# US 12,214,872 B2 · Tip end joint arrangement for a rotor blade with reconfigurable attributes for structural and aerodynamic tuning > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,214,872 B2 - Document ID: US12214872B2 - Status: Granted - Kind: B2 - Application number: 18/132,330 - Filed: 2023-04-07 - Published: 2024-10-10 - Granted: 2025-02-04 - Earliest claimed: 2023-04-07 - Assignees: Lockheed Martin Corporation - Applicants: Lockheed Martin Corporation - Inventors: Timothy James Conti; Eric S. Parsons; Joshua A. Breon; Benjamin E. Isabella; William Paul Adams; Christopher Michael Colschen - Web page: https://patentgrep.com/patent/US12214872B2 ## CPC - B64C 27/463: {Blade tips} - B64C 27/008: {Rotors tracking or balancing devices} - B64C 27/467: Aerodynamic features - B64C 27/473: Constructional features - B64C: AEROPLANES; HELICOPTERS ## Abstract A rotor blade configured to be installed on a rotary-wing aircraft includes a main blade body including an inboard end configured to be coupled to a rotor blade hub and an outboard end. The rotor blade includes a blade tip removably coupled to the outboard end of the main blade body, the blade tip including an inner cavity. The rotor blade further includes a tip block including an inboard portion coupled to the outboard end of the main blade body and a cantilevered portion extending beyond the outboard end of the rotor blade and into the inner cavity of the blade tip. ## Claims ### Claim 1 A rotor blade configured to be installed on a rotary-wing aircraft, the rotor blade comprising: a main blade body comprising an inboard end configured to be coupled to a rotor blade hub and an outboard end; a blade tip removably coupled to the outboard end of the main blade body, the blade tip comprising an inner cavity; and a tip block comprising an inboard portion coupled to the outboard end of the main blade body and a cantilevered portion extending beyond the outboard end of the main blade body and into the inner cavity of the blade tip without directly contacting the blade tip, such that loads generated at the blade tip are transferred to the main blade body independently of the cantilevered portion. ### Claim 2 (depends on 1) The rotor blade of claim 1, wherein the cantilevered portion is cantilevered within the blade tip with sufficient clearance to not hit an inside surface of the inner cavity and does not directly contact the blade tip. ### Claim 3 (depends on 1) The rotor blade of claim 1, wherein the main blade body comprises a spar with an internal spar cavity, an upper blade skin, and a lower blade skin, and wherein the inboard portion of the tip block extends into the internal spar cavity and is coupled to the spar by a plurality of fasteners. ### Claim 4 (depends on 3) The rotor blade of claim 3, wherein the upper blade skin or the lower blade skin includes an opening exposing an outer surface of the spar and surrounding the plurality of fasteners, each fastener comprising a fastener head. ### Claim 5 A rotor blade configured to be installed on a rotary-wing aircraft, the rotor blade comprising: a main blade body comprising an inboard end configured to be coupled to a rotor blade hub and an outboard end; a blade tip removably coupled to the outboard end of the main blade body, the blade tip comprising an inner cavity; and a tip block comprising an inboard portion coupled to the outboard end of the main blade body and a cantilevered portion extending beyond the outboard end of the main blade body and into the inner cavity of the blade tip, wherein the cantilevered portion of the tip block comprises a first weight cup cavity configured to receive one or more weights for adjusting a balance of the rotor blade. ### Claim 6 (depends on 5) The rotor blade of claim 5, wherein a first weight cartridge containing the one or more weights is structured to be received in and removably coupled to the first weight cup cavity. ### Claim 7 (depends on 6) The rotor blade of claim 6, wherein the one or more weights are removably coupled to the first weight cartridge such that the first weight cartridge and the one or more weights are configured to be installed in and removed from the first weight cup cavity without being decoupled from the first weight cartridge. ### Claim 8 (depends on 6) The rotor blade of claim 6, wherein the blade tip comprises an opening positioned above the first weight cup cavity and shaped to allow the first weight cartridge to be inserted therethrough. ### Claim 9 (depends on 8) The rotor blade of claim 8, further comprising a cover plate coupled to the first weight cartridge and shaped to cover the opening, an outer surface of the cover plate being substantially flush with an adjacent outer surface of the blade tip. ### Claim 10 (depends on 5) The rotor blade of claim 5, further comprising a second weight cup cavity configured to receive a second set of one or more weights, the second weight cup cavity positioned at the same radial station as the first weight cup cavity. ### Claim 11 A rotor blade configured to be installed on a rotary-wing aircraft, the rotor blade comprising: a main blade body comprising an inboard end configured to be coupled to a rotor blade hub, an outboard end, a spar with an internal spar cavity, an upper blade skin, and a lower blade skin; a blade tip removably coupled to the outboard end of the main blade body, the blade tip comprising an inner cavity; and a tip block comprising an inboard portion coupled to the outboard end of the main blade body and a cantilevered portion extending beyond the outboard end of the main blade body and into the inner cavity of the blade tip, wherein the inboard portion of the tip block extends into the internal spar cavity and is coupled to the spar by a plurality of fasteners, and the upper blade skin or the lower blade skin includes an opening exposing an outer surface of the spar and surrounding the plurality of fasteners, each fastener comprising a fastener head, the rotor blade further comprising a retention plate positioned between the plurality of fastener heads and the outer surface of the spar. ### Claim 12 (depends on 11) The rotor blade of claim 11, wherein each fastener head incudes a flat edge and the retention plate includes raised portions each with a flat side positioned adjacent the flat edge of a corresponding fastener head, the flat sides and the flat edges configured to restrict the rotation of the fasteners. ### Claim 13 (depends on 12) The rotor blade of claim 12, wherein the raised portions include threaded holes configured to receive threaded fasteners for coupling a cover plate to the retention plate. ### Claim 14 (depends on 11) The rotor blade of claim 11, further comprising a cover plate coupled to the retention plate and shaped to cover the opening, an outer surface of the cover plate being substantially flush with an adjacent outer surface of the upper blade skin or the lower blade skin. ### Claim 15 A rotor blade configured to be installed on a rotary-wing aircraft, the rotor blade comprising: a main blade body comprising an inboard end configured to be coupled to a rotor blade hub, an outboard end, a spar with an internal spar cavity, an upper blade skin, and a lower blade skin; a blade tip removably coupled to the outboard end of the main blade body, the blade tip comprising an inner cavity; and a tip block comprising an inboard portion coupled to the outboard end of the main blade body and a cantilevered portion extending beyond the outboard end of the main blade body and into the inner cavity of the blade tip, wherein the inboard portion of the tip block extends into the internal spar cavity and is coupled to the spar by a plurality of fasteners, and wherein the main blade body is coupled to the blade tip by a tip rib, the tip rib comprising: a mounting bracket extending into the internal spar cavity; an upper flange coupled to an upper tip skin of the blade tip; a lower flange coupled to a lower tip skin of the blade tip; and a gap between the upper flange and the lower flange and extending between an upper portion of the mounting bracket and a lower portion of the mounting bracket, wherein the inboard portion of the tip block extends into the gap. ### Claim 16 (depends on 15) The rotor blade of claim 15, wherein the plurality of fasteners further couple the mounting bracket to the spar and to the inboard portion of the tip block. ### Claim 17 (depends on 15) The rotor blade of claim 15, further comprising: a doubler plate positioned on an outer surface of the upper tip skin or the lower tip skin, the doubler plate comprising a flange that extends into a slot in the tip rib; and a second plurality of fasteners extending through the upper tip skin or the lower tip skin, the corresponding flange of the tip rib, and the doubler plate.