Abstract: A vacuum transport tube vehicle for evacuating a vacuum transport tube has a first end, a second end, and a body comprising a piston head. The vehicle has a blade-actuator assembly, comprising a circumferential blade member sealed to the piston head and having a blade perimeter portion defining a first end outer surface forming an annular gap with an inner surface of the vacuum transport tube. The vehicle further includes a plurality of blade segment actuators arranged circumferentially around the piston perimeter portion and configured to actively adjust a radial position of the blade member at the corresponding blade circumferential locations in a manner accommodating non-uniformities in an inner surface profile of the vacuum transport tube, and maintaining the annular gap at a substantially constant and relatively short gap distance during movement of the vehicle through the vacuum transport tube.

Abstract: An ultrashort nacelle configuration employs a fan cowl having an exit plane and a serrated trailing edge. A variable pitch fan is housed within the fan cowl. The variable pitch fan has a reverse thrust position inducing a reverse flow through the exit plane and into the fan cowl. The serrated trailing edge forms a plurality of vortex generators configured to induce vortices in the reverse flow.

Abstract: There is provided a turbofan engine for an aircraft. The turbofan engine has a core with a fan cowl and a variable pitch fan (VPF) configured to only rotate in a first rotation direction. The VPF has a plurality of fan blades each configured to over-pitch to an over-pitch position relative to a feathered position. The turbofan engine has outer guide vanes (OGVs) axially disposed downstream of the VPF, and has a rotation control device to prevent the VPF from rotating in a second rotation direction opposite the first rotation direction, during an engine out (EO) condition of the turbofan engine. When the VPF is prevented from rotating during the EO condition, the fan blades are over-pitched to the over-pitch position relative to the feathered position, to achieve no or minimal air flow separation about the OGVs, and to reduce drag of the turbofan engine during the EO condition.

Abstract: There is provided a propulsion system for an aircraft, the system having a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft. The engine has a core, a variable pitch fan, and a nacelle having a nacelle trailing edge with a top-most portion positioned above a wing leading edge. The engine has an L/D ratio of the nacelle in a range of from 0.6 to 1.0, and a fan-pressure-ratio in a range of from 1.10 to 1.30. The forward over-wing-flow installation enables, during all flight phases of the aircraft, a fan flow exhaust to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing. During a cruise flight phase of the aircraft, the engine minimizes scrubbing drag of the fan flow exhaust to the wing.

Abstract: A modular tube volume reduction assembly for use at a vacuum tube vehicle station is provided. The assembly includes a modular station vacuum tube having a tube volume and a plurality of cavities longitudinally formed around a circumference of the modular station vacuum tube, and a volume reduction assembly integrated with the modular station vacuum tube, where the volume reduction assembly includes a plurality of blocks longitudinally coupled to a cavity interior of each of the plurality of cavities. The assembly includes a control system coupled between the modular station vacuum tube and the blocks. The control system radially moves the blocks to and from a vehicle outer surface of a vacuum transport tube vehicle at the vacuum tube vehicle station. The assembly displaces the tube volume between a station wall and the vehicle outer surface, and reduces the volume to be evacuated at the vacuum tube vehicle station.

Abstract: A vacuum transport tube vehicle for evacuating a vacuum transport tube has a first end, a second end, and a body comprising a piston head. The vehicle has a blade-actuator assembly, comprising a circumferential blade member sealed to the piston head and having a blade perimeter portion defining a first end outer surface forming an annular gap with an inner surface of the vacuum transport tube. The vehicle further includes a plurality of blade segment actuators arranged circumferentially around the piston perimeter portion and configured to actively adjust a radial position of the blade member at the corresponding blade circumferential locations in a manner accommodating non-uniformities in an inner surface profile of the vacuum transport tube, and maintaining the annular gap at a substantially constant and relatively short gap distance during movement of the vehicle through the vacuum transport tube.

Abstract: A vacuum transport tube vehicle, system, and method for evacuating a vacuum transport tube are provided. The vehicle has a first end having a first end outer surface. An annular gap is formed between the first end outer surface and an inner surface of the vacuum transport tube. The vehicle has a second end having a second end outer diameter, and a body in the form of a piston with a structural framework. The vehicle has an orifice extending from a first inlet portion in the first end to a second outlet portion of the vehicle. The vehicle has a drive assembly coupled to the body, and a power system. The vehicle evacuates the vacuum transport tube by reducing pressure within the tube with each successive vehicle pass through the tube, until a desired pressure is obtained and a vacuum is created in the interior of the tube.

Abstract: There is provided a propulsion system for an aircraft, the system having a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft. The engine has a core, a variable pitch fan, and a nacelle having a nacelle trailing edge with a top-most portion positioned above a wing leading edge. The engine has an L/D ratio of the nacelle in a range of from 0.6 to 1.0, and a fan-pressure-ratio in a range of from 1.10 to 1.30. The forward over-wing-flow installation enables, during all flight phases of the aircraft, a fan flow exhaust to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing. During a cruise flight phase of the aircraft, the engine minimizes scrubbing drag of the fan flow exhaust to the wing.

Abstract: There is provided a turbofan engine for an aircraft. The turbofan engine has a core with a fan cowl and a variable pitch fan (VPF) configured to only rotate in a first rotation direction. The VPF has a plurality of fan blades each configured to over-pitch to an over-pitch position relative to a feathered position. The turbofan engine has outer guide vanes (OGVs) axially disposed downstream of the VPF, and has a rotation control device to prevent the VPF from rotating in a second rotation direction opposite the first rotation direction, during an engine out (EO) condition of the turbofan engine. When the VPF is prevented from rotating during the EO condition, the fan blades are over-pitched to the over-pitch position relative to the feathered position, to achieve no or minimal air flow separation about the OGVs, and to reduce drag of the turbofan engine during the EO condition.

Abstract: A modular tube volume reduction assembly for use at a vacuum tube vehicle station is provided. The assembly includes a modular station vacuum tube having a tube volume and a plurality of cavities longitudinally formed around a circumference of the modular station vacuum tube, and a volume reduction assembly integrated with the modular station vacuum tube, where the volume reduction assembly includes a plurality of blocks longitudinally coupled to a cavity interior of each of the plurality of cavities. The assembly includes a control system coupled between the modular station vacuum tube and the blocks. The control system radially moves the blocks to and from a vehicle outer surface of a vacuum transport tube vehicle at the vacuum tube vehicle station. The assembly displaces the tube volume between a station wall and the vehicle outer surface, and reduces the volume to be evacuated at the vacuum tube vehicle station.

Abstract: An ultrashort nacelle configuration employs a fan cowl having an exit plane and a serrated trailing edge. A variable pitch fan is housed within the fan cowl. The variable pitch fan has a reverse thrust position inducing a reverse flow through the exit plane and into the fan cowl. The serrated trailing edge forms a plurality of vortex generators configured to induce vortices in the reverse flow.

Abstract: A vacuum volume reduction system and method for reducing a volume to be evacuated at a vacuum tube vehicle station are provided. The system has a station vacuum tube in an interior of a station wall of the vacuum tube vehicle station. The station vacuum tube has a tube volume. The system has a volume reduction assembly coupled to the station vacuum tube, and a control system for radially moving the assembly to and from a vehicle outer surface of a vacuum transport tube vehicle, to engage around the vehicle outer surface, for loading and unloading of passengers and/or cargo. The system further has door seal(s), an air supply assembly, and a vent-to-vacuum assembly. The system displaces the tube volume between the station wall and the vehicle outer surface, and in turn, reduces a volume to be evacuated at the vacuum tube vehicle station.

Abstract: A vacuum volume reduction system and method for reducing a volume to be evacuated at a vacuum tube vehicle station are provided. The system has a station vacuum tube in an interior of a station wall of the vacuum tube vehicle station. The station vacuum tube has a tube volume. The system has a volume reduction assembly coupled to the station vacuum tube, and a control system for radially moving the assembly to and from a vehicle outer surface of a vacuum transport tube vehicle, to engage around the vehicle outer surface, for loading and unloading of passengers and/or cargo. The system further has door seal(s), an air supply assembly, and a vent-to-vacuum assembly. The system displaces the tube volume between the station wall and the vehicle outer surface, and in turn, reduces a volume to be evacuated at the vacuum tube vehicle station.

Abstract: A vacuum transport tube vehicle, system, and method for evacuating a vacuum transport tube are provided. The vehicle has a first end having a first end outer surface. An annular gap is formed between the first end outer surface and an inner surface of the vacuum transport tube. The vehicle has a second end having a second end outer diameter, and a body in the form of a piston with a structural framework. The vehicle has an orifice extending from a first inlet portion in the first end to a second outlet portion of the vehicle. The vehicle has a drive assembly coupled to the body, and a power system. The vehicle evacuates the vacuum transport tube by reducing pressure within the tube with each successive vehicle pass through the tube, until a desired pressure is obtained and a vacuum is created in the interior of the tube.

Abstract: A vortex generator may include a depression in an aerodynamic surface, and a vortex generator leading edge located in the depression. The vortex generator leading edge may include a leading edge upper surface. The leading edge upper surface may be positioned at or below a tangent line defined at a location along the aerodynamic surface upstream of the depression relative to an oncoming local flow.

Abstract: A vortex generator may include a depression in an aerodynamic surface, and a vortex generator leading edge located in the depression. The vortex generator leading edge may include a leading edge upper surface. The leading edge upper surface may be positioned at or below a tangent line defined at a location along the aerodynamic surface upstream of the depression relative to an oncoming local flow.

Abstract: Systems and methods are described for controlling flow disturbances emanating from a protrusion, such as a beam propagating device. In one embodiment, a method includes positioning a flow control element at least partially around a base portion of a protrusion, wherein the flow control element includes at least one flow expanding feature. A reduced pressure zone is generated proximate an aft portion of the protrusion by expanding at least a portion of a flowfield. One or more flow disturbances emanating downstream from the protrusion are deflected using the at least one reduced pressure zone.

Abstract: Systems and methods are described for controlling flow disturbances emanating from a protrusion, such as a beam propagating device. In one embodiment, a method includes positioning a flow control element at least partially around a base portion of a protrusion, wherein the flow control element includes at least one flow expanding feature. A reduced pressure zone is generated proximate an aft portion of the protrusion by expanding at least a portion of a flowfield. One or more flow disturbances emanating downstream from the protrusion are deflected using the at least one reduced pressure zone.