IMPROVEMENTS FOR ABATING EXHAUST NASA Case No. ARC-10712 Australia, Canada, France, Address inquiries to: Mail Code: 200-11A Moffett Field, CA 94035 [Corresponding to U.S. Patent No. 3,830,431] A noise abating improvement for jet engines including the provision of apparatus in the primary flow stream of gas turbine engines such as turbojet, turbofan, turboprop, and other jet engines such as ram jets, scram jets and hybrid jet engines, or in either the primary and/or secondary flow streams of turbofan engines or the like, for imparting to the exhaust gases a component rotation or swirl about the engine's longitudinal axis. The rotary component in the exhaust gases has the effect of substantially suppressing the build up on sound energy normally produced by an axial flow exhaust stream. The closed cell, semi-rigid, fiber-loaded self-extinguishing foam of the present invention has properties of retarding penetration of incendiary ballistics, prevention of fire in the void spaces of the aircraft, providing support for the fuel cell, and strengthening the aircraft frame. The foam is based on a polyurethane resin and is filled with fibers and contains a fire retardant material. It does not produce noxious fumes when heated and the strength of the foam is enhanced by the fibers being oriented parallel to the surface of the substrate on which the foam is sprayed. *Exclusively licensed to AVCO Corporation. Please direct inquiries to: Fire Protection Materials, AVCO Corporation, AVCO Systems Division, Lowell Industrial Park, Lowell, Massachusetts, 01851, U.S.A. Salt crystals used in IR spectrocopy required they be preserved in areas that are not dehumidified. If moisture forms on the crystal, etching results which destroys the effectiveness of the crystal. This invention contemplates coating the crystal with a perfluorinated polymer which not only prevents attack by moisture, but often has the added advantage of acting as an anti-reflective coating so that transmission is increased in nearly all regions of the IR spectrum. Although there are many critical loads that must not be exceeded on an aircraft, in the past no attempt has been made to measure all of these loads during flight. In a piloted aircraft, the pilot is subject to the same acceleration loads as the aircraft, and he automatically attempts to regulate them. However, in a remotely-piloted vehicle, the remote pilot is unable to sense the acceleration loads being experienced by the aircraft, and can inadvertently cause the aircraft to exceed its g-load limits thereby causing severe damage and even destruction of the airframe. This invention is an Optical Radiation Frequency Converter employing metal vapor which is useful in the ultraviolet region of the spectrum. The invention comprises a cell for retaining the metal vapor or gas which is surrounded by an oven. Monochromatic radiation passes through windows in the cell and oven. In the preferred embodiment, the metal vapor for accomplishing third harmonics is one which has its fundamental harmonic frequencies resonance in the spectral region between the fundamental frequencies and the third harmonic. The metal vapor must have a suitable refractive index to provide for phase matching. |