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    Re: Solstice Sun Lines
    From: Tracy Shrier
    Date: 2017 Dec 25, 20:25 -0800

    Dear David and Kermit,

    Your interest is wonderful, I should have introduced myself a bit more, but I see Frank has done that for me.

    I am using a Link A-12, 2 minute sights, attempting to trigger a altitude every 10 seconds, then recording all altitudes and averaging. I'm also noting a 'visual average' to compare as I gain experience. Great story on the origin of the 2 minute sight David, I also belive that somewhere in the several Weems books that I have collected he recomended 2 minutes as well. I'm very interested David in your comments on technique, what is AP1234? I should find a copy.

    I'm flying Bombardier CRJ's, manual thrust levers, yaw dampers and Mach pitch trim on the autopilot. I do of course shoot from 'straight and level' flight and have observed that the planes are stable in pitch (sights forward often will only have 10-15" variation) but noticable dutch roll (30-60" variation on shots abeam). For these Sun lines we were begining to run out of time prior to descent. We had finally gotten out of the chop, but still had 50-75' of wave with 5-10kts airspeed variation, dificult conditions for a hand held A-12. I know there is application of turning and acceleration error in H.O 216; the 1930/40's training materials that I have don't get into this. I'm thinking that with hand held sights, where I see no heading changes and maybe a few knots airspeed variation over 2 minutes, that I have more error holding the sextant than anything else. But this would be interesting to persue; I have a Mk 4A David, where might I get an acceleration error card? Lastly Corriolis correction definately adds to accuracy of the fix, for this plot, knowing that I did not have stable sight conditions, I did not apply it.

    Thanks Gentlemen, more to come.

    Tracy

       
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