Curtiss HS-2L Biplane Prop?

[holly]

Gentlemen,
I'd appreciate your help with an I.D. I'd like to mount this prop which was my dad's, in a place of honor with it's description on an engraved brass plate. I believe it to be the aft blade of a 2-blade prop (making it a 4-tip prop. SEE 'Prop Hub Rear' photo) from a 1917 Curtiss H2-SL flying boat built for the US Coast Guard (see anchors stamped on blade in 'Prop Serial No' photo) and powered by a Packard Liberty V-12 400 hp engine. Below are its dimensions:

Length = 103”
Weight = 34 lb
Material: mahogany (I think); copper tips (I think)
Center bore diameter = 3 1/8”
Bolt holes = 8
Bolt hole pattern diameter = 8”
Bolt hole diameter = ½”
Hub diameter = 13 ¼”
Hub countersink diameter = 10 ¼”
Hub front countersink depth = 11//16”
Hub rear countersink stepdown is 5/8” then another 5/8”

I discovered on your site (woodenpropeller.com/Curtiss_HS2L.html) a different prop and am curious if I am incorrect about mine or if many props were made to fit various engines.

I've enjoyed your excellent website for years, because of this legacy left me. Thanks for your expertise and assistance. Holly

[Dave]

I think it's more likely from one of the many other Curtiss Boats used by the Navy in the late teens, and more likely from the larger Libery 450 engine. The only HS2L props I've seen were just stacked together, but I've seen a lot of the larger bladed props with the notching seen on yours, inlcuding some that were stamped for the H16.

[holly]

Thanks Dave. Any idea where I can research this to nail it down? I'd like to be as accurate as possible with the engraving. Thanks, h.

[Dave]

Without drawing numbers it wouldn't be possible to be 100% sure. I'm a little surprised there are none, since I think that's the leading surface that isn't notched, and that's usually where the stampings were evident.

The general shape is very typical of the early Liberty engine propellers, however there were thousands of them made for dozens of different aircraft models.

[holly]

Hi Dave,
The prop is 100 miles from my home. I travelled there Saturday to write down the stamped markings that do not show well in the attached photo. Working from the blade tip toward the hub there is an anchor with a "U" just off the left end of the stock and an "S" just off the right. Centered below that is a "1"; below that "P5 255"; below that "88X511"; below that "P5247". Below that and inverted (to be read while looking at the hub) is "SE364-159"; below that are a pair of 3-blade "Y's". Each blade being wider at the tip than at the axis. Maybe this detail sheds a little light for you. taking a second look at the HS-2L phot I sent earlier, the blade appears to mean to have the angle along the blade that I see on mine and not a smooth sweep as the one in woodenpropeller.com/Curtiss_HS2L.html .

Thanks, h

[Dave]

I think the "SE" number is from the Navy "Steam Engineering" department, which was in charge of procuring propellers. I'll look through some stuff to see if I can find SE364-159. The other numbers and stampings refer to the diameter and pitch.

It may be from an HS2-L, but nothing I see at this point would substantiate that, and there are LOTS of other possibilities. It would more likely be the forward blade on a Liberty engine used in a pusher configuration, as it's a left hand rotation.

[holly]

Thanks Dave. I'll await your reply. I know you have many inquiries you are accommodating. In the meantime, I've attached my amateur sketch of the stamped markings. The upside down alphanumerics are around the bolt pattern. Thanks for your help. h

[Bob Gardner]

Holly,

The prop was made by the Lang Prop Co around late 1917. Lang was an English prop maker lent to the USN at their request in 1917 when America joined WW1.

With kind regards,

Bob

[Dave]

Bob, do you have references for the numbers like SE364-159? I wasn't able to find one.

Which reminds me, I need to order the new book . . .

[Bob Gardner]

Holly and Dave,

Holly; the mortised joint shows that it is half of a four bladed prop. This does suggest an H2SL boat because there was limited space for the prop, so a four bladed prop with short blades had to be used. But (there is always a but) none of the markings that you record are anything like those for an H2SL boat. Not much help !!

Dave; parts three and four of my book on British props are at the printers and might be available in a month or so. Part three describes the work of Dashwood Lang, both in England and in the States.

With kind regards,

Bob