ID Help? 95" Hartzell, No Decals, 8 bolts @ 6.75", etc

[Motorace]

HARTZELL is stamped into the scalloped brass sheathing in several places but there are no decals or name stamps in the wood.

The only number I found stamped in the wood is on the back face of the hub and it appears to read 15312, which I'm assuming is a serial number (or could it be a design number?) If 15312 doesn't match anything, could it be 15812? (see photo)

The diameter is exactly 95"

The hub is 6" thick (8 layers of 3/4" wood)

8 bolt holes of 1/2" diameter each in a bolt circle of 6.75" (6-3/4")

Center hole in hub is 4.4"

Outer diameter across center of hub is 9.25"

The hub doesn't show any signs of having been impressed by a metal hub flange, but the brass on the leading edges near the tips appear to have been indented from having struck small rocks/pebbles, so I am guessing it has been used.

Condition = very original. There is no indication it has been restored in any way. The tips are cloth covered over the last 15.75" of each tip

What kind of aircraft and/or engine was it designed for?
What year was it made?
What kind of wood is it made from?
What else would you like to see a photo of?
Why 95" dia. and not 96"? (Why make it 7'11" and not a nice even 8')? (Was that for for shipping purposes to fit inside an 8' box?)


Thanking you (all) in advance for any help you can give me!

[Motorace]

Here are a few more photos.

I'm curious to know what the purpose of the three small (~1/8" dia) drilled-looking holes in the very tips of the brass sheath were for (see first two photos below). Did they have anything to do with noise abatement?

[pmdec]

Hi,

The holes are for water to be evacuated. All shieldings have this kind of hole, but the more frequent are half-circle ones on the edge of the shielding.

Regrads,
PM

[Motorace]

Would the shape of these holes (not being half-circles) give any indication as to the age of this propeller? i.e. Were the half-circles a later, more advanced design on Hartzell propellers?

[pmdec]

Sorry, but I am not able to give an age info from this: First, I don't know enough about American props, ans, second, in France this detail can't be use for that (the three kind of holes I have seen, circle, half circle or corner shape, are not age related).
PM

[Motorace]

The name Hartzell is stamped in several places - but always/only on the protective brass sheathing. There are no Hartzell decals. I've also not been able to find any numbers other than the one mentioned above (#15312) which tells me that this must be a very early propeller.

Given the absence of Hartzell decals, it crosses my mind to ask the question - is there any possibility this wooden propeller was made by another company - who then subcontracted Hartzell to add the brass sheathing? Does anyone know if that was a practice?

Or...Is it possible that the demand for propellers in WW1 was so great that Hartzell may have needed to subcontract the making of the wooden forms to another supplier and then Hartzell finished it with the cloth and brass, but chose not to add their own decals?

I'm still looking for help in identifying the application this propeller was made for.

[Dbahnson]

I think that it's unlikely that Hartzell would manufacture the sheathing for another manufacturer.

The general design is not typical of WW1 props manufactured by Hartzell. It's much more likely to be WW2 vintage, or even later.

[pmdec]

Hi,
Just from the general aspect of the prop, it is not from WW1. If I have to make a guess, it would be from after WW2. Just a guess.
Regards,
PM

EDIT: Sorry, Dave, I have not seen your post before typing... (and I am slow at that!).

[Dbahnson]

We're simultaneous! 9:42 p.m.

[Motorace]

As a newbie to wooden props, I defer to your judgements on the age of this one being closer to WW2 era. I was basing my WW1 era guess on the lack of identifying numbers such as part numbers, drawing numbers, serial numbers, manufacturing date, batch number, etc... I imagine those were much more commonly used by WW2 to trace and maintain quality control, whereas I could find only the one number on this propeller.

Also, from Hartzell's webpage on identifying their products, I read:
"Generally, a really early wooden propeller is a lot longer than a modern one; eight feet, maybe longer. They usually have eight bolt holes and made of a darker wood. The blade patterns sometimes have a scimitar shape. The modern ones are shorter, usually between six and eight feet, usually have six bolt holes, and are made of lighter-colored wood.”
http://hartzellprop.com/identify-his...ft-propellers/

Mine lacks the scimitar shape of some early props, but it meets the 8' criteria with 8 bolt holes, so I thought he was describing mine.

Did WW2+ era props sometimes have only one number stamped into them?

For my education, could you please say more about what the "aspects" are that say "WW2-era" to you? The pitch?, the design of the brass sheathing? the plan view outline? the lettering font for "Hartzell"? What is your trained eye seeing that a new guy would not notice?

Thanking you in advance for your guidance!