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Garrett
01-26-2017, 09:11 AM
I have recently come to own what seems to be a vintage propeller. I am interested in finding the age, application, and ballpark value. Any information would be greatly appreciated. It is 8'8" long and has 8 bolt holes.

Dbahnson
01-26-2017, 10:24 AM
It's likely late teens or early twenties manufacture. The "CP" refers to "Curtiss Propeller". It's a left hand thread which indicates a likely pusher configuration.

The "SE 364-398" refers to the blueprint ("drawing") number under which it was manufacturesd, with the "SE" referring to Steam Engineering, which was the Navy department that was responsible for procuring a large number of propellers at the end of WW1. Many of those manufactured quickly became obsolete and were sold off as surplus in the twenties. There were a large variety of flying boats developed by the Navy during that time, and this is likely a propeller left over from that activity.

I can't find that drawing number listed anywhere, so it will be hard to identify. It looks like it might be a hub size for a Liberty engine. Refer to this page (http://www.woodenpropeller.com/Hubmeasure.html) to see if you can eliminate some other engines.

Garrett
01-26-2017, 10:43 AM
Thanks for your input. I too am having zero luck in trying to research for more information. I plan on hanging it on a high wall in my home but would like to know approximately what its value would be. Thanks again!

Dbahnson
01-26-2017, 12:07 PM
Well, now that I see closer pictures of the hub I can tell that it's actually half of a 4-blade combination. There's another blade that interlocks with those notches and line up all of the bolt holes. It's rare to find matching blades, which would have a much higher value.

No one really has a good database for "market value" since the market is small, but I'm guessing that it would sell for somewhere between $900 and $1500. That's not to say that it might sell for more than that on some markets, but not to a "knowledgeable" buyer.

Garrett
01-26-2017, 01:30 PM
Good info to know! Thanks again.

longhorizon
12-14-2017, 02:41 PM
Hi. I have an identical prop, though what I believe is the forward half equivalent. It's been hanging over our fireplace for many years. I've made one other attempt to get information on it, prior to the internet days. Though I learned nothing specific, what I was told is consistent with the comments on this thread. I'll get some markings off the back side of the hub tomorrow if I can. I would really like to narrow this down to a single type of plane and engine if possible. Thank you.

Bob Gardner
12-15-2017, 06:11 AM
Long Horizon,

Your prop was made by the Lang Propeller Co of America for the USN probably at the new factory in Whitestone, Long Island built for Lang by the USN. It started production late in 1917.

Dashwood Lang was a leading British prop maker. When America entered WW1 in 1917 there was no mass production of propellers in the USA, so the USN asked the British Royal Navy for help and the British government sent Watts as a designer and Lang as a maker.

The angular shape of the prop blades is very distinctive.

I have seen several of these props. Some were marked CA, for Canadian Aeroplanes to whom Lang sub-contracted before the Whitestone factory was finished.

Most of the handful of these props (or half-props) that I have seen were made for the Curtiss HS seaplanes, often for the H2SL powered by the Liberty engine.

With kind regards,

Bob

longhorizon
12-16-2017, 10:19 AM
Hello Mr Gardner, Dbahnson, Garrett, et al.

Thank you all. Thank you for taking the time to respond to my query. I have since dismounted the propeller, noted the markings, and taken some photographs...

I know nothing of its provenance.

It is made of laminated mahogany, brass clad at the ends. Diameter 104". Maximum blade width ~ 8.5". Hub recess diameter ~ 10.25". Center to center distance between bolt holes ~3". Center hole diameter ~ 3.25". Eight mounting bolt holes, one additional smaller hole.

Markings are on back of blades close to the hub, one set on either blade. No decals.

On blade marked 1 >>>
275 - 7
P6706 (last digit indistinct, may be a 5 or an 8)
8'8" x 5'11" (diameter and pitch)

On blade marked 2 >>>
275-7
SE 364-410 (engineering drawing #?)
CP6 766 2LH (serial number?)

Does this information (together with stamped numbers supplied by Garrett) further confirm your suspicions?

Is there any way to tell what engine this was configured for? If, as you suggest, a Curtiss HS-2L, then most likely a Liberty L-12?

Is there any way to tell whether my propeller has actually been used on an airplane (as opposed to sold new as surplus)?

Quite interesting about Lang Propellers... We happen to live within 15 miles of Whitestone. Now very densely populated; hard to believe that there were once factories there!

Any chance that the original blueprints (or copies) may exist in a museum somewhere?

Thank you again, ever so much. I occasionally participate in a few forums related to automobiles and boats. You are truly outstanding.

6934

6935

6936

6937

Bob Gardner
12-16-2017, 11:18 AM
Good photographs! And a good-looking prop.

If it is a flown example the bolt holes will be slightly elongated in the thrust plane from the crankshaft on which it sat.

On the front page of this website there is a link to Dave Bahnson's decal page which has an example of a US Lang decal.

If you want to know more about Lang and the USN one of my books has sixty pages describing his British work and his American adventure. They are described on my website at aeroclocks, with the usual world wide web initials in front and dot com at the end. I describe it thus to escape the bots!

It is in Part Three of British Propeller Makers of WW1. If you'd like a copy don't buy it on line. Tell me via a private message (see top right of your screen!) and I'll invoice you through PayPal with a discount.

With kind regards,

Bob

Dbahnson
12-16-2017, 03:50 PM
The critical measurement on the hub is actually the "bolt circle diameter" which you get from measuring from center to center across the center of the hub. (Same measurement if you measure from, say, the left edge of one bolt hole across the hub to the left edge of the opposite one.)

For a Liberty engine this measurement should be 8 inches. There weren't many other engines with that bolt circle.

While I agree with Bob that this is typical of the Lang design, the "CP" in the drawing number was used by the Curtiss Company to designate their own manufacture (http://www.woodenpropeller.com/Abbreviations.html). That system was instituted by the Navy in July 2018.

longhorizon
12-18-2017, 08:48 AM
8 inches it is! Exactly. Thanks very much for narrowing that down for me. That part then is certainly consistent with an application for a Curtiss HS - 2L.
I'll do some more research on Curtiss propeller manufacture. Thank you again.

Dbahnson
12-18-2017, 08:58 AM
Well, I'm not quite sure it could be specific to the HS 2L. The Navy had a large number of different aircraft employing the Liberty engine, although many of them were tractors. The HS 2L was a pusher configuration and your prop having a left hand thread coupled with a Liberty engine makes it one of the pushers, so it's certainly a possibility it could have been used on that model.

A well-established and commonly found design for the HS2L was this one (http://woodenpropeller.com/HS2L.html), which was paired with an identical prop to make the 4 blade combo. That certainly doesn't in any way preclude yours from also being used on that model, but I think you'd have to consider all of the Liberty engine pusher aircraft employed by the Navy in the teens and early twenties. I don't know how many of those there were, but I think the number may be fairly high.

longhorizon
12-18-2017, 09:03 AM
Understood, thank you. I'll do some more research off site after the holidays (Smithsonian, US Navy, and the Curtiss museum). I'll post back anything of interest and substance that I learn. Thank you again. Happy Christmas.

Bob Gardner
12-22-2017, 11:16 AM
Kai,

I've sent you a PM. I'll post the book in ten days time just after 1 January. Our local post office has a backlog and the only books of mine that became lost in transit were for American customers, a year or two ago.

With best wishes for Christmas and the New Year,

Bob