HANG Newsletter - Royal Institute of Navigation

Royal Institute of Navigation
This link, from the Australian Aviation Museum, seems to reflect my
instrument:
http://www.aamb.com.au/DRIFT.HTM
Unfortunately, when I contacted them, they indicated that they had received
their Mk IV as a donation and had no further information on the device.
For the record, I am an electrical engineer by profession, and a person who
finds great beauty in the design and fabrication of precision machinery. I am
also a student of history, and one who thinks that treasures like my drift sight
are to be appreciated, preserved and ultimately passed on. I'd like to properly
identify my drift sight, what aircraft it came from, and what Ministry
publications might make mention of its proper use. Ideally, I hope to be able to
pick up some of this documentation on eBay. Frankly, I'd be happy to have a
few scanned pages if all else fails. The end game is to add some pages to
my web site to make this information public.
On a related note, here are a couple of web pages that I have already
constructed to provide information on some retired military radios I've
acquired, one from WW2, the other from the Iraq war:
http://www.hpfriedrichs.com/rr-bc-348.htm
http://www.hpfriedrichs.com/rr-tr-vp-13.htm.
Firstly – I checked on these links. Both of them are examples of thorough and
almost forensic research to bring an old radio artefact back into use. Good
reading and I recommend them.
I wrote back to Pete telling him that this instrument is a Tail Drift Sight Mk4,
ref 6B/110 and was used in the 1930’s. To quote AP1234 (1935) Manual of
Air Navigation… “The tail drift sight is used for taking readings on an object
over which the aircraft has passed. The object is followed astern through the
optical system of the sight, the drift angle being read from a scale. In the Tail
Drift Sight Mk4 it is not necessary for the aircraft to pass directly over the
object as a correction for the initial displacement of the object is automatically
applied when the sight is used. Details of the construction and use of the tail
drift sight MkIV will be found in AP1275 section 9 chapter I”
AP1234 (1935) describes finding the drift by using, in order, the Course
Setting Bombsight, the Drift Indicator Bearing Plate or the Tail Drift Sight.
However by the time of the issue of the AP1234 (1941) Air Navigation drift is
said to be measured by the Drift Recorder Mk II (an entirely different
instrument), the Course Setting Bombsight or by Back Bearings. The Tail
Drift Sight had dropped from favour. When you combine this with the
markings of Pete’s Tail Drift Sight which indicate dates of 1939, 1940 and
1936 it seems that the Tail Drift Sight was a significant player in the
measurement of drift over the years 1935-1940.
Pete wonders what aircraft may have used the Tail Drift Sight. My guess
would be any RAF aircraft with a navigator that was operational in the years
1935-1940. Pete referred to the Bristol Beaufort and that just comes within
this bracket. Bristol Beauforts first saw service with Coastal Command and
then the Fleet Air Arm from 1940, until they were withdrawn from operational
service in the European theatre in 1942. RAF Beauforts operated as torpedo
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