dh 5 propellor

[ncar]

I am seeking information on a propellor boss I have just bought (on a bit of a impulse at a local auction, my main interest is medals). I found the link to this site from theaerodrome website where I have just posted a question about the propellor under the name ncar.
I see from one of your other postings that someone may have some information on AID stamps of which there are some on the propellor. Can the AID numbers give some clue which plane the propellor was on, when it was in service or where it was stationed ?.
Thanks
Neil

[Dave]

They might, but it's a long shot. Bob Gardner is the one who has been studying those and may have some correlation between specific AID inspectors and specific time frames. You really would need a drawing number from the propeller to be able to identify it, though.

[ncar]

Dave,
Thanks for your very quick reply, from information I have got from the aerodrome website the drawing number is 1708 which is stamped on along with 2T and 5970. Hope these numbers mean something to you ?.
Thanks again
Neil

[Dave]

Oh, I see the thread there. Here it is if anyone wants to connect the 2.

I agree, the drawing number is actually "LP" 1708, the LP standing for Lang Propeller. I suspect that the other numbers are just production numbers with no useful significance.

It would be unusual to link your propeller hub to a specific airplane or even a specific time frame.

[Bob Gardner]

Hello Neil,

Thank you for your interesting e-mail. I regret to say that props cannot be linked to individual aircraft. The ratio of props to aircraft was large and from occasional insights it would seem to be between 10:1 and 30:1. Most of these props were at second and third line and in the production pipeline. One pilot is recorded as loosing five props in a week.

The drg no. 1708 was a design of the Royal Aircraft Factory (RAF) where the letter T indicated the RAF. Usually it was stamped as T1708.

When the design was delegated to other makers, the same number, 1708, was used with code letters for the maker. In this case there were two, Lang Propeller (LP) and AIRCO (AM). Thus LP1708 and AM1708. Both the RAF and LP sometimes omitted their code letters.

All RAF props and LP props were used on the DH5 aircraft, but AIRCO made the prop for the Camel.

The RAF subcontracted the making of DH5 props to Darracq, who were famous makers of cars before the war. Darracq seem to have stamped the name of the man who made the prop on the hub. So far I have seen the names Harris and Blisson and now this one, Coombes. But such names do not appear on all Darracq props.

Lang Propeller sub contracted the making of props to Tibbenham in Ipswich.

I am rewriting my book on British WW1 props and would like to include some of your information, if I may. If so, could you please send me some close up photographs of the data on the hub, the stamp of the name Coombes, the Darracq decal (if it has survived) and the AID numbers.

I should add that the AID stamps are from the Aeronautical Inspection Department. They indicate that the props had passed airworthiness checks during manufacture. Usually two inspectors examined each prop and applied their individual stamp twice, so that four stamps occur close together. Sometimes one or two others occur which might indicate a further successful inspection. Inspectors were present at each place of manufacture, not only of propellers but also every aspect of an aircraft; engines, spars, linen, wheels and even raw wood selected for aviation use. Some major makers with their own quality control department were allowed to issue their own airworthiness authority.

With regards,

Bob

[ncar]

Bob,
Thanks for very imformative reply ( on both websites ). The propeller is currently at work ( a colleague of mine wanted to see it ). I would be happy to take some photos for you and will try and send them in the next few days.
From memory the letter T does appear on the boss above the number, does this perhaps suggest that it could be quite an early one. I think it has as many as 6 AID stamps on it which I will also forward details of.
Thank again
Neil

[Bob Gardner]

Thanks Neil,

Your prop dates from around 1917. The T1708 seems to be a minority prop because it was never listed in Air Board bulletins as the standard prop (ie; the preferred prop). This accolade fell to the LP1708.

I look forward to the photographs. Could you send them at the highest resolution possible to the e-mail listed on my web site (link below). I get enough spam as it is!

With thanks,

Bob