Abstract: A holographic optical system includes a hologram which is located at an instrument panel so as to reflect or transmit an image from a source located off the panel. The image is redirected only to an area at which the viewer may observe the image and is not directed to other areas so as to prevent unwanted reflections and glare such as where the instrument panel is within an aircraft cockpit.

Abstract: The invention provides an inflatable sleeping bag having a wall structure defining a sleeping envelope and including outer and inner skins spaced from one another in use. A shoulder cover is provided which is held in place by engaging an inflated pillow. A double zipper holds the upper and lower portions of the bag together in such a way that internal air pressure prevents the leakage of air into or out of the occupant's area of the bag. A plurality of strap structures are attached between the skins to hold the skins generally in parallel one with the other after inflation, and an insulating material is contained between the skins and located against movement by the strap structures. Inflation means is associated with the wall structure for inflating the bag and including exhaust means operable to deflate the bag. The strap structures can be used in any similar inflated structure.

Abstract: A holographic optical element is applied over existing aircraft panel and instruments thereon so as to display an image which is reflected from a source located off the panel. The image is reflected only to an area at which the viewer may observe the image and is not directed to other areas so as to prevent unwanted reflections and glare within the aircraft cockpit.

Abstract: A ground support vehicle has a rear drive track. Cleats extending transversely of the outer surface of the track are outwardly curved to facilitate leaning of the vehicle and its rider as the vehicle travels around a curve. In a preferred embodiment the vehicle includes a ski mounted on front forks so that the vehicle can be used for recreational purposes in snow or directly on unpaved ground and tracks. A wheel can be fitted in place of the ski if desired.

Abstract: The invention provides an artificial horizon device having a light source of limited power which can be positioned remotely from the aircraft cockpit. A scanning mechanism is mounted in the cockpit to receive light from the light source and to project a light bar representing the true horizon by scanning a projected light beam along the perceived bar at a frequency sufficiently high that the bar is perceived as a continuous projection.