Multilayer riblet applique and methods of producing the same are described herein. One disclosed example method includes applying a first high elongation polymer material to a web tool, where the web tool is to be provided from a first roll, and heating, via a first heating process, the first high elongation polymer material. The disclosed example method also includes applying a second high elongation polymer material to the first high elongation polymer material, and heating, via a second heating process, the second high elongation polymer material. The disclosed example method also includes applying, via a laminating roller, a support layer to the second high elongation polymer material.

A system and method for controlling hypersonic boundary layer transition for a hypersonic flight vehicle are disclosed. The reduction or elimination of hot streaks that naturally occurs in the boundary layer transition process during hypersonic flight is achieved by utilizing various techniques. One such technique utilizes roughness elements to counteract streak development. The techniques for reducing or eliminating the streaks are tailored such that the nonlinear stages of transition are profoundly altered. This results in significant drag reduction, and consequently an increase in range of the vehicle, and also a reduction of the weight penalty due to the Thermal Protection Systems (TPS) as less protective material would be required, thus allowing for an increased payload and/or range of the vehicle.

In one embodiment, a method for reducing drag includes forming a smooth surface on a first portion of a physical object. The method also includes forming periodic riblets on a second portion of the physical object. The method further includes generating a flow over the periodic riblets of the second portion of the physical object and over the smooth surface of the first portion of the physical object. The second portion of the physical object is adjacent to the first portion of the physical object. Each peak of each riblet of the periodic riblets of the second portion of the physical object is located above a plane of the smooth surface of the first portion of the physical object. Each valley between adjacent riblets of the periodic riblets of the second portion of the physical object is located below the plane of the smooth surface of the first portion of the physical object. A length of each riblet of the periodic riblets runs parallel to a direction of the flow.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.

An irregular surface texture fabricated on a body which travels through fluid in order to reduce the flow drag incurred by the body moving relative to the fluid. The dominate orientation of the irregular surface texture runs in the longitudinal direction, however, ridge and valley structures may occur in any orientation so that the resulting texture mimic the turbulence characteristic present in the surrounding flow field.

A lifting device including: a movable discontinuity (1) located in a surface of the lifting device, the movable discontinuity (1) being movable between: an active position in which the movable discontinuity (1) acts as vortex generator, and a passive position in which the movable discontinuity (1) is integrated into the surface of the lifting surface, a conduit (2) located in the spanwise direction of the lifting surface and in communication with the movable discontinuity (1), the lifting surface including openings (3) in its surface spanwise distant from each other in communication with the conduit (2), the movable discontinuity (1) and the conduit (2) being configured such that when an airflow goes through the conduit (2), this airflow activates the movable discontinuity (1) to act as a vortex generator of the lifting surface.

The present invention provides a riblet structure that further reduces drag, which is a sum of turbulent friction drag and pressure drag, and an object including such a riblet structure. An object such as an aircraft, plant, and pipeline includes a wavelike riblet pattern on a surface. The wavelike riblet pattern includes a large number of wavelike riblets. Each of the large number of wave riblets includes a wavelike ridge line, and a height thereof changes cyclically with respect to a fluid flow direction. With such a configuration, drag, which is a sum of turbulent friction drag and pressure drag, can be further reduced.

An aerodynamic device for enhancing lift and reducing drag on a body, comprising a plurality of raised members, each having a symmetric profile and including a central portion having an elongated profile, and first and second outer portions having elongated profiles and arranged substantially parallel to and on opposing sides of the central portion, wherein the plurality of raised members are situated adjacent one another to form a continuous structure on or defining at least a portion of a surface of the body and oriented such that the raised members are substantially aligned with a direction of localized flow on the body. An aerodynamic device for enhancing lift and reducing drag of a flying disc, wherein the plurality of raised members are situated adjacent one another to form a continuous structure and the raised members are oriented in a substantially circumferential direction on the surface of the flying disc.

A processing apparatus has: a light irradiation apparatus that irradiates a surface of an object with a plurality of processing lights; and a first change apparatus that changes an intensity distribution of the plurality of processing lights from the light irradiation apparatus on the surface of the object, the processing apparatus changes a thickness of a part of the object by irradiating the surface of the object with the plurality of processing lights.

A processing apparatus has: a light irradiation apparatus that irradiates a surface of an object with a processing light; and a measurement apparatus that measures a position of an irradiation area, which is formed on the surface of the object by the light irradiation apparatus, relative to the object.