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    Re: Bubble sextant trials
    From: Gary LaPook
    Date: 2007 Feb 17, 00:11 -0800

    Something you should not put off is reading Chichester's book,
    "Seaplane Solo" (also sold as "Alone Over the Tasman Sea") documenting
    the first solo crossing by air of the Tasman Sea from New Zealand to
    Australia. He did this in 1931 in an open cockpit Gypsy Moth plane. En
    route he had to use his marine sextant to take sun lines in order to
    find two small islands on the way where he could stop to refuel. He
    used what is now known as the single LOP landfall technique by aiming
    off to one side of the island until intercepting the sun line that he
    calculated ran through the island and then turning his plane to follow
    the LOP. He did his calculations using a Bygrave Sliderule all the
    time flying the plane, (no autopilots in those days) taking sights and
    operating the sliderule. A truely remarkable book and a great read.
    
    He had previusly flown the gypsy moth from England to Australia,
    becoming only the second man to fly that route. His book about that
    flight, "Solo to Sydney" is also worth reading.
    
    Gary laPook
    
    On Feb 15, 7:33 pm, Bill  wrote:
    > Alex
    >
    > As my texts deal with marine navigation, I had surmised the fly boys with
    > bubble sextants had come up with interesting ways to use the stars.
    >
    > > You are welcome to borrow my copy of Lecky.
    > > He is a big fan of stars (and opponent of the Lunars)
    > > and he advocates meridional altitudes of stars.
    > > Not only upper culminations but
    > > also lower culminations.
    > > (Of circumpolar stars)
    > > But he also writes that "soon the LOP navigation
    > > will be the only method used in practice",
    > > and was is right.
    >
    > Still interesting.
    >
    >
    >
    > > The Russian manual of 1966 or so, has a brief discussion
    > > of "near meridian" Sun altitudes, but nothing else
    > > except LOP. The only reason why meridian and near meridian
    > > altitudes survived to 1966 was that the reduction
    > > is very simple. With the spread of calculators,
    > > this last reason disappeared.
    >
    > I was familiar with ex-meridian sun sights with Ho adjusted to maximum via
    > Bowditch tables.  The star thing sounds like fun.
    >
    > > In asto navigation manuals for airplanes
    > > (I read the 2 volume set by Chichester
    > > he wrote this before his circumnavigation when he
    > > was working in the MkIX factory during WWII. Purdue
    > > aerospace library has it. I can check it for you
    > > if you wish)
    > > he also spends a lot of time on stars
    > > (rather than the Sun) emphasizing that you can have
    > > an immediate fix with two stars.
    > > And the stars are always visible from an airplane
    > > at night, and you don't care about the horizon etc.
    >
    > Thanks.  I'll wait on Chichester until I work through the other
    > volumes/papers we mentioned on our trip to Strictly Sail.
    >
    > Bill
    
    
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