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    Re: Early methods of air navigation
    From: UNK
    Date: 2014 Nov 22, 06:16 -0000

    Fascinating stuff. I think Brown used a standard sextant with spirit level attachment to give AH/bubble?

    Don’t think he had the Booth bubble in 1919, did he? But he did have the “Baker navigation machine” which looks interesting, rolling continuous chart with pre-computed Altitudes?

    Curious that for his  1931 Tasman sea flight, Chichester had tried the Booth bubble sextant, found his navigation 700 miles out and reverted to a standard sextant and natural horizon altitudes. He claims to have invented his own “pre-computed   sun Alts” system. Would he have been aware of the already invented Baker machine?

    Any views Gary?



    From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Gary LaPook
    Sent: 21 November 2014 18:56
    To: francisupchurch@gmail.com
    Subject: [NavList] Re: Early methods of air navigation


    This should answer your question, see attached.




    From: Fred Hebard <NoReply_Hebard@fer3.com>
    To: garylapook---.net
    Sent: Friday, November 21, 2014 9:21 AM
    Subject: [NavList] Early methods of air navigation


    The discussion of the Brown-Nassau CN Plotter brought to mind the following question. What methods did the early pioneers of trans-Atlantic flight use for navigation, such as Alcock and Brown?  Brown was the navigator on that flight.  They made landfall near their intended destination.  Running down a line of latitude would be a clear choice, but how measure the latitude?  They flew at low elevations, so perhaps using the actual horizon?  Dip scales as the
     square root of elevation.  The error for being 50 feet off in elevation is less than two minutes of arc at 200 feet.  In contrast, Admiral Coutinho installed levels on his Plath in 1919.  Had the British?  Then there is RDF, which was available in the U.S. by the Point Honda disaster.
    Those are some guesses.  What does the documentary evidence say?
    Fred Hebard


    Attached File:

    (img/129345.alcock & brown precision astrolabe_0001.jpg: Open and save)

    Attached File:

    (img/129345.alcock & brown precision astrolabe_0002.jpg: Open and save)

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