A supersonic aircraft jet engine installation having engine inlet structure comprising: an inlet ramp and a cowl having a lip spaced outwardly of the ramp so that entering air flows between the ramp and lip, characterized in that ramp is configured to produce a first oblique shock system that extends outwardly from a forward portion of the ramp to pass ahead of the lip, a second oblique shock system that extends outwardly from said ramp aft of said first oblique shock system to intersection within the lip with a terminal shock that extends outwardly from a rearward portion of the ramp, the ramp in axial radial planes in the flow direction having: a first portion that has outward concavity; a second portion which is straight and configured to produce said first oblique shock system that extends generally forward of said lip and within the flow path of air through the inlet structure providing substantially no additional compression; a third portion located rearwardly of said second portion, said third portion being outwardly concave and configured to produce an oblique shock system that extends from said third portion toward a part (at 50) of said terminal shock that is spaced from the lip; a fourth portion that is straight and follows said third portion, close to the terminal shock; and a fifth portion providing initial turning of the flow towards the engine ahead of the terminal shock, said fifth portion extending uninterruptedly from said fourth portion, said inlet system creating a compression and shock system and total pressure distribution that is intentionally non-uniform across any axial plane located rearwardly of the terminal shock. an inlet ramp and a cowl having a lip spaced outwardly of the ramp so that entering air flows between the ramp and lip, characterized in that ramp is configured to produce a first oblique shock system that extends outwardly from a forward portion of the ramp to pass ahead of the lip, a second oblique shock system that extends outwardly from said ramp aft of said first oblique shock system to intersection within the lip with a terminal shock that extends outwardly from a rearward portion of the ramp, the ramp in axial radial planes in the flow direction having: a first portion that has outward concavity; a second portion which is straight and configured to produce said first oblique shock system that extends generally forward of said lip and within the flow path of air through the inlet structure providing substantially no additional compression; a third portion located rearwardly of said second portion, said third portion being outwardly concave and configured to produce an oblique shock system that extends from said third portion toward a part (at 50) of said terminal shock that is spaced from the lip; a fourth portion that is straight and follows said third portion, close to the terminal shock; and a fifth portion providing initial turning of the flow towards the engine ahead of the terminal shock, said fifth portion extending uninterruptedly from said fourth portion, said inlet system creating a compression and shock system and total pressure distribution that is intentionally non-uniform across any axial plane located rearwardly of the terminal shock. a first portion that has outward concavity; a second portion which is straight and configured to produce said first oblique shock system that extends generally forward of said lip and within the flow path of air through the inlet structure providing substantially no additional compression; a third portion located rearwardly of said second portion, said third portion being outwardly concave and configured to produce an oblique shock system that extends from said third portion toward a part (at 50) of said terminal shock that is spaced from the lip; a fourth portion that is straight and follows said third portion, close to the terminal shock; and a fifth portion providing initial turning of the flow towards the engine ahead of the terminal shock, said fifth portion extending uninterruptedly from said fourth portion, said inlet system creating a compression and shock system and total pressure distribution that is intentionally non-uniform across any axial plane located rearwardly of the terminal shock.