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
    Name or NavList Code:
    Email:
       
    Reply
    Kollsman's Azimuth Counter and TH Bearings Relationship
    From: Ed Popko
    Date: 2022 Apr 18, 06:02 -0700

    I'm trying to understand how the azimuth and relative bearing compass roses work on the Kollsman periscopic sextant.
    I have read setups in Air Force manuals, looked at Carbonara’s Astrocompass patent for Kollsman (in patent-eze language) and followed many of Gary LaPook's links about the sextant. But frankly, I'm still struggling to visualize the mechanical relationship of the two compass roses (one displayed in the Rotation Counter and the other seen in the eyepiece).
    How are these two roses, cranked and manual, physically related?


    Perhaps some Kollsman user can simply explain it.

    Some run-on confusions statements-questions:
    - when the Kollsman is mounted, I assume it is fixed in the mount (perhaps clamped) and the only ways to rotate it about the periscope’s axis is to manually crank the Azimuth Crank or physically rotate the sextant by hand. I assume most sights involve both rotation methods.
    - The Azimuth Crank rotates the sextant relative to the fixed roof mount adapter? The Rotation Counter shows how many degrees and it is the relative bearing from the front of the plane, clockwise when viewed from above. Thus, to set up for a precomputed body at 90 Zn at a given time, simply Crank the periscope till the Counter displays 90 degrees. This 90 degrees is relative to the lubber line of the plane. If the True Heading of the plane was 0 degrees and Altitude was correctly set, the body would be within the eyepiece at the precomputed time (or near so) and need only refined collimation for a sight taking?
    - when the True Heading of the plane is not 0 degrees, the sextant must be further rotated clock- or counter clock-wise to that heading to see the body.  The actual direction the periscope faces is a combination of Azimuth Crank and manual rotation to account for the plane’s TH?
    - The bearing rose visible in the eyepiece is a view (reflected up) to a rose that is clockwise when viewed from under the sextant and looking up (its sealed and only visible in the eyepiece)?

    Ed

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

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

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

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

    Email Settings

    NavList ID 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