Aerotrack, air-navigation triangulation computer

Claim 1

In an air-navigation computer, apparatus for determining both ground speed and wind drift and wind direction and velocity, comprising; a first, base disc member inscribed with a logarithmic scale representing a slide rule and marked with speed and distance indicia; a second, trigonometric scale-inscribed member mounted for movement relative to said base disc element; a third, movably mounted, compass indicator member positioned adjacent said second named member; a fourth, wind direction scale member incorporating a wind direction pointer element; a fifth, relative bearing pointer member rotatably positioned on said base disc member about a pivot center and interposed between and providing a common support for said trigonometric scaleinscribed, compass indicator and wind direction pointer members; a master cursor member supported on the upper surface of said computer and arranged in fixed relation to said relative bearing pointer member for common rotation therewith about said pivot center; and a secondary cursor element having an index line and rotatably adjusted about the pivot center of said computer and positioned on the bottom surface of said base disc member; said master cursor member having a pair of aligned opposing tip elements extending in opposite relation over the upper surface portion of the computer and comprising a first, relatively long tip portion having an index line in direct alignment with a predetermined point on said relative bearing pointer member and a second, relatively short tip portion incorporating an extension of said index line; said base disc and compass indicator members being rotatable to place certain values on the scales thereof respectively corresponding to a selected air speed and true course under the master cursor-index line of the longest tip portion of said master cursor; said wind direction scale member being rotatably mounted for adjustment about the pivot center of said computer to thereby align the selected wind direction on said compass indicator member and thus determine the relative wind angle on said trigonometric scale-inscribed member from the value appearing directly under said wind direction poinTer element; said trigonometric scale-inscribed member being thereafter adjustable relative to its supporting relative bearing pointer member to thereby orient said previously determined relative wind angle directly under said master cursor-index line and thus determine drift angle on said last named scale member from the degree value inscribed thereon and appearing directly opposite the value representing the selected wind velocity on said base disc member, the value on the said base disc member appearing directly opposite the point on the trigonometric scaleinscribed member representing the sum of said relative wind angle and said drift angle constituting a measure of the computed ground speed for the selected airspeed and wind; said trigonometric scale-inscribed member being further adapted to be adjustable relative to said master cursor until the difference in the degree values between the selected true airspeed and precomputed ground speed on the said base disc member is made equal to the precomputed degrees of drift to thereby determine the relative wind angle from the value to be read directly under the cursor-index line opposite the true airspeed; said wind direction pointer being further adjustable from the selected true course, through the true heading, until said wind direction pointer element indicates the relative wind angle and the wind direction corresponding thereto found on said compass indicator member.