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Thread: Hurricane Mk1 R4118 P3351 P3717 and maybe the new Mk1s all without correct spinners.

  1. #1
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    Hurricane Mk1 R4118 P3351 P3717 and maybe the new Mk1s all without correct spinners.

    Hi,
    With the flying Spitfire Mk1s having gone the extra mile (as its not a cheap exercise) to feature the correct shaped spinners, hearing of more Mk1 Hurricanes not far from appearing at airshows, I am hoping they will also feature the correct look up front at last as we have never yet seen a correct looking Mk1 Hurricane !

    The three currently airworthy have incorrect spinners.

    Vachers Hurricane never did, in having the later bullet spinner. R4118

    P3351 has an incorrect later bullet spinner.

    P3717 has an incorrect later bullet spinner.

    I see news of four Mk1 Hurris under restoration.

    What spinner will V7497 feature for example ?

    Are the restoration teams in fact aware of this spinner situation ? I recall mentioning the spinner to Peter Vacher who didnt believe it was wrong, not aware of the Battle of Britain shapes, thought it was correct. There are thousands of pics in books showing the short pointed De havilland as per Spit Mk1's or bulbous rounded Rotol spinner.

    http://www.britmodeller.com/forums/i...dellers-guide/

    With enough Mk1s flying or about to, the cost of machining for one might be prohibitive, though was done for the first Mk1 Spit (casenoves), at Duxford, so I hope the increasing numbers of Mk1 Hurris could see owners manage to get costs down in a combined spinner multiple copies process. It would also be good to see the fibreglass replicas also feature the correct spinners as well ! Even Hendons Hurricane. Its now or never, the Hurri Mk1 needs to look correct up front !

    DBenz

  2. #2
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    I stand to be corrected, but I think that very much part of the problem may well be that the 'correct' spinner shapes may well not fit with the propeller assemblies under the spinners. Someone like Gordon Riley or Bruce will know.

    On the other hand, Spitfire P9374 had a specially constructed and 'correct' DH bracket propeller assembly. Thus, there was no difficulty in getting the right spinner shape for the right propeller.
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  3. #3
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    You'd be right there Andy - the spinner geometry would be determined by type of hub the prop has, and if the prop fitted to a restored aircraft carrying its original markings is not what that aircraft was fitted with originally then I suspect that there is nothing that can be done about it.

  4. #4
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    Agreed. The problem is an absence of bracket-type DH props - apart from the extraordinary (and extraordinarily expensive) new-build one on P9374 Andy mentioned. That might be the only three-blade one flying now - Hamilton and DH simply stopped making them 75 years ago.

    The blades sit differently on Hydro hubs, and the internal spinner archtecture doesn't need to accomodate counter-weights.
    Last edited by Beermat; 17th February 2017 at 07:27.

  5. #5
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    I don't think that's a problem: the DH bracket prop sat under a spinner of the same base diameter and shorter length than the current "bullet" spinner. Getting the right blades may indeed be a different matter, for either the DH or earlier Rotol spinner. However, it would be interesting to have it confirmed that the spinners for Hydromatic units were different from those with brackets: I'm thinking here of later Spitfire Mk.Vs. If so, this doesn't appear to be obvious in photos.

    Drifting slightly, I have an impression that the current Hurricane "bullet" spinners are slightly more bulbous and thus less shapely than the WW2 variety, at least of the earlier examples. Can this impression be backed or destroyed by definite evidence?
    Last edited by Graham Boak; 17th February 2017 at 09:59.

  6. #6
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    Maybe the counterweights are a red herring - it was something I read about the Canadian Hurricanes. It's to do with attachment points IIRC.


    However, there are differences -the blade roots sat 3/4 inch further out in radius terms and also marginally further forward. This comes from RTFM. Furhermore the Hydromatic unit was longer. So - same base diameter, but needing a different curvature. As you say, the bracket type sat under a shorter spinner because it could. This, and differing modes of attachment meant a different profile. Put basically, to apply a 'correct' spinner would need a smaller hub - as Andy said, that's why that Spitfire uniquely has the correct profile spinner - they spent silly money getting the correct prop assembly replicated and no-one else has.

    There were blade equivalences with Hamilton blades (I listed them in some other obscure thread) but once dh started doing their own this broke down. Because the hubs were different sizes changing from bracket to hydro on the same aircraft actually made your prop diameter slightly larger, if you stuck to the same blade profile.

    Whether there is a US Hydromatic equivalent to a Spitfire or Hurricane bracket-type blade is the 64,000 dollar question, and it depends on which side of the Atlantic the original profile came from. No-one knows.

    So here's the difference between Spit DH Bracket and Spit DH Hydro (of which there weren't all that many) - it's subtle but it's there - Aussie Spit on left (Hydro), Standard DH Spit prop middle, and Rotol for comparison right.
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    Last edited by Beermat; 17th February 2017 at 15:22.

  7. #7
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    just o put a spanner in the works P3351 was built as a MK1 but was upgraded to a MK11a and i believe flies in that configuration even though she's in the markings she wore as a MK1.....not sure about the others.

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    R4118 also had a de havilland bracket prop on originally but it was so badly corroded they changed to rotal propeller because there was no DH props available at the time of restoration! That's what it said on plane restoration anyway

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    In relation to the Rotol unit being fitted to a MkI Hurricane, the reason that new builds are fitted with the longer bullet spinner is solely down to the longer hub. The Battle of Britain era Hurricanes were fitted with a Rotol prop that had a shorter hub which meant that a blunt bulbous Spinner could be fitted, the later Rotols had a longer hub that needed the bullet type spinner. It would be lovely to see the Hurricanes fitted with the correct props and spinners but i can`t see it happening unfortunately.

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    Quote Originally Posted by R4118 View Post
    R4118 also had a de havilland bracket prop on originally but it was so badly corroded they changed to rotal propeller because there was no DH props available at the time of restoration! That's what it said on plane restoration anyway
    I have my own theory on this. I believe that originally R4118 went into service with a Rotol unit. The picture of her in flight in early 1941 that is in the book quite clearly shows a blunt rotol spinner. I think that by the time she was crated up and sent to India, it was decided to send her with an older DH metal prop, that would bear up to the harsh conditions of the Indian heat better than a wooden bladed prop unit. Also as an ancient MkI, she would not need to have a modern propeller for the use that she was going to be put to.

  11. #11
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    I think I'm correct in saying that HAC Hurricane has a Hamilton Standard prop, so again causing spinner shape problems to accommodate a very different prop and to replicate something looking vaguely like a European theatre Mk I.
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    Quote Originally Posted by DBenz View Post
    Its now or never, the Hurri Mk1 needs to look correct up front !
    DBenz
    I dare to venture that even if you reduce life's scope to the world of aircraft preservation, then there are more pressing and important problems that need to be dealt with.

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    Quote Originally Posted by oz rb fan View Post
    just o put a spanner in the works P3351 was built as a MK1 but was upgraded to a MK11a and i believe flies in that configuration even though she's in the markings she wore as a MK1.....not sure about the others.
    This is what I was about to say - built a I, upgraded to IIa and restored as IIa.
    "those who know keep quiet, and those who don't are frowned upon for asking." - snafu

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    Quote Originally Posted by One of the Few View Post
    I have my own theory on this. I believe that originally R4118 went into service with a Rotol unit. The picture of her in flight in early 1941 that is in the book quite clearly shows a blunt rotol spinner. I think that by the time she was crated up and sent to India, it was decided to send her with an older DH metal prop, that would bear up to the harsh conditions of the Indian heat better than a wooden bladed prop unit. Also as an ancient MkI, she would not need to have a modern propeller for the use that she was going to be put to.
    All the Hurricane Mk.II and Mk.IV in India flew with wooden Rotol props, so I don't think that could be the reason. It was said to be the reason why DH props were used in the Desert on Mk is, but again the standard Rotol was there on Mk.IIs. I suspect someone earlier believed that logistics would be easier with just one type, and chose the DH.

    The later "Bullet" props were seen on late production Mk.Is. I wonder if the age of R4118 meant that the cg had crept too far aft and so the heavier DH unit was chosen to bring it forward again, as on the Sea Hurricane Mk.I. Otherwise, perhaps it was just someone's mistake. A few Mk.Is did fly against the Japanese at the end of the Burma campaign, and from Ceylon, but I've not seen any photo to know what props they had.

  15. #15
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    Kenneth #6 post, any chance you can tweak the pics as the one with the chair is mostly hidden under the one above it, unless its my Firefox browser.

    Beermat...I dare to venture that even if you reduce life's scope to the world of aircraft preservation, then there are more pressing and important problems that need to be dealt with.
    We for years accepted 6 port exhausts, and dome sided canopies when 3 port and flat side was correct. Then someone decided to make things more accurate, try and show what the aircraft originally truly looked like, we had 3 port and flat sided canopies, we also lost the high gloss finishes, it was a joy to see such, so just hoping here that someone might try again and shows us true looking Mk1 Hurricanes, and it does make a big difference at the front end. For me P9374 was a long wait come true, to see a Battle of Britain spitfire all 100% correct in shape was tear jerking. As there are a few Mk1 Hurris, it might help reduce the costs of making the correct 'gubbins' under the spinner, or so I hope.

    Spitfire Mk1's AR213 N3200 X4650 and P9374 feature the early spinners, though X4650's is a bit longer than P9374 , N3200 and AR213 so its happening for spits, somehow they manage to get hold of the early 'gubbins'. Not sure what Peter Monk did there unless that's what fits a later 'gubbins' if one tries ?
    P7350 has gone partway with 3port fishtail then I see 3 port ejector as per most BoB spits, though longer spinner and blown sided hood.

    DBenz

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    To reply to a point in Beermat's post (#6); the Americans did/do have an equivalent to the de-H bracket type - it's called the Hamilton Standard Bracket propeller. It was the first design HS licensed (around mid 1930's) to de-H and was used on a lot of pre- and early wartime aircraft on both sides of the Atlantic. A licence was even taken out by the Japanese pre-war to be manufactured as Mitsubishi-Hamilton units. Just look at the 1930's US, UK and Japanese aircraft and most of them had bracket-type props. We fitted them to Spitfires, Blenheims, Battles, Wellingtons, Hampdens, Beaufighters and other aircraft. It was the best prop available at the time.

    Called the 3-E-50, it was the first major high-power, variable-pitch design by HS though was superseded by the good old 23-E-50 Hydromatic/23EX (as used on the Hurricane) as this was, essentially, an improved model to cope with higher powers, less maintenance, fully-sealed and able to operate over a more diverse pitch range. The list of applications for the 23-E-50 is almost endless and hundreds of thousands of that superb design were built. There are many hundreds still in service and (apart from the Rotols and the odd Curtiss) they are fitted to most warbirds flying today.

    Many of the early bracket props were actually imported HS units as were quite a few of the early Hydromatics (I have seen a US-built hydromatic, described as a de-H, built by Nash Kelvinator from a Lanc crash site) all in the name of an increasing US assistance in supplying us with much needed components for our war effort.

    I'm surprised that there is such difficulty in sourcing bracket-type props as the Americans must have quite a few (as is their way with war surplus), the only difference being the SAE-50 spline spider as opposed to the SBAC-50 for UK applications. Surely a SBAC-spline spider could be machined relatively easily to replace the US one - or is that a case of component replacement requiring lengthy testing and certification?

    Anon.
    Last edited by Anon; 19th February 2017 at 09:01.

  17. #17
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    Don't know about the spinner issue, but aren't they using modified DC3 blades?
    If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: It's all balls. RJM.

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    Were any WW2 Hurricanes fitted with the Hydromatic hub? It didn't appear on Spitfires until mid 1942, which is long after (about 18 months) the longer "bullet" spinner was standardised on Hurricanes. I'm sure you are correct that the current examples have it, and this may explain why they appear to have a slightly more bulbous variant. I believe that some of the later wartime examples have this too, but it is difficult to be certain from photographs. I think the Mk.V had a more bulbous spinner, but that was a 4-blade hub so perhaps excused.

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    The Hydromatic hub was fitted to many of the Merlin XX-powered Hurricanes. Of course, the Rotol pulled the rest though knowing little else about the Hurricane technically I have no idea of the proportions of each variant. That's one for the Hurri Historians.

    Anon.

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    The early ones being Rotol certainly rule out any connection between the shape of their "bullet" fairing and the later Hydromatic hub. However, I'm doubtful about the latter such combination. It isn't mentioned in Mason's books, which do list the variations of Rotol props fitted to the Mk.II, and it isn't in the RAF Museum's The Hurricane II manual. This, quoting AP1564B Vol 1 Leading Particulars, modified by AL26, actually refers to "Rotol variable pitch external cylinder group (see AP 1538E Vol.1) or DH bracket type (see AP1538H Vol.1)". Something odd there, but I presume that the phrase "variable pitch external cylinder" actually refers to what we'd now call the constant speed variant, Rotol not having a 2-position variable pitch alternative. So passing this across to Hurri historians, which Hurricane Mk.IIs were powered by DH props, and was it possible to distinguish them? Presumably by the blade roots and shape, but not the spinner?

  21. #21
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    Anon. I am of course aware of the Hamilton bracket prop!

    The problem is there are no Right Hand 3 E X's anywhere. I was keeping designations out of it.

    Machining won't help, I believe. The problem is the spline - different number and shape.

    To clarify,I was thinking about blade profiles when I talked of equivalents.

    The Hydromatic was more than an improved bracket hub - it was a different mechanism.

    DBenz, why did you add my 'name' to that quote? I have never commented on the matter.
    Last edited by Beermat; 19th February 2017 at 18:51.

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    Beermat. The Hydromatic was indeed an improved bracket propeller - by, principally, deleting the counterweights and having a fully sealed pitch change piston mechanism.

    I did make it clear that the splines were different and hadn't suggested machining a SAE50 to SBAC50 spline. This wouldn't have been possible as the shaft diameters were the same and there would not have been enough metal left from the broad-spline US pattern for the fine-spline UK unit to allow a full set of splines. The spider is a precision part but surely not beyond the capacity of modern technology to reproduce from the same, or equivalent, material. It is manufactured from billet, not wrought first so no need for an expensive process to produce the initial blank. The rest of the HS/de-H prop parts of the hub are pretty much identical and interchangeable.

    The dome that the Hydromatic had was longer and larger, though narrower overall, than the original bracket/piston mechanism, so this would change the profile needed for the spinner shell. Quite a few modern Hurricane restorations use the Hydromatic because it is (relatively) cheap and plentiful. Certainly more so than the Rotol models, supplies of which the Spitfire operators have probably cornered or nearly exhausted.

    It's possible that DC-3 blades have been used as these were designed for the hydromatic hub though, whilst relatively plentiful, I'd have thought they weren't quite long enough for a Hurricane prop. I did supply someone around ten years ago with a set of DC-4 blades, which are a fair bit longer than the DC-3's, for a Hurricane project, so that may be where the possible confusion arose. Being such a large paddle blade there was plenty of meat on them to allow them to be re-shaped to a Hurricane blade profile.

    Anon.

    Edit: The Rotol airscrew was associated almost exclusively with wooden blades and the de-H with metal. Whilst the de-H/HS props couldn't/didn't use wooden blades the Rotols could use both materials and several metal-bladed Rotols were produced earlier in the war, Aluminium alloy and magnesium being the principal two blade materials, until Rotol seemed to settle exclusively on wooden-bladed props. The question for me is; were there metal-bladed Rotols used on Hurricanes early in the war? If so, this may explain why different spinner shapes were seen on metal-bladed props. My feeling is that the Hydromatic, due to the large pressure dome, dictated a more bulged profile to house it. I admit that I know little about Hurricane development otherwise.
    Last edited by Anon; 19th February 2017 at 22:11.

  23. #23
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    Hi


    The pitch change mechanism relied on a centrifugal effect - spinning weights on brackets - to drive pitch change in the 'coarse' direction in a bracket prop, so operation was somewhat different. The Hydromatic was an improved means of achieving a variable pitch prop, but one would be hard pressed to call it an improved bracket prop. Mainly because it didn't have brackets!

    It would be like calling a Tesla an improved Mini. Bit pedantic of me, sorry! It's because it niggles the nerd in me that folk call all variable-pitch metal Hamilton or DH props 'Hydromatic' - not you, but I am keen on the distinction!
    Last edited by Beermat; 20th February 2017 at 11:43.

  24. #24
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    I have been looking at this for a while. The scarcity is not of bracket props in general, there are loads of D-shank units sloshing around - I have half a dozen in my garage.

    E - shank bracket prop components are hen's teeth, and there are in fact variations of fit. Tables of interchangeability do exist in the manuals but are largely hypothetical when the parts don't exist any more. I challenge anyone to find an SAE 50 spline E shank BRACKET application - never mind an SBAC 50 one - since the war. Hence the necessity to re-manufacture all the components at great expense - or just use a Hydromatic instead, different spinner and all.
    Last edited by Beermat; 20th February 2017 at 09:46.

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    OK, if it pleases you to see it that way then who am I to argue. Perhaps my words put slightly differently would have been better but I don't think the overall message was lost or misconstrued.

    You are wrong about the operation of the bracket prop though, Beermat. The counterweights were just that - to offset the aerodynamic tendency of the blades to twist to fine pitch so preventing unnecessarily adverse loads on the pitch change mechanism components. The Hydromatic propeller numbered a more powerful mechanism to change the pitch of the propeller amongst its many advantages over the bracket type.

    What spline is inside your D-shank props? Are they early taper shaft units (Blenheim, Wellington, Hampden)? Perhaps it may be worth asking the Japanese if they have a few Mitsubishi-Hamilton bracket props surplus!

    Anon.
    Last edited by Anon; 20th February 2017 at 16:58.

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    So not trying to teach you anything as I know you are way ahead of me on this stuff through hands-on experience. I am more explaining myself with this..


    I believe that the blades without any countering force would tend towards finer-than-optimum pitch due to aerodynamic forces alone.. The countering force in a bracket prop comes from the counterweights which apply more force the faster they spin, and are linked to provide force in the coarse direction. This may be progressively over-ruled by oil pressure in the cylinder, tending the blade back to fine against the counterweights.

    In a single-acting hydromatic the tendency to fine is countered by oil pressure, not counterweights. In a double acting one there is pressure on both sides of the piston. The oil provides a force in the opposite sense to that in a CW, in both cases. This is why I argue that it is a different thing and far more than a deletion of the weights.
    Last edited by Beermat; 21st February 2017 at 22:47.

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    If there are surplus 3E50 Japanese props then that would make some people very happy indeed - except for a few people who have just spent an awful lot of money.. I do doubt it.

    Mine are rusty ex-Otter Hamiltons, relatively common so not interesting (unless you're really into propellers ) or expensive in any way.
    Last edited by Beermat; 21st February 2017 at 08:01.

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