4 bladed mahogany propeller id needed

[Pete Hearson]

I wondered if anybody could help me on this Four bladed prop i have just found.
The dimensions are exactly to the LE RHONE 80 hp engine, but i am unsure to which aircraft would have had a four bladed fitted, i have been through the list of prop dimensions and it for a Le Rhone, but it only measures 76 inches length, left top to right bottom. There are some markings still visible , see pictures, any info would be greatly appreciated.P1020311.jpg

P1020313.jpg

P1020314.jpg

P1020315.jpg

P1020317.jpg

P1020318.jpg

[Dave]

It's impossible to read the numbers accurately from the photo, but you may be able to do so with a magnifying glass and by moving the light source to various different locations.

It's a left hand thread, which might indicate a pusher configuration for a LeRhone engine, but could also mean an altogether different application with a more modern engine of some kind. The hub dimensions can rule OUT a certain engine but they won't positively rule a specific one IN.

[Pete Hearson]

Four Blade Propeller

Thanks Dave,
i thought it may be a pusher aircraft from the dimensions, some of the markings are hard to read, but i will try again and get some more pictures tomorrow.

[pmdec]

Hi,
On pic 1020314, the numbers are pitch (60") and diameter (76"). IMHO, both are very small for aircraft use. Could have been for snowmobile or something like that, but it seems these ones have only 6 bolts and not 8 like your prop. So ?
PM

[Bob Gardner]

'Morning Pete,

I too am surprised at such a small four-bladed prop.

I have a record of a prop made by the Royal Aircraft Factory which is 6' 8" c.f. yours at 6' 4". But no other data.

When you write The dimensions are exactly to the LE RHONE 80 hp engine are you referring to the bolt holes?

On one of your photographs I can perhaps make out RHT for right hand rotation tractor and possibly Drg No 141, and below it POBJOY, an engine much used for civilian light aircraft in the 1920's and 30's. It is obviously a flown example. The use of eight bolt holes possibly suggests a military prop. The shape suggests a prop design of the Royal Aircraft Factory.

I look forward to some more photographs.

With kind regards,

Bob

[Pete Hearson]

4 Blade Propeller

Hello Bob, nice to hear from you,
I have rechecked the measurements and every one is identical to the list of prop dimensions for the Le Rhone 80hp
Hub Thickness 4 and a quarter
Center hub 2.3
Hub metal dim 5.9
bolt size .394
Bolt circle 4.7
These measurements are in inches.
I will try and get some better pictures, any ideas to which aircraft if Military,
Thanks Peter.

[Bob Gardner]

Hi Pete,

I doubt if it is military but nonetheless it has that sort of feel to it.

It seems likely that Pobjoy was competing with French rotary engines and so offered one prop for all! But I have never come across such a thing before.

Perhaps Googling Pobjoy and variations on that theme such as Pobjoy four bladed propeller etc might find some info.

With kind regards,

Bob

[Pete Hearson]

More pictures of 4 Bladed prop.

HP1020341.jpg

P1020342.jpg

P1020343.jpg

P1020344.jpgere are some more pictures Bob.

[Bob Gardner]

Pete,

A brief Google reveals that all Pobjoy engines were radials, so the fact that the mounting is the same as a Le Rhone radial is obviously intentional.

I think the word under Pobjoy is OUTER. Pobjoy's firm were co-located with Shorts, who made two four-engined aircraft with Pobjoy engines. The Short Type S22, later called the Scion Senior; and the half scale Short Stirling. The word outer does not apply to a two-engined aircraft or a monoplane. So it is possible that this prop comes from one of Short's four-engined aircraft.

With kind regards,

Bob

[pmdec]

Hi,

Could the first pic (P1020311) flipped? Because I also clearly read RHT and this pic seems showing a left handed prop.
A 4-bladed prop on a Pobjoy engine there:
http://www.fiddlersgreen.net/models/...nn-Aircar.html
but the prop is made with two 2-bladed prop.
Also on this page: http://flickrhivemind.net/Tags/aircar/Recent (2nd line, last pic).

If "OUTER" is the word under Pobjoy (for me, I read OL?ER with ? = H or M), it could also be the front one of 2 counter-rotating props. In the 20' and 30', there were some strange aircraft like this:


Regards,
PM

[Pete Hearson]

4 Blade Propeller

The word under POBJOY looks like OLNER or OLMER,
there is possibly another letter before this that has worn out, it is a bit of a strange one, hopefully someone might be able to come up with the answer.

[pmdec]

Hi,

You have there: http://www.flightglobal.com/pdfarchi...?search=pobjoy
and there: http://www.flightglobal.com/pdfarchi...?search=pobjoy
pics of a Pobjoy engine which a metallic hub which can, IMHO, fit the bolt holes and mounting marks of your prop.

You can explore FlightGlobal archives with the word Pobjoy for an answer to the ?OL?ER marking, but there are hundreds of occurences. As the search is limited to 100, you have to explore the archives 5 years by 5 years (and even year by year for the 30's) from 1926 to the 70's...

Regards,
PM

[Pete Hearson]

I wondered if anybody had come across a Probjoy propeller before and how rare are they.

[Bob Gardner]

The word under POBJOY looks like OLNER or OLMER,
there is possibly another letter before this that has worn out, it is a bit of a strange one, hopefully someone might be able to come up with the answer.

The Pobjoy engine was famously used with the Comper Swift. But I can't quite make COMPER fit into OLNER OR OLMER. And anyway the Swift had a two-bladed prop.

Pierre-Michel, Je vous souhaite une heureuse nouvelle année!

With kind regards,

Bob

[Bob Gardner]

This link gives a list of aircraft which used Pobjoy engines.
http://en.wikipedia.org/wiki/Pobjoy_R

British Aircraft Swallow
Comper Swift
Cosmopolitan Light Plane
Couzinet 101
General Aircraft Monospar
Hendy Hobo
Kay Gyroplane
Lippisch Delta IV
Mauboussin M.121P Corsaire Major
Miles Satyr
Pander Multipro
Pobjoy Special
Short Scion
Short Scion Senior
Spartan Clipper

Pete, Pobjoy props are certainly rare, although I suspect that they are so rare that they have little value, because no one knows what they are! I have seen at least three German props made by Heine marked for a Pobjoy engine.

Bob