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Subject: Astro Compass History
From: Robert Eno (enoid@XXX.XXX)
Date: Tue Oct 29 2002 - 18:46:13 EST
Greetings List,
I did some digging about this question which came up about one month ago. I got an answer of sorts, though not a totally satisfactory answer.
My acquaintance is an authority on Arctic air navigation because he was a pioneer in this field in the 1940's and 1950's. Here's what he had to say:
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The first appearance of a "sun compass" (the forerunner to the astro
compass), occurred in 1917 when the American patent was issued for a
transparent sundial to be mounted in the wing above the pilot. It required
further development and appeared to have been dropped by the designer.
With an interest in polar flying, and attendant problems of using the
magnetic compass near the magnetic pole, attention was directed towards
perfecting sun compasses incorporating a clock running on solar time. In
the mid 1920's Albert Bumstead, of the National Geographic Society, devised
one for Byrd's use on his northern flights in 1925. At the same time,
Goerz, a German firm, developed a similar compass for use by Amundsen and
Ellesworth in the arctic in 1925. Throughout the 1920's and 1930's, up to
W.W.11, one or the other of the sun compasses was used on high latitude
flights.
By W.W.11, the astro compass, a derivative of the sun compass, was in use
and became quite popular as aircraft heading could be determined from any
celestial body whose position could be computed from an almanac.
The design of the astro compass appeared to have not changed to any degree
during W.W.11 and after. The American and British produced compasses, as
far as I remember, were identical. For some reason unknown to me the
British compass was referred to as RAF Astro Compass MK 11. I suspect the
initial patents were American as they were involved in more long range
flying just prior to the war than the British.
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So there you have it gentlemen (and ladies).
I will keep the list posted on any additional information that I manage to dig up. Of course this does not mean the rest of you should be sitting by waiting for my pronouncements. I would certainly welcome any additional information that might be out there.
Oh ya, by the way, reason number 37 why the 1966 reprint of the 1962 Bowditch is my favourite: it has a nice illustration and description of the astrocompass on page 626.
cheers,
Robert
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