Abstract: An article (10) such as a grid fin that controls the direction of flight of a vehicle, has precisely formed passages (14) with porous locating walls (52A, 52B) and a layer of fibrous material (86) such as graphite cloth lying against one or both opposite sides of the locating wall, and with the locating wall and fibrous material impregnated with resin (84). Locating blocks (30) of foam are molded and the fibrous material (42) is wrapped around each block. The wrapped blocks (44) are each inserted into a passage (54) of a locating grid (50), so the fibrous material is compressed. The locating grid lies in a grid-holding mold (60). With the fiber-wrapped blocks inserted, the grid-holding mold is closed and resin is injected into the mold and allowed to harden. The foam blocks are removed by eroding them, as by sand blasting them, to leave a final article.

Abstract: A surface-reinforced article includes a core assembly (12) comprising a foam core (20) with a surface region (22) that includes fine inner fibrous material intimately surround by foam that is integral with foam of the core, and an outer reinforcing covering (14) which includes an outer layer (32) of fibrous material and a resin (30) surrounding the outer layer of fibrous material and covering the primarily foam core assembly. The fine inner fibrous material (91-94) includes coupling fibers (100) with inner ends (102) embedded in the foam and outer ends (106) embedded in the resin, to better hold the resin to the foam. The primarily foam core assembly is molded within a first mold cavity (64) formed between spacers (60, 62) that lie within a second mold cavity (50).

Abstract: A method is provided for molding an article (10) that includes a polymer (100) such as an epoxy resin, reinforced by fibrous material (102) such as fiberglass which is embedded in the polymer material, especially for a hollow article such as a shell. The method includes placing spacers (42, 44) in a mold cavity (30), where the spacers conform closely to the cavity surface and leave a free, or empty volume (64) within themselves. Foamable material (60A) is placed in the free volume and allowed to expand and push the spacers toward the cavity walls while forming a foam core (70) within the spacers. The mold is opened and the spacers and foam core are removed. Next, the foam core is covered with an impervious layer and the fibrous material (72) is wrapped around the foam core. The foam core is placed back in the mold, with the fibrous material spacing the foam core from the walls of the mold.

Abstract: A shell part formed of honeycomb (20) with fibrous reinforcing regions (21, 24) at inner and outer surfaces of the honeycomb and with foam material (26) penetrating the honeycomb cells and reinforcing regions, where the outer surface of the article is convexly curved and the inner surface of the article is concavely curved. This permits the construction of a hollow object (10) by connecting the ends of two shell parts together. Each shell part is formed by laying an outer region of fibrous material including cloth (30) sandwiched between tissue paper layers (32, 34, 35), against a mold wall 44. Next, a honeycomb sheet is laid over the outer region and an inner region (21, 60, 62) of fibrous material is laid over the honeycomb. Then, foamable material (26) is laid in the mold and the mold is closed to cause the expanded foam to penetrate the honeycomb and most of the fibrous layers.

Abstract: An article such as an airfoil that is of light weight and high bending strength, includes a primarily foam core part (20), fibrous strengthening layers (22, 24) at the top and bottom of the core part with the strengthening layers held by threads (64, 72) sewn through the combination, and with resin (32) forced into spaces between the fibers of the strengthening layers and forming smooth surfaces at the top and bottom of the article. The core part includes a thick body (40) of light weight foam (42) and top and bottom reinforcing layers (44, 46) lying against the top and bottom of the body, with the reinforcing layers each having spaces or pores that are filled with foam that is integral with the foam of the body. The moderate strength near the surfaces of the core part, enable the core part to resist crushing of the light weight foam during sewing of the threads and can resist pullout of fasteners that project only partially into the core part.