Abstract: An aircraft with a fluid-duct system for extraction of the laminar layer and/or blowing out of fluid at vulnerable places of the outer skin, wherein the fluid-duct system (26, 19, 18) by means of switchable valves (6, 4) is connectable to a pump facility (3), which is driven by the exhaust air from the cabin for generating a reduced pressure for the extraction of the laminar layer.

Abstract: A flow control actuator 10 for a body exposed to fluid flow comprises first and second flow surfaces 14, 16 spaced to define an elongate gap 20 therebetween. An elongate control element is disposed in or adjacent the gap and has an externally facing arcuate surface and defines a first slot 24 between the control element and said first flow surface and a second slot between said control element and said second flow surface 26. The control element 22 is moveable to allow the width of said slots to be adjusted generally proportionally. The flow of pressurized flow control fluid passes from a plenum chamber 30 out through one or both slots 24, 26 to be deflected around the arcuate surface under the influence of the Coanda effect. The flow control actuator 10 may be provided in the trailing or leading edge of an aerofoil; alternatively it may be provided between two surfaces spaced to provide said gap but otherwise providing a generally continuous surface.

Abstract: An air pump positioned within a hollow space in an aerodynamic structure for controlling the flow over an aerodynamic surface thereof, includes a movable member linearly displaced by a very low friction piston mechanism and a compression chamber open to the exterior of the aerodynamic surface through an orifice. Reciprocal displacement of the very low friction movable member changes the volume of the compression chamber to alternately expel fluid (e.g., air) from and pull fluid into the compression chamber through the orifice. The movable member includes a piston oscillating within a piston housing each having an ultra-low friction coating for improved thermal performance and reduced maintenance. Fluid intake to the compression chamber may be increased through the use of a one-way valve located either in the aerodynamic surface, or in the piston. Multiple flapper valves may surround the orifice in the aerodynamic surface for increased fluid control.

Abstract: The present invention provides a system and method for actively manipulating fluid flow over a surface using synthetic pulsators. Synthetic pulsators produce pulsed jet operable to manipulate the primary fluid flow proximate to the synthetic pulsator. The synthetic pulsator includes a synthetic jet actuator(s) located within an ambient pressure chamber, wherein the synthetic jet actuator is operable to produce an oscillatory flow. The oscillatory flow of the synthetic jet(s) produces the pulsed jet operable to manipulate the primary fluid flow. These synthetic pulsators may then be actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

Abstract: An apparatus comprises a platform configured to move in a streamwise direction, an actuation unit associated with a control surface of the platform, a fluid source configured to supply an airflow to the actuation unit, and a control unit for moving an air jet across the control surface. The actuation unit is configured to form a traversing air jet pointing in the streamwise direction.

Abstract: An aerofoil defining geometric upper and lower surfaces which together form a leading edge region and a trailing edge region, and comprising a blowing device having a slot in the lower geometric surface in the leading edge region for injecting fluid into the airflow over the aerofoil, wherein the slot is located forward of the leading edge stagnation point at the critical angle of incidence of the aerofoil, and wherein the blowing device is adapted to inject the fluid forwardly of the slot and substantially parallel to the lower surface. Also, a method of improving the performance of the aerofoil by injecting fluid into the airflow over the aerofoil from the slot. The upper surface of the aerofoil can be kept clean, giving the potential for laminar flow during cruise without significantly compromising the high lift performance of a blown leading edge at high incidence.

Abstract: The invention pertains to a de-icing system for an aircraft with at least one heat source and at least one air delivery means for delivering air into regions of the aircraft to be de-iced. In comparison with the prior art, the invention is characterized in that the air delivery means is connected to an air-conditioning system of the aircraft for discharging air from the cabin of the aircraft via an air heating device, wherein the air heating device is connected to at least one heat source in order to heat the air from the cabin of the aircraft. The de-icing system according to the invention is able to realize a wing de-icing that not only fulfills an anti-icing function, but also a de-icing function on the ground without additional expenditure of energy.

Abstract: Lift produced by an airfoil of an aircraft is increased by suppressing fluid detachment from the surface of the airfoil. An engine cowling extends outwardly from the surface of the airfoil that has an exit plane configured for directing exhaust gases toward a rear of the aircraft. Fences extending outwardly from the surface and proximate to the exit plane of the engine cowling are configured to guide the exhaust gases along at least a portion of the airfoil surface, thereby restricting spanwise movement of the gases and increasing the Coanda Effect exhibited by the gases, thereby increasing the amount of lift produced along the surface of the airfoil. Such techniques may be used in short take-off and landing (STOL) aircraft.

Abstract: A fully fixed, non-articulating geometry vehicle that includes a number of virtual control surfaces operable to replicate a mechanical control surface's functionality. These virtual control surfaces further include a number of flow control devices on the non-articulating vehicle surface. The plurality of flow control surfaces is operable to induce secondary flow structure(s) within a boundary layer of a fluid flow over the non-articulating vehicle surface. A virtual control surface controller is operable to dynamically adjust a frequency and amplitude of the secondary flow structure(s) in order to reposition the virtual control surface. A vehicle control and stability system communicatively coupled to the plurality of virtual control surfaces is operable to direct positioning of the plurality of virtual control surfaces in response to vehicle control commands.

Abstract: A system and method of use are provided for introducing tangential control fluid flows along the surface of an aerodynamic member. The fluid flows are directed toward a coanda surface disposed at the trailing edge of the aerodynamic member. At least two injection slots are provided on opposite sides of the aerodynamic member to produce opposing forces. Control of the flow of fluid from each slot determines the net effect of these opposing forces. Smart material actuators are used to control the flow of fluid from each slot by varying the size of each slot.

Abstract: An aircraft leading edge is extended by an aerodynamic surface providing an aerodynamic flow and where air discharges are arranged preventing separation of the aerodynamic flow. The air discharges are arranged in at least two rows essentially parallel to the leading edge and in an offset manner for at least two consecutive rows. At least one block is inserted between two walls that form the aerodynamic surface. The block includes, on the one hand, an outside surface extending the aerodynamic surface, a first inclined surface contacting the first wall forming the aerodynamic surface, and a second inclined surface contacting the second wall that forms the aerodynamic surface, and, on the other hand, projecting and/or hollow shapes that are made at the inclined surfaces and that are arranged in an alternating fashion from one surface to the next, allowing air to pass on both sides of the aerodynamic surface.

Abstract: An onboard system for a rotary wing aircraft detects a limit cycle oscillation in the tail mast and provides a timely indication of the limit cycle oscillation to an aircrew before serious damage to the airframe is likely to occur.

Abstract: An aircraft having a gas turbine engine with vectorable cold and hot nozzles. The aircraft is provided with a ducting in the wing which extends from an inlet facing downwards to an outlet in the upper surface of the wing directed rearwardly. The cold vectorable nozzles of the engine are designed so that they can be swung from a vertical downward position to provide vertical lift to a horizontal position directed rearwardly to produce forward thrust, to a position where they are directed upwardly and discharged into the ducting 24. In this way, the air discharged through the outlet of the ducting 24 enhances the aerodynamic lift produced by the wing at slower speeds by inducing the air flow over the wing. In addition, the forward component of the thrust produced in the ducting provides a forward thrust on the aircraft, whilst additional forward thrust is produced by swiveling the hot nozzles.

Abstract: This invention relates to a method and system (10) for controlling the boundary layer of an airfoil (12) to reduce profile drag during flap deflection. The system (10) comprises first means for blowing air from a lower surface (14) of the airfoil (12) to trip airflow from laminar flow to turbulent flow during positive flap deflection; and second means for applying a suction force at the lower surface (14) of the airfoil (12) to preserve laminar flow during negative flap deflection.

Abstract: Device for delaying the separation of a boundary layer in flow of air (10) on a wall (12), including holes (14) formed in the wall (12) and connected to compressed air supply valves (18) by means of channels (16), the frequency of the valve opening and closing cycles and the valve opening duration being selected so as to generate peak output velocities from the holes (14) which occur in quasi-continuous succession. The invention is particularly suitable for aircraft wings and motor vehicle bodies.

Abstract: A boundary layer control arrangement comprises a pulse generator communicating with a surface having a fluid boundary layer thereacross. The boundary layer control arrangement further includes a fluid supply means for supplying a fluid to the surface via the pulse generator. The pulse generator is constructed such that fluid acts on the pulse generator to cause the fluid to pulse. Pulsing fluid passes from the pulse generator to the surface.

Abstract: The present invention provides a system and method for actively manipulating fluid flow over a surface using synthetic pulsators. Synthetic pulsators produce pulsed jet operable to manipulate the primary fluid flow proximate to the synthetic pulsator. The synthetic pulsator includes a synthetic jet actuator(s) located within an ambient pressure chamber, wherein the synthetic jet actuator is operable to produce an oscillatory flow. The oscillatory flow of the synthetic jet(s) produces the pulsed jet operable to manipulate the primary fluid flow. These synthetic pulsators may then be actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

Abstract: Aircraft exhaust systems and methods are disclosed. In one embodiment, an integrated propulsion assembly includes a wing assembly having an upper surface and a lower surface, and a propulsion unit at least partially disposed within the wing assembly. An exhaust system is configured to conduct an exhaust flow emanating from the propulsion unit to an exhaust aperture. The exhaust aperture is positioned proximate a trailing edge of the wing assembly, and has an aspect ratio of at least five. In further embodiments, the wing assembly includes a flap member moveably coupled along a trailing edge portion of the wing assembly, and the exhaust aperture is configured to direct the exhaust flow over at least a portion of the flap member.

Abstract: A nacelle structure for a gas turbine engine includes an inlet aft of an exit guide vane for supplying air flow to a forward plenum. Air is exhausted from the plenum into an air intake opening and over an inner surface of the nacelle for controlling air flow characteristics within the nacelle.

Abstract: An actuator including a first and second conductor on a dielectric, wherein application of a voltage to the first conductor creates a plasma, thereby modifying a fluid flow in communication with the actuator. Related systems and methods are also provided.

Abstract: The present invention provides a system and method for actively manipulating and controlling aerodynamic or hydrodynamic flow field vortices within a fluid flow over a surface using micro-jet arrays. The system and method for actively manipulating and controlling the inception point, size and trajectory of flow field vortices within the fluid flow places micro-jet arrays on surfaces bounding the fluid flow. These micro-jet arrays are then actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

Abstract: The present invention provides flow field control techniques that adapt the aft body region flow field to eliminate or mitigate the development of massive separated flow field zones and associated unsteady vortical flow field structures. Embodiments of the present invention use one or more distributed arrays of flow control devices (submerged in the boundary layer) to create disturbances in the flow field that inhibit the growth of larger vortical structures and/or to energize the aft body shear layer to keep the shear layer attached the aft body surface. These undesirable aerodynamic phenomena produce increased vehicle drag which harms vehicle range, persistence, and loiter capabilities. Additionally, the unsteady nature of the turbulent vortical structures shed in the aft body wake region may produce increased dynamic buffeting and aft body heating by entraining nozzle jet exhaust (a.k.a. jet wash) —requiring additional structural support, shielding, and vehicle weight.

Abstract: A method of generating lift for a vehicle including heating a flow of gas using a gas generator mounted on the vehicle that contributes no more than about ten percent of thrust used to propel the vehicle in a forward direction, and driving a lift fan using the heated gas flow to generate lift for the vehicle.

Abstract: Apparatuses and methods for the controlled trailing wake flows. An apparatus in accordance with one embodiment is directed to an aircraft system that includes an airfoil having first and second oppositely facing flow surfaces and a tip. The system can further include a vortex dissipation device carried by the airfoil, with the vortex dissipation device including a fluid flow nozzle, a valve device, and a controller. The fluid flow nozzle can be coupleable to a source of pressurized fluid and can include an orifice positioned to direct a flow of fluid outwardly from the tip. The valve device can be coupled in fluid communication with the fluid flow nozzle to selectively control the flow passing through the orifice. The controller can be coupled to the valve device to direct the operation of the valve device. Accordingly, the vortex dissipation device can be activated to accelerate the rate at which vortices (e.g., wing tip vortices) dissipate after they are generated.

Abstract: Methods and apparatus for controlling the attitude of a mobile platform with a resolution suitable for vernier attitude control. In one embodiment a method includes flowing fluid through an orifice of an aerodynamic surface. The method also includes modifying a boundary layer of the aerodynamic surface with the flowing fluid. Another embodiment provides an aerodynamic member of a mobile platform. The aerodynamic member includes an aerodynamic surface, an orifice, an actuator, and a fluid moving member. The orifice is in the aerodynamic surface and the actuator is subject to friction and backlash. The fluid moving member communicates with the orifice and causes the fluid to flow through the orifice to modify the boundary layer of aerodynamic surface.

Abstract: Air pressure distribution for airfoil lower and upper surfaces is utilized to divert airflow using ducts formed in space-curve shapes placed inside the airfoil volume, through span-wise located inlets from high pressure areas on the airfoil lower surface near the leading edge and through chord-wise spaced inlets on the side face of the airfoil wing tip correspondingly to the side face of the airfoil wing tip through chord-wise spaced outlets on the side face of the airfoil wing tip and to span-wise located outlets to the low pressure areas on the airfoil upper surface. Triboelectric materials on the wing surfaces are employed to static charge the air in drag. Inside the ducts, the employment of either triboelectric linings and materials, or HV-supplied electrodes, or both, help to static charge the diverted air flow to and from the airfoil wing tip side face to diffuse wing tip vortex core early.

Abstract: A system and method for controlling boundary layer flow over an aircraft wing are provided. The system includes at least one wing element, and a plurality of ports defined in the wing element and in fluid communication with one another. The system also includes at least one fluidic device operable to continuously ingest the fluid through at least one of the ports and eject the fluid out of at least one other port to control boundary layer flow of the fluid over the wing element.

Abstract: A fully fixed, non-articulating geometry vehicle that includes a number of virtual control surfaces operable to replicate a mechanical control surface's functionality. These virtual control surfaces further include a number of flow control devices on the non-articulating vehicle surface. The plurality of flow control surfaces is operable to induce secondary flow structure(s) within a boundary layer of a fluid flow over the non-articulating vehicle surface. A virtual control surface controller is operable to dynamically adjust a frequency and amplitude of the secondary flow structure(s) in order to reposition the virtual control surface. A vehicle control and stability system communicatively coupled to the plurality of virtual control surfaces is operable to direct positioning of the plurality of virtual control surfaces in response to vehicle control commands.

Abstract: An airfoil boundary layer control system may be provided. The airfoil boundary layer control system may include at least one airfoil that may include a first surface and a second surface coupled together at a leading edge and a trailing edge; at least one hollow chamber defined within the at least one airfoil; and an aperture defined in the airfoil and positioned substantially near the trailing edge, the aperture coupled in flow communication with the at least one hollow chamber; a pressure source coupled in flow communication with the at least one hollow chamber.

Abstract: A system for controlling unwanted flow separation. One or more microjets are placed to feed auxiliary fluid into a region of suspected flow separation. If the separation is intermittent, sensors can be employed to detect its onset. Once separation is developing, the microjets are activated to inject a stream of fluid into the separation region. This injected fluid affects the flow and serves to control the flow separation. A steady-state embodiment can be used to continuously fluid. On the other hand, sensors and a rapidly reactive control circuit can be used to inject fluid only when it is needed to inhibit flow separation. The sensors and control circuit can operate off of simple pressure gradient detection or predictive algorithms that anticipate when flow separation will occur.

Abstract: A system and method for dissipating vortices that form at the wingtips on aircraft and from other airfoils. A jet air stream is discharged in a location at or proximate to the outer end portion of the airfoil into the vortex flow, and the jet air stream is moved cyclically back and forth. The cyclic movement can be at lower or higher frequencies to alleviate at least in part intensity of the vortex or accelerate instability of the vortex which leads to vortex dissipation.

Abstract: An apparatus and method for reducing surface friction drag on the hull of a surface vessel by entraining air into water flowing in the boundary layer flow along the hull. The apparatus creates a reduced pressure region by diverting a first portion of the flow away from the surface of the hull. An air pocket is formed in the reduced pressure region and a second portion of the flow is directed through the air pocket by nozzles, which acts as a plunging jet and entrains air into the boundary layer.

Abstract: A method and system to optimize the process a spreading the weight of supersonic aircraft downstream over a large area to reduce the pressure and intensity on the ground as function of air flow velocity, temperature, and/or pressure is provided.

Abstract: A rotational position-adjusting system (6) for a vertical takeoff and landing aircraft (4). The system (6) includes multiple detectors (60) that generate rotor signals. The rotor signals are indicative of the position of each rotor (8) of the aircraft (4). The rotors (8) provide lift to the aircraft (4). A controller (24) is coupled to the detectors (60) and adjusts the rotational speed of one or more of the rotors (8) in response to the rotor signals.

Abstract: Lift produced by an airfoil of an aircraft is increased by suppressing fluid detachment from the surface of the airfoil. An engine cowling extends outwardly from the surface of the airfoil that has an exit plane configured for directing exhaust gases toward a rear of the aircraft. Fences extending outwardly from the surface and proximate to the exit plane of the engine cowling are configured to guide the exhaust gases along at least a portion of the airfoil surface, thereby restricting spanwise movement of the gases and increasing the Coanda Effect exhibited by the gases, thereby increasing the amount of lift produced along the surface of the airfoil. Such techniques may be used in short take-off and landing (STOL) aircraft.

Abstract: Coanda Effect and lift produced along a surface of an airfoil are increased by ducting compressed fluid from the engine to the surface of the airfoil. An engine produces exhaust gases that are predominantly directed toward an aft end of the aircraft by a cowling or other structure as an exhaust plume. One or more internal ducts extend from the engine to the surface of the airfoil to thereby transmit a compressed fluid from the engine to the surface in order to suppress flow separation along the surface, thereby causing the engine exhaust flow to remain attached to the surface over a wider span. Such structures and techniques may find particular use in aircraft designed to exploit upper surface blowing (USB) techniques and structures for short takeoff and landing (STOL) performance.

Abstract: A high-lift flap of an aircraft is provided having a device for influencing the flap vortex as well as a device for influencing the flap vortex at the lateral edge of the aerodynamic high-lift flap, which can be achieved effectively and at low cost.

Abstract: The present invention provides a system and method for actively manipulating and controlling aerodynamic or hydrodynamic flow field vortices within a fluid flow over a surface using micro-jet arrays. The system and method for actively manipulating and controlling the inception point, size and trajectory of flow field vortices within the fluid flow places micro-jet arrays on surfaces bounding the fluid flow. These micro-jet arrays are then actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

Abstract: An aircraft capable of making short takeoffs and landings includes essentially a fuselage, a wing secured to the fuselage, a front horizontal stabilizer secured to the fuselage on the front end of the fuselage and at least two jet engines for propulsion. According to the architecture proposed, the propulsion engines are arranged side by side above the fuselage in a rear part of the fuselage with a width at least equal to the width of the propulsion group, a fuselage flap device is arranged in the back of the fuselage so that the fuselage flaps adopt at least a position in which the flaps are considerably in a horizontal plane and take at least a high-lift position in which the flaps are turned downward in such a way that the blast created by the jet engines is channeled towards the top surface of the fuselage flaps to induce a blowing effect.

Abstract: Upper surface (13) of an aerofoil (or rotor blade) is provided with nozzles or slots (14, 16) at leading portion (15) and trailing portion (17) to assist attachment of airflow by discharging gas towards trailing edge (11). Gas discharged may be heated, eg coming from rocket-type combustion chambers within the aerofoil. The aerofoil may be adjustable between high profile (as shown) and low profile (for supersonic flight) using jacks that pivot sections of upper surface (13) at leading and trailing edges (10-11).

Abstract: A method for ensuring the safety of an aircraft flying horizontally at low speed. According to the invention, with the flaps (5) being in a maximum extended position and being blown on by the airscrews (4), said flaps (5) are at least partially retracted, automatically, when the thrust of the engines (3) is at least equal to a predetermined lift value.

Abstract: The present invention provides a system and method for actively manipulating fluid flow over a surface using synthetic pulsators. Synthetic pulsators produce pulsed jet operable to manipulate the primary fluid flow proximate to the synthetic pulsator. The synthetic pulsator includes a dual diaphragm synthetic jet coupled to high performance dual actuator solenoids, wherein the synthetic jet is operable to produce an oscillatory flow. The oscillatory flow of the synthetic jet(s) produces the pulsed jet operable to manipulate the primary fluid flow. These synthetic pulsators may then be actively manipulated to control the flow behavior of the ducted fluid flow, influence the inception point and trajectory of flow field vortices within the fluid flow, and reduce flow separation within the primary fluid flow.

Abstract: A linear cavity is provided on the leading edge of an object that is subject to the flow of liquids or gasses, where said cavity preferably has a wall that follows the curvature of a diminishing sine wave, although other configurations are possible that do not follow a specific sine wave. The cavity accepts the flow of liquids or gasses that enter into the cavity, and where the dimensions of the cavity cause the flow of liquids or gases within it to form a pressure node that extends forward of the cavity. The pressure node provides a wedge means to cause oncoming gasses or liquids to divert around the object body ahead of the object body itself, decreasing turbulence around the periphery of the object. The cavity may be spherical, in the instance of a missile, plane, or underwater transportation means, or may be linear, in the instance of an automobile grill that is subject to wind, or a bridge support, where the bridge support has to maintain position against the flow of current.

Abstract: A device and method for conversion of the energy of medium flows are provided. The proposed device and method ensure suppression of the vortex streams in the flow on the leg of its motion along the radially converging trajectories and concentration of the flow energy, which is expressed by the increase of its velocity and decrease of the summary area of the cross section of the converging trajectories. As the flow runs along the first system of helical trajectories the following takes place: the harmful secondary vortex jets continue attenuating, the degree of concentration of the flow energy increases and velocity components form in the flow, which correspond to natural vortex streams, for instance, tornadoes, whirlpools.

Abstract: Separate upper and lower plenums within an aircraft airfoil or a sea hydrofoil conduct fluid under different pressures to nozzle slots from which jets emerge to augment lift in accordance with different travel conditions. Lift is induced by nozzle slot emergence of a primary jet from one of the plenums along a reverse flow path relative to secondary jet outflow from the other plenum. This capability involves angularly adjusted deflection of the primary jet outflow along forward, reverse or vertical directional flow paths from the trailing end of the airfoil or hydrofoil under zero and other different speed conditions by emergence of the secondary wall jet.

Abstract: A method of improving lift of an aircraft wing. The method consists of a single step of mechanically generating a supplemental laminar air flow over the aircraft wing with a view to creating an area of low pressure over the aircraft wing which serves to enhance lift properties of the aircraft wing.

Abstract: An apparatus and method for reducing surface friction drag on the hull of a surface vessel by entraining air into water flowing in the boundary layer flow along the hull. The apparatus creates a reduced pressure region by diverting a first portion of the flow away from the surface of the hull. An air pocket is formed in the reduced pressure region and a second portion of the flow is directed through the air pocket by nozzles, which acts as a plunging jet and entrains air into the boundary layer.

Abstract: A dynamic cavity air flow system reduces the highly unsteady flow over exposed aircraft cavities by incorporating a series of microjets proximate the leading edge of a cavity. The microjets, which may articulate, issue a supersonic jet flow toward the rear or trailing edge of the cavity whenever the cavity is exposed during flight. The microjets receive the air for the flow from either a dedicated pressurized gas source aboard the aircraft or from bleed air taken from an engine of the aircraft. Appropriate sensors and controllers are provided for control of the system.

Abstract: An apparatus comprising: an aerodynamic surface adapted for producing an adverse pressure gradient in a fluid flow; and a first pulse detonation actuator disposed adjacent the aerodynamic surface and adapted for impulsively detonating a fuel/air mixture to produce a pressure rise and velocity increase of combustion products therein, the aerodynamic surface having a plurality of separation control holes adapted for communicating combustion product flows from the first pulse detonation actuator to the aerodynamic surface for modulating separation of the fluid flow from the aerodynamic surface.

Abstract: A wing for an aircraft has a passive jet spoiler for providing yaw control by increasing drag on the wing. The spoiler comprises an inlet located near the leading edge of a lower surface of the wing and at least one outlet formed on the lower surface or on an upper surface of the wing. An internal passage connects the inlet and each outlet for allowing air to pass from the inlet to the outlet. The air exits the outlets generally normal to the respective surface of the wing, causing a laminar flow to separate from the surfaces downstream of each outlet. The separated flow increases the drag on the wing, producing a yawing moment on the aircraft. Selective placement of the outlets on the upper and lower surfaces limits undesirable roll and pitch moments. Valves are provided for selectively controlling the amount of air passing through the spoiler.