optimized to provide high hover efficiency and produce a pressure distribution that provide high lift forces. The airfoil profile is further optimized to counteract the undesirable nose-up pitching moments experienced by ducted rotary-type UAVs in forward translational flight.

Shroud geometry for unmanned aerial vehicles

A shroud-fin integration shelf for a helicopter empennage structure that includes a shroud embodying a ducted fan antitorque device, a vertical stabilizer contiguous with the shroud, and a horizontal stabilizer intersecting the vertical stabilizer. The shroud-fin integration shelf is structurally configured and dimensioned to eliminate adverse aerodynamic effects experienced by the vertical stabilizer in reverse thrust operating conditions wherein mass airflow exiting the ducted fan antitorque device may flow along the shroud and interfere with longitudinal mass airflow over the suction surface of the vertical stabilizer. The integration shelf, which provides an acute transition between the shroud and the vertical stabilizer, has an overall predetermined width that includes a first shelf width on the ducted fan antitorque device inlet side of the empennage structure and a second shelf width on the opposite side of the empennage structure. The first shelf width is greater than the second shelf width to ensure attached mass airflow over the shroud is sharply separated at the shroud - shroud-fin integration shelf. The first and second shelf widths have dimensional magnitudes in the range of about four percent to about sixteen percent of the diameter of the fan assembly of the ducted fan antitorque device. Preferably, the shroud edge defining the structural boundary between the shroud and the shroud-fin integration shelf is sharp, i.e., approximately ninety degrees. The empennage structure also includes an aft shroud closure having a generally 'V' shaped configuration to fix the separation points of mass airflow over the aft portions of the shroud.

Shroud-fin integration shelf for a helicopter empennage structure

A helicopter blade of moderate 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.

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Seymour, CT, United States of America

Robert C Moffitt