Apparatus for projecting artificial horizon viewable by peripheral vision

Claim 1

Apparatus for projecting an elongated light bar representing an artificial horizon upon an interior surface of an aircraft cockpit in front of a pilot for viewing by the peripheral vision of said pilot, of a roll and pitch light image of said aircraft with respect to a center of a reference datum line on said interior surface in said aircraft cockpit, comprising: first means in said aircraft for maintaining a vertical reference axis which remains perpendicular to the earth's curvature regardless of the amount of angular pitch and roll of said aircraft wherever said aircraft may travel, said first means providing a pitch output indictive of the pitch of said aircraft and a roll output indicative of the roll of said aircraft; a second means fixed to said aircraft and coupled to said roll output of said first means; light generating means for producing a light beam in said cockpit; a movable optical means arranged to convert said light beam to a plane of light projected on said surface in front of said pilot, to cast on said surface an elongated light image viewable by the peripheral vision of said pilot, said movable optical means coupled to said second means; and mechanical means connecting said movable optical means to the pitch output of said first means for controlling movement of said movable optical means, corresponding to the pitch of said aircraft, so that said light image always remains substantially perpendicular to said vertical axis regardless of the amount of said angular roll of said aircraft, whereby said datum line appears to remain stationary, while said elongated light image appears to turn angularly with respect to said datum line on said surface as said aircraft rolls and to move perpendicularly to said roll light image as said aircraft pitches.