Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Height by sextant angle
    From: David Pike
    Date: 2014 Dec 4, 13:41 -0800

    While we're talking about sextants and height over the sea.  I recently had to read a friends paper that included the statement that the on the first two-way crossing of the Atlantic by the the Airship R34 in 1919, the crew checked the accuracy of the altimeter by the use of sextant readings on it's shadow knowing she was 640ft long.  I decided I could do with some Power Point slides so added slide 1.  I then decided that unless the sun was directly above, this wasn't so simple (slide 2).  I asked the audience to think about it and I'd check again at the end of the lecture.   My suggestion was take the shadow angle whilst flying directly into sun.  Mark 640ft to scale on graph paper.  Mark the sun's altitude.  Use fishing line through the hole in a Douglas protractor, slide the protractor up the sun line until the fishing line subtends the angle measured by the sextant.  Read the airship's height to scale from the graph paper.  Comments please.  Hope the PPt slides come out OK. Dave



    File:
    R34-Height-by-sextant-reading.ppt

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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