Rotol propeller; help please!

[Bob Gardner]

Good Evening David,

It's looking good. I do hope you find some drawings. Have you discovered where the Rotol archives went to? Rolls-Royce or Bristol?

With kind regards,

Bob

[dairwin]

Bob,

My understanding is that Dowty have (had) them, but most were lost in a river flood (I believe in July 1968 ) when the archive was flooded. Some were saved.

My enquiry has been forwarded to Dowty and I am hopeful that they may know more.

The important reference that I do have is that the blade profiles are defined on a drawing reference GA1571. If I can find it!

DAI

[Bob Gardner]

So did Dowty take over ROTOL? As an aside for other forumites, the Bristol and Rolls-Royce companies merged their prop companies into one company just before WW2, 1937 I think, hence the name ROTOL.

Bob

[dairwin]

From the Wiki website, entry on Dowty: The Company was founded by George Dowty in 1935 making aircraft equipment in Cheltenham under the name Dowty Aviation. In its early years the Company invented the first internally sprung aircraft wheel and went on to make landing gear for Frank Whittle's jet-propelled Gloster aeroplane. In 1960 the Company acquired Rotol Airscrews, giving it a propellor manufacturing capability (Dowty Rotol).

Today, they seem to manufacture undercarriage legs for many aeroplanes, including Airbus. For over ten years, they are wholly owned by a French Aerospace company.

Regards,

DAI

[Bob Gardner]

Thank you David!

Please keep us up to date.

With kind regards,

Bob

[dairwin]

Thank you David!

Please keep us up to date.

With kind regards,

Bob

Bob,

In the two months since my last messages, there has been several advances relating to this propeller.

The research has yielded only five drawings of the hub, and no further information on the blade type. However, there is now sufficient information on the hub to dismantle it fully. Also, the blades are likely to be like all early (late 1930s) Rotol blades; a clarke-y section and simple/tapered blade roots.

In the last week I have had tools fabricated to unscrew the two castellated nuts per blade, and the removal of the blade adaptors from the hub. Inside, there is light corrosion, but the running surfaces for the variable pitch cylinder are corrosion free (still full of engine oil).

I have located similar rotol blades for another R5 propeller, and will assess whether these can be used as a basis to fabricate a set appropriate for the R5/3 hub.

I will send you a PM as well.

Kind regards,

David.

[dairwin]

re: R5 and Watts

Thank you David!

Please keep us up to date.

With kind regards,

Bob

Bob,

It has been a several months since my last posting regarding the Rotol R5 propeller I am rebuilding. Work on the R5 blade adaptors is now advanced, and I plan to start the wooden blade fabrication later this year. The hub has been restored in readiness for the blades.

However, I would also like to fit the engine with a Watts prop, but as they are not available, I would like to evaluate what is involved to replicate one for ground running.

I know at least one forum member who has restored a Watts I am keen to acquire information on the blade dimensions, profile, photos of restoration, etc.

On a separate but related note; in order to fabricate the wooden R5 blades (and a Watts if I do) I am looking for a blade duplicator machine. I am having problems locating one suitable to make blades of 4 feet length (8 feet prop diameter). I would welcome advice from members.

Kind regards,

David

[Bob Gardner]

Thank you, David, for keeping us up to date. I remain impressed by what you do.

As a general observation, I think you should contact all the Merlin rebuilders in the country, if you haven't already. They will be interested in your work and they might have some lifed bits, about to be scrapped.

Guy Black had a prop replicating machine when I last saw him. He bought it on eBay. I'm not sure it works, but ask him. He also restores vintage aircraft and has an engine restoration company, Retrotec. He owns a flying Spitfire Mk. Vb (G-MKVB), Hawker Hurricane XIIa (G-HURI), Hawker Nimrod II (G-BURZ) and Hawker Fury (G-CBZP)

A company in the South West, Spitfire Spares, makes replica WW1 props using a period prop copying machine. I think they are the people to make blades for you. You'll need a blank or existing blade to copy. Presumably for running at low revs on the ground a solid prop rather than a laminated one would suffice? It would be easier.

I'll e-mail both of them to let them know you'll be in touch.

Please keep updating us.

With kind regards,

Bob

[dairwin]

Thanks Bob for your reply.

Please see my PM.

Thanks,

David

[Bob Gardner]

As an afterthought, we have restored several wooden fixed-pitch props designed by Dr HC Watts and made by the Airscrew Company, which include one Spitfire prop, two Hurricane props and a Kestrel prop. But we have no details of them other than dimensions and pitch. The same hub fitments were used on both the Spit and the Hurricane fixed pitch props, so from your point of view either prop would fit your Merlin.

With kind regards,

Bob

[dairwin]

That is very interesting, as these are the props I am interested in; specifically the Hurricane Watts, as the engine in question is configured for Hurricane use.

I understand there are several Hurricane Watts propellers, but they all seem to have the same diameter of 11.25' and a pitch of 21.3'.

DAI