Stoke Museum

[dharding]

Hi Folks
Just read this article in my local newspaper.

http://www.thisisstaffordshire.co.uk...ail/story.html

To me, it looks more like a WW1 prop than something they would have used in the 30's. Tell me what you think?
Cheers
Dom

[Bob Gardner]

Morning Dom,

I don't think it is from a Spitfire. It is too slender. I restored the only known fixed pitch Spitfire prop a few years ago. It was much larger with wider blades and has a huge streamline fairing around the hub. It was designed by HC Watts of the Airscrew Company whose designs are very distinctive.

This one appears to be of WW1 construction and seems to conform to the design of Lucien Chauviere; the straight trailing edge. If you can discover from the museum any of the data on the hub, particularly the drawing number I will probably be able to identify it.

The thought of the museum giving it TLC is ominous. It is a valuable antique and needs to be conserved rather than painted with a modern lacquer.

With kind regards,

Bob

[dharding]

Hi Bob
Thanks for your reply. I requested the info and had the following reply.


'Hi Dominic,

Thank you for contacting the museum about the Mitchell propeller.

The propeller has 2 blades and the total length measures approx. 2640 mm (104 inches) - which I know makes it probably too short for a Spitfire. It is constructed entirely of wood and is comparatively lightweight for its size. The most notable feature is that a number - 73 - is stamped onto the front of it. The information stamped around the hub is very difficult to read but may include the following:

B Y

AD 81

110 HP OHE

The attached pictures might help, despite them being of fairly poor quality.


Any suggestions as to its origin would be gratefully received - one suggestion so far is that it might perhaps have been fitted to a wooden mock-up of one of the Schneider aircraft? I would be happy to show you the propeller in store if you wish - please contact me with suitable dates.

Please reassure Bob Gardner that we will not be sanding or lacquering the propeller - the TLC is treating it to some much needed Renaissance wax* as it has been in the entrance hall of the school since 1989.

Regards

Don'

Do we think AD81 - is the drawing no - Air Dept, Admiralty?
I guess the '110HP OHE' is probably 110HP LE RHONE or 110HP GNOME
You probably know better than me.
I've attached some of the photos, the one of interest (hub) is proving a bit difficult to reduce and still make anything out.

If you need any more info, Don has invited me to go and look at it.
Thanks
Dom

[Dave]

Do we think AD81 - is the drawing no - Air Dept, Admiralty?
I guess the '110HP OHE' is probably 110HP LE RHONE or 110HP GNOME
You probably know better than me.
I've attached some of the photos, the one of interest (hub) is proving a bit difficult to reduce and still make anything out.

Dom

If you want to send me a full size photo of the hub I can fractionate the stampings images down for posting here. Use dbahnson at gmail.com.

[Bob Gardner]

Well done Dom!

It is not from either a Spitfire or a Schneider Trophy aircraft, nor from the 1920's or 30's. It's WW1 both in construction and in the presentation of the data.

For info, the Spitfire fixed pitch prop was 10.67 feet in length. This prop is 8ft 8ins, 2ft shorter.

I haven't got anywhere definitive on the data yet. We need some good photographs. AD suggests a RNAS drawing number, where AD indicates the Air Dept of the Admiralty, as you say. But the Royal Navy didn't use Le Rhone engines except in a very few instances. Mostly Gnome and Clerget.

I'm off to do a search on the diameter, which might give us the answer.

With kind regards,

Bob

[Bob Gardner]

Mmm!

There seem to be two possibilities.

Statistically it is likely to be from a Sopwith One-and-a-half-Strutter.
Diameter is 2640mm, Clerget 110hp engine, drg no AD555, where perhaps a '5' has been read as '8.' This seems a strong possibilty.

However, the Sopwith Baby would match the letters BY. It had D2650 and a Gnome 100hp Monosoupape. Drg No LP690. This is less convincing other than the 'baby' bit.

The Strutter prop AD555 was also used on the Avro 504.

We need your photographs to proceed.

Bob

[dharding]

Hi Bob
I've sent Dave the photo. I'm going to see if I can arrange to take some more.
On a different line of thought, and this could be a complete red herring, there appears to be strong links between RJ Mitchell and the Air Dept. of the Admiralty. From 1916 upto the end of the war it appears that Mitchell was heavily involved in the re-design of the Air Dept. Seaplanes. I'm not sure what engines they were using but it might be a line of enquiry.
Regards
Dom

[Dave]

I got the photo, but the problem is the lighting, as the glare obscures the details of the stamping. I can reduce the file size, etc., but unless you can get a better photo to show the stampings it probably won't be of much value.

Options include "wetting" with turpentine and/or adjusting the set up so that the light strikes much more from the side. You might have to experiment with both of those.

Also, a polarizing filter on the camera can help reduce glare and bring out detail as well.

[Bob Gardner]

Dom,

RJ Mitchell became the assistant in 1917 to Hubert Scott-Paine who owned the Supermarine Co. At this time it was very much a second-rate organisation, only just escaping bancruptcy. By 1918, Mitchell was the assistant works manager. In 1919 he became the designer and in the 1920's designed a series of successful flying boats that led to the design of the Supermarine sea-planes used in the Schneider trophy. I don't think he did any work on Royal Navy aircraft. By mid-1918 the RNAS no longer existed and had been incorporated with the RFC into the RAF.

I should add that the histories that come with propellers are frequently wrong, even though their owners devoutly believe them to be true. One reason for this is that until Dave Bahnson and Lamar set up this forum (at their own expense) there was no way of making enquiries about a prop.

Bob

[dharding]

Hi Bob
Yes you are probably right however the following links tend to suggest that Mitchell may have worked on the Navy planes

http://flyingmachines.ru/Site2/Crafts/Craft25603.htm
http://britishaviation-ptp.com/id70.html

Regards
Dom

P.S. I'm going visiting the Museum on Friday and I hope to take some photos.

[Bob Gardner]

'Morning Dom,

Yes, they do. Perhaps the role of assistant to Scott-Paine means that he was a design assistant and the role of assistant works manager included design work.

Bob

[dharding]

Hi Guys
I had a look at the prop in the museum, unfortunately the markings on the hub are very dufficult to make out and even more difficult to photograph.
The markings that can be seen are as follows

B.*
AD6**
110HP LERHONE
*****
*****

Also on the blade near the hub is the no. 73
Near to one of the bolt holes is the no. 548

I couldn't seen any decals on the blades although there were small dowels at even intervals along the blades
I've included the best of the photos.
Anyway, I'll be interested to see what you think.














EDIT: Some of the photos shown as links below added as attachments for convenience.



http://www.freeimagehosting.net/20b13
http://www.freeimagehosting.net/121bb
http://www.freeimagehosting.net/342df
http://www.freeimagehosting.net/6bdd5
http://www.freeimagehosting.net/5dd52
http://www.freeimagehosting.net/36eaa
http://www.freeimagehosting.net/813dc
http://www.freeimagehosting.net/b2620

[Bob Gardner]

Well done Dom,

You've done a good job.

It's a Sopwith Camel prop, drawing number AD644. This was an Air Department of the Admiralty drawing number but this does not necessarily mean that it is from a Naval Camel. When the Air Board was formed in 1917 to bring about the formation of the RAF from the RFC and the RNAS one of the first tasks was to sort out the huge numbers of different types of propeller. Mostly this was done by comparing the performance of different props on a trials aircraft. The Navy's AD644 proved to be marginally better than the Sopwith's own prop LP2850. (By this time Sopwith had bought the Lang Propeller Co. who had been a major supplier of props to Sopwith and the company became Sopwith's prop department, although the name never changed.) Most surviving Camel props are AD644. The diameter was 2660mm and the pitch was 2650mm. The diameter of this prop at 2640mm can be explained by the licence given to prop makers to vary the length by up to 10mm because each prop was handmade, and by the possibility that damage to the tip was smoothed out either in service or by a later owner. The top letters in the data are B & P for Boulton & Paul who made large numbers of these props for the RFC and later RAF. I have seen an example with the serial number 15258 so perhaps the number 548 on this one is part of a similar number. The patination on the prop is lovely, just as it should be. Hopefully the Stoke Museum will just polish it with a few coats of pure bees wax. This was a standard Camel prop from November 1917 to the end of the war.

With kind regards,

Bob

[dharding]

Hi Bob
Thanks for your help, I'll pass the info onto the museum staff. They appreciate the importance of the prop and don't intend doing anything other than give it a good waxing. They intend to eventually show it in the same hall as the mark XVI Spitfire currently on display.
Regards
Dom

[Bob Gardner]

Thanks Dom. It's lovely that we had a successful outcome!

With kind regards,

Bob