# US 2010/0166554 A1 · Lift fan flow path device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0166554 A1 - Document ID: US20100166554A1 - Status: Published application - Kind: A1 - Application number: 12/630,743 - Filed: 2009-12-03 - Published: 2010-07-01 - Earliest claimed: 2008-12-30 - Assignees: Rolls-Royce North American Technologies Inc. - Inventors: Douglas David Dierksmeier - Web page: https://patentgrep.com/patent/US20100166554A1 ## CPC - B64C 29/0025: {the propellers being fixed relative to the fuselage} - B64C: AEROPLANES; HELICOPTERS ## Abstract A flow path is disclosed that is capable of being deployed when needed and stowed in a relatively small space when not in use. The flow path device is flexible and may be made from a variety of materials. In an illustrative embodiment the flow path device is annular and transitions from an ellipsoidal annular shape to a quadrilateral annular shape. A vane box can be disposed at one end of the flow path device. Doors can be coupled to the vane box to cover the flow path device. The doors can be used to provide a structural load path for the flow path device and vane box. The doors and the flow path device can be moved together such that the doors uncover the flow path device as the device is deployed. ## Claims ### Claim 1 An apparatus comprising: an extendable lift fan airflow duct having a flexible portion operable to be extended from a folded position and having a first end configured to receive a flow of working fluid from a lift fan and a second end configured to eject the flow of working fluid. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the extendable lift fan airflow duct includes an annular airflow passage formed between an outer airflow boundary and an inner airflow boundary. ### Claim 3 (depends on 2) The apparatus of claim 2, which further includes a cover operable to close the second end of the extendable lift fan airflow duct. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the flexible portion comprises one of aromatic polyamide and graphite/polyurethane. ### Claim 5 (depends on 1) The apparatus of claim 1, which further includes a cover operable to close the second end of the extendable lift fan airflow duct, the cover coupled to the extendable lift fan airflow duct through a track and roller assembly. ### Claim 6 (depends on 1) The apparatus of claim 1, which further includes the lift fan and an aircraft having a gas turbine engine, the lift fan installed in the aircraft to provide a vertical lift force; and wherein the device includes an at least partially rigid extension attached to the second end of the extendable lift fan airflow duct. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the extendable lift fan airflow duct includes an axis of extension substantially parallel to an axis of rotation of the lift fan. ### Claim 8 An apparatus comprising: a collapsible lift fan airflow duct having an annular flow path formed between a first collapsible airflow member and a second collapsible airflow member, the first collapsible airflow member having open ends, the second collapsible airflow member capable of being received within an interior of the first collapsible airflow member, and the collapsible lift fan airflow duct operable to be extended from a compact position to an operating position. ### Claim 9 (depends on 8) The apparatus of claim 8, which further includes a vane box located at an outlet end of the collapsible lift fan airflow duct. ### Claim 10 (depends on 9) The apparatus of claim 9, which further includes a cover operable to close a portion of the vane box and coupled to the vane box through a track and roller assembly. ### Claim 11 (depends on 10) The apparatus of claim 10, wherein the vane box further includes a track and the cover further includes a roller operable to be received within the track. ### Claim 12 (depends on 10) The apparatus of claim 10, wherein the cover includes two doors operable to be independently moveable from a closed position to an open position. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the collapsible lift fan airflow duct is installed on an aircraft having a lift fan operable to provide vertical lift for the aircraft. ### Claim 14 (depends on 8) The apparatus of claim 8, wherein the first collapsible airflow member includes a foldable portion that comprises one of aromatic polyamide and graphite/polyurethane. ### Claim 15 (depends on 8) The apparatus of claim 8, wherein an inlet of the collapsible lift fan airflow duct is ellipsoidal in shape and an outlet of the collapsible lift fan airflow duct is quadrilateral in shape. ### Claim 16 An apparatus comprising: a collapsible lift fan conduit having an outlet operable to convey a flow path for an air stream provided by an aircraft lift fan; a cover operable to close at least a portion of the outlet; and means for removing the cover to expose the outlet. ### Claim 17 A method comprising: extending a collapsible lift fan flow directing device from a stowed position to a final position; withdrawing a cover operable to at least partially enclose the collapsible lift fan flow directing device; and flowing a working fluid through the collapsible lift fan flow directing device to provide vertical lift for an aircraft. ### Claim 18 (depends on 17) The method of claim 17, which further includes folding the collapsible lift fan flow directing device from the final position to the stowed position. ### Claim 19 (depends on 17) The method of claim 17, which further includes rotating a lift fan to produce a flow of working fluid. ### Claim 20 (depends on 17) The method of claim 17, wherein withdrawing a cover further includes sliding the cover relative to the collapsible lift fan flow directing device as the collapsible lift fan flow directing device moves between the stowed position and the final position.