Abstract: Radially extending fibers are disposed over a conical surface at predetermined sites. The sites correspond to vertices of a pattern of contiguous congruent isosceles triangles inscribed onto the surface of a sector of a circle which may be conformally mapped onto the conical surface so that vertices of the pattern coincide along the join line meridian of the conical surface. Fibers are disposed between the radially extending fibers in three different directions which respectively correspond with the sides of the triangles. The material obtained exhibits an invariant fiber volume fraction along the axis of the conical surface. The material may be used to reinforce a conical object. Also, an object, such as a preform, having a conical surface and method for reinforcing an object having a conical surface, in accordance with the present invention, are described.

Abstract: A cover for an elongated antenna window of a nose cone of a reentry type missile includes a four directional composite material. A respective portion of a plurality of fibers are disposed in each of the four directions. The directions are oriented so that the fibers provide increased resistance to expected aerodynamic pressure-induced shear forces, especially during reentry, in the plane of the longitudinal axis of the window. The fibers comprise a refractory ceramic such as silica, boron nitride, alumina, aluminum nitride or a combination thereof having a filler material including a refractory ceramic disposed in the interstices between the fibers.

Abstract: A tri-element carbon based heat shield has an outer layer including a carbon-carbon composite, a middle layer including pyrolytic graphite deposited onto an inner surface of the outer layer and an inner layer including carbon felt or foam having low density and high mechanical compliance. The thickness of each layer is selected for optimizing thermal protection over the expected operating temperature range. Although a carbon-carbon composite has a higher thermal diffusivity (inversely related to thermal insulation efficiency) than pyrolytic graphite, the carbon-carbon is selected as the outer layer in a minimum thickness sufficient to satisfy the structural strength, ablation and recession requirements of the heat shield. The resulting thickness of the outer layer determines the operating temperature range of the middle layer.

Abstract: Radially extending fibers are disposed over a conical surface at predetermined sites. The sites correspond to vertices of a pattern of contiguous congruent isosceles triangles inscribed onto the surface of a sector of a circle which may be conformally mapped onto the conical surface so that vertices of the pattern coincide along the join line meridian of the conical surface. Fibers are disposed between the radially extending fibers in three different directions which respectively correspond with the sides of the triangles. The material obtained exhibits an invariant fiber volume fraction along the axis of the conical surface. The material may be used to reinforce a conical object. Also, an object, such as a preform, having a conical surface and method for reinforcing an object having a conical surface, in accordance with the present invention, are described.

Abstract: Multifilament fibers of alumina are fabricated into a multi-directional preform which is densified through repeated infiltration with an aqueous solution of colloridal alumina, dried and fired.