# US 2015/0147181 A1 · Differential blade design for propeller noise reduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0147181 A1 - Document ID: US20150147181A1 - Status: Published application - Kind: A1 - Application number: 14/091,700 - Filed: 2013-11-27 - Published: 2015-05-28 - Earliest claimed: 2013-11-27 - Assignees: Hamilton Sundstrand Corporation - Applicants: Hamilton Sundstrand Corporation - Inventors: Chad M. Henze; Daniel W. Shannon; Robert Hans Schlinker - Web page: https://patentgrep.com/patent/US20150147181A1 ## 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 11/18: Aerodynamic features - 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 propeller is provided including a hub and a first blade group and a second blade group. The first blade group includes at least one first propeller blade and the second blade group includes at least one second propeller blade. The at least one first propeller blade and the at least one second propeller blade are mounted to and equidistantly spaced about the hub. The at least one first propeller blade of the first blade group has at least one geometric characteristic different from the at least one propeller blade of the second blade group. The different blade groups will generate different noise signatures over a wider range of frequencies allowing for the design of low noise propeller systems. ## Claims ### Claim 1 A propeller comprising: a hub; a first blade group having at least one first propeller blade; and a second blade group having at least one second propeller blade, the at least one first propeller blade and the at least one second propeller blade being mounted to and equidistantly spaced about the hub, wherein the at least one first propeller blade of the first blade group has at least one geometric characteristic different from the at least one second propeller blade of the second blade group. ### Claim 2 (depends on 1) The propeller according to claim 1, wherein the geometric characteristic is one of length, chord, camber, blade angle, and twist. ### Claim 3 (depends on 2) The propeller according to claim 2, wherein each of the first propeller blades of the first blade group are substantially identical and each of the second propeller blades of the second blade group are substantially identical. ### Claim 4 (depends on 3) The propeller according to claim 3, further comprising a third blade group having at least one third propeller blade mounted to and equidistantly spaced about the hub, where each of the third propeller blades of the third blade group are substantially identical. ### Claim 5 (depends on 4) The propeller according to claim 4, wherein at least one geometric characteristic of the at least one first propeller blade of the first blade group is different from the at least one third propeller blade of the third blade group. ### Claim 6 (depends on 5) The propeller according to claim 5, wherein the at least one second propeller blade of the second blade group and the at least one third propeller blade of the third blade group are substantially identical. ### Claim 7 (depends on 5) The propeller according to claim 5, wherein at least one geometric characteristic of the at least one second propeller blade of the second blade group is different from the at least one third propeller blade of the third blade group. ### Claim 8 (depends on 5) The propeller according to claim 5, further comprising a fourth blade group having at least one fourth propeller blade mounted to and equidistantly spaced about the hub, where each of the fourth propeller blades of the fourth blade group are substantially identical. ### Claim 9 (depends on 8) The propeller according to claim 8, wherein at least one geometric characteristic of the at least one first propeller blade of the first blade group is different from the at least one fourth propeller blade of the fourth blade group. ### Claim 10 (depends on 9) The propeller according to claim 9, wherein at least one geometric characteristic of the at least one second propeller blade of the second blade group is different from the at least one third propeller blade of the third blade group and the at least fourth propeller blade of the fourth blade group. ### Claim 11 (depends on 10) The propeller according to claim 10, wherein at least one geometric characteristic of the at least one third propeller blade of the third blade group is different from the at least one fourth propeller blade of the fourth blade group. ### Claim 12 A propeller comprising: a hub; a first blade group having at least one first propeller blade; and a second blade group having at least one second propeller blade, each of the first propeller blades being substantially identical and each of the second propeller blades being substantially identical, the at least one first propeller blade and the at least one second propeller blade being mounted to and equidistantly spaced about the hub, wherein the at least one first propeller blade of the first blade group is configured to generate noise at a first noise signature and the at least one second propeller blade of the second blade group is configured to generate noise at a second noise signature, the first noise signature and the second noise signature being different from one another. ### Claim 13 (depends on 12) The propeller according to claim 12, further comprising a third blade group having at least one third propeller blade, each third propeller blade being substantially identical, the at least one third propeller blade being mounted to and equidistantly spaced about the hub, the at least one third propeller blade of the third blade group being configured to generate noise at a third noise signature. ### Claim 14 (depends on 13) The propeller according to claim 13, further comprising a fourth blade group having at least one fourth propeller blade, each fourth propeller blade being substantially identical, the at least one fourth propeller blade being mounted to and equidistantly spaced about the hub, the at least one fourth propeller blade of the fourth blade group being configured to generate noise at a fourth noise signature. ### Claim 15 (depends on 14) The propeller according to claim 14, wherein each of the first noise signature, second noise signature, third noise signature, and fourth noise signature are substantially different.