Abstract: A helmet features a fixed length vertical extension, originating at the rear-bottom-center of the helmet, with height adjustable features at the bottom of the extension, connected to a fixed bracket, at the rear-top-center of current state-of-the-art shoulder pads or shoulder harness. The fixed In-place helmet is located above the head, without contact, and permits the wearer to move his head in all directions. A shock absorbing cap is worn and fills a portion of the space between the top of the head cap and the inside of the helmet, leaving sufficient room for head motion. There are no moving parts in the assembled system. The vertical helmet extension when attached to the shoulder pad bracket will resist elongation or compression along the vertical axis when impacted, but undergo flexure displacement in any lateral direction, followed by shape recovery after impact.

Abstract: A helmet features a fixed length vertical extension, originating at the rear-bottom-center of the helmet, with height adjustable features at the bottom of the extension, connected to a fixed bracket, at the rear-top-center of current state-of-the-art shoulder pads or shoulder harness. The fixed In-place helmet is located above the head, without contact, and permits the wearer to move his head in all directions. A shock absorbing cap is worn and fills a portion of the space between the top of the head cap and the inside of the helmet, leaving sufficient room for head motion. There are no moving parts in the assembled system. The vertical helmet extension when attached to the shoulder pad bracket will resist elongation or compression along the vertical axis when impacted, but undergo flexure displacement in any lateral direction, followed by shape recovery after impact.

Abstract: Methods for improving the erosion resistance of composite airfoils are disclosed as are the resultant structures. Wire mesh materials are coated with an erosion-resistant coating, formed to the shape of the airfoil leading edge, and molded into the leading edge during airfoil fabrication.

Abstract: An annular groove formed on the inner surface of the porous sheet of an acoustical aircraft or jet engine liner spaced from the front edge and adjacent to the adhesive bonding material serves to prevent dislodgement of the entire porous sheet upon an impending peeling of the porous sheet. The groove also serves as a circuitous path for cracks propagating upstream from a fault manifested downstream therefrom.