Unknown Propeller

[richardgrosser]

We were given a 12 foot long, reverse pitch wooden propellor. We do not know what it is from. I have posted photos at
http://www.warbirdflightline.com/misc/prop.html
If anybody knows what it is we would very much appreciate the information.

Thanks,

[Dave]

It sure doesn't look familiar to me, and the hub dimensions don't match up to any of the commonly used engines in the teens and twenties. The left hand thread might mean it was a pusher application, although there's no way to know that without knowing what engine it was designed for.

[pmdec]

Hi,

If on left bottom picture intrados is up, it is probably a tractor prop, as 99% of props hub central hole are made like this (look at the black circle [you have to be connected to see the picture]) :



"Front plate" is a "rear plate" on pusher. Propeller extrados is always frontward, and, 99% sure, central hole flare is on engine side (but there are special fittings which are made opposite way).

Round numbers in centimeters for bolt circle, central hole and plate : do you think it is european production ?

Twelve feet is very large! Perhaps for a seaplane ? Can you give a very precise measure of prop diameter and hub thickness ?

And is it possible you post a close up picture of markings ?

Regards,
PM

[richardgrosser]

I have a hunch that it is from a zeppelin. I will check the shaft taper tomorrow.

Richard

[Bob Gardner]

Richard,

Why do you think it might be from a Zeppelin?

With kind regards,

Bob

[Bob Gardner]

Richard,

The construction of your prop and the style of the brass sheathing has a British look to it. It might be an unflown prop as the bolt holes seem round and not oval in the thrust plane through wear, and there seem to be no witness marks from hub plates.

The metal sheathing on a British prop indicates either a pusher or a seaplane prop.

A diameter of 3660mm was used on British seaplanes made by Fairey (the Campania and the III). It was powered by the Sunbeam Maori engine of 260hp. Drawing numbers were FA4476 and FA5274.

With kind regards,

Bob

[Bob Gardner]

As an afterthought, the Maori engine had a left hand rotation and the 2 bladed 3660mm props were left hand rotation tractor props.


Bob

[richardgrosser]

Unknown Propeller

The engine shaft hole is perfectly straight and has no taper. There are witness marks from the mounting plates clearly visible. The bolt holes show a pattern of asymmetrical wear that indicate that the prop was turning clockwise when viewed from the front of the prop, i.e pushing. The Thickness at the hub is 18 cm. I don't have a specific reason to think that it is a from a zeppelin, however it seems like a likely possibility.

[pmdec]

Hi,

French hubs "C" type from the late WW1 have an 18cm hub thickness. Majority of them have an 8cm central hole but some have a 7cm. But on those props, bolts circle (centers of bolts) is 17 or even 15cm.

And yes, there is an "enlargement" (I don't know the exact word) of the central hole on extrados side and no enlargement on intrados side (respectively right and left bottom pictures of page http://www.warbirdflightline.com/misc/prop.html ). To my knowledge, this prop has to be a pusher OR a LH tractor fitted to a special hub as the Breguet licensed one (see picture).
There are exactly same kinds of "enlargement" on French props. But if there are no other markings on the sides of the hub, I think it is not a French aircraft prop, as all have engine and/or aircraft identification and serial numbers on the sides of the hub.

Sorry for my Frenchie Engish : I didn't want to ask if central hole is tapered.

Regards,
PM

Prop6_arr.jpg is your not shown picture I found in the same directory as html page.
Direct access to Breguet hub patent: http://v3.espacenet.com/publicationD...C&locale=en_EP (see drawings section)

[Bob Gardner]

Hi Everyone,

Some more thoughts.

It's not a coincidence that 3660mm equates to twelve feet.

Twelve feet was the chosen dimension, which suggests that it is of British or American design. It was converted into mm because the convention was to express prop dimensions in mm following the French lead in aviation. The construction of the prop and sheathing are, I think, of British design, not American.

Zeppelin props were much larger. These naval airships below, shot down during air raids on London, had the following diameter and pitches.

Airship L31 Potters Bar 5100 4000
Airship L32 Great Burstead 5000 4000
Airship L33 Little Wigborough 5300 4000
Airship L34 Hartlepool 4700 4000

These props are both tractors and pushers. Pusher props had no need of metal sheathing on airships because they were sufficiently high above the ground to avoid FOD.

The largest German WW1 prop that I have recorded was 7000mm, for the Linke-Hofmann RII.

Zeppelin aircraft, such as the RXIV, had props of 4300mm, and also Gothas.

With kind regards,

Bob