Compass mount

In our museum, we have a display case of "orphan" items. We know what each item is (at least we think we do), but we have no other parts it relates to, so it in an "orphan." One such item is a "Compass Mount -- Magnetic compass mounting bracket from a British Lancaster bomber." At least that's what the little sign with it says. I confess that I made that sign many years ago, on the say-so of somebody else (maybe aviation artist David Gray?). Just last week, our President asked me if I would make a fixture so it would stand up properly. I told him I would, and make a better sign as well.

A couple days ago I set out to build the fixture, but then realized I don't know the proper orientation for the item. Which way is up? Which is front or back? I could make a guess, but I would like to be sure. Where was it located in the airplane? What did it look like with a compass in it? (Maybe I have a proper magnetic compass for it.) So I went to the internet and searched. I couldn't find a picture, so I still don't know how to proceed. Using the c344646 number cast into the main body, I did get reference to an Avro Lancaster bomber, so I think that's the right track. But I sure would like a picture, both for orientation, and to use on the new descriptive sign.

I took several different view pictures of the item, with a ruler in the foreground for size. It's roughly 4 inches wide x 6 inches tall x 5 inches deep (if that's the correct orientation). Besides the cast-in number, there is a number printed on it in black ink, 883, and on the gray collar there is a partial scale of some sort, and the letter A, maybe a /, space, and then 345. There is something before the A, but the paint is gone. The main piece and the gray collar are aluminum, but the fasteners are all steel (magnetic). That's odd, because fasteners around magnetic compasses are usually brass (non-magnetic). One last point: The mounting holes in the gray collar are elongated, so it can be rotated maybe 10 degrees. Compass adjustment or compensation???

I used a real camera to take the pictures; not my cell phone. That's how I got so close to the numbers. It would be really nice if one of you could come up with pictures of the item, how/where it was mounted, and maybe with a compass in it. Thank you for your help. Merry Christmas ----- Larry

IIMHO it is not for a magnetic compass, I believe it is the Standard base (AFT unit) with a mount for the Astro Compass Mk.II. It is similar to the 6A/366 also used for the device. It could be mounted on any large RAF bomber and transport kite and also the USA aircraft that had the Astro station/dome for the astro-navigation. What is more the base and the Astro Compass were also made in the USA. The Astro Compass Mk.II itself was usually stored in a protective wooden or bakelite case when not in use. The "Standard" mounting base was a permanent fixture in the aircraft.





the pic source: the net.

Wurger, that's really neat! We may well have an Astro Compass. I'll check in the next day or two. Where in the cockpit was the permanent mount located? Could you direct me to a good picture?

Thank you for this.

Larry

Finding of a pic may be a trouble because the Astro Compass could be used with a bubble sextant interchangeably. The sextant didn't need a such mount and base because it was handheld device or hanged from a hook in the top of the astrodome mostly. But I can try to find something.
Generally, the Astro Compas had should be mounted on a flat, horizontal surface according to the device handbook. Because the view at the Sun or stars is required for the type of compass , a window is needed for that. For the reason the device was either mounted at the astrodome or in the cockpit.

Here is a such mount for the B-17 ... the B-24, B-25, B-29 or C-47 and other kites with the kind of astrodome could have the same type of the mount.



and here the exposure of the base ... from the astro compass handbook ...


the pic source: the net

BTW ... the British Air Ministry reference number of your part is 106A/345.