# US 8,540,481 B2 · Rotor blade assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,540,481 B2 - Document ID: US8540481B2 - Status: Granted - Kind: B2 - Application number: 12/758,856 - Filed: 2010-04-13 - Published: 2011-10-13 - Granted: 2013-09-24 - Earliest claimed: 2010-04-13 - Assignees: ROLLS-ROYCE plc - Applicants: Daniel Kent Vetters - Inventors: Daniel Kent Vetters - Web page: https://patentgrep.com/patent/US8540481B2 ## CPC - F01D 5/282: {Selecting composite materials, e.g. blades with reinforcing filaments} - B64C 11/205: {for protecting blades, e.g. coating} - B64D 27/00: Arrangement or mounting of power plants in aircraft; Aircraft characterised by the type or position of power plants - F01D 5/288: {Protective coatings for blades} - F02K 3/06: with front fan - F04D 29/023: {especially adapted for elastic fluid pumps} - F04D 29/324: {Blades} - B64D 2027/005: {Aircraft with an unducted turbofan comprising contra-rotating rotors, e.g. contra-rotating open rotors [CROR]} - F05D 2300/603: Composites; e.g. fibre-reinforced - Y02E 10/72: Wind turbines with rotation axis in wind direction - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - Y10T 29/49337: Composite blade - 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 - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A rotor blade assembly is disclosed herein. The rotor blade assembly includes a composite blade portion extending a length from a root to a tip. A leading edge of the composite blade portion extends from the tip to an end point along the length between the tip and the root. The rotor blade assembly also includes a base portion fixed to the composite blade portion proximate to the root. The rotor blade assembly also includes a sheath extending around the composite blade portion. The sheath is positioned along the length adjacent to the base portion and between the root and the end point of the leading edge. ## Claims ### Claim 1 A rotor blade assembly comprising: a composite blade portion extending a length from a root to a tip, wherein a leading edge of said composite blade portion extends from said tip to an end point along said length between said tip and said root; a base portion fixed to said composite blade portion proximate to said root; and a sheath extending around said composite blade portion and positioned along said length adjacent to said base portion and between said root and said end point of said leading edge, wherein said sheath is spaced apart from said composite blade portion by a gap therebetween that extends along the length; and wherein said sheath is mounted on said base portion and/or wherein said sheath is mounted on said composite blade portion. ### Claim 2 (depends on 1) The rotor blade assembly of claim 1 wherein said sheath is spaced outwardly from said composite blade portion along all of a portion of said length between said root and said end point of said leading edge. ### Claim 3 (depends on 1) The rotor blade assembly of claim 1 wherein said sheath is spaced outwardly from said composite blade portion about the entire perimeter of said composite blade portion. ### Claim 4 (depends on 1) The rotor blade assembly of claim 1 wherein said sheath is spaced outwardly from said composite blade portion about a majority of the entire perimeter of said composite blade portion along at least part of a portion of said length between said root and said end point of said leading edge. ### Claim 5 (depends on 1) The rotor blade assembly of claim 1 wherein said sheath includes first and second halves respectively mountable on opposite sides of said composite blade portion. ### Claim 6 (depends on 1) The rotor blade assembly of claim 1 further comprising: a conduit including an opening positioned in the gap between said sheath and said composite blade portion along all of a portion of said length between said root and said end point of said leading edge. ### Claim 7 (depends on 6) The rotor blade assembly of claim 6 wherein said conduit extends through said composite blade portion along at least part of said length between said root and said end point of said leading edge. ### Claim 8 (depends on 6) The rotor blade assembly of claim 6 wherein said conduit is spaced from said composite blade portion along most of a portion of said length between said root and said end point of said leading edge. ### Claim 9 (depends on 6) The rotor blade assembly of claim 6 further comprising at least one aperture defined at least in part by said sheath, wherein said at least one aperture is operable to exhaust fluid directed into said gap by said conduit. ### Claim 10 (depends on 9) The rotor blade assembly of claim 9 wherein said at least one aperture is further defined as a plurality of apertures formed in said sheath and arranged about a perimeter of said composite blade portion. ### Claim 11 (depends on 9) The rotor blade assembly of claim 9 wherein said at least one aperture is further defined as formed in part by said sheath and in part by said composite blade portion. ### Claim 12 A method comprising the steps of: extending a composite blade portion a length from a root to a tip, wherein a leading edge of the composite blade portion extends from the tip to an end point along the length between the tip and the root; fixing a base portion to the composite blade portion proximate to the root; extending a sheath around the composite blade portion and positioned along the length adjacent to the base portion and between the root and the end point of the leading edge, wherein said sheath is spaced apart from said composite blade portion by a gap therebetween that extends along the length; and releasably connecting the sheath to at least one of the base portion and the composite blade portion. ### Claim 13 (depends on 12) The method of claim 12 further comprising the step of: directing cooling fluid between the sheath and the composite blade portion. ### Claim 14 (depends on 13) The method of claim 13, wherein said directing step further comprises the step of: routing the cooling fluid first through the composite blade portion along the length between the root and the end point of the leading edge and second into the gap between the sheath and the composite blade portion. ### Claim 15 An aircraft propulsion device comprising: a compressor section; a combustor section operable to receive compressed fluid from said compressor section; a turbine section operable to receive combustion gases from said combustor section; an exhaust section operable to receive combustion gases from said turbine section; a rotor assembly positioned downstream of said exhaust section and including: a composite blade portion extending a length from a root to a tip, wherein a leading edge of said composite blade portion extends from said tip to an end point along said length between said tip and said root; a base portion fixed to said composite blade portion proximate to said root and formed from a different material than said composite blade portion; and a sheath extending around said composite blade portion and positioned along said length between said root and said end point of said leading edge, said sheath positioned such that combustion gases exiting said exhaust section directly impinge on said sheath, wherein said sheath is mounted on said base portion and/or wherein said sheath is mounted on said composite blade portion. ### Claim 16 (depends on 15) The aircraft propulsion device of claim 15 further comprising: a cooling fluid delivery system operable to bleed fluid from said compressor section and route the fluid to a gap between said sheath and said composite blade portion. ### Claim 17 (depends on 15) The aircraft propulsion device of claim 15 wherein said sheath includes first and second halves respectively mountable around opposite sides of said composite blade portion and each of said first and second halves includes at least one stand-off such that a radial gap is defined at least partially around said composite blade portion between said composite blade portion and said sheath.