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    Running down an Astro-Position Line
    From: David Pike
    Date: 2021 Mar 13, 02:59 -0800

    I have copies of Parts 1, 2, and 3 of the ‘Observers Book of Astro-Navigation’, but if I ever had a copy of  Part 4, I can no longer find it.  Gary LaPook has copied us pages 31 to 34? here Chichester-s-explanation.pdf (fer3.com) .  Many non-specialist journalists and articles talk of ‘Running down a Position Line’ as if it’s a brilliantly conceived idea which makes homing to small objective a piece of cake.  Whichever way I examine it, I can’t see that it’s still not a pretty complicated operation, because the Sun is moving west all the time you’re doing it.  It’s not like you’re flying west at the same speed as the Sun like we did in the Vulcan on E-W Atlantic trips. 

    Please will someone post copies of the pages before p.31 where hopefully Chichester explains his rationale and explains the full technique. 

    As far as I can see from his chart, on his final run-in towards Norfolk Is and Lord Howe Is. Chichester only looked at the Sun a couple of times at the most, unless he was looking more frequently and working out oodles of intercepts in his head.  E.g. pre flight calculation 0500GMT Hc=27°46', 0530GMT Hc=21°48' rate of decease = 12’ per minute.  If I was on track at 05.20 with a particular Ha, my Ha at 15.30 needs to be 2° less, and my Ha at 15.30 needs to be 4° less.  DaveP

       
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