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Aerohistorian
01-29-2018, 02:59 PM
I am trying to identify 2 wooden prop hubs, the first one has the following information on it:-

Engine - Beardmore
Pitch - 5.61
Dia - 9.6
153.5 HP
Drg - 2832V
V 2 1692
Series 101

The second one has the following information on it:-

HP 80 Gnome
H Farman
B 21038
BG2356

Any help appreciated

Dbahnson
01-29-2018, 06:26 PM
I don't find that combination of numbers on my references. I'm hoping Bob Gardner chimes in . . .

Bob Gardner
01-30-2018, 03:40 PM
Greetings Aerohistorian,

Nor can I find these drg nos in my database either!

I cannot recall failing to identify a WW1 British drg no. before, leave alone two at the same time. My database is constructed from the table of authorised propellers published by the Air Board in 1917 and 1918, with additions from a later list, the date of which I've forgotten, but in the early 1920s.

Is it possible that what is stamped on these hubs is spurious, something added at a later date? I admit that this seems improbable. Can you post us photographs of this data?

Having said that these drg nos and data are close to published data from the Air Board in 1917/18.

The Vickers data is close to that for a Vickers Gunbus, the Vickers EFB9, but this aircraft was fitted with the 100hp Gnome Monosoupape. The drg no is V2052 with D2900 and P1680mm.

The successor was the FB14 fitted with the 160hp Beardmore engine with a prop diameter of 2900mm, the same as stamped on yours. But this engine was universally rated as 160hp. All these engines were, although the hp doubtless varied by + or - 10%. Some WW1 pilots took their engines to bits and rebuilt them carefully, thereby gaining a few bhp. The rating of 153.50hp suggests an experimental engine with an exactly known bhp.

The second hub has markings in the style of the UK branch of the French Integrale Company. Again, they don't match anything in the records. The Henri Farman biplane was powered by the 80hp Gnome but with the prop drg numbers of IPC2336 and IPC66.

So, none of these drg nos appear in the Air Board tables but they are very similar to those that do.

This suggests that they are spurious but I have not seen such a thing before. The alternative is that they are special props, perhaps experimental props, which were never intended to be standard issue props. The precise bhp recorded as 153.5hp for the Beardmore suggests this.

I look forward to seeing your photographs of these data!

With kind regards,

Bob

Bob Gardner
01-30-2018, 03:46 PM
Cher Pierre-Michel,

Do the IPC numbers B21038 and BG 2536 occur in the French lists?

With kind regards,

Bob

pmdec
01-30-2018, 06:54 PM
Hi Bob,

No, 20138 nor 2536 are known for French Chauvière. And I can tell the same as you: I have never seen a serial from WW1 era which is not listed on Military papers. But... It seems that some IPC numbers don't exist for French Chauvière.

The first number seems, IMHO, impossible for a Chauvière serial: It would be the 8th modification on a 2103 serial, but the higher number I have seen for any serial modification is 4th.

The other one, 2356, is possible, even if it don't exist in French models.

I am not sure it is productive to search more: any time I was contacted for a propeller which seems to have "curious" numbers, it was from misreading... So, without picture, nothing can be said, IMHO, and you are very kind to make the search without having yourself a reading of the markings! Everybody has a camera and posting them on the forum is very clearly explained.

Best regards,
PM

Bob Gardner
01-31-2018, 05:51 AM
Merci, Mon Ami,

You are quite correct. We should wait for the photographs. But I was intrigued with the precise hp of the Beardmore engine which suggests experimental work by the Royal Aircraft Factory and therefore the possibility that a host of similar numbers exist, unknown, somewhere!

The fact that Aerohistorian has two such hubs suggests that they come from the same source or location which would mean that they have been together for 100 years.

I am intrigued!

Cordialement,

Bob

Aerohistorian
01-31-2018, 01:47 PM
Thanks for your comments, the items are in store at the Lashenden Air Warfare Museum in Kent & I will photograph them at the weekend. The second one is a complete prop that has been cut in half through the centre of the boss. They came to the museum from different sources with no history.

Trevor

Bob Gardner
01-31-2018, 04:12 PM
Hi Trevor,

Even more intriguing. I look forward to the photographs!

With kind regards,

Bob

Aerohistorian
02-05-2018, 01:43 PM
Here are the pictures of the first prop

Aerohistorian
02-05-2018, 01:46 PM
Here are the pictures of the second prop also have the following extra wording

FIPC
DC256

Bob Gardner
02-06-2018, 12:47 PM
Trevor,

Thank you for the photographs. I regret they are of very poor quality and nothing further can be learned from them, except that the data stamped on them is certainly of the same age as the hubs.

Thank you for telling us about them.

With kind regards,

Bob

pmdec
02-06-2018, 10:01 PM
Hi,

The second one is clearly a Chauvière prop: a pic of the complete prop may confirm that but the markings, IMHO, are clear:
- IPC at the top
- DC 256 is probably DG 256
- Engine and plane (Henry Farman fitted with a Gnome 80HP)
- B 21038.
I don't know what they mean, but the English Chauvière have this DG xxx and Bxxxxx. I suspect that the B something is a prop number (a batch number seems too high!), and if true this prop is a late one but no more late that IPC did exist in England!

It's sure that better pics could be easier!

Regards,
PM

Bob Gardner
02-07-2018, 05:19 AM
Bonjour Mon Ami,

Yes! Pity about the photographs. I recall that I used to tell forumites to take the photographs in focus and well lit, to photograph both sides and any small numbers such as AID numbers. But I thought it was rather rude of me and I did not like doing it. Perhaps I shall start again.

I believe that both of these props must have been experimental props. For example, to find the best prop possible for these aircraft, the Vickers Gunbus FB14; and the H Farman.

Cordialement,

Bob

Dbahnson
02-07-2018, 10:28 AM
I believe that both of these props must have been experimental props.

Bob

Keep in mind that manufacturers, at least in the U.S, often did "whirling tests" which involved ground spinning them to failure of the blades. So I would expect some of those hubs to have been saved as souvenirs of sorts and maybe trimmed down for neatness.

I'm curious about this photo (http://woodenpropeller.com/forumvB/attachment.php?attachmentid=7015&d=1517856334) showing the hub cut in the middle. Note that the thickness of opposing surfaces don't match in size, suggesting that some material may be missing and may have included stamped information as well. What does the face of the hub look like? There's no good reason to cut a hub if the blades have been removed. The only purpose I've seen is to shorten the prop into two pieces to make easier to transport, knowing that it will only be used for display and can be re-assembled at the hub for display purposes.