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Canadian Hurricane Mk.XII, some detail observations and questions.


Troy Smith
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well,  this is my 10,000 post on here, so time for another bit of Hurricane trivia to celebrate that...

 

I have been corresponding with Carl Vincent @Carl V , who is Canadian aviation researcher, who says he's not very interested in Hurricanes but has amassed quite a bit of information on Canadian built Hurricanes and Canada's use of them.

I'll @airjiml2 and @dogsbody  as maybe well be of interest to them as well.  I have been corresponding with @StevSmar, about this, but he may have some observations?   

 

Anyway, I was tidying up and and rehosting images on the Hurricane props and spinners thread

https://www.britmodeller.com/forums/index.php?/topic/234980181-hawker-hurricane-propellers-and-spinners-a-modellers-guide/

 

And I wanted some more images of the 'Battle Hurricanes" 

Anyway, while looking at photos again, I noticed a detail I'd not regsistered,  in particular this from the Battle of Britain film,

8822787.jpg

The aircraft on the left is one of the BBMF Hurricanes, (either PZ865 or LF363),  note below the exhausts are two tubes, which IIRC are engine breather tubes.  They are on every Hurricane.... oh, hang on, the aircraft on the right, is C-GCWH see https://www.aerialvisuals.ca/AirframeDossier.php?Serial=40624

 

Apart from the Canadian spinner and Hamilton Standard prop,  note, no breather tubes.

Here's a decent image showing these

60f99840711cd253e9e671f2_Hawker-Hurrican

This is a Mk.IV in Burma, discussed here for those curious, as it is also a very informative image

https://www.britmodeller.com/forums/index.php?/topic/235074537-hurricane-iv-42-sq-burma-1945/

 

 

A look through here

https://www.silverhawkauthor.com/post/canadian-warplanes-3-hawker-hurricane

 

60f9983f92e03f47aa2bbe86_Hawker-Hurrican

 

60f9983c4875b8c158751492_Hawker-Hurrican

 

60f9983ed3fe0efb4ef69b18_Hawker-Hurrican

 

60f77177bd85393cab977f59_Hawker-Hurrican

 

60f9983d2e94075edd8a5440_Hawker-Hurrican

 

Canadian_Hurricane_with_ski_undercarriag

 

Now the Mk.XII had a US made Packard Merlin.  These were not compatible with Rolls Royce Merlins, and are the defining difference between certain  marks of British aircraft, specifically Lancaster I (RR merlin) Lancaster III (Packard Merlin)  and Spitfire IX (RR merlin) and Spitfire XVI (Packard Merlin),  and it is mentioned  in the F.K.Mason Hurricane book that a Hurricane Mk.III was to have a Packard Merlin, so I presume this maybe the explanation for this difference.

 

 

I'd also seen on another CCF Mk.XII image something else, 

Look just above the wing faring, on the cowl side, there is a small projection, I though it might be a venturi, but the dark line is a shadow.  Again, note no tubes under exhaust.

 

60f9983c92e03f57182bbdb9_Hawker-Hurrican

 

it's also visible here

60f9983f318fc16890e8fd24_Hawker-Hurrican

 

OK, on some, but not all. Why?

 

Hmm,  well, Carl also said this, in relation to the lack of spinners on CCF Hurricanes, 

"The spinnerless installation of the Hamilton propeller in the “Battle Hurricane” and the Hurricane IIB (Can)/XII seems to have been looked at with suspicion right from the word go. The chief worries were fumes (see attached sketch), cockpit overheating and air pressure. For example, several unexplained crashes in WAC were related to suspected carbon monoxide poisoning though whether actually attributable to the lack of the spinner is uncertain and, in 1 OTU, an aircraft doing aerobatics had the cockpit hood and emergency hatch blown off, once again attributed to air pressure around the propeller. I cannot trace a date, but it was obvious that the RCAF requested a spinner for these aircraft. As a result, in a communication dated 5 December 1942, CCF reported: We have now received drawings often Air Ministry approved spinner suitable for the Hurricane Mark II B (Can), namely de Havilland spinner drawing P30380A....... We are taking immediate steps to put this spinner in production and will supply 400 at no further cost to the Department. It is improbable that delivery will be possible before March 1943. This was designated by the RCAF Modification Hurr II/101. Production was subcontracted to the Opal Manufacturing Co., Toronto. The first example was delivered in July 1943 and four more in August, afterwards rising to 25 per week. Test flying was done in July 1943 and the spinner seems to have been quite suitable with the fringe benefit of an increase in the aircraft’s speed of 3 to 4 mph. The spinner was fitted to all surviving Hurricane XII and XIIA’s by the end of October 1943. It appears to have been completely successful – certainly, nothing more seems to have been said about it or derived problems in the files."

 

This is the drawing mentioned above

51808087341_4248c2d121_b.jpg03 by losethekibble, on Flickr

 

I'm wondering if  that projection is a vent pipe for the engine bay?  That 'pipe' is about in line with the engine bay firewall, which would be a good place to put , if like, an "engine bay exhaust" as the firewall has some sealing strip, so path of least resistance would be a vent just in front of firewall, low down. May well be wrong, just a suggestion to fit some observations.

 

Finally, Canadian built Hurricanes were exported, and used outside of Canada, but they were sent minus the Packard Merlins, and regined with Rols Royce Merlins

 

Images of CCF Hurricanes used outside of Canada, and thus re- engined.

 

Sea Hurricane JS355

Fleet-Air-Arm-Sea-Hurricane-XII-JS355-du

JS327

Sea_Hurricane_Mk.XII_JS327.jpg

neither are that clear, but I can see pipes just

 

This Canadian built, probably JS403,  the '403' is not clear, but the 'JS' is the film clip this is taken from, and the pilot is know, and serial taken from logbook.  Anyway,  has the breather tubes.

51425138514_bce26a900e_b.jpgHurricane arjan singh tiger 1 by losethekibble, on Flickr

 

This one deserves a thread all of its own though. 

 

 

 

This is likely to have been Canadian built

Soviet_Hurricane.jpg

 

Why?

Note the radiator inlet shape.

see here for this

https://www.britmodeller.com/forums/index.php?/topic/235086563-hurricane-radiators-is-there-a-tropical-or-later-type-on-the-mkii-and-iv-and-is-there-a-different-canadian-inlet-shape/

 

 

 

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Wow, I’m deffo bookmarking this as a rich seam of info, so it’s with some trepidation that I’m submitting some info!

 

Looking at the ‘Battle’ Hurris at the top of the post, I’m convinced that the one on the left is LF363, on the basis that the arial mast on the left is canted aft slightly. No idea why this was and I’m sure it’s been cured (after it’s prang no doubt), but I’ve noticed it on many contemporary photos.

 

Trevor 

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As I remember it, the two small items below the portside exhaust are the inlet and outlet for the generator cooling air.

 

 

Chris

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2 hours ago, Max Headroom said:

Looking at the ‘Battle’ Hurris at the top of the post, I’m convinced that the one on the left is LF363, on the basis that the arial mast on the left is canted aft slightly. No idea why this was and I’m sure it’s been cured (after it’s prang no doubt), but I’ve noticed it on many contemporary photos.

Thanks Trevor, I did consider trying to pin it down, but was wrapped up in a load of other details, and know if was one or the other, it was a a diversion that I thought I'd leave for another time, and AFAIK, they are the same.

1 hour ago, dogsbody said:

As I remember it, the two small items below the portside exhaust are the inlet and outlet for the generator cooling air.

Excellent.  I shall have to go on an information dig to check.  I was a bit wrapped up in finding photos and trying to be coherent in the "new" detail I was mentioning.

How the Packard Merlin 29 varied from Merlin XX I don't know,  but seems a reasonable explanation.     What I find amusing is I have been looking at that photo in the Hurricane Props and Spinner thread for years and not noticed the difference until now! 

 

 

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Just to add to the mystery of the presence of those cowl inlet/outlets, the original port cowl for our Hurricane Mk. XII s/n 5389 had an aluminum patch riveted over the location of that detail. 

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  • 6 months later...

Troy, just finishing my Canadian spinnerless Hurricane on skis as per the image you posted earlier. Was it painted in Dark Earth and Dark Green rather than Grey and Green ? 

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8 hours ago, Adrian Hills said:

Was it painted in Dark Earth and Dark Green rather than Grey and Green ? 

AFAIK the standard factory finish on all (except for the very first batch)  Canadian built Hurricanes was Canadian made Dark Green/Dark Earth/ Sky,  the first batch had aluminium undersides.

 

A few later were Green/Grey,  as mentioned in that Random Thoughts Canadian IPMS pdf you have,  but I'll @dogsbody  @airjiml2 @Carl V if they  know any more.

HTH

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Cheers, underside already Sky so will do Dark Earth and Dark Green. In Frome at the moment and bought more Dark Earth Gunze at the fantastic model shop they have here. 😊

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Our restored Hurricane XII s/n 5389 started life in DE/DG but showed evidence of the DE being overpainted with grey and yellow leading edges added. I don't know any details about the ski version being discussed.

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51 minutes ago, Crimea River said:

Our restored Hurricane XII s/n 5389 started life in DE/DG but showed evidence of the DE being overpainted with grey and yellow leading edges added. I don't know any details about the ski version being discussed.

 

 

These ones:

 

52211872491_51b8b33a4d_z.jpg

 

52212359360_c5698c2b25_z.jpg

 

52211894638_1a96548b71_c.jpg[/url]

 

 

 

 

 

Chris

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Regarding the Canadian Hurricane production as it applies to propellers as recorded in June 1942:

 

·       400 Mk II’s were to be produced (no doubt @Geoffrey Sinclair has a precise reference).

·       Hamilton propellers ‘had proved to be unsuitable.’ Engines used were Merlin 29’s and were American splined. Thus no British propeller could be fitted on to them.

 

The ski-equipped Hurricanes posted above by @dogsbodyare very good. I make one observation in relation to #1362 which is fitted with a bracket type propeller. I believe the blades are not the ‘standard’ dH type and are Hamilton Standard. It seems to me that this aircraft is a Mk I although I can’t be absolutely certain.

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1 hour ago, V Line said:

It seems to me that this aircraft is a Mk I although I can’t be absolutely certain.

1362 is a Mk.I, they were the only ones fitted  with Battle props, and you can see the cowl fasteners, only 4

52211894638_1a96548b71_c.jpg

 

5624 is a Mk.XII

 

 

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The standard story.  In late 1941/early 1942 the RCAF received 30 mark I incomplete airframes from storage, built for the RAF but retained in Canada as part of a plan for expanding the training system.  To make them flyable they needed to take Merlin III engines and (cut down) propellers from Fairey Battles. The original RAF AG serials became RCAF 1351 to 1380.  In addition the RCAF operated 50 Canadian built Sea Hurricane I, BW835 to BW884, with Merlin III, no information about propellers.

 

On 27 August 1941 Canada ordered 400 Hurricanes, 100 for the Netherlands East Indies, 300 for China, this changed to 72 for the Netherlands East Indies, 328 for the USSR, to use Merlin 28 and US built propellers and shipped across the Pacific. By the time production started it was 400 mark XII for the RCAF, serials 5376 to 5775 but in 1943 150 were set to the RAF, these giving rise to the spurious mark XI designation (Merlin 28 RCAF equipment), they were given RAF PJ serials and stripped so as to be the same standard as mark II production, becoming incomplete airframes before being shipped.  The US built 240 Merlin 29 February to April 1942 and another 240 July to December 1942, along with 480 Hamilton Standard 23E50 propellers March to August 1942, for the Canadian order.  As already noted Merlin 29 were fitted for US propellers, the Merlin 28 British propellers.

 

With the surplus engines and propellers the survivors from 1351 to 1380 and BW835 to BW884 were later upgraded to mark XII.

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3 hours ago, Geoffrey Sinclair said:

In addition the RCAF operated 50 Canadian built Sea Hurricane I, BW835 to BW884, with Merlin III, no information about propellers.

from @airjiml2 blog

https://www.ascalecanadian.com/2015/06/the-sea-hurricane-in-canada.html

 

these look to be the DH Hurricane prop/spinner

BW866.JPG

 

 

interestingly there is some colour film of these Sea Hurricanes.

see here 

https://www.youtube.com/watch?v=tO8ui1Wt9Nc

 

this is a still

24483603611_9228e7eea0_b.jpgCanadian  Sea Hurricane Mk.Ib. by Etienne du Plessis, on Flickr

 

the other footage in the film has been discussed on here as well, @Adrian Hills this looks again to be standard Canadian factory finish.

https://www.britmodeller.com/forums/index.php?/topic/235049441-canadian-hurricane-5656/

 

45798113815_aec486a1f9_b.jpg

 

the other is this

https://www.britmodeller.com/forums/index.php?/topic/235049405-hurricane-footage-on-youtube-desert-scheme-repaints-in-colour/

 

 

 

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1.            There's been a lot of good stuff posted here recently. While I'm away from my research notes, I do not believe that senile forgetfulness has advanced so far as to render the following comments/recollections totally valueless.

2.            As far as I can tell, all Hurricanes produced for the RCAF were in DE/DG. There were, during the last year or so of their squadron service, a handful (possibly less) were, for some obscure reason, repainted with green and grey, one or two even with rear-fuselage bands.

3.            The exception to this was the 50 Sea Hurricanes produced in the standard FAA Extra Dark Sea Gray/Slate Grey. When, in 1943, the surviving Sea Hurricanes  were converted to XIIA's and issued to 1 OTU, they appear, judging by the few photos I have, to have been totally repainted, presumably to DE/DG.

4.            As far as the Sea Hurricane propellers are concerned, when the initial contract for 100 (later reduced to 50) was issued, among the items that CCF had to order from the UK were deHavilland propellers.

5.           It is worth noting that when the Sea Hurricanes and Battle Hurricanes were upgraded with Merlin XXIXs, they were not designated Hurricane XII but, rather, Hurricane XIIA, the primary difference being the retention of the eight-gun wing.

6.            Ski Hurricanes. The most intriguing aspect of these aircraft, to my mind, is the fact that the RCAF had no interest in this equipment. While it is commonly assumed that this was simply part of the perceived RCAF propensity to put skis under the majority of its aircraft, this ceased in the early part of the war, at least as far as operational aircraft were concerned. The request for this (and also for the Ventura) was by the British Air Ministry. I have no idea regarding the motivation of this request. All of my inquiries have been met by various speculations, but no hard information.

7.            In response to the request, in early 1942, the RCAF grudgingly allotted one of its precious Battle Hurricanes, 1362. The conversion, using the skis developed for the Harvard I (which I believe were only fitted to Harvard 1321) was undertaken at CCF. This was not completed by May 1942 and, despite protests from the UK where it was believed that snow should certainly be available in Canada at that date, the aircraft, which I do not believe ever flew on skis, was reconverted and taken back into service.

8.            As the Air Ministry still wished the trial to continue, the RCAF provided Hurricane IIB (Can) – re-designated Hurricane XII after 16 April 1943– 5624. It was essentially the same conversion as the previous one, the trials were undertaken in March 1943 and a report written in April. They were quite successful – I have a copy of the report and of the accompanying photos. The aircraft was restored to normal condition almost immediately and I have not been able to find anything more to date about the UK reaction.

9.            There are a few more things I’d like to say, but I have probably said enough. I hope somebody out there has found this of interest.

 

Carl

 

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On 1/8/2022 at 9:02 PM, Troy Smith said:

The aircraft on the left is one of the BBMF Hurricanes, (either PZ865 or LF363),  note below the exhausts are two tubes, which IIRC are engine breather tubes.  They are on every Hurricane.... oh, hang on, the aircraft on the right, is C-GCWH see https://www.aerialvisuals.ca/AirframeDossier.php?Serial=40624

Apart from the Canadian spinner and Hamilton Standard prop,  note, no breather tubes.

 

On 1/8/2022 at 9:43 PM, dogsbody said:

As I remember it, the two small items below the portside exhaust are the inlet and outlet for the generator cooling air.

 

On 7/12/2022 at 6:43 PM, Crimea River said:

Our restored Hurricane XII s/n 5389 started life in DE/DG but showed evidence of the DE being overpainted with grey and yellow leading edges added. I don't know any details about the ski version being discussed.

 

Returning to the OP question, a quick look at photos of RCAF Battle Hurricanes and Sea Hurricanes suggests that all these aircraft had the two protruding tubes. Interestingly, CCF-built AG665 was displayed at the Canadian National Exhibition still as a Mk. I, and also shows the two tubes. All of these aircraft had the original British Rolls-Royce Merlin III and engine-driven generator, so it seems reasonable for them to conform to the standard. As seen in other photos in this thread, British-built machines retained this arrangement also on the Merlin XX until production ended. Indeed, a search on the Internet suggests that "Battle of Britain" film serial H3243, as seens in the photo, was carried by PZ685 "The last of the many".

 

Most present-day Hurricane warbirds are CCF-built Mk.XIIs. Photos show that some of those Hurricanes have a small air intake protruding from the cowling side panel in the position where the two tubes were. I found a photo of the engine bay of 5711 G-HURI, that is fitted with the Packard Merlin 29, showing a different arrangement of the cooling air tubes on the generator, which may explain the intake.

Some warbirds have an even later-model Merlin, where engine accessories may differ, whereas wartime Hurricane Mk. XIIs seem to have no air intake at all. Maybe the (initial) lack of spinner helped?

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38 minutes ago, ClaudioN said:

I found a photo of the engine bay of 5711 G-HURI, that is fitted with the Packard Merlin 29, showing a different arrangement of the cooling air tubes on the generator, which may explain the intake.

This is what I think is the answer, just a different set up on the Merlin 29.  Needs a bit more research, what is odd is how this does not seem to have been noticed before.    I'm sure it has been, just not noted in the usual places. 

 

Next on is what the other tubes/rods are....  

 

 

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Agreed, but on wartime Mk. XIIs there was seemingly no intake or tubing at all on the cowling panel.

Pervesely, I might think that, because of the lack of spinner, air flow within the cowling was enough to cool the generator... no, this seems too much.

 

The other tubes/rods look like kind of a radio dipole to me, but the position is distinctly odd in this case.

 

Claudio

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Posted (edited)

This is a pic I found online, not very large, but does show the Merlin 29,  which has what I presume is the generator in the same place

 

aircraft_hurricane_3.jpg?itok=A6p5spfD

 

this is at the NASM, model not listed.  Not having much luck find a decent pic of a Merlin 29

deliveryService?id=NASM-A19520106000cp10

 

Any Merlin 29 pics in the file @dogsbody @Carl V

Edited by Troy Smith
change pic
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The NASM Merlin is reportedly a V-1650-7, our Merlin 29 would be a V-1650-1. I searched for pics on the web, but no luck.

The engine-driven generator (the black cylindrical object right in front) has a round metal (silver) front cover with no inlet/outlet at all.

 

Thanks for the Hurricane photo, that shows well the details we are discussing. There is no opening on the cowling panel the two airmen are holding (or, it was faired over) and the engine-driven generator is the only part of the engine in full sunlight. It is the cylindrical object over the top engine bearer and, again, its front cover appears to be a round plate with no inlet/outlet.

 

Merlin engine expert needed...

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It would be interesting to know –perhaps @Carl V has the information- to what diameter the Battle blades were reduced together with their designation.

 

The Battle prop diameter was 12ft 6ins and the dH Hurricane 11ft 0ins (with a maximum achievable for the aircraft of 11ft 3ins).Quite a reduction, but not uncommon. Technically it must have been an interesting exercise. As an emergency measure it clearly worked although there may have been an impact on performance.

 

The 20o dH bracket hubs were broadly the same except for different pitch settings which were to match the blades but the settings could of course be adjusted. I should imagine, therefore, that Battle hubs were also used. It seems to me the original blade pitch remained the same although the length and (by the looks of it) the tip radius was quite different.

 

On the matter of engines, both the Merlin 28 and 29 were similar to the Packard V-1650-1 which as noted above, was in turn a version of the Merlin XX. With the exception of the spline, the Merlin 28 was mechanically the same as the Merlin 29 but with a higher reduction gear ratio and for anyone looking for photos of the accessory arrangements, a search for 28’s may be prove fruitful. The generators fitted may have been identical or similar.

 

All the above engines had an electrical generator mounted on the left hand side. The generator could vary according to contract requirements. For the Rotax 12v generator fitted to the Merlin II and others, different vent pairings could be used for the air inlet/outlet cooling pipes i.e top/bottom or frontal pair or one front and one upper/lower and could alternate in terms of flow. By this means there could be some flexibility with regard to pipe routing. Later versions appear to have side and frontal vent inlet/outlets working on the same principle.

 

As far as the Merlin Hurricanes are concerned, it appears there were at least 3 types (models) of generator (A.P.1564B). It is quite possible that the American generators did not have the front face openings and that the electrical connection to the suppressor was fitted at the rear rather than the front.

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It has been said that all the DH propeller sizes were simply shortened versions of the HS original design, so the change from Battle to Hurricane would be straightforward.  The implication is that the performance would be identical to UK Hurricane propellers.  However the Merlins in the Battle would presumably have different gearing to allow for the larger diameter.  This suggests that changing the Mark Number of the Merlin to allow for different propeller gearing was not universal, at least at this stage.  There were limitations on the pitch angle variation with the DH bracket prop, which was the advantage of the later Hydromatic version.

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I have both the Overhaul and Service Manuals for the Merlin 28/29/31 and there is no mention of cooling requirements for the generator. Our restored Hurricane Mk XII 5389 has evidence of the cowl opening mentioned above but it had been faired over with a patch. If you pause the below video at 0:46 and 1:53 you can make out the patch on the cowl. This patch was not added during the restoration process.

 

https://www.youtube.com/watch?v=_3eB9EuWR1k&t=63s

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12 hours ago, Crimea River said:

I have both the Overhaul and Service Manuals for the Merlin 28/29/31 and there is no mention of cooling requirements for the generator. Our restored Hurricane Mk XII 5389 has evidence of the cowl opening mentioned above but it had been faired over with a patch. If you pause the below video at 0:46 and 1:53 you can make out the patch on the cowl. This patch was not added during the restoration process.

 

https://www.youtube.com/watch?v=_3eB9EuWR1k&t=63s

 

 

One of these days I hope to get down there to see the Hurricane.

 

 

 

Chris

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