Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: The Great Circle Challenge
    From: Gary LaPook
    Date: 2014 Dec 26, 19:39 -0800
    That one is easy. The distance is 3600 NM, the initial course is 360° and the final course is 180°

    See prior posts:


    From: David Pike <NoReply_DavidPike@fer3.com>
    To: garylapook@pacbell.net
    Sent: Friday, December 26, 2014 5:41 PM
    Subject: [NavList] Re: The Great Circle Challenge

    Well, if this was a navigation course, the leader would say “What have you learned today”.  I’ve learned a lot.  I’ve seen some interesting methods, and some I’d like to try out.  I also learned a couple of other things.  Firstly, don’t let your enthusiasm trick you into calculating spherical geometry when you’re tired.  I started after a day out driving the family around and walking in the cold, and my first attempt was a disaster with the distance coming out as 6573nm.  A quick Google of “Distance New Zealand to Hawaii” showed I’d screwed up big-time.  This led to another discovery.  I read that the cosine rule isn’t suitable for big triangles, so at first I thought that was the problem and that I’d have to get into haversines for the first time in 40 years.  However, after a little nap, I decided to have one last try with the cosine rule, this time using a triangle based on the South instead of the North Pole. While doing this I realised that in my haste, first time I’d used the lat and not the co-lat of the destination.  My second attempt: distance = 4069nm Initial bearing = 025.88degrees agrees with most others.  The time taken for the second attempt was 39minutes, but working longhand I have to check all the written figures at least three times.  My working is shown in the snaps below.
     By way of redemption, let’s try the B52’s great circle route in Stanley Kubricks “Dr Strangeglove” from Burpleson Air Force Base 61d 15’N 149d 48’ W to the Doomsday Device 58d 45’N 030d12’E.  Dave

    Attached File:

    (CS-to-WB-1-Large.JPG: Open and save)

    Attached File:

    (CS-to-WB-2-Large.JPG: Open and save)

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site