New Member <Prop ID Help>

[Danny]

Family heirloom from my great uncle shot down in WW I. Would the "Wooden Prop Family" help me in identifying the airplane he was piloting? Thanks for any help you can provide.

Manufacturer: unknown
Length from tip to tip: 10 feet
All numbers stamped anywhere on the propeller: Yes ... see pictures
Number of bolt holes: 8
Laminations: 5
Blade width at widest part: 9 5/8 inches
Fabric covered tip, OD green
Writing on hub:
One-side of the hub

275.ROLLS.ROYCE.M.3

G.186.N.27

Other side of the hub

DRG.2610.

L.H.

Stamps on the hub face

AID

21 J

Pics:

[Danny]

More Pics

Some additional pics

[Dave]

I'm not sure what that's from. Most (?all) British prop drawing numbers are preceeded by a letter or letters. There are two listings that include those numbers (AM2610 and IPC2610), both of which refer to Rolls Royce engines used on DH4, DH9 or DH10 aircraft, but those are all listed as right hand tractor and as 4 bladed propellers.

[Bob Gardner]

Good Morning Danny and welcome to this forum.

The drawing number 2610 was made under contract for the Air Board by a number of propeller manufacturers during WW1 where it was mostly described as AB2610 and also by the Integral Propeller Company where it was IPC2610 and by the Airco Company, whose famous designer was Geoffrey de Havilland, as AM2610. Occasionally, as here, the designation letters of AB, AM etc were omitted.

Although the data stamped on your prop is minimal there are some clues which indicate your prop was made by IPC late in 1917 for the DH4, a new style of bomber which was faster than most German aircraft. The clues are:
1. the early batch number, G186, which dates it to the latter half of 1917.
2. M3 is an unusual way of describing the 275hp Mark Three Rolls Royce Eagle and I have only seen it on IPC props.
3. Fabric on the tip of the prop also suggests 1917. In 1918 fabric covered the entire blade.

An improved version of the DH4, the DH9 was introduced in the Spring of 1918. It proved to be considerably inferior to the aircraft it was replacing. These early DH9 aircraft did not use the RR Eagle engine.

The hub of your blade is thin, which indicates that it is actually half of a four-bladed propeller. The two halves were held together by the same bolts that secured the prop to the engine crankshaft. The benefit of this was simply in storage and transportation where two halves on top of each other occupied a fraction of the space needed for one four-bladed prop.

The RR Engine was designed with heavy twin-engined bombers in mind and was therefore built in both left hand and right hand rotation which countered torque swing on take off. LH props carried the drg no, 2610, matched by a blue colour-coded band on the blade root, where as RH props had the number 2611 and a red band.

With kind regards,

Bob

[Danny]

Thanks

Bob & Dave ... thanks sooooo very much for the help.

Bob, the hub actually does have two wood pins that I couldn't figure out their purpose. With your explanation I would expect them to serve as alignment pins (see picture). Additionally, I missed a stamped "CC" in the hub. I expect it verifies "CouterClockwise" rotation ... hmmmm, not sure about my assumption though.

As I attempt to further resolve details about Uncle Harolds WW I service, allow me to ask a follow-up question:

Would there be any way (now, with this time stamped data) to find out what squadrons the airplanes were assigned to which would ultimately help me in finding out further details on my great uncles involvement in the allied efforts?

Once again, thank you for the assistance with my quest.

[Bob Gardner]

Props cannot be attributed to an airframe, not least because one aircraft could use ten propellers during its lifetime of a few hundred hours. Additionally, by late 1917 there appear to have been at least twenty props per aircraft in the pipeline; at Sqn level; second and third line in France and at depots in GB.

The first DH4 Sqn in France was 55 Sqn RFC on 6 March 1917, followed as production allowed by 18, 25, 27, 49, and 57 Sqns RFC. It was also issued to Nos 5, 6 and 11 Sqns of the RNAS which became 205, 206 and 211 Sqns on 1 April 1918 when the RAF was formed from the merger of the RFC and RNAS.

The RAF Air Historic Branch and/or the RAF Museum in Hendon might well have your great-uncle's record card which will list his various postings.

With kind regards,

Bob

[Danny]

Bob, this is the strength of this forum ... what an amazing base of knowledge.

All, Thank you so much for your help, advice and information. I'm now on my quest into the RAF's files.

Kind regards and many thanks,
Dan