Abstract:
A method of supersonic thrust generation includes generating a thrust supersonic exhaust plume having a first average velocity from an engine, and expelling a bypass exhaust plume having a second average velocity from the engine, the first average velocity greater than the second average velocity, so that the bypass exhaust plume inhibits coalescence of an engine exhaust plume compression shockwave.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/222,074 filed Sep. 22, 2015, the contents of which are incorporated by reference herein for all purposes. 
     
    
     BACKGROUND 
     Field of the Invention 
       [0002]    The field of the invention relates to supersonic aircraft structures, and more particularly systems to mitigate sonic ground effects of such aircraft. 
       Description of the Related Art 
       [0003]    Government agencies administer policies on noise limits for civil supersonic aircraft that are intended to protect the public from excessive and environmentally damaging noise pollution caused by earthward propagating compression shockwaves (i.e., sonic booms) from such aircraft. For example, since March 1973, supersonic flight over land by civil aircraft has been prohibited in the United States. Past efforts at mitigating such sonic booms include attempts at re-shaping or reducing the peak intensity of such compression shockwaves impacting at ground level, such as Gulfstream&#39;s “spike” that transforms the traditional N-wave sonic boom into a smooth and more rounded pressure wave shaped roughly like a sine wave or sideways “S”. ( Federal Register /Vol. 76, No. 100/Tuesday, May 24, 2011/Notices P. 30231). 
         [0004]    There has been a long and unmet need for civil supersonic air transportation in many countries. The National Aeronautics and Space Administration in the United States projects that supersonic flight over land may result in a 50% reduction in cross country travel time, facilitate movement of time-critical cargo, including life-saving medical supplies, and enhance homeland security through rapid transportation of critical responder teams. ( Fixing the Sound Barrier Three Generations of U.S. Research into Sonic Boom Reduction . . . and what it means to the future . FAA Public Meeting on Sonic Boom. Jul. 14, 2011 (http://www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/supersonic_aircraft_noise/media/NASA %20Presentation.pdf, accessed Sep. 16, 2016) 
         [0000]    Without significant reduction in compression shockwave energy received at ground level, supersonic flight by civil aircraft over land will not become a reality in most countries. 
         [0005]    A need continues to exist to reduce the peak intensity of sonic booms reaching the ground, or to eliminate them entirely, for aircraft flying greater than the speed of sound. 
       SUMMARY 
       [0006]    A method of shock wave mitigation in supersonic vehicles may include generating an earthward propagating wing compression shockwave from a curved wing, expelling a first supersonic exhaust plume having a first average velocity from an engine, the engine having an engine housing, reflecting a majority of the earthward propagating wing compression shockwave back towards the curved wing using the engine (see below for engine casing reflection vs. thrust reflection), expelling a bypass exhaust plume having a second average velocity adjacent to the first supersonic exhaust plume, the second average velocity being slower than the first average velocity, and inhibiting coalescence of an engine exhaust plume compression shockwave extending from the first supersonic exhaust plume using the bypass exhaust plume. The step of reflecting a majority of the earthward propagating wing compression shockwave back towards the curved wing using the engine may further include reflecting the wing compression shockwave off of the engine housing. The method may also include moving the engine housing to meet the wing compression shockwave, and the step of moving the engine housing may include translating the engine along the axis of freestream air flow about the engine. In some embodiments, the method may include slidably moving the wing relative to a fuselage that is itself slidably coupled to the wing so that the wing compression shockwave is moved relative to the engine to meet the engine housing for reflection. In other embodiments, reflecting a majority of the wing compression shockwave back away from the earth may also include reflecting the wing compression shockwave off of the first supersonic exhaust plume. The reflection of the wing compression shockwave off of the first supersonic exhaust plume may establish an upward propagating reflected compression shockwave. The second average velocity (of the bypass exhaust plume) may be approximately the same velocity as a freestream velocity about the wing. In certain embodiments, the bypass exhaust plume is expelled from the engine, and the bypass exhaust plume may include air sourced from (i) bleed air taps from a compressor in the engine or (ii) bleed air taps at inlet shock ramps disposed at a front of the engine. In certain embodiments of the engine, the engine may have a first nozzle expelling the first supersonic exhaust plume and a second nozzle expelling a bypass exhaust plume that has an average velocity that is slower than an average velocity of the first supersonic exhaust plume. The wing may have a bottom surface shape configured to direct the compression shockwave toward the engine. The step of generating a downward propagating wing compression shockwave from the curved wing towards the earth may include propagating a majority or substantially all of the compression shockwave toward a rear portion of the engine housing. In other embodiments, generating a downward propagating wing compression shockwave from the curved wing towards the earth comprises propagating substantially all of the compression shockwave toward the first supersonic exhaust plume. The curved wing may have an outboard portion shape that is straight or upward curving so that a high-pressure underwing to freestream low pressure interface channels a sound propagating vector that is at an inclination to the ground and parallel to the ground, respectively. The engine may be selected from the group consisting of a jet engine, turbojet engine, ramjet engine, scramjet engine, high bypass turbojet, variable cycle engine, and adaptive-cycle engine. In other embodiments, less than the entire wing compression shockwave is reflected back towards the curved wing using the engine. 
         [0007]    A method of supersonic thrust generation includes generating a thrust supersonic exhaust plume having a first average velocity from an engine, and expelling a bypass exhaust plume having a second average velocity from the engine, the first average velocity greater than the second average velocity. The thrust supersonic exhaust plume and bypass exhaust plume may be substantially aligned when exiting the engine. The bypass exhaust plume may be generated from a source selected from the group consisting of (i) bleed air taps from a compressor in the engine, (ii) bleed air taps at inlet shock ramps disposed at a front of the engine. 
         [0008]    An air vehicle may include a fuselage, an engine comprising an exhaust plume nozzle, a bypass plume nozzle disposed adjacent to the exhaust plume nozzle, and a curved supersonic wing coupled to the fuselage, the curved supersonic wing curving about the engine. The engine may also include the bypass plume nozzle rather than apart from the engine. The engine may be translatable in relation to the curved supersonic wing. In an alternative embodiment, the curved supersonic wing may be translatable in relation to the engine. The air vehicle may also include an engine casing disposed on the engine, the engine have a wing-facing curved portion that has a center of radius that substantially coincides with a center of radius of an underside of the curved supersonic wing. A plurality of control surfaces may also be included, the control surfaces not operable to extend downwards during supersonic flight. In other embodiments, an engine casing is coupled to the engine, the engine casing having a flat bottom portion that is in a plane parallel to freestream air flow when such freestream air flow is greater than Mach 1 during flight. The engine may be operable to provide supersonic thrust through the exhaust plume nozzle that has an average supersonic velocity that is greater than a supersonic velocity provided through the bypass plume nozzle. 
         [0009]    A method of shock wave mitigation in supersonic vehicles may include generating an earthward propagating wing compression wave region from a curved wing, expelling a first supersonic exhaust plume having a first average velocity from an engine, the engine having an engine housing, and translating the engine to expel the first supersonic exhaust plume immediately upstream from the earthward propagating wing compression wave region, wherein the earthward propagating wing compression wave region is inhibited from coalescing into a compression shockwave by the first supersonic exhaust plume. The method may also include expelling a bypass exhaust plume having a second average velocity adjacent to the first supersonic exhaust plume, the second average velocity of the bypass exhaust plume being slower than the first average velocity of the first supersonic exhaust plume, and inhibiting coalescence of an engine exhaust plume compression shockwave extending from the first supersonic exhaust plume using the bypass exhaust plume. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the invention. Like reference numerals designate corresponding parts throughout the different views. Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which: 
           [0011]      FIGS. 1 and 2  are front and top plan reviews, respectively, of one embodiment of a supersonic aircraft having two curved wings to direct earthward propagating wing compression waves to respective bifurcated exhaust engines for compression wave mitigation; 
           [0012]      FIGS. 3 and 4  are rear plan views illustrating two implementations of a bifurcated exhaust engine; 
           [0013]      FIG. 5  illustrates one embodiment of a bifurcated exhaust engine having a single turbojet engine and using a bypass exhaust plume to inhibit coalescence of an engine exhaust plume compression shockwave; 
           [0014]      FIGS. 6-10  are rear plan views illustrating alternative implementations of a bifurcated exhaust engine; 
           [0015]      FIG. 11  illustrates another embodiments of a bifurcated exhaust engine having two turbojet engines and using a bypass exhaust plume to inhibit coalescence of an engine exhaust plume compression shockwave 
           [0016]      FIG. 12  illustrates an engine that is operable to translate in relation to a supersonic wing to enable reflection of an earthward propagating wing compression shockwave back up and away from ground; and 
           [0017]      FIGS. 13, 14 and 15  illustrate different embodiments of a curved wing and bifurcated engine, with respective wings having concave, straight and convex outboard wing portions. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    A bifurcated exhaust engine and wing configuration are disclosed that are operable to inhibit coalescence of any supersonic exhaust plume compression shockwave and that are capable of reflecting an earthward propagating wing compression shockwave back up and away from the ground to eliminate or substantially reduce transmission of sonic booms to ground level for aircraft flying greater than the speed of sound. 
         [0019]      FIGS. 1 and 2  are front and top plan reviews, respectively, of a supersonic aircraft having a fuselage coupled between two curved supersonic wings, and respective engines that are positioned to intercept and reflect earthward propagating wing compression shockwaves, with the engines also designed to mitigate exhaust plume compression shockwaves. Each of the curved supersonic wings  102  may be attached to the fuselage  104  in a high-wing configuration, with each engine  106  connected underneath to its respective wing  102  through an engine pylon  108  to provide supersonic thrust for propulsion of the supersonic aircraft  100 . Each engine  106  may be positioned with an engine outlet  110  terminating in front of a respective wing compressive lift shock region  112  that provides lift to the curved wing  102  during supersonic flight. Each engine  106  is preferably slidably coupled to its respective curved supersonic wing  102  to enable roll axis linear translation from a fore engine position to an aft engine position (see  FIGS. 11 and 12 ). In an alternative environment, each engine  106  is capable of two-dimensional translational movement, such as a linear translation along the roll axis and along the yaw axis. Such capability would allow each engine outlet  110  (otherwise referred to as “nozzles”), to move closer to or further away from its adjacent wing compressive lift shock region  112 , or closer to or further from the underside  114  of each respective wing  102 . In an alternative embodiment, each engine  106  may be slidably coupled to the fuselage  104 , rather than to the wing  102 , to enable translation along the roll and or yaw axis of each engine  106  with respect to its associated wing  102 . An engine casing  118  may be slidably or fixedly coupled to the engine  106  and disposed on and encompassing a rear portion of each engine  106 . The engine casings  118  may each have a wing-facing curved portion for receipt of an earthward propagating wing compression shockwave (indicated by dashed arrows). In one embodiment, each engine casing  118  has a center of radius R H  having a center point C that substantially coincides with a center point C of a radius R W  of an underside of the curved supersonic wing  102 . 
         [0020]    Each of the curved supersonic wings  102  may be formed in a curved anhedral or curved dihedral spanwise configuration, with the engines  106  generally centered at a respective center of radius for each of the curved lower surfaces of the wings. During supersonic flight, each curved wing  102  generates an earthward propagating wing compression shockwave that is directed toward an aft portion of its associated engine casing  118  or its associated supersonic exhaust plume (see  FIG. 5 ). In embodiments using engines  106  that are operable to translate fore and aft, the engines  106  may translate to more closely match movement of the earthward propagating wing compression shockwave as it translates with varied supersonic aircraft speeds. In further embodiments, the wings  102  may be slidably coupled to the fuselage  104  to enable variable displacement between the engines  106  and respective wings  102  should the earthward propagating wing compression shockwave translate fore or aft with aircraft speed. The wing planforms may be rectangular or delta or may consist of another planform deemed desirable for supersonic flight. 
         [0021]    In the illustrated embodiment, the supersonic aircraft has a vertical stabilizer  120  and two aft mounted control surfaces  122  for pitch and roll control. The control surfaces  122  are not operable to extend downwards during supersonic flight so as to avoid additional earthward propagating compression shockwaves. The fuselage  104  is flat-bottomed and configured with the two wings  102  to be parallel to the freestream air flow during supersonic flight to reduce the possibility of unintended compression shockwave formation propagating earthward during upright flight. 
         [0022]      FIGS. 3 and 4  are rear plan views illustrating two implementations of a bifurcated exhaust engine having an engine casing positioned to receive an earthward propagating wing compression shockwave from a curved supersonic wing  102 . The engines ( 300 ,  402 ) may be located at approximately a center of radius C of the underside of the curved supersonic wing  304 . In  FIG. 3 , an outer surface of the engine casing  306  is substantially cylindrical at the anticipated point of reflection of the wing compression shockwave, and is configured in complementary opposition to an underside  308  of the curved wing  102  such that an earthward propagating wing compression shockwave  310  emanating from the curved wing  102  is reflected by the engine casing  306  back to the curved wing  304  within the illustrated plane of the figure. In  FIG. 4 , an engine casing  402  does not have a spherical upper surface and so not all of an earthward propagating wing compression shockwave  404  is reflected back to the curved wing  304 . However, the engine casing  402  is shaped at the anticipated point of reflection such that a majority of the shockwave is reflected back towards the curved wing  304  (i.e., using the engine) and substantially none of the shockwave is directed towards the ground during level flight of the aircraft. 
         [0023]    High speed and low speed engine exhaust regions may be provided in the bifurcated exhaust engine, with an upper exhaust plume nozzle ( 312 ,  406 ) providing the high speed exhaust region and the adjacent lower bypass plume nozzle ( 314 ,  408 ) providing the low speed engine exhaust region. As used herein, “high speed” and “low speed” are intended to indicate relative speed between them, rather than absolute speed values. For example, a high speed average flow exiting the upper exhaust plume nozzle may be Mach 1.0-4.0, while a “low speed” average flow exiting lower bypass plume nozzle may be Mach 0.9-2.5, so long as the high speed average velocity is higher than the low speed average velocity at any point in time. As used herein, “higher” and “lower” are also relative positions having a reference frame of an aircraft that is upright and relatively level with respect to the Ground. In  FIG. 3 , the engine casing has a substantially circular cross section and is parallel to the free stream at an anticipated area of reflection of the wing compression shockwave  310  to provide more complete reflection back to the curved wing  102 . Each of the high and low speed exhaust plume nozzles ( 312 ,  314 ) may be truncated at their exit planes and not wholly circular, such as to form semicircles at their exit planes. In  FIG. 4 , each of the high and low speed exhaust plume nozzles ( 406 ,  408 ) are substantially circular at their exit planes and the engine casing  410  may be substantially ellipsoid and parallel to the free stream at the anticipated area of shockwave reflection. 
         [0024]      FIG. 5  depicts a bifurcated exhaust engine that expels a bypass exhaust plume to inhibit coalescence of an engine exhaust plume compression shockwave, and to reflect an earthward propagating wing compression shockwave that is reflected off an engine housing of the bifurcated engine. The engine, illustrated as a turbojet engine  500 , may have an inlet cone or dual inlet ramps ( 502 ,  504 ) that may be disposed in front of and between an upper thrust air intake  506  and lower bypass air intake  508 . Upper and lower oblique shock waves ( 510 ,  512 ) may form at the dual inlet ramps ( 502 ,  504 ) at free stream air speeds of greater than Mach 1. The upper thrust air intake  506  leads to a subsonic diffuser section  514  that delivers subsonic air to a compression section  516 , with the compressed air then delivered to a combustion chamber  518  for mixing with a fuel, combustion, and hence to a turbine section  520  for expansion of the resultant gases out of a nozzle section to expel a supersonic exhaust plume  522 . 
         [0025]    The lower oblique shockwave  512  may be reflected internally within the lower bypass air intake  508  before producing a normal shockwave  524  immediately in front of a subsonic flow region  526 . The subsonic flow region  526  receives the resulting high-pressure air. Bleed air may be provided to the subsonic flow region  526 , such as from bleed air taps  528  leading from the compression section  516 , from the inlet shock ramps ( 502 ,  504 ), or from the upper supersonic exhaust plume  522  (before it exits its respective nozzle) using direct ducting of the exhaust that has been slowed to ‘near free stream’ velocity. The high-pressured air may then be presented to a bypass throat  528  for expulsion from a second nozzle section  530  as a bypass exhaust plume  532 , with the second nozzle section  530 . The bypass exhaust plume  532  has an average speed that is slower than the supersonic speed of the supersonic exhaust plume  522 . Although the actual velocity of the bypass exhaust plume  532  may be greater than, equal to, or less than Mach 1.0 when expelled from the second nozzle, its relative velocity to the free stream  534  is subsonic (M&lt;1.0) to avoid transmittal shock to the free stream  534  upon contact with it during supersonic flight. A shockwave front  536  that would otherwise exist from the supersonic exhaust plume  522  is abated in response to freestream contact with the bypass exhaust plume  532 . 
         [0026]    The engine  500  may have an engine housing  538  having a top cylindrical surface or otherwise curved exterior surface that is parallel to the free stream air  534  to prevent generation of a compression shock wave. An earthward propagating wing compression shockwave  540  is illustrated extending down and reflecting off of the engine housing  538  during normal flight to reflect a majority, or as illustrated, “all,” of the earthward propagating wing compression shockwave  540  back towards the curved wing (see  FIG. 1 ). The supersonic exhaust plume  522  is deflected down due to pressure  542  behind the reflected wing compression shockwave  540 , with the deflected supersonic exhaust plume  522  causing a similar deflection downward of the bypass exhaust plume  532 . Because the bypass exhaust plume  532  is at a relative velocity that is subsonic (M&lt;1.0) with respect to the free stream  534 , coalescence of an engine exhaust plume compression shockwave  536  is inhibited. 
         [0027]      FIGS. 6-10  are rear plan views illustrating different embodiments of a bifurcated exhaust engine that may be used to inhibit coalescence of an engine exhaust plume compression shockwave, and to reflect an earthward propagating wing compression shockwave. More particularly,  FIG. 6  illustrates a bifurcated exhaust engine  600  having an upper exhaust plume nozzle  602  and a lower bypass plume nozzle  604 . The engine casing  606  encompassing both nozzles ( 600 ,  602 ) is substantially circular in cross section, with both the upper exhaust plume nozzle  602  and lower bypass plume nozzle  604  both having substantially a semi-circular cross section at their exit planes. In another embodiment illustrated in  FIG. 7 , the entirety of the engine casing  700  is not semicircular in cross section, but rather may form a flat lower portion such as a flat lower surface  702  underneath the lower bypass plume nozzle  604 . The engine casing  700  may have sidewalls ( 704 ,  706 ) extending down from either side of the semi-circular upper surface  708 . The upper exhaust plume nozzle  602  and lower bypass plume nozzle  604  may each have a semi-circular cross section as in  FIG. 6 . In  FIG. 8 , the engine casing may take the form of two separate engine casings, with the upper engine casing  800  encompassing the upper exhaust plume nozzle  802  and the lower engine casing  804  encompassing the lower bypass plume nozzle  806 . In  FIG. 9 , the engine casing  900  has upper and lower semicircular exterior surfaces ( 902 ,  904 ) and side panels ( 906 ,  908 ) extending between the upper and lower semicircular exterior surfaces ( 902 ,  904 ) and encompassing the upper exhaust plume nozzle  802  and lower bypass plume nozzle  806 . In  FIG. 10 , the engine casing  1000  may have a semicircular upper reflecting surface  1002 , a flat lower surface  1004  and side panels ( 1006 ,  1008 ) encompassing the upper exhaust plume and lower bypass plume nozzles. 
         [0028]    It may be understood that the described engine casings need not have the same cross section in the longitudinal direction (i.e., in the fore-to-aft aircraft dimension). Rather, the outer engine casing may have a shape that maintains an upper and lower orientation of the exhaust plume nozzle and a lower bypass plume nozzle, respectively, and may maintain a pre-determined upper reflecting surface at the anticipated area of compression shockwave reflection. Also, although the engine casings are illustrated as substantially semicircular or circular, they may be formed in other shapes, including elliptical and rectangular, and may be independent from the supersonic nozzle shape. For example, the engine casings illustrated in  FIGS. 6-10  may each encompass bell-shaped nozzles, plug nozzles, variable flap ejector nozzles, aerospike engines, expanding nozzles or other nozzles that accomplish the task of supersonic flight with the low speed engine exhaust region having a relative subsonic velocity with the free stream. 
         [0029]      FIG. 11  depicts a bifurcated exhaust engine that has upper and lower engines producing an upper thrust exhaust plume and lower bypass exhaust plume, respectively, with the lower bypass exhaust plume having an average velocity that is subsonic relative to a free stream. In one embodiment, the engines are upper and lower turbojet engines ( 1100 ,  1102 ). Upper and lower subsonic diffuser sections ( 1104 ,  1106 ) deliver subsonic air to respective compression sections ( 1108 ,  1110 ), with the compressed air then delivered to respective combustion chambers ( 1112 ,  1114 ) for mixing with a fuel, combustion, and hence to respective turbine sections ( 1116 ,  1118 ) for expansion of the resultant gases resulting in an upper supersonic exhaust plume  1120  and bypass exhaust plume  1122 . With such a configuration, bleed air may not be collected from bleed air taps, but rather the bypass exhaust plume is generated from the lower turbojet engine  1102  itself. Similar to the embodiment illustrated in  FIG. 5 , an earthward propagating wing compression shockwave  540  is illustrated extending down and reflecting off of the engine housing  1124  during normal flight to reflect a majority, or as illustrated, “all,” of the earthward propagating wing compression shockwave  540  back towards the curved wing (see  FIG. 1 ). The supersonic exhaust plume  1120  is deflected down due to pressure  542  behind the reflected wing compression shockwave  540 , with the deflected supersonic exhaust plume  1120  causing a similar deflection downward of the bypass exhaust plume  1122  to inhibit coalescence of an engine exhaust plume compression shockwave  1126  that would extend from the first supersonic exhaust plume. 
         [0030]      FIGS. 12 and 13  illustrate a side plan view of an engine that is operable to translate along the axis of freestream air flow to meet a wing compression shockwave for subsequent reflection back up and away from ground. A supersonic wing  1200  and engine, such as a turbojet engine  1204 , are configured to be movable in relation to one another. For example, the supersonic wing  1200  and turbojet engine  1204  may be slidably coupled together, such as through an engine pylon with a sliding mechanism. In other embodiments, the turbojet engine  1204  may be slidably coupled to a fuselage (not shown) that is itself fixedly coupled to the wing  1200 , or the wing  1200  may be slidably coupled to the fuselage with the fuselage fixedly coupled to the turbojet engine  1204 . In any of the described configurations, an engine casing  1206  encompassing at least a portion of the turbojet engine  1204  is illustrated initially positioned in a fore position to intercept an earthward propagating wing compression shockwave  1208  extending from the supersonic wing  1200 . The earthward propagating wing compression shockwave  1208  is illustrated as extending approximately perpendicularly from a leading edge  1210  of the supersonic wing  1200  relative to a free stream supersonic flow  1212  having a first velocity, such as Mach 1.0. As a speed of the free stream supersonic flow  1212  increases, such as approaching Mach 1.4, the earthward propagating wing compression shockwave  1208 ′ may begin to extend back from perpendicular and away from the turbojet engine  1204 . In one embodiment, the turbojet engine  1204  may be linearly translated to position  1204 ′ concurrently with rearward movement of the shockwave  1208 ′ so that the earthward propagating wing compression shockwave  1208 ′ continues to impinge on the engine casing  1206  for reflection. Similarly, as the free stream airflow continues to increase in velocity, such as to Mach 1.8 and onward to Mach 2.2, the position of the earthward propagating wing compression shockwave may continue to move ( 1208 ″,  1208 ′″) and the turbojet engine  1204  translated concurrently to intermediate position  1204 ″ and aft position  1204 ′″, respectively, to enable all or nearly all of the earthward propagating wing compression shockwave to reflect off of the engine casing  1206 . In other embodiments, the turbojet engine is a bifurcated exhaust engine and the bifurcated exhaust engine is translated in accordance with the scheme described, above. 
         [0031]    In an alternative embodiment, the engine casing  1206  or other outer surface is operable to translate independently, or in addition to, translation of the engine  1204  to meet the earthward propagating wing compression shockwave. In such an embodiment, reference numerals  1204 ′,  1204 ″ and  1204 ′″ may represent only the engine casing  1206  or other outer surface, and a majority of the engine  1204  may remain substantially fixed to the wing or fuselage. For example, the wing  1200  may remain fixed with respect to the engine  1206 , but the engine casing  1206  may extend along the axis of freestream air flow to meet the shockwave ( 1208 ,  1208 ′,  1208 ″,  1208 ′″) for subsequent reflection back up and away from ground. In a further embodiment, the engine  1204  moves with respect to the wing  1200  and the engine casing (or other outer surface) is operable to move with respect to the engine  1204  to extend along the axis of freestream air flow to enable the engine casing (or other outer surface) to meet the earthward propagating wing compression shockwave. Such translation capability of the engine  1204  and/or engine casing  1206  may enable to expulsion of the first supersonic exhaust plume immediately upstream from the earthward propagating wing compression wave region to eliminate or substantially reduce transmission of sonic booms to ground level for aircraft flying greater than the speed of sound. 
         [0032]      FIGS. 13, 14, and 15  are rear plan views illustrating starboard supersonic curved wings in a dihedral configuration, and associated engine nozzles, with the curved wings having outboard portion shapes that are concave, straight and convex (i.e., upward curving), respectively. During supersonic flight, high pressure areas ( 1300 ,  1400 ,  1500 ) may exist underneath respective curved wings ( 1302 ,  1402 ,  1502 ). Pressure gradients ( 1304 ,  1404 ,  1504 ) will develop that extend from such high pressure areas ( 1300 ,  1400 ,  1500 ) to the freestream adjacent wing tips ( 1306 ,  1406 ,  1506 ) of each wing. Such pressure gradients ( 1304 ,  1404 ,  1504 ) may not be sufficient to generate a compression shockwave perpendicular to the direction of flight. However, they may result in propagation of a resulting pressure wave, as guided by an underside ( 1308 ,  1408 ,  1508 ) of each respective wing, that is analogous to a megaphone directing sound. The sound will tend to fall off away from a centerline ( 1310 ,  1410 ,  1510 ) of such a pressure gradient. As illustrated in the different wing configurations of  FIGS. 13-15 , the centerline (otherwise referred to as a “datum line” or “sound propagating vector”) may extend an angle (Ø) from ground during level flight depending on the configuration of the outboard wing portions. In  FIG. 14 , the straight outboard wing portion  1412  (indicated with dashed lines) serves to direct the datum line at an angle (Ø 2 ) to ground that is greater than the angle (Ø 1 ) generated by the convex outboard wing portion  1312  of  FIG. 13 . Similarly, in  FIG. 15 , the convex outboard wing portion  1512  may direct the datum line to an angle (Ø 3 ) that is approximately 90 degrees away from the ground. Less sound energy is received at ground level with increasing angle (Ø). The resulting high-pressure underwing to freestream low pressure interfaces ( 1404 ,  1504 ) illustrated in  FIGS. 14 and 15  channel their respective sound propagating vectors ( 1410 ,  1510 ) at an inclination to the ground and parallel to the ground, respectively. 
         [0033]    While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention.