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
    Re: Fairchild A-10A in practice
    From: Bill Morris
    Date: 2017 Jul 3, 15:24 -0700

    Noell and David,

    The median is preferred over the mean because it is a more robust estimate of central tendency in that it is less sensitive to skewed results and outliers. It also requires no calculation.

    Early dedicated aeronautical sextants required the observer to decide when an observation was "good" and to take a reading or press a button. However, a constant acceleration of the aircraft could give a stationary bubble even though vertical was not being sensed by it, so automatic devices that read at regular intervals were devised, that averaged or gave a median, as in the Mk IX A and A10-A , or integrated as in the German SOLD. All that was then required of the observer was to try to keep the bubble centred on the body and to keep the time. The latter could be done with a split seconds stop watch, starting it off the navigational watch, stopping the first hand at the beginning of the observation and stopping the other hand at the end, or with the help of an assistant.

    Random errors decrease in proportion to the square root of the number of observations and by about 60 observations, diminishing returns become very prominent. Additionally, the period of slow oscillation of many aircraft, called "phugoid oscillations" by Frederick Lanchester, is about 2 minutes, so 60 observations in 2 minutes tended to become the norm. No doubt this felt a very long time to be flying straight and level over hostile territory and some instruments like the MK IX BM and SOLD allowed for shorter periods.

    Bill Morris

    Pukenui

    New Zealand

       
    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