Advanced search  
Pages: 1 [2]   Go Down

Author Topic: Drift Meter?  (Read 2265 times)

Ross Devitt

  • TIGHAR member
  • *
  • Posts: 33
Re: Drift Meter?
« Reply #15 on: February 18, 2020, 03:42:34 PM »

Sorry for adding more 'junk', but this colour picture shows a little more clearly the model of Pelorus in the Luke Field Inventory, and just how simple the thing is.  Also how easy it is to move from one base to another and the simple directional thingummies.

https://timeandnavigation.si.edu/multimedia-asset/mark-iib-pelorus-drift-sight

While I can't find a reference to using one at night, it would be possible to get a rough 'direction' of a star not too high above the horizon by aiming the thing like a shotgun.
I'm not suggesting Fred would have been clever enough to do that, but I'm damned sure I would have been using that, in combination with a sextant or octant.

It is so many years since I was properly active on the forum, that I can't remember if Fred carried an Octant aboard.  I do recall something about the sextant box and an unusual eyepiece. 
Anyway, I found the download links for my early WWII Navigation manual and it talks about how to use a 'Bubbie Octant'.

The other 275 odd pages are great homework for anyone still interested in the LOP and the Celestial Navigation stuff (How to completely miss an island on a simple over water hop).
It is probably on the Forum under Celestial Choir - but here 'tis for Drift Fans..
The Pelorusy stuff is around Page 30ish.
https://archive.org/download/aircraftnavigati00unit/aircraftnavigati00unit_bw.pdf

EDIT
For any Newer Members of the forum who missed Choir Practice (see the Celestial Choir pages) there are lots of references on the forum to 'the LOP.  The manual linked above has information about advancing a Line Of Position around page 170, and how to use a 'Bubble Octant' about page 176ish.

Noonan carried both an octant and a sextant.
Navigators aboard ships use a sextant, among other devices to find their position.
Airborne Navigators can also use a sextant, but it requires the horizon to be visible to be accurate.
A bubble sextant or bubble octant uses a bubble, like that in a spirit level but round and of a variable size, as I understand it, to give a reference point that simulates a horizon if none is visible.

The info above is 'simplified' - NOT 'technically correct'.
« Last Edit: February 20, 2020, 12:39:37 AM by Ross Devitt »
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5742
  • "Do not try. Do or do not. There is no try" Yoda
Re: Drift Meter?
« Reply #16 on: February 20, 2020, 07:05:47 AM »

While I can't find a reference to using one at night, it would be possible to get a rough 'direction' of a star not too high above the horizon by aiming the thing like a shotgun.
I'm not suggesting Fred would have been clever enough to do that, but I'm damned sure I would have been using that, in combination with a sextant or octant.

There is every reason to think Noonan had and used a bubble octant for celestial observations during the Lae/Howland flight. I would think a pelorus is useless for getting meaningful information from celestial observations.
Logged

Ross Devitt

  • TIGHAR member
  • *
  • Posts: 33
Re: Drift Meter?
« Reply #17 on: February 26, 2020, 05:33:56 AM »

Quote
Quote from: Ross Devitt on February 17, 2020, 10:59:16 PM
In BOTH cases the instrument must be able to be used from BOTH sides of the cockpit.  And the Luke Field Inventory lists a 'spare' base for both Pelorus AND Drift Meter.
However the bases are NOT 'Spare'...  There are Two Bases for Each instrument.

I agree, except in this case the pelorus mounts were in the two standard cabin windows, as shown in the March 7, 1937 photo below of AE and Manning.

I Edited my original post.  I intended to type 'able to be used from BOTH sides of the Aeroplane'  But I wrote 'cockpit' because I was tired.

So it seems either or both, drift meter and Pelorus could be used from the same bases and mounts through either or both cabin windows.
Logged

Arthur Rypinski

  • TIGHAR member
  • *
  • Posts: 47
Re: Drift Meter?
« Reply #18 on: April 14, 2020, 07:32:24 AM »

W.r.t. to Noonan as a sloppy navigator, I am reminded of something that Pan Am pilot Horace Brock wrote in his memoirs.  Brock was trained at Pan Am's navigation school in April 1937, He wrote:

"The first day we started on navigation. The instructor and chief navigator was Judd Ingram, an experienced navigator from the merchant marine. He was a tough taskmaster. He would say: 'Navigation is easy.  It is learning never to make a mistake that is hard.'"

On another project, I examined Harold Gatty's papers in the Library of Congress.  I was looking for some reference to the sextant box or the Fiji bones, and found nothing of interest.  I did, however, incidentally, see his navigation logs--not for his successful round-the-world flight (different file box) but for some of his other flights.  Gatty was meticulous, writing out all of his calculations on successive pages of a notebook in a beautiful, clear hand.

By contrast, Richard Byrd, who may or may not have overflown the North Pole in 1928, left chicken scratches.  If Gatty thought he might have made a mistake, he had a chance to find it.
Logged
Pages: 1 [2]   Go Up
 

Copyright 2020 by TIGHAR, a non-profit foundation. No portion of the TIGHAR Website may be reproduced by xerographic, photographic, digital or any other means for any purpose. No portion of the TIGHAR Website may be stored in a retrieval system, copied, transmitted or transferred in any form or by any means, whether electronic, mechanical, digital, photographic, magnetic or otherwise, for any purpose without the express, written permission of TIGHAR. All rights reserved.

Contact us at: info@tighar.org • Phone: 610-467-1937 • Membership formwebmaster@tighar.org

Powered by MySQL SMF 2.0.15 | SMF © 2017, Simple Machines Powered by PHP