Port Victoria PV8 Eastchurch Kitten

[GRB81]

Hi, my name is Graham and I have just registered on this forum. I am an aviation enthusiast in England and have an interest in an experimental World War 1 aircraft called the Port Victoria PV8 Eastchurch Kitten. Information on the aircraft is scant and I have been in contact with a number of museums regarding the limited information they hold in archives. Whilst they have been helpful in my search there seems to be a lack of technical information in existence. The Yorkshire Air Museum has built a recreation of the aircraft but had to make many assumptions given the lack of technical detail available.

As such I thought I would enquire as to whether you have any knowledge on the propeller used on this aircraft? I know it is a long shot as only 1 aircraft of this type was built and my assumption is that there is no information on the propeller used given that there was little need to mass produce propellers for this aircraft type. The engine used on the PV8 was an ABC Gnat 35 hp 2 cylinder. I have attached a couple of old pictures of the aircraft but a few more are on the Imperial War Museum website. At present there are no further technical details I can find.

I would be interested in any information people may have but apologies if this enquiry is a forlorn hope.

Kind regards,

Graham

04 Side.jpg

08 Front.jpg

[Bob Gardner]

Good Morning Graham, on this snowy Yorkshire morning.

Both the PV7 and the PV8 used the angular Lang Propeller visible in your photo (which is what one would expect because Lang was the major supplier of props to the Royal Navy) with the drawing numbers LP2300 and LP2340. But I don't have the diameter or pitch for these props on the PV7 and PV8.

However, the drawing number LP2340 was also used on the Grahame White XV (with the 80hp Gnome engine) with Diameter 2600 and Pitch of 1500. Therefore I think we can be reasonably certain that a replica Lang prop of these dimensions can be fitted to the YAM replica.

But another possibility is a prop owned by the IWM, a Lang Prop LP3300 with D1950 and P2170, for a 40hp ABC engine which might be an improved ABC Gnat.

The ABC Wasp engine was much more powerful at 170hp, and was used in several other small light aircraft which surprisingly used props of similar dimensions to those used with the Gnat engine, but these are Air Board drawings rather than Lang drawings:

Firstly, The Westland Wagtail with prop AB8623 with D2360 and P1800 .

And secondly, the BAT Bantam and Sopwith Snail, also AB8623 with the same diameter, 2360mm, but with pitch 1870mm.

With kind regards,

Bob

[GRB81]

Many thanks for this very useful information Bob, I will pass it onto my contacts at the YAM. I am amazed at the level of detail you have unearthed. Are there any ways of accessing the drawings you refer to?

Just out of interest is there any reason that the diameter and pitch of British propellers of this age were expressed in metric measurements rather than the imperial units more commonly used at that time?

Many thanks for all your efforts, Kind regards, Graham

[Bob Gardner]

'Evening Graham,

I regret that the drawings for WW1 propellers do not exist, or at least, not at this moment. The contents of the library of the Royal Aircraft Factory, (later known as the RAE etc) have been gathered together in Farnborough and several years work lies ahead of who ever decides to catalogue them. They probably have blue prints of RAF (Royal Aircraft Factory) propeller drawings.

But I suggest that a replica prop could be constructed by YAM to the diameters I have listed, using your head-on photograph as a template, which would give your replica a degree of verisimilitude.

France was the leading aeronautical nation from 1908 to c1915 and thus all the European nations followed suite, using metric measurements. All the initial experimental and scientific work was conducted by Lucien Chauvière. This extended into motoring and motorsport as well; hence Grand Prix, Droit du Seignure, and Parc Ferme as well as aileron, fuselage etc. Hence prop diameters were expressed in mm for several decades after 1908.

The info I have found for you comes from copies of tables published in 1917 by the Royal Aircraft Factory and by the Air Board in the 1920's and later.

With kind regards,

Bob

[GRB81]

Hi Bob,

Many thanks for your very informative reply and for taking the time to answer my many questions. It is very much appreciated.

Kind regards,

Graham

[GRB81]

Lang Propeller images

Further to my post above I have followed up the Lang propeller used on the ABC 40 hp and that is held by the IWM. They very kindly sent me some pictures of it so I have posted them here in case they are new to the forum. Apologies if you have already seen the propeller or these images and many thanks to Toby Cavallo, Senior Collections Assistant at IWM Duxford for kindly searching their collection. To my untrained eye it looks different to the angular prop on the Kitten but I would be interested in any professional views! Kind regards, Graham

[GRB81]

More pictures. Regards, Graham

[Dbahnson]

Wow. Nice prop, apparently in original condition. Whatever it was fitted to, it's great to see one that hasn't had an attempt at "restoration".

[Bob Gardner]

Dave,

The Imperial War Museum are good curators. They don't restore their propellers and many other aviation items in their collection. They helped me in my researches by allowing me to photograph all the WW1 propellers in their collection, for which I remain most grateful.

Graham,

The IWM prop for the ABC 40hp sadly does not conform to the traditional angular Lang design. I have recorded a few other Lang designs which don't follow the norm. I guess the YAM team must construct a replica of the usual angular shape. I have many photographs of Lang props if that will help, but I expect the photo that you have is sufficient to make a replica.

Tell me if I can help further. I doubt if I can!

With kind regards,

Bob

[GRB81]

Hi again,

Thanks to the very kind people at the Smithsonian National Air and Space Museum in the US I now have my hands on a copy of the original Report No. M. 153 on the Eastchurch Kitten from Nov 1917. Among the details provided in this report there is a listing of the airscrew used. It states;

Type: Two blader, Drg. 2340 L.H.
Maker: Lang
Maker’s series no.: No. 1. 16932
Pitch: 955
Diameter: 1677
Maximum blade width: 190

I know it might be a silly question but what does L.H. stand for after the drawing number?

Kind regards,

Graham

[Dbahnson]

I know it might be a silly question but what does L.H. stand for after the drawing number?

Kind regards,

Graham

LH is the direction of the thread, i.e. "left hand". Propellers are really just sections of a screw device ("airscrew") and will have a thread direction and a pitch, even though all you see of it is the one section that forms the blade. By convention (at least British, U.S., French, and others) as you look at the propeller from behind when it turns, if it moves forward by turning clockwise it's a right hand thread, just as turning a right hand threaded screw clockwise pulls it forward. The pitch is the distance between threads and similarly can be visualized as fine thread or coarse thread - and everything in between.

Most aircraft engines rotate in a direction such that a right hand propeller provides a tractor configuration. If the engine is mounted backwards, the thread needs to be reversed and acts as a pusher.

Some engines were configured to rotate in the opposite direction, and some engines were geared, which reversed the direction, and those also used left hand threaded propellers. The photo on your initial post shows a left hand thread.