Muffler for internal combustion engines, especially in aviation of improved geometry and material

A muffler device for the exhaust of an internal combustion engine comprising a tube (1) formed of at least a cone and a cylinder of a single piece of perforated sheet metal with alternating holes of varying diameters distributed over its length, the tube (1) being surrounded with a coaxial envelope formed of a cylindrical and/or conical front portion (2) and a back portion (3) with a conical nozzle terminating in an exhaust pipe at an angle to permit exhaustion of gas, the exhaust gases passing through an annular space between the tube and envelope through outlet parts or walls whose form and geometry prevent the formation of a turbulence generating back pressure in cooperation with the varying diameters of the said alternating holes.