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    Ball drop sextant report, 1949
    From: Paul Hirose
    Date: 2006 Sep 19, 21:45 -0700

    In the U.S. Dept. of Transportation archives I found a 1949 Civil
    Aeronautics Administration report on a new aircraft sextant of the "ball
    drop" type, developed by the U.S. Naval Observatory. The CAA tested it
    against a conventional Pioneer bubble sextant, best known by its
    military designation AN5851-1 or A-14.
    The ball drop sextant performed poorly. "The only possible conclusion to
    be reached from the flight tests is that the ball drop sextant fails by
    a great deal of attaining the accuracy necessary for celestial
    navigation in the air."
    Unfortunately, the report does not go into its principle of operation
    much beyond "the ball drop sextant uses the line of fall of a small
    steel ball to establish a vertical line".
    You will have to navigate to the page. My attempts to create a clickable
    link have failed, probably due to the way Javascript is used at the
    site. Also, if you have Internet Explorer's security settings turned up,
    it will be necessary to add the site IE's list of trusted sites.
    Click "FAA and CAA Research Reports"
    Then look for the ball drop sextant report (the browser Search function
    will find it if you enter "sextant").
    The page has an small portion of the report, and a link to download a
    PDF scan of the whole thing, which is about 1.2 MB.
    I block messages that contain attachments or HTML.

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