Abstract: A relatively thin thermoplastic sheet material, vacuum molded to form a sign letter base including hollow wall members and hollow light-fixture supports upstanding from a single-thickness horizontal bottom member. The base inverted forms a mold itself for receiving a flexible plastic foam inserted to a suitable height and disposed within the vertical walls and fixture supports for providing compressible elasticity to the thin molded sheet in predetermined locations for enabling cooperative interaction of the same with retainer members used to secure a display sign face and gas filled lighting tube structures in proper location onto the base. A rigid polyester resin is cast as a ring encircling the letter walls, located and supported by the flexible foam to stabilize and support the thin nature of the base.

Abstract: Instrument flight training glasses including a voltage controlled, liquid crystal lens system having upper and lower contiguous lens systems independently operable with respect to each other, for limiting a pilot's vision to the instrument control panel of his aircraft when so desired. The lens systems are opacity variable for simulating flight through particular weather and cloud conditions while providing instant clearing of the lower lens system as the pilot views the aircraft control panel. During a landing approach an interlock system is manually actuable to prevent opaque obscuring of the lens system.

Abstract: An instrument flight training hood including a voltage-controlled, liquid crystal viewing lens operable to a first state of transparency when a wearer is viewing the instrument control panel of his aircraft and operable to a second state of opacity to instantaneously occlude viewing when wearer changes his line of vision outside of the aircraft. A uniform passageway recessed within the hood directionally communicates light received from an area of space substantially along the wearer's line of sight, to a photocell for lens state actuation responsive to a manually preset light intensity threshold. A manual switching arrangement permits maintenance of lens transparency to provide vertigo simulation capabilities upon flight landing approach whereby wearer changing his line of sight outside of the aircraft to occlude his viewing, and thereafter manually switching the lens to its transparent state enters a condition of vertigo.