Any help appreciated-Curtis Prop

[Marked]

Can anyone help?
Prop from my grandfather served in R.F.C./RAF (4sqn then 17sqn) transferred from Glosters in WW1 to join his brother. (1Sqn)
Prop has been in the family and now in my possession and would like to know a little more.

Pictures attached including pic in his RFC uniform and service record for those interested in social history.

Was a talented carpenter so It would be nice to think he worked on the plane the prop came from.

Stamped 90 HP90 Curtiss D2438 & LP5795 AD503 Ser no 10718

[Dbahnson]

Both stamped alphanumeric "AD503" and "LP5795" are consistent with stampings of the "Air Department, Admiralty" and "Lang Propellers". AD503 is listed for a Rolls Royce Hawk engine on an SSP airship, but that can't explain the additional "LP" stamp, and I don't have a listing for LP 5795. The AD503 does list a 4 bladed tractor prop, which this is.

It's possible that it was designed for the airship then retrofitted for a Curtiss 90 HP engine (likely an OX5) and stamped with the engine at that time.

So there's really not much to go on other than it was a four-blade tractor that likely had been fitted to two separate engine models.

My guess is that it was used on a post-WW1 aircraft, but I'm not sure how it can be further identified.

[Marked]

That’s great both my Dad and his brother know he came back from the war with it when he was discharged at the end of the war. Thanks very much for the quick reply

[Dbahnson]

Well, I'll change my guess about the date of manufacture then, and if it's stamped AD503 (are you sure about the "5" not being a "6"?) then I'd go with the theory that it was originally mounted for an airship then later converted to use on the Curtiss engine when it was then damaged and removed from service.

It's not a bit unusual to find prop hubs that were salvaged from crashed planes, since the hub was usually preserved along with one or more blades, and some 4-bladed props were intentionally cut to two blades just to transport them as souvenirs.

[Marked]

Well, I'll change my guess about the date of manufacture then, and if it's stamped AD503 (are you sure about the "5" not being a "6"?) then I'd go with the theory that it was originally mounted for an airship then later converted to use on the Curtiss engine when it was then damaged and removed from service.

It's not a bit unusual to find prop hubs that were salvaged from crashed planes, since the hub was usually preserved along with one or more blades, and some 4-bladed props were intentionally cut to two blades just to transport them as souvenirs.

Definitely a "5" the numbers are clear on the pictures Ive added. Its good to know and understand a bit about the blade and its possible history, if only I could have had a conversation with him about it, Im sure a few stories about "DIY" fixes they had to make especially out in Salonika where he ended up.

[Mtskull]

AD503 is listed for a Rolls Royce Hawk engine on an SSP airship
So there's really not much to go on other than it was a four-blade tractor

Has anybody spotted the further mystery? -The SSP airship used a pusher, not a tractor, propeller.

[Dbahnson]

Has anybody spotted the further mystery? -The SSP airship used a pusher, not a tractor, propeller.

I didn't look any further into details of the SSP, just that the data sheet listed that model as a four blade tractor, so your information is interesting.

I don't have any explanation for the discrepancy. Of course any propeller can be used as a pusher or a tractor depending on the rotation of the engine, which generally is clockwise looking from the rear. That of course is reversed when the engine is geared (e.g. some SPAD engines) and I'm aware of at least one engine that was reverse engineered to counter-rotate from its matching twin engine, so that there were two versions of the same model propeller, one left hand and one right hand.

I'd also guess that the nomenclature listed is incorrect, since the "P" stands for pusher in this case and the propeller is listed as tractor in the same description. So you are correct - something is amiss.

[Mtskull]

After more investigation, I have ascertained that the Rolls-Royce Hawk and Curtiss OX-5 engines rotate in opposite directions, consequently this propeller would have been suitable for the Hawk in a pusher configuration and the OX-5 in the tractor configuration, rotating clockwise when viewed from the rear.

This is only my opinion but, in view of both the “AD503” stamp and the very obvious and thorough Curtiss markings, my conclusion would be that this propellor was originally designed and manufactured for the OX-5 engine and subsequently repurposed for the Hawk. Possibly the Curtiss application is not referenced to the British design number because the British never used that engine?

[Dbahnson]

This is only my opinion but, in view of both the “AD503” stamp and the very obvious and thorough Curtiss markings, my conclusion would be that this propellor was originally designed and manufactured for the OX-5 engine and subsequently repurposed for the Hawk. Possibly the Curtiss application is not referenced to the British design number because the British never used that engine?

That would make the most sense since the inner bolt circle appears to be consistent with the OX5 hub but the center bore looks too wide to be an original OX5 size. That would eliminate it as an original hub drilling for the Hawk since you can't easily narrow the center bore but can easily enlarge it. That would also explain the dual stampings for different drawings, which might have been identical diameter and pitch but a different hub.

What I find harder to explain is why, if the prop was designed for an OX5 engine, is the hub diameter so large? Most OX5 hubs are only an inch or two wider than the OX5's metal hub, which is only 5 1/4 inches. It's possible that the extra width was needed to add strength to the joinery of 4 blades instead of two, but I have no idea if that's correct.

[Marked]

I find it fascinating the “possible” history, I can’t help wondering how my Grandad came back from serving with 17sqn in Salonica with it as far as I’m aware they only had be2c https://salonikacampaignsociety.org....s/rfc-and-raf/

[Mtskull]

I find it fascinating the “possible” history, I can’t help wondering how my Grandad came back from serving with 17sqn in Salonica with it as far as I’m aware they only had be2c https://salonikacampaignsociety.org....s/rfc-and-raf/

Are you 100% certain that this propeller came into your grandfather’s possession in Salonika or even during WW1?
I ask because I see from his service record that he re-enlisted in the reserves in 1939, at Filton.
As an active airfield and the headquarters of the Bristol Aeroplane Company, I would have expected Filton to be as likely a place as any to find an old propeller lying around...

[Marked]

Are you 100% certain that this propeller came into your grandfather’s possession in Salonika or even during WW1?
I ask because I see from his service record that he re-enlisted in the reserves in 1939, at Filton.
As an active airfield and the headquarters of the Bristol Aeroplane Company, I would have expected Filton to be as likely a place as any to find an old propeller lying around...

After some more research I have found out it was actually his brother who came back with the prop but gave it to the family.
Definitely brought back from WW1-Brother was in France with 1 Squadron-also a carpenter