The present disclosure is directed to a fan section positioned on a tail section of an aircraft, in which the fan section defines a circumferential direction, a radial direction, and an axial direction. The fan section includes a fan and a nacelle. The fan includes a plurality of fan blades and a fan shaft, in which the plurality of fan blades are rotatable with the shaft. The nacelle includes a wall at least partially enclosing the fan. The wall includes a first portion and a second portion. The first portion translates relative to the second portion between a first, closed position in which the wall of the nacelle circumferentially encloses the fan and a second, open position in which at least a portion of the fan is unenclosed by the wall of the nacelle.

The present disclosure is directed to a fan section positioned on a tail section of an aircraft, in which the fan section defines a circumferential direction, a radial direction, and an axial direction. The fan section includes a fan and a nacelle. The fan includes a plurality of fan blades and a fan shaft, in which the plurality of fan blades are rotatable with the shaft. The nacelle includes a wall at least partially enclosing the fan. The wall includes a first portion and a second portion. The first portion translates relative to the second portion between a first, closed position in which the wall of the nacelle circumferentially encloses the fan and a second, open position in which at least a portion of the fan is unenclosed by the wall of the nacelle.

The aerodynamic element includes an ionization system which ionizes flow of air flowing over the top face of the aerodynamic element and a control system which generates at least one electromagnetic force associated with an electrical current and a magnetic field, the at least one electromagnetic force being oriented in the direction opposite to that of the flow of the ionized air flow such that the electromagnetic force reduces the instabilities of the flow of the airflow.

A method and system delay the laminar-to-turbulent transition of a supersonic or hypersonic boundary layer flow moving in a flow direction over a surface. For supersonic boundary layer flow, oblique first-mode instability waves present in the boundary layer and propagating at an oblique angle relative to the flow direction cause a laminar-to-turbulent transition in the boundary layer flow. These instability waves have a wavelength associated therewith in a direction perpendicular to the flow direction. Flow disruptors are used to generate modulations within the boundary layer flow wherein a wavelength of the modulations along the direction perpendicular to the flow direction is less than one-half of the wavelength of the instability waves. For hypersonic boundary layer flow, the flow disruptors generate modulations within the boundary layer flow wherein the wavelength of the modulations is less than streak spacing for optimal transient growth or, equivalently, in the range of one to two times the boundary layer thickness.

An arrangement for mechanically changing a surface includes an insulating layer, a pair of electrodes, which is arranged on or in the insulating layer, and a piezo element, which is arranged on or in the insulating layer. The piezo element is separated from the pair of electrodes by the insulating layer. The pair of electrodes is designed to generate in a region of the piezo element an electric field, which causes the piezo element to carry out a mechanical change of shape, in order in this way to mechanically change a surface of the arrangement. The pair of electrodes is also designed to generate the electric field such that the electric field has a minimum field strength in a surrounding area of the arrangement, in order in this way to generate a plasma in the surrounding area of the arrangement.

An aircraft and an aircraft wing assembly for an aircraft. The wing assembly includes a wing body assembly including a wing body; and at least one protruding portion connected to the wing body. The protruding portion extends aftwardly from an aft side of the wing body assembly, a leading edge of the wing body assembly defining a leading edge line, a trailing edge of the wing body assembly defining a trailing edge line extending between the inboard end and the outboard end, the trailing edge including a trailing edge of the protruding portion, the trailing edge line being a smooth line, a chord distance being defined longitudinally from the leading edge line to the trailing edge line, the chord distance at a center of the protruding portion being greater than the chord distance inboard of protruding portion and outboard of the protruding portion.

An aircraft and an aircraft wing assembly for an aircraft. The wing assembly includes a wing body assembly including a wing body; and at least one protruding portion connected to the wing body. The protruding portion extends aftwardly from an aft side of the wing body assembly, a leading edge of the wing body assembly defining a leading edge line, a trailing edge of the wing body assembly defining a trailing edge line extending between the inboard end and the outboard end, the trailing edge including a trailing edge of the protruding portion, the trailing edge line being a smooth line, a chord distance being defined longitudinally from the leading edge line to the trailing edge line, the chord distance at a center of the protruding portion being greater than the chord distance inboard of protruding portion and outboard of the protruding portion.

Disclosed are methods and apparatuses for mitigating the formation of concentrated wake vortex structures generated from lifting or thrust-generating bodies and maneuvering control surfaces wherein the use of contour surface geometries promotes vortex-mixing of high and low flow fluids. The methods and apparatuses can be combined with various drag reduction techniques, such as the use of riblets of various types and/or compliant surfaces (passive and active). Such combinations form unique structures for various fluid dynamic control applications to suppress transiently growing forms of boundary layer disturbances in a manner that significantly improves performance and has improved control dynamics.

An aircraft surface cover is provided. The aircraft surface cover includes a cover member that is configured to be removably secured to an aircraft structure. The cover member includes an exterior surface that has a microtextured surface including microtexture ribs that are configured to improve aerodynamic performance of the aircraft structure.

An aircraft including an aft-mounted boundary layer energisation system is shown. The system comprises a nacelle arranged around a tailcone of the aircraft which thereby defines a duct, the duct having, in axial flow series, an intake, a heat exchanger, and a nozzle, and no turbomachinery therein, whereby the system energises a boundary layer of the aircraft by means of Meredith effect.