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Jakes
10-12-2015, 11:00 AM
Dear all,

Found this prop I want to identify. From the little research I have done it seems to be a Rotol Airscrew.

The following markings are visible:
1) On bottom DA531 & D210591
2) On side RA 5812 in reqtangular box
3) On side in circle A78
4) On side in double circle 112 (not 100% sure of this because very feint)
5) On side the number 31995

There was a clear type epoxy coating on the wood, but that has been removed.

Thank you, hope someone can shed some light as to from what aircraft this might have come, and the year.

Bob Gardner
10-13-2015, 07:05 AM
Good Morning Jakes,

Welcome to the forum.

The prop blade DA531 was used on the Hurricane II and IV with the Merlin XX engine. It was a three bladed prop.

RA5812 indicates the type of adaptor which was also used with the Merlin XX engine on the Beaufighter II; and with Merlin VIII and Mk 30 engines on the Fulmar and Barracuda.

With kind regards,

Bob

Jakes
10-13-2015, 12:29 PM
Thank you very much Bob, nice to know from what aircraft it came.

Will clean it up a bit and let it stand in my study.

Kind Regards
Jakes

Jakes
10-13-2015, 12:45 PM
Hi Bob,

I looked at photos and illustrations of Hurricanes on the net, and it seem that all of them, the blade is a black color, mine was covered in a clear thick resin of some sort - is this normal?

Are these specific blades rare or are they quite common? Read somewhere that there were more than 14 000 Hurricanes manufactured...

I know the condition is not great, but is it worth something? Not that I would ever sell it.

Thanks for the opportunity to pick your brain!

Kind Regards
Jakes

Bob Gardner
10-14-2015, 07:35 AM
Jakes,

These propellers were the next generation of the laminated wooden propellers used during WW1. Your prop blade is an early example of the use of composites, which were far stronger than laminated propellers. The process was called Hydulignum. Google should give you a detailed description.

In outline, several thin laminations of birch were compressed at a high temperature and pressure whilst immersed in resin. The coating to which you refer was a resin-soaked cloth stocking which was slid over the blade and covered with a rubber sheath. The blade was then compressed under pressure in resin at 80 deg F for twenty minutes by which time the stocking and rubber sheath had become part and parcel of the blade. It was a superb almost indestructible coating. Removing it, even eighty years later, requires a powerful machine tool and lots of time and patience.

There are quite a few of these prop blades around and my guess is that someone wishing to collect them could find several during the course of a year. They do not sell for much; around 100 GBP.

The value of yours has been reduced by removal of the original black sheath but the appearance has been improved! If you polish it every few months with pure bees wax out of a tin bought from B & Q, the appearance will improve considerably and the wood will be preserved.

With kind regards,

Bob

pmdec
10-15-2015, 07:55 PM
Hi,

You can also search "Permali" and "Micarta".
We have a variable pitch 2-bladed prop for a Dewoitine 520 with Permali blades. It is a prototype and it seems that the blades were never protected nor painted. Lenght : 3.10 m, blade width 310 mm.

Regards,
PM

Bob Gardner
10-16-2015, 05:57 AM
Bonjour Pierre-Michel,

Lovely to hear from you. Does the Ratier Propeller Museum continue to grow and flourish? Perhaps you could post a few photographs? I'm sure our regular readership would be most interested.

With kind regards,

Bob

MrSunu
10-19-2015, 11:46 AM
Hi Bob,
You're mentioning "There are quite a few of these prop blades around and my guess is that someone wishing to collect them could find several during the course of a year. They do not sell for much; around 100 GBP."

May I ask if you could point me a bit to where "around" might be to find one? Feel free to send me a PM if appropriate.

Many thanks

zzxxcc2525
11-30-2015, 10:45 PM
nice to know from what aircraft it came.
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