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Old 04-13-2018, 07:36 AM   #1
pmdec
 
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Default A question for Bob, I presume...

Hi Bob, hi all,

What could be "deduced" if a propeller shows the A letter at the end of the arrow, vs one showing WD, supposing both show the 4 square airworthy stamps?

There is an example on page 83 of Bob book about Design and Manufacture, but only the airworthy stamps are "commented" (because one shows five).

And a "collateral" question: why an arrow?

Best regards,
Pierre-Michel
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Old 04-13-2018, 09:16 AM   #2
Bob Gardner
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Hello Pierre-Michel,

Good to hear for you.

The arrow is described as the Ordnance Broad Arrow and signifies that the object it is stamped on is military and the property of the crown, which means the ruling King or Queen or her Ministers.

The stamp WD indicates the War Department, showing that the item so stamped is the property of the Army. You will recall that the RFC, the Royal Flying Corps, was part of the British Army. When it became the Royal Air Force on 1 April 1918 the letter changed to A with the Broad Ordnance Arrow to indicate the Air Ministry.

The Royal Navy and thus the Royal Navy Air Service later called the Fleet Air Arm used a different symbol but my ancient brain can't quite recall it at the moment!

With kind regards,

Bob
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Old 04-13-2018, 09:41 AM   #3
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Hi Bob,

Thank you very much for your answer.
So, a prop showing WD has to be earlier than april 18? And then, it may not have the G and N numbers markings?
And, to the contrary, a prop showing a A have to be stamped with G and N numbers?
Or I misunderstood your answer and what is in your books?

Best regards,
Pierre-Michel

EDIT: Replace "could" by "may" (it may happen it has not G and N numbers).

Last edited by pmdec; 04-13-2018 at 12:44 PM.
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Old 04-15-2018, 10:41 AM   #4
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Bonjour mon Brave,

I have spent about ten hours so far drafting a reply which runs to about four pages. It attempts to record the chaos of planning and evolution that existed in British military procurement from 1913 to 1919. But my account is too complicated and I cannot yet smooth out the contradictions.

I shall write a brief and succinct precis in the next few days.

With kind regards,

Bob
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Old 04-16-2018, 12:01 PM   #5
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Hi Bob,

Thank you for trying

Don't bother for contradictions and, first, don't be "ashamed" for the mess about those markings: I suspect English authorities were "infected" by French ones: the props I saw with markings in compliance with what I found in papers are ... very rare! So, if you want, send me your 4 pages by mail: reading what you write is always very informative!

Best regards,
Pierre-Michel

And good luck for birds! Baby birds seem early this year: yesterday, I saw a baby blackbird learning to fly, and I live in a (relative) cold place.
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Old 04-17-2018, 12:44 PM   #6
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Pierre-Michel,

Up here in the more northerly latitudes we are some weeks behind. The Blackbirds in our garden have only just finished gathering nesting material which suggests that the nests are only now complete. So I don't think we'll see any fledging's for some weeks.

With kind regards,

Bob
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Old 04-17-2018, 09:49 PM   #7
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Hi,
Quote:
Originally Posted by Bob Gardner View Post
.../... Up here in the more northerly latitudes we are some weeks behind. .../...
It's very early for my place, I think. I am not specially interested in birds, but I pay attention when lawn mowing... and habitually I don't see baby birds on first runs, that is before I have to stop mowing an area where orchids are growing. This year, I saw this baby blackbird before orchids were visible and I took a pic to show it to my daughters...

Perhaps Dave will find all this is totally out of place here... And the pic is very noisy, sorry for that also!

Regards,
PM
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Old 04-18-2018, 11:34 AM   #8
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Mon Brave,

Dave is a very tolerant and humane man, partly because he is a retired surgeon, but also because he answers politely even the most inane of questions! He won't mind us talking about Blackbirds. We might even have a query now about the SR71!

With kind regards,

Bob
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Old 04-18-2018, 11:38 AM   #9
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The bird is certainly a member of the Thrush family. Is it brown and spotty? An immature Robin also looks something like that.

With kind regards,

Bob
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