A compound helicopter includes a fuselage, a fixed wing, a rotary wing, and a barrier member. The fixed wing is fixed to the fuselage. The rotary wing is rotatably coupled to the fuselage. The barrier member is attached to a part, of the fuselage, that is above the fixed wing and is between the rotary wing and the fixed wing. The barrier member is configured to generate no lift upon forward flight.

A flow control method is a flow control method of controlling flow around a blade of a rotary wing, a plasma actuator being disposed at the blade. The flow control method includes: determining a characteristic frequency ratio that is a characteristic value among frequency ratios, each of the frequency ratios being a ratio between an actuator driving frequency and an angle of attack changing frequency, the actuator driving frequency being a frequency of an applied voltage applied to the plasma actuator, the angle of attack changing frequency being a frequency at which an angle of attack of the blade changes in accordance with a rotation angle of the blade; setting the actuator driving frequency such that the frequency ratio becomes the characteristic frequency ratio; and applying a voltage of the set actuator driving frequency to the plasma actuator to control the flow around the blade.

Lifting devices are described that provide aeronautical lift by either pushing air sideways off its top surface, or by pulling away from top surface air, without changing upward air pressure on its bottom surface. In a first implementation, a pyramid shaped structure is composed of a stack of thin sections whose dimensions are rapidly extended and retracted using ultrasonic movements. Top surface air is pushed sideways when extended followed by momentary low pressure when retracted, thus providing lift. In a second implementation, a rapidly rotating lifting device is composed of a stack of thin round teethed plates, resembling circular saw blades, in which the diameter of each upper plate is slightly smaller than each lower plate. This device also creates lift as teeth push air sideways and gaps between teeth create momentary low pressure. In a third implementation, a lifting device top surface contains an array of MicroElectroMechanical Systems (MEMS) devices, such as Capacitive Micromachined Ultrasonic Transducers (CMUTs), which momentary produce lift by their upper pointing membranes rapidly pulling away from lifting device top surface air when oscillating at high frequency.

Systems and methods for enhancing operations of an aircraft may include a plasma generator, a sensor, and a controller. The plasma generator may be positioned on an exterior of the aircraft such that it can provide localized heating thereon. The sensor may be configured to sense and transmit information regarding a transonic flight condition such as speed to the controller. The controller may be configured to activate the plasma generator in response to information from the sensor, so as to mitigate a transonic shock wave through localized heating.

A hypersonic aircraft includes one or more leading edge assemblies that are designed to cool the leading edge of certain portions of the hypersonic aircraft that are exposed to high thermal loads, such as extremely high temperatures and/or thermal gradients. Specifically, the leading edge assemblies may include an outer wall tapered to a leading edge or stagnation point. A coolant supply may be in fluid communication with at least one fluid passageway that passes through the outer wall to deliver a flow of cooling fluid to the stagnation point. In addition, a nose cover is positioned at least partially over or within the at least one fluid passageway and is formed from a material that ablates or melts when the leading edge is exposed to a predetermined critical temperature, the nose cover being configured for restricting the flow of coolant until the nose cover is ablated or melted away.

A free-streamline airfoil includes a front portion, the front portion including a leading edge geometry configured to force a sudden separation of the flow, and a contoured rear portion.

In an embodiment, an aircraft includes a fuselage and a first support boom extending from the fuselage and having a first boom thickness. The aircraft also includes a first propulsion assembly coupled to the first support boom. The first propulsion assembly includes a first rotor hub and first rotor blades extending from the first rotor hub and operable to rotate in a first rotor plane with the first rotor hub. The aircraft also includes a first separation between the first rotor plane and the first support boom of not less than approximately 1.5 times the first boom thickness.

A compound helicopter includes a fuselage, a fixed wing, a rotary wing, and a barrier member. The fixed wing is fixed to the fuselage. The rotary wing is rotatably coupled to the fuselage. The barrier member is attached to a part, of the fuselage, that is above the fixed wing and is between the rotary wing and the fixed wing. The barrier member is configured to generate no lift upon forward flight.

A system for controlling turbulence of fluid flowing past a window includes an imaging device compartment defining an interior and an exterior separated by a window, wherein the window encloses at least a portion of the interior, wherein the exterior includes at least one turbulator on a side upstream of the window positioned to induce turbulence over the entirety of a boundary layer of the fluid flowing past the window for even heat transfer between the fluid and the window.

Electroaerodynamic devices and their methods of operation are disclosed. In one embodiment, ions are formed by dielectric barrier discharge using a time varying voltage differential applied between a first electrode and a second electrode. The ions are then accelerated in a downstream direction using a second voltage differential applied between a third electrode and the first and/or second electrodes, where the third electrode is located down stream from the first and second electrodes. The ions may then collide with naturally charged molecules and/or atoms within a fluid to accelerate the fluid in the downstream to create an ionic wind and an associated thrust.