help id this wooden propellor

[terry]

Hello, this is the first time I have used this site. I was given a wooden propellor some time ago and would appreciate some help intrying to id it.
The hub has 9 holes and the following letters and numbers are stamped on it:
G1731 N78
A L 7901 RH
200 LHP SIDDELEY

2000
P2000

Looking forward to your help
Terry

[Dave]

How certain are you of the stampings? There is an AB7901 RH model that used a Siddely Puma engine for a Bristol Fighter or a DH9. It is 290 cm in length (pitch of 232 cm). Check the length on yours and re-check the stampings. Here's a different drawing number for a similar prop.

In my listings, there are no drawing numbers that begin with "AL".

A picture might help.

[Bob Gardner]

Hi Terry,

Your prop dates from 1917 and was fitted to either the Bristol F2B fighter or the DH9 bomber, both equipped with the 200 HP engine designed by BHP (Beardmore, Halford and Pullinger) but built by Siddeley Deasy. A later version developed 230hp and was called the Siddeley Puma.

There is a restored example on my website
http://www.aeroclocks.com/Prop_pages/1164.htm

With regards,

Bob Gardner
www.aeroclocks.com

[Dave]

Bob,
I wonder if that gives us a clue about the "G" and "N" numbers often seen on British props. Yours has the same G number as Terry's, and N is 78 on Terry's and 42 on yours. I'm assuming that they are production numbers, and I guess the N is closer to a serial number, but do you think that the G tells us anything specific, or does that also just reflect a production run number?

[Bob Gardner]

Hi Dave,

I have little knowledge of these numbers, having done no research into them. The Windsock data file WW! British Aeroplane Propellers describes them as production group number; and serial number within that group. Therefore in this case, Terry's prop is number 78 in production group 1731.

I have always accepted this but have never recorded them. Perhaps I should go through my photo database and correlate them.

These group numbers must have been issued centrally, probably by the Aeroplane Inspection Department (AID) whose airworthiness stamps occur on all British props from this time.

Another number which occurs is said to be a Royal Navy Air Service stores number, from the central store at White City within London. The Windsock data file seems to suggest that all props, both RFC and RNAS, went to this depot. There is a reference to them being painted on a prop but I have never seen any number painted on a British WW1 prop.

Sometimes a stamped serial no. occurs and perhaps this is the White City number but I must admit to an element of doubt.

I would be most grateful if anyone could add to this; and provide a source for a complete list of G nos and White City nos!

I suppose I should add that the important number in identifying a British prop is the drawing no, many of which are known. Interestingly, one should not take them as absolute. Quite often I find a prop with a slightly different diameter and pitch from that quoted. And sometimes a prop which is attributed to only one type of aircraft turns up marked for a different type of aircraft, although always with the same engine type.

Spelling mistakes are common and sometimes individual letters are upside down, perhaps an indication of the boredom of stamping up these props with individual letters.

On one occasion I found a prop stamped for an SE5 aircraft with a 180hp Wolseley Viper engine, of which there is no record in the published drawing nos and which several experts have point blank denied existed, it being universally agreed that the Viper only ever produced 200hp!

However the Viper was unreliable when first introduced and so perhaps a derated version was used initially? I suppose my point is that you have to keep an open mind and not follow the written word too closely, particularly if the facts in front of you differ.

Hope this helps,

Bob Gardner
www.aeroclocks.com