Abstract: Method and arrangement for reducing the effects of a sonic boom created by an aerospace vehicle when said vehicle is flown at supersonic speed. The method includes providing the aerospace vehicle with a first spike extending from the nose thereof substantially in the direction of normal flight of the aerospace vehicle, the first spike having a second section aft of a first section that is aft of a leading end portion, the first and second sections having a second transition region there between and each of the sections having different cross-sectional areas, the leading end portion of the first spike tapering toward a predetermined cross-section with a first transition region between the predetermined cross-section and the first section. The first transition region is configured so as to reduce the coalescence of shock waves produced by the first spike during normal supersonic flight of the aerospace vehicle.

Abstract: Method for configuring and operating an aircraft for minimizing sonic boom effects at ground level during supersonic flight of the aircraft. The method includes configuring an aircraft and flying the aircraft at supersonic speed so that in the supersonic flight, a lower profile of the aircraft is presented and generally groundwardly directed; and generating multiple different magnitude pressure disturbances below the aircraft, and radiating therebelow, and controlling the different magnitude pressure disturbances generated below the aircraft so that differentials thereamong are sufficiently minimized that ground level sonic boom effects are minimized during the supersonic flight.

Abstract: Method and apparatus for providing a turbofan blade 40 adapted to initiate and control a boundary layer transition at a side surface of the blade 40 during operation as a component in a turbofan assembly 35. The turbofan blade 40 includes a leading edge 55, a trailing edge 58, and two side surfaces including a high-pressure side surface 49 and a low-pressure side surface 52. At least one of the two side surfaces has an essentially smooth surface portion 61 located between the leading and trailing edges, and the essentially smooth surface portion is interrupted by a surface deviation 64. The surface deviation is configured to fix a positionally unstable laminar to turbulent boundary layer transition 24 at a location toward the trailing edge from the surface deviation during operation of the turbofan blade in the turbofan assembly.

Abstract: Method and arrangement for reducing the effects of a sonic boom created by an aerospace vehicle when said vehicle is flown at supersonic speed. The method includes providing the aerospace vehicle with a first spike extending from the nose thereof substantially in the direction of normal flight of the aerospace vehicle, the first spike having a second section aft of a first section that is aft of a leading end portion, the first and second sections having a second transition region therebetween and each of the sections having different cross-sectional areas, the leading end portion of the first spike tapering toward a predetermined cross-section with a first transition region between the predetermined cross-section and the first section. The first transition region is configured so as to reduce the coalescence of shock waves produced by the first spike during normal supersonic flight of the aerospace vehicle.

Abstract: A method for modeling the acoustic signature produced by an aircraft of interest flying at a particular supersonic Mach number/altitude operating point of interest. The method includes operating a sub-scale aircraft that is a sub-scale version of the aircraft of interest at a supersonic Mach number and at an altitude that are respectively different from the Mach number and the altitude associated with the operating point of interest. The Mach number and altitude at which the sub-scale aircraft is operated is selected such that peak overpressure generated by the sub-scale aircraft and time to rise to peak overpressure are the same as peak overpressure and time to rise to peak overpressure caused by operating the aircraft of interest at the operating point of interest.

Abstract: A method for modeling the acoustic signature produced by an aircraft of interest flying at a particular supersonic Mach number/altitude operating point of interest. The method includes operating a sub-scale aircraft that is a sub-scale version of the aircraft of interest at a supersonic Mach number and at an altitude that are respectively different from the Mach number and the altitude associated with the operating point of interest. The Mach number and altitude at which the sub-scale aircraft is operated is selected such that peak overpressure generated by the sub-scale aircraft and time to rise to peak overpressure are the same as peak overpressure and time to rise to peak overpressure caused by operating the aircraft of interest at the operating point of interest.

Abstract: Embodiments of the invention relate to a supersonic inlet employing relaxed isentropic compression to improve net propulsive force by shaping the compression surface of the inlet. Relaxed isentropic compression shaping of the inlet compression surface functions to reduce cowl lip surface angles, thereby improving inlet drag characteristics and interference drag characteristics. Using supersonic inlets in accordance with the invention also demonstrated reductions in peak sonic boom overpressure while maintaining performance.

Abstract: Method and arrangement for reducing the effects of a sonic boom created by an aerospace vehicle when said vehicle is flown at supersonic speed. The method includes providing the aerospace vehicle with a first spike extending from the nose thereof substantially in the direction of normal flight of the aerospace vehicle, the first spike having a second section aft of a first section that is aft of a leading end portion, the first and second sections having a second transition region therebetween and each of the sections having different cross-sectional areas, the leading end portion of the first spike tapering toward a predetermined cross-section with a first transition region between the predetermined cross-section and the first section. The first transition region is configured so as to reduce the coalescence of shock waves produced by the first spike during normal supersonic flight of the aerospace vehicle.

Abstract: Method and arrangement for reducing the effects of a sonic boom created by an aerospace vehicle when said vehicle is flown at supersonic speed. The method includes providing the aerospace vehicle with a first spike extending from the nose thereof substantially in the direction of normal flight of the aerospace vehicle, the first spike having a second section aft of a first section that is aft of a leading end portion, the first and second sections having a second transition region therebetween and each of the sections having different cross-sectional areas, the leading end portion of the first spike tapering toward a predetermined cross-section with a first transition region between the predetermined cross-section and the first section. The first transition region is configured so as to reduce the coalescence of shock waves produced by the first spike during normal supersonic flight of the aerospace vehicle.

Abstract: Method and apparatus for providing a turbofan blade 40 adapted to initiate and control a boundary layer transition at a side surface of the blade 40 during operation as a component in a turbofan assembly 35. The turbofan blade 40 includes a leading edge 55, a trailing edge 58, and two side surfaces including a high-pressure side surface 49 and a low-pressure side surface 52. At least one of the two side surfaces has an essentially smooth surface portion 61 located between the leading and trailing edges, and the essentially smooth surface portion is interrupted by a surface deviation 64. The surface deviation is configured to fix a positionally unstable laminar to turbulent boundary layer transition 24 at a location toward the trailing edge from the surface deviation during operation of the turbofan blade in the turbofan assembly.

Abstract: An aircraft includes a spike projecting forward from the leading end of the fuselage and/or rearward from the trailing end of the fuselage. The spike can include a single section or two or more sections of varying cross-sectional area. Transition regions between sections of varying cross-sectional area are located and shaped to reduce coalescence of shock waves created thereby during supersonic flight. The spike can be collapsible and can be retracted into the fuselage. The spike can have a cross-sectional shape wherein the nose thereof lies on a line formed by the intersection of the bottom of the spike with a plane tangent to the bottom of the spike. A spike thus shaped causes an asymmetric pressure distribution during supersonic flight, wherein the ground-directed pressure contour is of lesser magnitude than the pressure contour propagating in other directions.

Abstract: An aft facing step situated across the span of an airfoil. A chemical or thermal deicing or running wet anti-icing device is located in or on the airfoil upstream of the step, and causes water to run back towards the step. The step suddenly reduces the thickness of the airfoil chord section, which causes a disturbance in the boundary layer across the span of the airfoil downstream of the step. The aforementioned disturbance causes runback water to form droplets and be blown clear of the airfoil surface downstream of the step, thereby preventing ice from being formed on the airfoil surface downstream of the step.

Abstract: A special contour near the trailing edge of an airfoil which improves the airfoil effectiveness. The contour is a combination of a blunt airfoil base, a local region of high surface curvature, typically on the airfoil lower surface, and upper surface and lower surface trailing edge slopes that diverge from each other.