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    Re: Lutz 252 Slide Rule for Navigation
    From: Francis Upchurch
    Date: 2017 Aug 21, 06:42 -0700

    Thanks Greg.

    I have tested both your examples using Bob Goethe's mark  2 (simple copy using Bob's scales, re-sized and high quality printed and stuck to the empty back of my 50 year old Thornton.) Works fine and uses Tans, not cotans. It is very quick and easy with multiple trig scales in parallel allowing direct multiplication and division using the Bygrave equations.Not quite so accuate as,or any quicker than my cylindrical Bygrave replica, but not far out.

    Results.

    1) L=34°10', d=13°10'N, t (H)=13°23'

    Mk2SR. W(x) =13°31' (same as calculator and Bygrave).

    Az =33°15' ( Bygrave and calc.33°16')

    Hc= 65°48' (Bygrave and calc 65°44')

    2) L=34°10'N, d=12°13'N,t(H)=50°32'

    W(x)=18°48',(Bygrave and calc=18°49')

    Az=76°46' (Bygrave and calc=76°48')

    Hc =39°5' (Bygrave and calc= 39°11'. Not sure of reason for the inaccuarcy here).

    Anyways, not bad for 10' SR. Congrats to Bob.

    I still think the cylindrical Bygrave replica wins for accuracy and speed.

    Best wishes

    Francis



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