# US 2014/0154084 A1 · Non-uniform blade distribution for rotary wing aircraft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154084 A1 - Document ID: US20140154084A1 - Status: Published application - Kind: A1 - Application number: 13/689,941 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Sikorsky Aircraft Corporation - Inventors: Mark R. Alber - Web page: https://patentgrep.com/patent/US20140154084A1 ## CPC - F01D 5/02: Blade-carrying members, e.g. rotors (rotors of non-bladed type F01D1/34; stators F01D9/00 {; selecting particular materials F01D5/28}) - B64C 27/22: Compound rotorcraft, i.e. aircraft using in flight the features of both aeroplane and rotorcraft - B64C 27/82: characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft - B64C 2027/8236: {including pusher propellers} - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - B64C: AEROPLANES; HELICOPTERS ## Abstract A translational thrust system for a rotary wing aircraft is provided including a propeller system. The propeller system includes more than one pair of propeller blades extending radially outward from a rotatable propeller hub. Each pair of propeller blades includes a first propeller blade and a second propeller blade arranged diametrically opposite one another about a circumference of the propeller hub. Each pair of propeller blades is arranged at an angle to an adjacent pair of propeller blades such that the angle is less than is the pairs of propeller blades were uniformly distributed around the circumference of the propeller hub. ## Claims ### Claim 1 A translational thrust system for a rotary wing aircraft comprising: a propeller system having more than one pair of propeller blades extending radially outward from a rotatable propeller hub, wherein each pair of propeller blades includes a first propeller blade and a second propeller blade arranged diametrically opposite one another about a circumference of the propeller hub, and each pair of propeller blades is arranged at an angle to an adjacent pair of propeller blades such that the angle is less than if the pairs of propeller blades were uniformly distributed around the circumference of the propeller hub. ### Claim 2 (depends on 1) The translational thrust system according to claim 1, wherein the first propeller blade and the second propeller blade of each pair are substantially identical. ### Claim 3 (depends on 1) The translational thrust system according to claim 1, wherein the propeller system includes at least two pairs of propeller blades, and the angles formed between each pair of adjacent first propeller blades are generally equal. ### Claim 4 (depends on 1) The translational thrust system according to claim 1, wherein the pairs of propeller blades are indexed about a horizontal axis such that when the hub is stationary a clearance exists between the propeller blades and a surface below the translational thrust system. ### Claim 5 (depends on 1) The translational thrust system according to claim 1, wherein the propeller system is a pusher propeller system. ### Claim 6 (depends on 1) The translational thrust system according to claim 1, wherein the first propeller blades and the second propeller blades are arranged within a plane. ### Claim 7 (depends on 6) The translational thrust system according to claim 6, wherein each first propeller blade and each second propeller blade is configured to rotate within the plane relative to the hub. ### Claim 8 A rotary wing aircraft comprising: an airframe; at least one rotor system; a propeller system mounted to a tail end of the air frame, the propeller system including more than one pair of propeller blades extending radially outward from a central rotatable hub, and each pair of propeller blades is arranged at an angle to an adjacent pair of propeller blades such that the angle is less than if the pairs of propeller blades were uniformly distributed around a circumference of the propeller hub; wherein a first vertical clearance exists between the hub and the rotor system, and a second vertical clearance exists between the hub and a surface below the rotary wing aircraft, and the first vertical clearance is larger than the second vertical clearance. ### Claim 9 (depends on 8) The rotary wing aircraft according to claim 8, wherein each pair of propeller blades includes a first propeller blade and a second propeller blade mounted diametrically opposite one another about the hub. ### Claim 10 (depends on 9) The rotary wing aircraft according to claim 9, wherein the first propeller blade and the second propeller blade of each pair are substantially identical. ### Claim 11 (depends on 9) The rotary wing aircraft according to claim 9, wherein a length of each first propeller blade and each second propeller blade is about equal to the first vertical clearance. ### Claim 12 (depends on 9) The rotary wing aircraft according to claim 9, wherein the propeller system includes at least two pairs of propeller blades, and the angles formed between each pair of adjacent first propeller blades are generally equal. ### Claim 13 (depends on 8) The rotary wing aircraft according to claim 8, wherein the pairs of propeller blades are indexed about a horizontal axis, parallel to the surface below the rotary wing aircraft, when the rotary wing aircraft is stationary. ### Claim 14 (depends on 8) The rotary wing aircraft according to claim 8, wherein the propeller system is a pusher propeller system. ### Claim 15 (depends on 9) The translational thrust system according to claim 9, wherein the first propeller blades and the second propeller blades are arranged within a plane. ### Claim 16 (depends on 15) The translational thrust system according to claim 15, wherein each first propeller blade and each second propeller blade is configured to rotate within the plane relative to the hub.