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    Re: bubble sextant in U-2
    From: Gary LaPook
    Date: 2013 Jan 11, 21:33 -0800
    Interesting, here is a link direct to the U-2 flight manual, the sextant starts on page 192 of the PDF.

    Reading about its operation is appears to be a modified Kollsman periscopic sextant.


    --- On Fri, 1/11/13, Paul Hirose <cfuhb-acdgw---.net> wrote:

    From: Paul Hirose <cfuhb-acdgw---.net>
    Subject: [NavList 21888] bubble sextant in U-2
    To: garylapook---.net
    Date: Friday, January 11, 2013, 5:16 PM

    One of the most unusual sextants was operated by U-2 pilots. It's 
    described in the 1959 flight handbook now online at the CIA. This 
    sextant was an optical system installed in the airframe. It viewed the 
    sky through a glass dome ahead of the cockpit. An optical train brought 
    the 15° field of view to a display which looked like a 6 inch radar 
    scope at top center on the instrument panel. An eyepiece wouldn't have 
    been practical for viewing through the faceplate of a pressure suit helmet.
    Except for electric illumination, the sextant was totally mechanical. 
    Azimuth and elevation were visible in the display. A clockwork 
    integrator accumulated an average for up to two minutes. The sextant was 
    fixed to the airframe; the manual says, "if the bubble is far off it may 
    indicate that the aircraft is not on a straight and level course." 
    Although it was only necessary to bring the body and bubble together, 
    best accuracy was attained if this occurred near the center of the display.
    The display was shared with the drift sight, which was similar to the 
    periscopic drift meter on transports and bombers of that era. A pull 
    knob switched the view from one to the other.
    Other navigation equipment included Doppler radar connected to an ASN-6 
    dead reckoning computer, MA-1 gyro stabilized flux valve compass, and an 
    ARN-6 radio direction finder.
    (link to manual at bottom of page)
    I filter out messages with attachments or HTML.

    View and reply to this message: http://fer3.com/arc/m2.aspx?i=121888

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