What is this???

Profile picture for user Peter

Member for

19 years 11 months

Posts: 10,012

Anyone have an idea on this item? I want to say Nav protractor but I can't seem to fnd anything like it online??

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Profile picture for user Moggy C

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19 years 11 months

Posts: 16,831

Well it's certainly a protractor, but aviation nav? I doubt it.

Reason for my doubt is the 1:500 scale noted on the 'ruler' part. Useless for flying, even slow-bimbling spam-cans won't use anything less than 1:250,000.

At 1:500 a trip to Berlin would need so many charts on board they'd have to leave the bombs at home.

Moggy

EDIT: However it looks like the ruler bit gives 4cm (from the white rule) = 20 somethings. If the somethings are nautical miles, then that isn't far off 1:800,000.

Profile picture for user Peter

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19 years 11 months

Posts: 10,012

It was found at a crash site Moggy raf bomber..

Profile picture for user Moggy C

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19 years 11 months

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As I have said, I really don't know. Just trying to think it through.

Notice that it would be useless for navigating to the West as it only has angles from 0-180 degrees, which kind of misses out 180 - 360

I am coming round to part of a sextant.

Moggy

Profile picture for user jeepman

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15 years 7 months

Posts: 1,913

Would an item of British origin show Met (presumably for Metres) like that?

And wouldn't an issue item have an A(Crown)M stamp and a date?

Even this little steel ruler I still use has a stores or pattern reference number and date

[ATTACH=CONFIG]235310[/ATTACH]

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Profile picture for user WV-903.

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12 years 2 months

Posts: 564

What an interesting bit of kit. First thing that comes to mind is it is like a school room protractor of modern times, but this being made of wood suggests earlier times. Could it be WW1 ? It does cover the rest of a compass circle round to 360 Degrees, but I guess you hold pencil in that small notch in centre and swivel the thing to where needed. So I'd say definitely used on Naval or early flying charts. I've never seen one of these wooden items before. If this was found at an RAF Bomber crash site, that means WW2 and who is to say what RAF Bomber navigators carried with them in their bags. The Nav who then may have used this one, must have had his reasons. (then again, I could well be way out wrong -lol :confused:. )

Bill T.

Diagonal scales being a way to more accurately measure things on a scale map and works in a similar way to a vernier scale.
eg to measure 14.6 on that scale you'd measure between the vertical "10" line and where the "4" line indicated on the bottom meets the "6" horizontal line.

I'm guessing Met is metres, since 10 units on the scale is 2 cm long and 2cm x 500 = 10 metres

So the long and the short of it is that it's a protractor with a rule at the bottom for reading distances in metres on a 1:500 scale.

It's presence in a crash site could be coincidental, or someone might have been using it just for the protractor part as 1:500 is a bit small. On the other hand 1:500 metres is 1:500000km or half mil which is a bit more aviationy

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11 years

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During my childhood EACH schoolboy/schoolgirl in our country was required to have such protractor in his/her schoolbag. Those individual protractors had size about one half of palm of the hand, and were made of tin-plate (most part of them) or aluminium (minor part). Later there were used - and are in use today - plastic protractors.
And each mathematical classroom in each school has large version of protractor with size like the 19'' computer display. Those large protractors were used for demonstration purposes and were made of hardboard with wooden parts.

Profile picture for user Peter

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19 years 11 months

Posts: 10,012

Thanks guy's i have never seen one like this before...

Profile picture for user Peter

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19 years 11 months

Posts: 10,012

So they werent british then?

Profile picture for user Moggy C

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19 years 11 months

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Metres have never been used in British aviation to my knowledge.

Moggy