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    Re: correct way to draw LOPs
    From: Robert Owens
    Date: 1999 Jun 23, 7:23 AM

    Ours had an artificial horizon if I remember correctly. Sort of like a
    pendulum. Physically it looked just like the bubble types. It also had the
    averaging system that took a two minute shot. It had a 15 degree field of
    view so mainly you had to precompute everything. A three star fix took
    between 12 and 15 minutes to shoot and plot. At an average of 8 nm's a
    minute it wasn't unusual to advance the first shot 50 to 100 nm's. Needless
    to say our triangles were huge. I don't believe I took 10 star shots during
    the 1 year I navigated. We always did a deviation check at least once a
    flight but looking back on it I don't know why. It was on just one heading.
    Kind of useless. Anyway we had three separate compasses on board.
    We used Pressure Pattern and mainly Loran for our navigation but most of our
    flights were at dawn and dusk so Loran wasn't reliable. Also we used an
    oscilloscope type method to measure the TD's and it was hard finding the
    correct signal(hop) to measure.
    Pressure Pattern was used every flight. This used an Absolute Altimeter that
    measured by radio or radar the altitude precisely. We read it every five
    minutes. If you were flying into a high pressure area  your absolute
    altitude would change to maintain a constant altimeter altitude. This change
    related to time would tell you the strength of the wind therefore the amount
    of drift to correct for. Into a high the wind was from your right. Away from
    a high or into a low the wind would be from the left. This is a very
    accurate way of flight navigation. Sometimes the only way.
    This was in the 60's on B 707 and DC-8's. Even the 747 had a sextant mount
    in the cockpit, but with 3 separate Inertial Navigation Systems it didn't
    need it.
    Celestial navigation in aviation goes back a long ways. I knew and used to
    fly with a guy who first used celestial navigation to fly over the pole in a
    single engine aircraft.(P-51) He was Charlie Blair a real pioneer in
    aviation. Sorry I'm so longwinded.
    Bob Owens
    -----Original Message-----
    From  Russell Sher 
    To: 'Navigation Mailing List' 
    Cc: 'tugly@WILD.NET' 
    Date: Wednesday, June 23, 1999 1:28 AM
    Subject: RE: correct way to draw LOPs
    >Sounds interesting - did you use celestial nav. then with bubble sextants?
    >Some time ago I found a second-hand dealer who had loads of second world
    >items including shelves of bubble sextants - I even got a user manual from
    >museum in Australia - This one had a clock-work averaging mechanism.
    >I would be keen to find out more about the history of celestial nav. in the
    >aviation context.
    >> -----Original Message-----
    >> From- Robert Owens [SMTP:tugly@WILD.NET]
    >> Sent: Tuesday, June 22, 1999 4:14 PM
    >> Subject: Re: correct way to draw LOPs

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