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Thread: RAF Mk IXa Bubble Sextant

  1. #1
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    RAF Mk IXa Bubble Sextant

    Hello all,

    What can you tell me about a RAF Mk IXa bubble sextant ref no 68/218 with serial no 17603/43? A friend of a friend found one and although he is familiar with sextants being a marine navigator, the intricacies of this version are beyond him. I have a feeling that the Varsity had some of these sextants on board but I'd like to know more about it. What other types used it? When was it used? Is it worth anything (it is complete with carrying case)?

    A Little VC10derness - A Tribute to the Vickers VC10 - www.VC10.net

  2. #2
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    As regards to its value, not a lot I fear!

    There are a good many of these around, usually in their shaped brown bakelite carry-boxes. I think they must have released thousands of these as surplus at the end of the war and they are surprisingly common.

    Possibly not what you wanted to hear....and I can add little or nothing as regards to technicalities or how they are used, exactly.

  3. #3
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    AP Scans

    Hope these help:

    (More to come)

  4. #4
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    More scans

    2 more of that AP and then the next:

  5. #5
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    Last few pages:

  6. #6
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    What Tangmere1940 said, I have close to 30 of them in storage which came from a place where there were hundreds a few years ago, some in woeful nick (cannot even open the case as the rubber has melted/fused the case shut, others in good condition - yours looks pretty good actually. I have a few that are slightly different in that the bakelite case has been substituted with a metal case - same shape but a more snug fit. Not sure why this was the case. A nice piece of gear though if it's in good condition, it's better than mine thats for sure !

  7. #7
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    TerryP, that is brilliant, thanks for that! Bellarine, Tangmere1940, I don't think that the current owner is looking to sell it. As I haven't been in touch with him directly it is unclear to me how he got it but for him it has a novelty value, being connected to his own trade as a navigator. He is more interested in the story and/or background behind the sextant.

    Can anyone shed more light on which aircraft used these sextants, and in what period?
    A Little VC10derness - A Tribute to the Vickers VC10 - www.VC10.net

  8. #8
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    When I was trained as a navigator 1950-51, we were taught how to lose ourselves using these monstrosoties. The sight is averaged by a clockwork motor so one has to keep the star or whatever in the bubble for that length of time. In an Anson bouncing about at a few thousand feet, not an easy task. We had to locate three stars and take a "three star fix" and plot out the resultant position line from each, transfer them forward to the time of the last star and so get the three lines to cross so as to form a "cocked hat" . by choosing stars nicely seperated one hoped to have a triangle plotted and one was somewhere within it. Reducing each sight entailed fumbling through the Air Almanac and a another great book of tables in order to produce each position line.

    A very laborious procedure which we were expected to carry out within 20 minutes, i.e take 3 sights, and plot them out. I well remember the laugh with my roommate produced his chart. We did triangular flights in the Anson, roughly 100 miles each leg, his fix formed an excellent star of David with his tracks, so at least he was somewhere in the vicinity of where he was supposed to be.

    Our poor bomber navs in the early part of the war had this tool as their main navaid, little wonder the Butt? enquiry found we were bombing the wrong towns, sometimes even the wrong country.

    Sorry to be longwinded, I was extremely glad to be posted onto a night fighter squadron and escape such contraptions.
    Last edited by PeterVerney; 14th February 2013 at 15:33. Reason: trypo
    Man is not lost. Only temporarily uncertain of his position.

  9. #9
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    A lovely description, Peter. Thank you!

  10. #10
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    I forgot a vital item, the timer ran for two minutes, the idea being to compensate for the unsteadiness of the aircraft.
    How Chichester did it in a single seat open cockpit I just don't know, I understand he had a hand in revising AP1234, the Air Navigation Manual. I would love to find one of them, we were certainly put through it at 1ANS at Hullavington.
    Man is not lost. Only temporarily uncertain of his position.

  11. #11
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    As to aircraft type and who, basically anything that carried a navigator with an astrodome into the 70's [yes, I know, you don't need the astrodome in the Catalina!]

    We learnt the basics at college in the mid-60's, taking shots from the roof of the college at night.

    Qantas navigators used them in the DC-4 service to Norfolk Island into the late '70's. A mate of mine used one in several North Atlantic crossings in his Navajo.

    Cumbersome and challenging at times [never could get a bubble without help!!], but reliable.

    G'day

  12. #12
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    Right, so that gives the end of the period as 70s, but when were they first introduced? Was that before, during or after WW II?
    A Little VC10derness - A Tribute to the Vickers VC10 - www.VC10.net

  13. #13
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    Here you are, a little search gave this
    http://amhistory.si.edu/navigation/o...dnumber=451521
    Man is not lost. Only temporarily uncertain of his position.

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