METHOD OF DECREASING SOUND SHOCK LEVEL Russian patent published in 2009 - IPC B64C30/00 

FIELD: aircraft engineering.

SUBSTANCE: invention relates to aircraft engineering, particularly, to methods of decreasing the aircraft sound shock levels. In compliance with proposed invention, cryogenic fluid is blown out at pressure across the incoming air flow at the bottom surface of fuselage nose blunted parts, nearby the area wherein an intermediate (trailing) shock wave is formed and on a site of the surface with cross-section sector that features angle φ not less than 90° and an untight perforation. Liquid nitrogen or aircraft engine cryogenic fuel is used as a cryogenic liquid. The plane comprises a fuselage with blunted nose part and a site of the surface with an untight perforation. The fuselage noise represents a polynomial body of rotation. The surface of the said body is smoothly aligned with surface of spherical blunting. The blunting radius is selected so that to provide the nose part frontal drag not exceeding that of the initial polynomial body of rotation of identical elongation The site of the surface with untight perforation is located in the area wherein an intermediate (trailing) shock wave is formed and on a site of the surface with cross-section sector that features angle φ not less than 90°. Note that this area if thermally isolated along the perimetre from the fuselage adjacent surface, while the degree of perforation on the said area decreases downstream of the airflow.

EFFECT: essential decrease in sound shock level without increase in aerodynamic drag.

4 cl, 9 dwg