Abstract: The present invention provides a system and method for rapidly and precisely controlling vortex symmetry or asymmetry on aircraft forebodies to avoid yaw departure or provide supplemental lateral control beyond that available from the vertical tail surfaces with much less power, obtrusion, weight and mechanical complexity than current techniques. This is accomplished with a plasma discharge to manipulate the boundary layer and the angular locations of its separation points in cross flow planes to control the symmetry or asymmetry of the vortex pattern. Pressure data is fed to a PID controller to calculate and drive voltage inputs to the plasma discharge elements, which provide the volumetric heating of the boundary layer on a time scale necessary to adapt to changing flight conditions and control the symmetry or asymmetry of the pressures and vortices.

Abstract: The present invention provides a system and method for rapidly and precisely controlling vortex symmetry or asymmetry on aircraft forebodies to avoid yaw departure or provide supplemental lateral control beyond that available from the vertical tail surfaces with much less power, obtrusion, weight and mechanical complexity than current techniques. This is accomplished with a plasma discharge to manipulate the boundary layer and the angular locations of its separation points in cross flow planes to control the symmetry or asymmetry of the vortex pattern. Pressure data is fed to a PID controller to calculate and drive voltage inputs to the plasma discharge elements, which provide the volumetric heating of the boundary layer on a time scale necessary to adapt to changing flight conditions and control the symmetry or asymmetry of the pressures and vortices.

Abstract: A method is provided for hypersonic laminar flow control which uses the effect of boundary layer stabilization by an ultrasonically transparent coating. A hypersonic body surface is covered by the coating which absorbs the flow disturbance energy and does not trip the boundary layer flow. In one embodiment, the coating is made from a porous material of regular structure containing cylindrical blind microholes normal to the body surface. In another embodiment, the porous material has random distributions of pore shape and orientation. Extraction of the flow disturbance energy by pores causes stabilization of the boundary layer on the coated surface and leads to laminar-turbulent transition delay. The method can be used to decrease the aerodynamic drag of hypersonic vehicles and reduce heat transfer on vehicle surfaces.

Abstract: A method and apparatus is provided for laser welding which utilizes the power reflected by the surface being welded to control the power input to the weld. A beam of laser light is projected on the surface to be welded and the power of the light reflected by the surface is measured by a wattmeter placed in the path of the reflected beam. The output from the wattmeter is used to control the laser power per unit area projected on the weld. In one embodiment the wattmeter output is used to control the speed of the skate motor which moves the surface being welded. In another embodiment, the wattmeter output is used to control the output of the laser.