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Old 01-26-2017, 09:11 AM   #1
Garrett
 
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Default Found. Curtiss propeller

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.
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Last edited by Garrett; 01-26-2017 at 10:47 AM.
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Old 01-26-2017, 10:24 AM   #2
Dbahnson
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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 to see if you can eliminate some other engines.
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Old 01-26-2017, 10:43 AM   #3
Garrett
 
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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!
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Old 01-26-2017, 12:07 PM   #4
Dbahnson
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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.
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Old 01-26-2017, 01:30 PM   #5
Garrett
 
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Good info to know! Thanks again.
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Old 12-14-2017, 02:41 PM   #6
longhorizon
 
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Default have a matching half

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.
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Old 12-15-2017, 06:11 AM   #7
Bob Gardner
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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
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Last edited by Bob Gardner; 12-15-2017 at 06:34 AM.
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Old 12-16-2017, 10:19 AM   #8
longhorizon
 
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Default Lang / Curtiss propeller

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" 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.

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Old 12-16-2017, 11:18 AM   #9
Bob Gardner
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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
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Old 12-16-2017, 03:50 PM   #10
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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. That system was instituted by the Navy in July 2018.
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