# US 7,607,607 B2 · De-rotation system suitable for use with a shaft fairing system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,607 B2 - Document ID: US7607607B2 - Status: Granted - Kind: B2 - Application number: 12/108,488 - Filed: 2008-04-23 - Published: 2009-04-02 - Granted: 2009-10-27 - Earliest claimed: 2005-05-26 - Assignees: Sikorsky Aircraft Corporation - Inventors: David A. Darrow, Jr.; Frank P. D'Anna; Thomas L. Sbabo - Web page: https://patentgrep.com/patent/US7607607B2 ## CPC - B64C 27/12: Rotor drives - B64C 7/00: Structures or fairings not otherwise provided for - B64C 27/10: arranged coaxially - B64C 27/14: Direct drive between power plant and rotor hub - B64C 27/04: Helicopters - B64C 27/20: Rotorcraft characterised by having shrouded rotors, e.g. flying platforms - B64C: AEROPLANES; HELICOPTERS ## Abstract A de-rotation system includes a first ring gear defined about an axis of rotation, a second ring gear defined about the axis of rotation and a gear set in meshing engagement with the first ring gear and the second ring gear to control a position of a housing about the axis of rotation. ## Claims ### Claim 1 A de-rotation system for a fairing comprising: a first ring gear rotatable about a rotor axis of rotation; a second ring gear rotatable about said rotor axis of rotation; a gear set in meshing engagement with said first ring gear and said second ring gear; a housing which supports said gear set, said gear set operable to control a position of said housing about said rotor axis of rotation; and a shaft fairing mounted to said housing for rotation about said rotor axis of rotation. ### Claim 2 (depends on 1) The system as recited in claim 1, wherein said gear set is operable to control an azimuthal position of said housing such that said fairing remains in an approximately fixed azimuthal position. ### Claim 3 (depends on 1) The system as recited in claim 1, wherein said shaft fairing is airfoil shaped. ### Claim 4 (depends on 1) The system as recited in claim 1, wherein said first ring gear and said second ring counter-rotate. ### Claim 5 (depends on 1) The system as recited in claim 1, wherein said gear set comprises a first pinion in meshing engagement with an inner diameter of said first ring gear and a second pinion in meshing engagement with an outer diameter of said second ring gear, said first pinion gear rotationally mounted to said second pinion gear through a pinion shaft. ### Claim 6 (depends on 1) The system as recited in claim 1, wherein said gear set comprises a first chain in engagement with said first ring gear and a second chain in engagement with said second ring gear. ### Claim 7 (depends on 6) The system as recited in claim 6, further comprising an upper gear set in meshing engagement with said upper chain, a lower gear set in meshing engagement with said lower chain and an idler gear set therebetween. ### Claim 8 (depends on 6) The system as recited in claim 6, further comprising: a first shaft rotatable about a first axis of rotation displaced from said rotor axis of rotation; a first driven gear mounted to said first shaft, said first driven gear in meshing engagement with said first chain; a first idler gear mounted to said first shaft; a first sprocket arm; a first idler sprocket mounted to said first sprocket arm, said first idler sprocket in meshing engagement with said second chain, said first idler sprocket rotatable about a first sprocket axis displaced from said first axis; a second shaft rotatable about a second axis of rotation; a second driven gear mounted to said second shaft, said second driven gear in meshing engagement with said second chain; a second idler gear mounted to said second shaft, said second idler gear in meshing engagement with said first idler gear; a second sprocket arm; a second idler sprocket mounted to said second sprocket arm, said second idler sprocket in meshing engagement with said first chain, said second idler sprocket rotatable about a second sprocket axis displaced from said second axis. ### Claim 9 (depends on 7) The system as recited in claim 7, further comprising a clutch system mounted to said first shaft to selectively disengage said gear set to permit said shaft fairing to rotate freely about said axis of rotation. ### Claim 10 (depends on 1) The system as recited in claim 1, wherein said gear set further comprising an upper gear set in meshing engagement with said first ring gear, a lower gear set in meshing engagement with said second ring gear and an idler gear set therebetween. ### Claim 11 (depends on 1) The system as recited in claim 1, wherein said gear set comprises a first driven gear in engagement with said first ring gear and a second driven gear in engagement with said second ring gear. ### Claim 12 (depends on 11) The system as recited in claim 11, wherein said first driven gear and said second driven gear cooperate through an idler gear set. ### Claim 13 (depends on 12) The system as recited in claim 12, wherein said idler gear set include a multitude of gears on a first shaft rotatable about a first shaft axis and a multiple of gears on a second shaft rotatable about a second shaft axis, said first shaft axis parallel to said second shaft axis. ### Claim 14 (depends on 12) The system as recited in claim 12, wherein said idler gear set include a multitude of gears on a first shaft and a multiple of gears on a second shaft, said first shaft driven by said first driven gear and said second shaft driven by said second driven gear. ### Claim 15 A counter-rotating coaxial rotor system comprising: a lower rotor hub mounted to a lower rotor shaft which rotates about a rotor axis of rotation; an upper rotor hub mounted to an upper rotor shaft which rotates about said rotor axis of rotation in a direction counter to said rotation of said lower rotor shaft, said upper rotor shaft mounted at least partially through said lower rotor shaft; an upper hub fairing mounted at least partially about said upper rotor hub; a lower hub fairing mounted at least partially about said lower rotor hub; a shaft fairing mounted between said upper hub fairing and said lower hub fairing for rotation about said rotor axis of rotation; a first ring gear defined about said rotor axis of rotation, said first ring gear mounted for rotation with said upper rotor shaft; a second ring gear defined about said rotor axis of rotation, said first ring gear mounted for rotation with said lower rotor shaft; a gear set in meshing engagement with said first ring gear and said second ring gear; and a housing mounted to said shaft fairing to support said gear set, said gear set operable to control a position of said shaft fairing about said axis of rotation. ### Claim 16 (depends on 15) The system as recited in claim 15, wherein said gear set comprises a first pinion in meshing engagement with an inner diameter of said first ring gear and a second pinion in meshing engagement with an outer diameter of said second ring gear, said first pinion gear rotationally mounted to said second pinion gear through a pinion shaft. ### Claim 17 (depends on 15) The system as recited in claim 15, further comprising: a first chain in engagement with said first ring gear; a second chain in engagement with said second ring gear; a first shaft rotatable about a first axis of rotation; a first driven gear mounted to said first shaft, said first driven gear in meshing engagement with said first chain; a first idler gear mounted to said first shaft; a first sprocket arm; a first idler sprocket mounted to said first sprocket arm, said first idler sprocket in meshing engagement with said second chain, said first idler sprocket rotatable about a first sprocket axis displaced from said first axis; a second shaft rotatable about a second axis of rotation; a second driven gear mounted to said second shaft said second driven gear in meshing engagement with said second chain; a second idler gear mounted to said second shaft, said second idler gear in meshing engagement with said first idler gear; a second sprocket arm; a second idler sprocket mounted to said second sprocket arm, said second idler sprocket in meshing engagement with said first chain, said second idler sprocket rotatable about a second sprocket axis displaced from said second axis. ### Claim 18 (depends on 15) The system as recited in claim 15, wherein said gear set further comprises: a first shaft rotatable about a first axis of rotation; a first driven gear mounted to said first shaft, said first driven gear in meshing engagement with said first ring gear; a first idler gear mounted to said first shaft; a second shaft rotatable about a second axis of rotation; a second driven gear mounted to said second shaft, said second driven gear in meshing engagement with said second ring gear; a second idler gear mounted to said second shaft, said second idler gear in meshing engagement with said first idler gear. ### Claim 19 An aircraft having a counter-rotating coaxial rotor system comprising: a lower rotor hub mounted to a lower rotor shaft which rotates about a rotor axis of rotation; an upper rotor hub mounted to an upper rotor shaft which rotates about said rotor axis of rotation in a direction counter to said rotation of said lower rotor shaft, said upper rotor shaft mounted at least partially through said lower rotor shaft; an upper hub fairing mounted at least partially about said upper rotor hub; a lower hub fairing mounted at least partially about said lower rotor hub; a shaft fairing mounted between said upper hub fairing and said lower hub fairing for rotation about said rotor axis of rotation; a first ring gear defined about said rotor axis of rotation, said first ring gear mounted for rotation with said upper rotor shaft; a second ring gear defined about said rotor axis of rotation, said first ring gear mounted for rotation with said lower rotor shaft; a gear set in meshing engagement with said first ring gear and said second ring gear; and a housing mounted to said shaft fairing to support said gear set, said gear set operable to control a position of said shaft fairing about said axis of rotation. ### Claim 20 (depends on 19) The aircraft as recited in claim 19, wherein said aircraft is a rotary-wing aircraft with a translational thrust system.