Abstract: An improved nozzle structure for an engine, such as a ramjet, rocket or turbojet, which generates thrust by expulsion of gaseous fuel combustion products along a thrust axis is described which comprises an annular wall structure defining an inlet and an outlet for the nozzle and having a contoured inner surface defining near the inlet a radially inwardly convergent annular ramp of predetermined length and convergence angle, near the outlet a radially outwardly divergent annular ramp of predetermined length and divergence angle, and a nozzle throat of predetermined diameter at the juncture of the annular ramps; a transverse web member disposed at the nozzle throat and extending diametrically of the annular wall, defining two substantially symmetrical passageways through the nozzle, having a leading edge near the inlet and trailing edge near the outlet, and having a double wedge shaped cross section symmetric with respect to a plane containing the thrust axis, the surface of the web member defining a pair of ra