An odd propeller

Air Britain ‘The Squadrons of the Royal Air Force’ has these squadrons based at Oban:
209 Sqn, Stranraers, 7 Oct 39-16 Jul 40
210 Sqn, Sunderlands, 13 Jul 40-28 Feb 42
228 Sqn, Sunderlands, 10 Mar 42-11 Dec 42
240 Sqn, Stranraer, 30 Jul 40-28 Mar 41 (text says Oban, tabular data says Stranraer, which appears to be a typo)
330 Sqn, Catalina, 28 Jan 43-12 Jul 43
524 Sqn, Mariner, 20 Oct 43-7 Dec 43

The first four squadrons also flew the London, although some years before moving to Oban. I suppose the possibility exists, though, that a London propellor might have been some sort of trophy or keepsake that got left behind during yet another move.

We have at last found an possible answer to this mystery prop from Oban. The owner noticed by chance a relatively close photo of an early Supermarine Stranraer fitted with lapped propellers in an MMP Stranraer detail book. He happened to notice that the hub of the Peggy X had 12 bolts as opposed to the more usual Bristol Pegasus 10 bolts used on two blade props (the Walrus (Peggy II, hub uses 10 bolts).

However there could be another contender which is the Saro London which also had the Pegasus X with lapped airscrews. 201 Sqn and 240 Sqn both used both of these boats. they were both at Invergordon, but were they at Oban at any time?

John

A little further research (Ross McNeill’s book, (Coastal Command Losses) shows that 240 Sqn were at Oban, arriving 19th July 1940 with Stranraer I’s.

Again thank you all for the input. Yes I’m now convinced that it is one half of a lapped propeller (or should it be Airscrew). The HP 42’s by the way used the two types of four blade props. The HP.42W (Western) for European destinations used the pukka fixed construction prop and the HP.42E (Eastern services) used the lapped type because it was for convenience of transport of propeller spares over the longer distances by air.

The prop in question is 10′ 9″ dia so it is too small for a HP.42 and I still have no evidence of production Jupiter’s using the 12 stud type of hub except for the original Cosmos. Eagles and Falcons of which some versions could run left hand (anticlockwise from the pilot) had 8 bolt hubs and the big Condor did run anticlockwise but again it’s a matter of finding a Condor engined aeroplane with a small four blade prop. All the ones I can find have props approaching 14′ in dia. So it’s the 12 bolt fixing which is the key.

John

Bulldog prop

John,
Would you be so kind as to give more physical details. Length, dia. of hub, thickness of hub, dia. of bolt circle, max width of blade, dia. of mounting bolts, dia. of hole. All this will help.
Cheers
Ed

Mate, this is what you want :
Top is Westland Wapiti, middle is Hawker Demon and bottom is Bristol Bulldog. Because you never reply to my posts I will not tell you where they are !:)

HP Clive

I am assisting to ID this prop. It was found in the Oban area. It is 10′ 9″ in dia and has no markings. The rotation is British LH and the usual candidates for such as this would be the Lion, Jaguar, Panther, Pegasus and Jupiter. However all these engines have 8 or 10 bolt hub fittings. This prop has 12 bolt/stud holes. Rolls Royce engines are opposite rotation (RH) though I believe some Falcons and Eagles had LH props but again used 8 stud hubs. The Condor did have a 12 stud hub but I think this prop is nowhere big enough.

I have found one candidate engine with 12 stud fitting and that is the very rare Cosmos Jupiter, later to become the Bristol Jupiter II. Most subsequent members of the Jupiter family used a 10 stud hub fitting Did some early Jupiter’s have 12 stud hubs?

Note the two countersunk brass fittings on the rear of the boss. Are they locators so that the prop if removed will go back at the same position relative to the crankshaft perhaps for gun synchronizing?

Any ideas gentlemen?

John

[ATTACH=CONFIG]225170[/ATTACH]

[ATTACH=CONFIG]225171[/ATTACH]

[ATTACH=CONFIG]225172[/ATTACH]

Attached is photo Of Handley Page Clive 1928, showing what looks like your 12 hole sandwich prop, with the obvious rational for brass locators ensuring a balanced assembly. The photo is from a HP company doc “Forty Years On” 1919 – 1949. Most of the early HP bombers had Falcons which is perhaps where the comfort with 12 hole hubs developed from. Later photos of HP 42 passenger airliner show four blade props, so perhaps the sandwich affair was the typical use of “off shelf” Falcon stock for new application with Jupiter in HP Clive, and once the Jupiter powerplant was established for HP use then a lighter four blade unit was worth investing in for later HP aircraft.

Another thought stems from reading “Flying Years” by CH Keith 1937, which relates to the interwar period in Iraq, and troubles associated with heavily laden takeoffs in ‘thin’ warm, tropical air. Perhaps two blades were used for light applications and four blades for heavy going in the tropics ? Perhaps the secondary blade was kept in the fuselage or workshops for monsoon conditions in places like India/Malaya/Singapore ?
Ed

I have just added further photos to the opening post and here is the info Bulldogbuilder requested.

Prop Dia 10′ 9″

Diameter of Hub: 13”
PCD of bolts 9”
Bore 4”
Depth of boss 4 710”
Max blade width 10 14”

John

Thanks for the input. interesting point re the brass locators The dia is 10′ 9″ and it’s the 12 stud fixing which is unusual, Bristols are usually 8 or 10. The rotation is certainly “Bristol fashion”

John

John

It looks like a HP42, Jupiter XIF Prop. around 141in. (359cm) diam. We have a mint one in our flight room, got it at a Onslow’s auction in London in 1985. They had five in the sale, four new and one used. We had a new one…..

I think the brass plates maybe are part of the locking to the second prop to make into a four bladed propeller….

Maybe..

Civil Aero

Thanks for the reply Ed. I have requested the information. I have been scouring my refs for the fixed pitch prop (wood 2 bld) fitted to the Blackburn Shark. Does anyone have a close front shot of the AW Tiger without the small spinner and not the three blade type?. I need to be able to see the number of bolts.

John

John,
Would you be so kind as to give more physical details. Length, dia. of hub, thickness of hub, dia. of bolt circle, max width of blade, dia. of mounting bolts, dia. of hole. All this will help.
Cheers
Ed