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Hurricane radiators - is there a tropical, or later type on the Mk.II and IV? And is there a different Canadian inlet shape?


Troy Smith

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The version with the straighter sides also seems to have a slight overlap at the top, so that the side slope slightly backwards.  There's no sign of this on the Mk.IId, which in the larger picture looks even more like a rounded intake.  There were no Canadian build Mk.IId.  It does however seem likely that the Canadian ones only had one style, which was the rounded.  I hadn't picked up on the visible signs of the glare shield on Canadian examples, but wouldn't these also be seen on British examples that had been fitted with the glare shield which was then removed?

 

When looking for those Mk.Xs converted to Mk.II, there appears to be many conversions missing from the Air Britain listing.  A few of those in this grouping went to India - and then to operational squadrons.  This is not a sign of retaining the Merlin III, particularly as one wasn't lost until 1944.  (Personal note - I hadn't listed AG338 in my 607 Sq records.  Thank you for that.  Now can you tell me codes and radiator fit...) 

 

Looking in the Arms&Amour press edition of the Hurricane Mk.II manual, there is nothing to suggest anything different for a tropicalised radiator - this would surely have to be listed under the modifications leading to a change of weight and cg position.  Neither is there anything suggesting a different radiator or fairing for the Mk.IV.

 

Reverting to the actual modelling of this, I don't believe that one of the straighter sides can be found on any of the 1/72 kits.  Have I missed anything?  Must look at my two Mk.IV kits, I can see one of them reverting to a Mk.II!

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On 1/11/2021 at 8:40 PM, 72modeler said:

...captioned as the radiator housing from the BBMF Hurricane

https://www.flickr.com/photos/sisaphus/4429664961/in/set-72157623970323344/


...new-build radiator/oil cooler core for a Mk 1, Mk II Note the non-standard shape of the oil cooler core in one photo

https://www.replicore.co.nz/gallery/MK1-and-MK2-Hawker-Hurricane-radiator-and-oil-cooler-cores/20

 

That’s a SWEET photo of the BBMF radiator housing!!!

 

Ive been looking for those replicore photos!

 

thanks.

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6 hours ago, Graham Boak said:

When looking for those Mk.Xs converted to Mk.II, there appears to be many conversions missing from the Air Britain listing.  A few of those in this grouping went to India - and then to operational squadrons.  This is not a sign of retaining the Merlin III, particularly as one wasn't lost until 1944.  (Personal note - I hadn't listed AG338 in my 607 Sq records.  Thank you for that.  Now can you tell me codes and radiator fit...)

What conversions are being talked about?  The 30 AG serial mark I airframes stored in Canada in the second half of 1941 that were mark II on arrival in Britain in roughly the March to May 1942 period?

 

As Carl Vincent has shown there was no Hurricane mark X as far as Canada is concerned.  There is some RAF documentation calling Canadian built mark I mark X, but mostly they are called mark I.  CCF built airframes meant for the Merlin XX or later were either retained in Canada with Merlin 29 as mark XII or exported to Britain, some with a Merlin 28 fitted, others engineless.  Rolls Royce make it clear after arrival in Britain either a Merlin XX was installed or the Merlin 28 were replaced by a Merlin XX, so making them all mark II.  A few test flights were done with the Merlin 28, but otherwise the engines went to Lancasters.


The RAF started a program of converting mark I to II, giving the conversions new serial numbers, BV155 to BV172, DG612 to DG651 and DR339 to DR394, 116 serials but DR375 to DR390 were not used, so exactly 100 conversions.

CCF built mark I to mark II conversions were
P5175 to BV159, Russia 7 September 1941.
P5190 to DG620, Middle East, Lost at Sea 24 August 1941,
P5195 to DG623, Russia 15 January 1942.
P5199 to DG632, Middle East 4 November 1941, Struck off Charge 19 January 1942.
P5204 to BV170, Middle East 18 July 1941, Struck off Charge 30 November 1941.
AE963 to DR366, Russia 17 April 1942, Lost at Sea 17 June 1942.

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I use the term converted because the Term Cv II is used  in Air Britain near the end of a batch described as Canadian-built Mk.Is.   In the case of AG122, this conversion takes place after service in 55 OTU and transfer to RR, where apparently it remained.  Clearly a special case.  Other conversions listed by Air Britain begin with AG292 and proceed to AG344, where Cv IIB (or Cv IIC) is either listed or no comment made.  The main user of these 53 aircraft was the RCAF, none of which are listed as conversions.  Three went to the Far East and were with operational units until 1943 and 1944:  I think it certain that these were converted, wherever it was done.  Another is listed with 128 Sq.  Of the nineteen actually listed as conversions twelve went to Russia, five to the  Admiralty, one to the Far East, one to the Middle East.  Of the ones noted as unconverted, two went to Russia (possibly converted examples?) but all the rest have RCAF serials.

 

AB states that the batch beginning AF945 were Mk.Is later redesignated Mk.Xs.  There seems to be no difference between that and your statement "mostly they are called".  It is however proper that the term Mk.X should only be applied to those Mk.Is remaining in the UK after the allocation of the Mark number, which may well have been after the arrival and re-engining of the versions with the Merlin 28s.  There certainly is room in the blanks between AG292 and AG344 for a number of aircraft built as Mk.Is and retained as such, or perhaps in one case delivered to 128 Sq?  But also a number of as-yet unidentified Mk.IIs, presumably among those sent to Russia?  Where these aircraft were "converted", whether in the UK or in Canada, or indeed actually built on the production line, isn't said.

 

There are another twenty aircraft AG665 to 684 delivered as Mk.IIB.  Or should that be with Merlin 28s?    One went to the Far East, two to the Admiralty, and one was lost before the remainder sent to Russia.  The dates quoted as sailing (presumably port loading dates, judging from the closeness of several)  overlapped with those from the earlier serials - unsurprisingly, really.

 

It is certainly possible that the AB book has been superseded since its publishing date of 2000.  Or, indeed, that Canadian and UK records differ.  However it does appear clear that more than thirty AGxxx serialed Canadian-built Hurricanes reached their units as Mk.IIs, one way or another. 

 

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Quick query:  It occurs to me that no one has commented on ALBentley's drawings of the Mk.II that he added to the rear of his Mk.I drawings.  Do these show anything about the radiator intake shape?  (My copy seems to be hidden by the Hobby Room Monster...)

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I can only stress no, nil, none, zero Merlin 28 in flying Hurricanes, beyond some test flights.  And the possibility AM270/HC3-287, the Dutch version prototype used one, though it was meant to have a US propeller.

 

It seems clear CCF with one exception delivered Hurricanes in RAF serial order to October 1941, the ones put into storage in 1941 for example had both their serial number and a 3 digit number painted on, AG303 had 439 for example, count the RAF serials allocated in order and AG303 is number 439.

 

CCF stopped production in August 1941, after building 485, that is to AG670 given AG341 was not built, 426 were exported, difference 59 which were stored, AG292 to AG340, AG342 to AG344, AG665 to AG670, when production resumed in October AG671 was delivered as a mark I and stored, we know this as Carl Vincent has provided a list, though it omits AG343 instead of AG341. AG665 flew to and was used in, and well photographed at, an exhibition in 1941, fully equipped as a mark I.  Mark II production began in November 1941 but in parallel to the first mark II CCF were building the 50 Sea Hurricane BW835 to BW884.

 

If the Air Britain definition of mark X is CCF built mark I with Merlin III, that is fine, if the definition is Merlin 28 then there are big problems beyond Rolls Royce saying no.  AF945 is serial number 181 so probably delivered in March 1941 and all AF and AG serials to AG290 had either been lost or were in Britain by end August 1941, some 246 airframes.  Packard delivered the first Merlin 28 in August 1941, managing 32 for the year, no hard data on when the first arrived in Britain.  CCF built Hurricanes with engines began arriving in March 1942, but the engines are reported as incomplete, meaning the aircraft could not be flown in Canada.

 

The 60 in storage in Canada were ultimately split 30 RCAF 30 RAF but although the first mark II airframes arrived in Britain in December 1941 these 30 mark I arrived as noted March to May 1942 and were recorded as being mark II by then.  The 1941 plan was to store 100 airframes in Canada for training, I am presuming the idea was to fit them with US Merlins and use them in things like Operational Training Units. Now AG292 is aircraft number 428, if you jump 100 serials to AM296 or AM297 depending on whether you count AM270 or not, you find they are the airframes arriving in Britain December 1941 onwards and all the subsequent AM serials to AM369 are reporting arrival or taken on charge dates in or before March 1942, while the initial non Sea Hurricane BW serials are March onwards.  Meanwhile back at the AG and early AM serial ranch, their first taken on charge dates are 28 February 1942 but are mostly March and April.

 

So far no explanation has been found for this, either CCF jumped production or had (part) assembled airframes that were not officially produced which joined the 30 from storage and were delivered to the RAF as mark II months after later serial mark II were delivered.

 

Where CCF switched from mark I to II airframes has been a mystery probably because of the reports of the stored AG serials being mark I by the RCAF and mark II by the RAF and the possibility the RCAF ones were mark II airframes with Merlin III, given they were later upgraded to mark XII with Merlin 29.  The list of stored Hurricanes explicitly states they were all mark I airframes.  For AG672 onwards everyone states they were mark II airframes, becoming mark XII when a Merlin 29 was fitted.  AG341 is also a mark II.

 

No Merlin 28.  The mark X (Merlin 28) and the mark XI designations simply never existed in the 1940's.

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As I said, AB refers to the AF/G batch of Canadian built Mk.1s as later redesignated Mk.Xs.  They do not quote a date for this.  Given that all reference to aircraft converted are to Mk.II, clearly these aircraft were not known as Mk.Is after conversion.

 

I did not mean to imply that aircraft were fitted with the M28 after arrival in Britain, but was simply repeating your comments that some of this batch were fitted with M28s and re-engined in the UK.  The aircraft at some stage were converted from the contracted short Hurricane Mk.Is to long Hurricane Mk.II - possibly directly in build or possibly after arrival in the UK.  The AG665+ and AM serials are all referred to as Mk.II.  The Merlin 28 is a Merlin XX variant and thus requires a long fuselage.

 

AB described AG671 as converted to a Mk.IIc and sent to the Far East.  Given that a change of wings was not normally noted, it seems likely to me that this and Carl's information agree.  AG341 is the one listed as converted to a Mk.IIc and sent to the Middle East.

 

Another point to consider is that an aircraft converted (by whatever means in whatever place) also requires a wing with additional guns.  Plus there is some question just when a strengthened wing was introduced on the Mk.IIB. but the timing of this appears opaque.

 

So all references to Mk.X, XI and XII are postwar?  Do you know why anyone bothered?  If the Mk.XII designation existed earlier then surely so did the Mk.X and XI?

 

 

 

 

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Great, good to confirm the Air Britain mark X definition is a CCF built mark I.  If you have the contracts that would be great, which contract and how many were ordered as mark I?  Various sources have different ideas about the first 600 aircraft.

 

Butler and Hagedorn, Air Arsenal North America
964753/38 for 40
BSB28 for 20
BSB166 (SB.6648) for 540

 

RAF Contract cards
964753/38 for 40 delivered as mark I.  Requisition 56/38.  Completed 2 Aug 1940
SB.6648 for 560 delivered as 386 I and 174 II.  Requisition 8/E1/39, note 100 of the II to be retained in Canada

 

US War Production Board.
BSB166 for 600 aircraft

 

Francis Mason
40 pilot production
100 first series production batch (list misses the 20 T serial aircraft)
340 second series production batch
100 third series production batch

 

Would "at some stage were converted from the contracted" be better as at some stage the contract was changed from "X" mark I to "X-Y" mark I and Y mark II?  It is hard to be converted directly in build.

 

We are dealing with the output of probably complete airframes but incomplete aircraft, lacking things like instruments and engine and more, the missing parts to be fitted after arrival in Britain.

 

The British aircraft import reports, AIR 19/524 and 20/2019 give Hurricane mark numbers and whether there was an engine fitted.  The list provided by Carl Vincent reports the 60 stored airframes as mark I.  A further document he supplied reports CCF mark II production had begun in November 1941. Put them together and you have as rolled out of CCF 486 mark I airframes built, 30 went to the RCAF, 30 others converted to mark II before shipment to the RAF (but since they did not fly in Canada, they first flew as mark II), there were the 50 Sea Hurricane I and all the rest of CCF production was mark II airframes, 400 of which, the RCAF order, were given Merlin 29 as mark XII.  Of course 150 of the RCAF order were sent to Britain, some with Merlin 28 installed, the rest as airframes and now with surplus Merlin 29 engines all surviving RCAF mark I and Sea I were upgraded to mark XII standard.

 

So far all the documents I have seen says CCF built A and B wing Hurricanes, that means any with C wings were converted after arrival in Britain.  I have contradictory lists about how many and which serials ended up as IIC, but it is a sizeable percentage.  The RAF did no conversions from mark I to II for AG292 or later but did do IIB to IIC.

 

To paraphrase Carl Vincent again.  The mark X was a proposed mark for Sea Hurricanes with Merlin 29 but not used, (back to me for a moment, though the Dutch called their Hurricane version a mark X and some RAF documentation refers to CCF built mark I as mark X).  The mark XI was also a proposed mark number for ex RAF order Hurricane I fitted with Merlin 29 but again not used.  While the RCAF order were officially Mark IIB (Can) until they were renamed mark XII on 16 April 1943.  Plus there was an informal plan to call RAF order Hurricanes with Merlin 28 expected to be retained in Canada as mark II (Eng). Someone came up with public definitions of mark X and XI early enough that they became the truth via cascade quoting, it was not by the air forces.

 

Now I find some evidence.  The 1945/46 Jane's All the World's Aircraft says the mark X was "Packard Merlin 28 driving a Hamilton Standard Hydromatic airscrew, corresponded to the British built mark I"  So sort of half and half, but no mark XI definition.  So a public mark X definition was around just post war, not in the 1950's as I thought, but no date for the mark XI.

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The quoted contract number for the AE/AF batch of 20 was to BSB166   The AF/AG batch is of 300, the later AG batches is of 20, and the AM batch of 100, all to BAC C.45, regardless of mark.  If there were earlier examples I haven't looked for them

 

If you say no aircraft were converted from Mk.I to Mk.II in Britain, then where were these examples converted?  There appears to me more examples than described.   I would agree that "converted on the production line" is not the best way of describing things, but where the change between marks is not known then some more general term is required: AB uses Cv in its tables which it describes as Converted in its Glossary.  Presumably this term is used on the Aircraft Record cards from which the AB tables were prepared.  It seems unlikely that merely changing the engine from a Packard to a RR Mk.XX would count as a conversion, but perhaps it did.  The DG block is described as being converted from Mk.I to Mk.II at RR, so they were certainly capable of converting any Canadian examples.  The DR block however is described as being rebuilt.  

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Not quite related to the Radiator thread, but interesting (to me...). A closeup of the radiator armour:

50832802146_7fa8ce0665_o.jpg

 

There definitely is no "triangle" at the rear of the radiator armour like seems to be shown on many scale drawings.

 

(It sure looks like it's a bit rough at the back of the armour... Maybe A&AEE were testing to see if filling in the gap with congealed porridge reduced the drag...)

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@StevSmar,

 

The photo and enlargement show the armored radiator as fitted to Mk IV and Mk V's; the armor, as seen in both photos, consisted of a 'saddle' that was attached at two points on each side by bolts/washers anchored at the base of the radiator housing. There have  been a couple of photos of the saddle detached from the radiator that have been posted by a couple of BM'ers that show the strap-on armor saddle and the 'ears' on each side that the attachment bolts pass through. Nice photos! Thanks for sharing them.

Mike

 

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44 minutes ago, ClaudioN said:

HMS Vindex, "squared" (flat sides) intake

HMS Vindex, "rounded" intake

Same ship, same time, different shape. No. 825 Squadron had both JS-serialled CCF-built Mk.IIs (converted to cannon-wing Mk. IICs) and NF-serialled Hawker-built Mk. IICs.

 

good spot, for ease of reference (and I'd not seen the 2nd Vindex pic before)

b19ea5fe028dfe8636a823d65ab4e424.jpg

large_000000.jpg

 

the top pic is later, after the introduction of shipboard improvised rocket rails.  

 

And again, seems to support the round side Canadian intake theory.

 

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31 minutes ago, Troy Smith said:

the top pic is later, after the introduction of shipboard improvised rocket rails

Thank you Troy, I need to learn how to include images directly.

Although no rocket rails are visible in the IWM photo (ref. no. A 25570), it is one in a group of photos, all dated 8 September 1944, collectively entitled "U-boat killers of the Vindex". If you look at other photos in the same group (for instance, by typing A 25571 into the search line), you will be able to see the rails.

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I have a copy of Hawkers drawing which shows the MkI Radiator Housing inlet geometry.

If I'm reading the drawing correctly it also says the profile of the inlet top right quadrant matches the profile of the other quadrants via mirroring.

 

I put this into a solid modelling program and drew a sketch using the dimensions shown for the MkI radiator housing. Then I modified the sketch to a MkII radiator housing by making it 2.07" deeper. This gave me:

50832594168_13a32f14f0_o.jpg

(Note how I've estimated the thickness of the inlet based on the general arrangement drawing. This is generally pretty inaccurate, but I have no other information)

 

I then inserted the A&AEE front views which @Troy Smith provided links to, and scaled them to a wingspan of 40'. With my sketch for the the MkII radiator housing inlet geometry overlaid I got the following:

- MkIIC

50833423347_35e78280d7_o.jpg

- MkIV

50833428502_fa9c49a87b_o.jpg

(Sorry it's a bit hard to see the overlaid geometry, Fusion 360 is for solid modelling, not graphics)

 

There seems to be a pretty good agreement between the radiator housing inlet geometry of the MkIIC and the MkIV, if I was forced to decide I'd say the inlet geometry appears to be the same.

 

If they are the same then this corroborates what the schedule of spare parts say- MkI and MkII radiator housings, MkI and MkII "temperate" and tropical radiator cores?

 

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Thanks for the contract details.  Unfortunately yet another source with different ideas, probably not surprising in early contract with the British, Canadians and Americans all involved.  The writing comes across as so sure of the subject it is making assumptions and so not letting the rest of us easily follow things.

 

13 hours ago, Graham Boak said:

If you say no aircraft were converted from Mk.I to Mk.II in Britain, then where were these examples converted?  There appears to me more examples than described.   I would agree that "converted on the production line" is not the best way of describing things, but where the change between marks is not known

I have said about conversions,
1) 6 CCF mark I were converted to mark II in Britain, 5 P serials and AE963, which were given new serial numbers, part of a hundred such conversions.
2) 30 AG serial mark I airframes were converted to mark II in Canada before shipment to Britain.
3) the survivors of the 50 Sea mark I and 30 ex RAF order mark I were converted to mark XII in Canada.
4) CCF built A and B wings, a number of the mark IIB were converted to IIC in Britain.

 

Where did I say "no aircraft were converted" and what are "these examples"?  I note at least 1 more mark I to II conversion that kept its original serial.  I know where the change of mark numbers listed above happened, I have the documents, all quoted.  If the documents are considered wrong please provide the counter evidence.

 

The fact is from the 1945/46 Jane's having a Merlin 28 meant mark X, later someone added the mark XI usually as "mark X with Canadian Equipment".  So "everyone" adopted the notation, mark II Merlin XX, mark X and XI Merlin 28, mark XII Merlin 29.  And let us not forget the ideas about mark IV engines.

 

I have no idea why Air Britain chose to describe the Hurricane mark I to II conversions that received new DG serials as converted and the DR serials as rebuilt, what do they use to describe the BV serials block?

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28 minutes ago, gingerbob said:

What has always puzzled me is why these I>II got new serials.  There's no reason that I'm aware of that this would be necessary.

I do not know whether this is yet another wartime myth, but I recall reading somewhere that the USSR wanted Mk. IIs, not Mk. Is. New serials would help somehow in building VVS confidence that converted Mk. IIs the RAF was sending were not old, worn-out machines.

 

3 hours ago, Geoffrey Sinclair said:

I have no idea why Air Britain chose to describe the Hurricane mark I to II conversions that received new DG serials as converted and the DR serials as rebuilt, what do they use to describe the BV serials block?

Just a thought: in interwar years some rebuilt RAF aircraft had an 'R' added to their serial, e.g., JRxxxx, KRxxxx. Maybe 'DR' was interpreted in a similar way?

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The cynical might suggest that it was to hide the production age from the Russians, but they were also widely used by the RAF.  Could still be true, of course.  

 

The previous system had simply included a R between the serial letter and numbers.  Possibly it was felt that doing something similar but with three letters could be confusing, with R already in use in an appropriate alphabetical place.  I don't believe I've ever seen any justification.  With the increase in fully metal structures, and mass production pushing new aircraft out, the need for significant mid-life rebuilds was reduced anyway.  Perhaps these Hurricanes required replacements in the wooden part of its structure as well as a new fabric covering?  Or perhaps it was to distance them from their sisters which still were around in Mk.I form?

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Hmm, Gomtuu, you do have a point.  However Mk.I vs Mk.II is also a relevant part of this investigation, since it directly affects the radiator housing (and core).  Perhaps we can at least try not to get too off on that tangent!?  Keeping things "strictly focused" is virtually impossible, and sometimes those seeming tangents bring in valuable information that contributes to understanding the original theme, but it also gets frustrating trying to keep track of where you encountered some good information when it bears no relation to the claimed "subject" of the thread.

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8 hours ago, gingerbob said:

What has always puzzled me is why these I>II got new serials.  There's no reason that I'm aware of that this would be necessary.

(It was because someone with a black sense of humour knew it would confuse future generation of modellers on the radiator sizes...) (sorry, I couldn’t help myself...)

 

I personally think it makes sense to have new serial numbers. After all they are no longer the same Mk of aircraft. 

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Getting back to the standard/tropical radiator discussion, and after reading all the posts and looking at all the diagrams/photos, I  am going to make two observations: firstly, there might have been different inlets/openings, with there being visible differences in the size of he Mk 1, Mk II, and Mk IV/V opening. Secondly, it doesn't appear that there is a difference in the depth/height of the radiator housings, but the strap-on armor plate saddle does give a deeper profile to the housing when fitted. It does look like in photos, that the two Mk V conversions and one Mk V  that was actually fitted with the Merlin 32, had a much deeper inlet than that of the Mk IV. My thinking is that the tropical radiators obtained their increased cooling by means of a longer core, as it would have a greater number of tubes through which the coolant would pass, thereby increasing the ability of the radiator to dissipate  heat; there sure looks like there is enough extra length in the housing to allow for this. Just an uneducated guess, to be sure!

Mike

 

Now, on to more important matters: "IIb or not IIb?) :giggle:

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9 hours ago, 72modeler said:

Getting back to the standard/tropical radiator discussion, and after reading all the posts and looking at all the diagrams/photos

I would add that, so far, only the "squared" inlet shape is shown to be documented in Hawkers drawings and that "rounded" versus "squared" shape is seemingly unrelated to "temperate" versus "tropical" radiator.

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