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
    Re: Aviation Bubble Sextant
    From: Ronald P Barrett
    Date: 2010 Aug 27, 17:02 -0700
    Mjans, You are a daring student. Nav schools in WWII varied in length,,, from16 to 32 weeks, then later went almost a full year!

    If you send me a USPS mailing address I will send you the Precomp forms for doing a celestial observation(shot). However with out the Celestial Tables, you can not  get there yet. Also you will need an accurate time hack - watch. As a help go to www.usaf-nav-history.com and also www.afnoa.org. You can post request on both sites.

    There are a few "Nav Instructors" out there still... maybe one lives near you. They are usually doing boat stuff though. They do know how to execute a celestail observation.

    I teach a short "Celestial nav" course onece and a while through the Airline History Museum in Kansas City, Mo. They also have a full Nav-harware exhibit.

    The just now National Navigators' History Program is being founded at the Savannah GA, Might Eighth Museum. At the 8th you will  find all the manuals and instruction you need in their Navigators' Section of their library,,, which will be in place by next Wednesday... hold on a few days as I am driving all of the course material to them as we speak. Dr. Viviain Rogers-Price heads up the History Program there. Tell her I sent you.

    Number one,,, you need to identify the type of sextant you have. Once we know that we can begin to tell you how to check it out.

    Number two: you will need the H.O. tables, and a current Air Almanac. Reference: Celestaire.com They all come now on CD.

    A good watch will cost a few hundred dollars. You have to be able to hack it or verify it is "on the right time."

    Our best to you, Ron Barrett, President & Historian AF Navigators Observers Association (www.afnoa.org) www.ronbarrett.com



    --- On Fri, 8/27/10, mjans <mjans19@hotmail.com> wrote:

    From: mjans <mjans19@hotmail.com>
    Subject: [NavList] Aviation Bubble Sextant
    To: NavList@fer3.com
    Date: Friday, August 27, 2010, 4:41 PM

    Hello,

    I have recently acquired my grandfathers WWII Bubble sextant. He has long passed away and left me no instruction on how to use it. No manuals, no spoken wisdom, nada... I've figured out how to make the bubble and how to collapse it, etc.. but still haven't quite figured out what corrections I need to apply to the sighting. When figuring out Ha from Hs, would I need to apply an Index correction? Since there doesn't seem to be an index mirror, I don't really see why?

    When taking a sighting, how big should the bubble be and where do I place the object? In the bubble or on top? This one seems to have a timer too, is there anyway to mechanically change the timing interval? It seems to only take a sight for about a minute!

    Assuming I was in an old DC-3 flying at 5000 ft, taking a LAN sight... What corrections would I apply.. I assume, temperature, pressure and altitude (pressure or density alt??) but would airspeed apply too? If so.. True Airspeed or Ground Speed? Would the correction be altitude only instead of Dip? If I have to correct for altitude, are there tables?

    Hoping you can help me shed some light...

    Thanks

    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com

    --- On Fri, 8/27/10, mjans <mjans19@hotmail.com> wrote:

    From: mjans <mjans19@hotmail.com>
    Subject: [NavList] Aviation Bubble Sextant
    To: NavList@fer3.com
    Date: Friday, August 27, 2010, 4:41 PM

    Hello,

    I have recently acquired my grandfathers WWII Bubble sextant. He has long passed away and left me no instruction on how to use it. No manuals, no spoken wisdom, nada... I've figured out how to make the bubble and how to collapse it, etc.. but still haven't quite figured out what corrections I need to apply to the sighting. When figuring out Ha from Hs, would I need to apply an Index correction? Since there doesn't seem to be an index mirror, I don't really see why?

    When taking a sighting, how big should the bubble be and where do I place the object? In the bubble or on top? This one seems to have a timer too, is there anyway to mechanically change the timing interval? It seems to only take a sight for about a minute!

    Assuming I was in an old DC-3 flying at 5000 ft, taking a LAN sight... What corrections would I apply.. I assume, temperature, pressure and altitude (pressure or density alt??) but would airspeed apply too? If so.. True Airspeed or Ground Speed? Would the correction be altitude only instead of Dip? If I have to correct for altitude, are there tables?

    Hoping you can help me shed some light...

    Thanks

    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com
    ----------------------------------------------------------------

       
    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