Aeronautic Instruments. Section VI : Aerial Navigation and Navigating Instruments (1923)
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AEKIAL NAVIGATION AND NAVIGATING INSTRUMENTS. 23 The protractor can be set with its arrow pointing magnetic north by means of the compass rose or by a convenient meridian and the known variation for the region. For measuring distances, two interchangeable protractors are provided, one graduated in… … FiG. 13.—Bigsworth chart board. tions are for the British Air Service), and the other graduated in miles and halves on a scale A special pencil is used for drawing on the celluloid surface, the marks being easily erased by rubbing with the finger. Map cases.—A number of map cases have been devised,…
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