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: Aircraft Octant Optimal Bubble Size
    From: Paolo Borchetta
    Date: 2013 Mar 5, 21:44 -0800

    Hi Greg,
    If my memory doesn't fail me, the A-7 bubble octant is an A-6 model with averager incorporated.
    Like the A-6 the upper and lower glasses of the bubble cell enclosure are concave down ward, the radius of the upper glass curvature is equal to the focal length between the object and eye piece lenses. This allows you close to almost 8.5deg field of movement (the diameter of the field of observation in the bubble chamber is 9 deg), this means that, to be on the safe side, anywhere within one sun diameter from the side of the bubble chamber,the readings are accurate as long as the bubble and body are centered. It then boils down to a size of bubble that allows you sufficient room around the body for collimation without being to small to stick due to surface tension (e.g. the larger the bubble within the limit the better results you get).
    Anywhere between 2 dia. to 3 dia. sun if fine as long as you feel comfortable with the aiming or in other words, as long as you have enough room around the body to judge alignment to the best of your ability.
    If you can find pure grade Xylene (Xylol) it is one of the top liquid for filling being about 15% less dense than water and very stable to temperature changes.
    My two cents.
    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

    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