Ditching a Sea Hurricane.

[Onslow]

If there was earlier consideration to using the Hurricane as a carrier fighter, or some extra design and development resources were available, could the Sea Hurricane's ditching problems have been addressed by modifying the radiator that was allegedly the main issue? I've seen pics of belly-landed Hurries that have lost the whole radiator - would it be possible to calculate the loads and reduce the fastenings so that in a ditching the whole radiator would come off under the impact, rather than turtle or sink the whole plane? Alternatively, would it be possible to fit some form of emergency device, similar to the cooling flap at the rear of the radiator, that would drop down and fair off the hole at the front of the radiator before ditching and therefore reduce the drag?

This is for an alt history I muse about, where a small country is replacing its Furies, Demons, Ospreys, Harts etc and because of its small size can effectively only run one single-seat fighter both on its carrier and on land and where the naval air arm forms a much larger proportion of the total a/c and therefore has more clout. It has been assembling and part-building Furies, Ospreys etc and some staff had been trained to modify existing designs.

On the same topic, while the Sea Hurrie has a bad rep for ditching has anyone looked at the actual survival rate and how it compares to that of comparable aircraft?

Thanks for any info

 

[ThomasP]

It would be possible to do what you have suggested re the shear forces allowing the radiator to detach on impact, but in terms of pilot survivability it would be more effective to install a flotation system of some sort - either sealed chambers in the airframe, or inflatable flotation bags, or a combination of the two. The idea of the flotation bags was that the bags would inflate automatically after impact with the water when contact with water set off the trigger for the inflation system. The flotation chamber system did not need compressed air inflation, instead relying on watertight integrity of the chamber to keep the aircraft afloat, or in case of damage delay the sinking of the aircraft, thereby allowing the pilot to get out of the cockpit safely.

Both systems were used by the various nations depending on the nature of the aircraft.

The US Navy F4F Wildcat flotation bag system - image from a Warbirds Information Exchange thread on the subject: "Warbird Information Exchange • View topic - Aircraft Emergency Flotation Bags ..."

 

[MikeMeech]

It would be possible to do what you have suggested re the shear forces allowing the radiator to detach on impact, but in terms of pilot survivability it would be more effective to install a flotation system of some sort - either sealed chambers in the airframe, or inflatable flotation bags, or a combination of the two. The idea of the flotation bags was that the bags would inflate automatically ofter impact with the water and contact with water set off the trigger for the inflation system. The flotation chamber system did not need compressed air inflation, instead relying on watertight integrity of the chamber to keep the aircraft afloat, or in case of damage delay the sinking of the aircraft, thereby allowing the pilot to get out of the cockpit safely.

Both systems were used by the various nations depending on the nature of the aircraft.

The US Navy F4F Wildcat flotation bag system - image from a Warbirds Information Exchange thread on the subject: "Warbird Information Exchange • View topic - Aircraft Emergency Flotation Bags ..."
View attachment 820485

Hi
Emergency floatation systems and internal air bags have been around a long time. The RNAS/RAF used and tested systems on various aeroplanes during WW1 for instance, internal air bags in the Sopwith Pup/Beardmore W.B.III conversion of 1917:

Part of image from 'Beardmore Aircraft of WWI' by Colin Owers.
Also the Emergency Floatation Gear fitted to a Sopwith 1 1/2 Strutter during 1918, inflated and deflated:

This is from 'When The Navy Took to the Air, The Experimental Seaplane Stations of the Royal Naval Air Service' by Philip MacDougall.
There are plenty of images around in various books as the photos are 'Official' ones taken at the time and 'originals' are found in museum collections such as the RAF and Fleet Air Arm museums.

Mike

 

[Greyman]

If there was earlier consideration to using the Hurricane as a carrier fighter, or some extra design and development resources were available, could the Sea Hurricane's ditching problems have been addressed by modifying the radiator that was allegedly the main issue? I've seen pics of belly-landed Hurries that have lost the whole radiator - would it be possible to calculate the loads and reduce the fastenings so that in a ditching the whole radiator would come off under the impact, rather than turtle or sink the whole plane? Alternatively, would it be possible to fit some form of emergency device, similar to the cooling flap at the rear of the radiator, that would drop down and fair off the hole at the front of the radiator before ditching and therefore reduce the drag?

The RAE looked at various designs of flaps / fairings ahead of the radiator. Some success was noted in certain types of landings, but '... none of them were dependable to any useful extent.'

Removing the radiator from the equation was also investigated. The actual radiator required about 6,000 lb to tear off, and it was calculated that this needed to be brought down to about 800 lb to allow it to snap off. If was figured that a radiator jettison mechanism would have been impracticable in reality. Both cases were trialed in model tests and although the diving characteristic was alleviated, there was still a very severe deceleration on hitting the water.

Looking at the very good ditching characteristics of the Fulmar, they also looked at modifying the Hurricane's radiator setup to one similar to the Henley. Very positive results were achieved with this. The deceleration was much less severe and much more even, with no tendency to dive.

In order to help keep the nose up before hitting the water they also looked at towing drogues, water kits, and tail hydrofoils. They even tried with the landing gear down in various states.

The only real hope for a stock Hurricane was to hit the water as slow as possible with the nose as high as possible. A relatively safe speed and attitude was only possible either with engine power still available or a very strong wind.

To ThomasP's point, the RAE noted that they only concerned themselves with the effects of hitting the water and coming to a stop -- and not with anything afterwards (IE: filling with water and sinking). 'Rapid filling with water might well be the most important difficulty ...'.

 

[don4331]

If there was earlier consideration to using the Hurricane as a carrier fighter, or some extra design and development resources were available, could the Sea Hurricane's ditching problems have been addressed by modifying the radiator that was allegedly the main issue? I've seen pics of belly-landed Hurries that have lost the whole radiator - would it be possible to calculate the loads and reduce the fastenings so that in a ditching the whole radiator would come off under the impact, rather than turtle or sink the whole plane? Alternatively, would it be possible to fit some form of emergency device, similar to the cooling flap at the rear of the radiator, that would drop down and fair off the hole at the front of the radiator before ditching and therefore reduce the drag?

This is for an alt history I muse about, where a small country is replacing its Furies, Demons, Ospreys, Harts etc and because of its small size can effectively only run one single-seat fighter both on its carrier and on land and where the naval air arm forms a much larger proportion of the total a/c and therefore has more clout. It has been assembling and part-building Furies, Ospreys etc and some staff had been trained to modify existing designs.

On the same topic, while the Sea Hurrie has a bad rep for ditching has anyone looked at the actual survival rate and how it compares to that of comparable aircraft?

Thanks for any info

I think if you're focusing on ditching survival rates of the Hurricane, you're focusing on the wrong things.

A small country can't afford a carrier: pre-WWII, the only countries operating carriers were RN, USN and IJN. (yes NM had a carrier, but it wasn't really functioning). A floatplane carrier (HMAS Albatross or hybrid is more likely) Hurricane float plane was proposed - to work from Norwegian fjords; Blackburn delivered Roc floats to Hawker but the loss of Norway put paid on the proposal.

Playing into your alt-history: Your country has Furies and Harts (with the various variants of same). Hawker was willing to sell "kits"/ licensed production. On the other hand, England and RR are much tighter with engine. But P&W is looking for sales, and sells "kits"/licensed production. So, let's say your country has built/manufactured Wasps and your factory/design team has done the modification to install on the Hawker airframes (rather than the historic P&W Hornet).

Come '38, you are successful in negotiating plans/pattern aircraft for Hawker's Hurricane along with P&W's Twin Wasp R-2000 (as you're set up for 5.75" slugs). Sort of a reverse P-36 -> P40. Solves your ditching issue (somewhat) and issues when RR can't/won't deliver Merlins because the RAF needs everyone they can lay their hands on.

 

[Onslow]

The RAE looked at various designs of flaps / fairings ahead of the radiator. Some success was noted in certain types of landings, but '... none of them were dependable to any useful extent.'

Removing the radiator from the equation was also investigated. The actual radiator required about 6,000 lb to tear off, and it was calculated that this needed to be brought down to about 800 lb to allow it to snap off. If was figured that a radiator jettison mechanism would have been impracticable in reality. Both cases were trialed in model tests and although the diving characteristic was alleviated, there was still a very severe deceleration on hitting the water.

Looking at the very good ditching characteristics of the Fulmar, they also looked at modifying the Hurricane's radiator setup to one similar to the Henley. Very positive results were achieved with this. The deceleration was much less severe and much more even, with no tendency to dive.

In order to help keep the nose up before hitting the water they also looked at towing drogues, water kits, and tail hydrofoils. They even tried with the landing gear down in various states.

The only real hope for a stock Hurricane was to hit the water as slow as possible with the nose as high as possible. A relatively safe speed and attitude was only possible either with engine power still available or a very strong wind.

To ThomasP's point, the RAE noted that they only concerned themselves with the effects of hitting the water and coming to a stop -- and not with anything afterwards (IE: filling with water and sinking). 'Rapid filling with water might well be the most important difficulty ...'.

Fantastic information, thanks very much. Did they do much research to see whether the altered radiator position was viable in other ways?

 

[tomo pauk]

Looking at the very good ditching characteristics of the Fulmar, they also looked at modifying the Hurricane's radiator setup to one similar to the Henley. Very positive results were achieved with this. The deceleration was much less severe and much more even, with no tendency to dive.

Is there a photo of such Hurricane avilable?

Come '38, you are successful in negotiating plans/pattern aircraft for Hawker's Hurricane along with P&W's Twin Wasp R-2000 (as you're set up for 5.75" slugs). Sort of a reverse P-36 -> P40. Solves your ditching issue (somewhat) and issues when RR can't/won't deliver Merlins because the RAF needs everyone they can lay their hands on.

British are supposed to have the R-2000 five years before the Americans?

 

[don4331]

British are supposed to have the R-2000 five years before the Americans?

a. It's not British - its a small country who had been operating Hawker aircraft - Sweden, Norway, Spain, Portugal, Belgium, Egypt, Iran and a few others operated Furies and/or Harts.
b. The small country has enough money and engineering talent to build an aircraft carrier. WNT says no one can sell them one, so this has to be an in-country effort. If you can build a carrier, you can bore an engine give all the original engineering data.
c. To nitpick, the R-2000 had to run in '41 as the C-54 (well really DC-4) flew with 4 on 14/Feb/'42. And noting the Sea Hurricane didn't fly until January '41. Which would be less than a years between the Hooked Hurricane and the enlarged P&W. They can fly on kit R-1830s until the indigenous engines are ready.
d. The USA had 100 octane fuel so the need for the R-2000 was less (it was originally developed to provide the same power on 87 octane that the R-1830 did on 100).
e. P&W USA was focused on mass production of the R-1830, and the R-2800 was the next generation, again the need for a R-2000 was less (and none for R-2090 ie. both 5.75" bore & stroke).

 

[yulzari]

The Sea Hurricane (and obviously the standard Hurricane) radiator in ditching issue is that it turns the aeroplane over by forcing the nose deep into the water as it all hits the water at speed. If you got as far as benefiting from floatation bags it had already been a successful ditching.

My step daughter's grandfather was a Royal Navy CAM pilot who successfully ditched his Hurricane over the Channel (not from a CAM launch) so it clearly can be ditched. He was spotted by both German and British Air Sea Rescue boats and the German one got to him first. He was less than chuffed that the British boat then just went away and left him to be a POW. He felt that he was more in danger from the random strafing attacks of the Americans as the POWs at the end of the war were forced to walk away from the advancing Soviets. They all attacked anyone on roads.

 

[fannum]

I'm surprised that no one has mentioned the Hurricanes that were tested, to be rocket catapulted from cargo ships and non-carriers in convoys to intercept and dispatch Axis aircraft shadowing convoys and reporting positions. This was obviously a one-way mission, requiring bailout and hopefully swift pickup by the convoy. Around 35 merchant ships were modified, and around ten German aircraft intercepted and shot down. Several Hurricane pilots were killed attempting to bail out.

They were used on the Murmansk convoys, but were they used there? That was the acid test of the system.

It would be interesting if any ditching/survival results for Hurricanes were tabulated, as there must have been many. Was this a real problem, or just well circulated rumor?

 

[Onslow]

I think if you're focusing on ditching survival rates of the Hurricane, you're focusing on the wrong things.

A small country can't afford a carrier: pre-WWII, the only countries operating carriers were RN, USN and IJN. (yes NM had a carrier, but it wasn't really functioning). A floatplane carrier (HMAS Albatross or hybrid is more likely) Hurricane float plane was proposed - to work from Norwegian fjords; Blackburn delivered Roc floats to Hawker but the loss of Norway put paid on the proposal.

Playing into your alt-history: Your country has Furies and Harts (with the various variants of same). Hawker was willing to sell "kits"/ licensed production. On the other hand, England and RR are much tighter with engine. But P&W is looking for sales, and sells "kits"/licensed production. So, let's say your country has built/manufactured Wasps and your factory/design team has done the modification to install on the Hawker airframes (rather than the historic P&W Hornet).

Come '38, you are successful in negotiating plans/pattern aircraft for Hawker's Hurricane along with P&W's Twin Wasp R-2000 (as you're set up for 5.75" slugs). Sort of a reverse P-36 -> P40. Solves your ditching issue (somewhat) and issues when RR can't/won't deliver Merlins because the RAF needs everyone they can lay their hands on.

The Twin Wasp idea is very interesting, thanks. I hadn't considered it as I'm unsure of the design and setup work involved. I'll check up Curtis' experience doing the same swap in reverse.

But the idea of US engines brings to mind the Allison, which (without looking at the details) could perhaps fit more easily into the Hurri airframe. I'll check it out.

Yep, I know it's a tiny country but without going into too much detail, I'm using the same defence forces/population ratio as the contemporary UK - in fact part of the setup was that at the time of each of the interwar naval treaties the ATL country accepted exactly the same per-capita tonnage for each class as the UK. Secondly, like the other advanced South Pacific economies of NZ and Australia, the ATL country has had very high GDPs per capita. Some sources say that Australia had a higher GDP per capita than the USA for some of the '30s and in the WW1 era Australia was close to the USA in per capital GDP and comfortably ahead of the UK. So we're looking at a small but wealthy maritime nation that, like the UK for much of its history, looks to the navy for its defence and needs flexible forces.

By calculating GDP per capita budgets, Royal Navy and RAF purchase and operating cost (ie those given by Chatfield and to Inskip) and the WW2 forces of the UK, NZ and Australia and other factors I'm confident that the ATL nation could afford a small carrier, largely because it's not trying to raise anywhere near as many divisions as other countries because of its geographical location and history.

They do possess a few floatplanes, as you suggest.

 

[Onslow]

I'm surprised that no one has mentioned the Hurricanes that were tested, to be rocket catapulted from cargo ships and non-carriers in convoys to intercept and dispatch Axis aircraft shadowing convoys and reporting positions. This was obviously a one-way mission, requiring bailout and hopefully swift pickup by the convoy. Around 35 merchant ships were modified, and around ten German aircraft intercepted and shot down. Several Hurricane pilots were killed attempting to bail out.

They were used on the Murmansk convoys, but were they used there? That was the acid test of the system.

It would be interesting if any ditching/survival results for Hurricanes were tabulated, as there must have been many. Was this a real problem, or just well circulated rumor?

I've been going to go through the CAM ship launches for the very reason you propose, but haven't done it yet. There were only a few launches, but there were also plenty of Sea Hurrie actions during Pedestal, I think, that could give some data.

 

[R Leonard]

And a small point . . . the flotation bags on F4Fs were removed in the summer of 1941 after some rather disconcerting crashes resulting from their inflation during flight. VF-42, for example, lost one off Chick's Beach at the mouth of the Chesapeake and the pilot killed. Bags inflated and, bang, right into the water.

 

[MikeMeech]

I'm surprised that no one has mentioned the Hurricanes that were tested, to be rocket catapulted from cargo ships and non-carriers in convoys to intercept and dispatch Axis aircraft shadowing convoys and reporting positions. This was obviously a one-way mission, requiring bailout and hopefully swift pickup by the convoy. Around 35 merchant ships were modified, and around ten German aircraft intercepted and shot down. Several Hurricane pilots were killed attempting to bail out.

They were used on the Murmansk convoys, but were they used there? That was the acid test of the system.

It would be interesting if any ditching/survival results for Hurricanes were tabulated, as there must have been many. Was this a real problem, or just well circulated rumor?

Hi
According to Eric Brown ('Wings of the Navy, Flying Allied Carrier Aircraft of World War Two', page 110):
"The CAM ships, themselves, undertook 175 voyages averaging 2.600 nm (4,820 km) over a little more than two years. 12 of the 35 vessels involved being lost as a result of enemy action. During the period there was a total eight Hurricat operational launchings of which six resulted in the destruction of an enemy aircraft, and only one of the "Catafighter" pilots lost his life."

Mike

 

[don4331]

But the idea of US engines brings to mind the Allison, which (without looking at the details) could perhaps fit more easily into the Hurri airframe. I'll check it out.

The issue with Allison: Production doesn't really ramp up until '41...

Yep, I know it's a tiny country but without going into too much detail, I'm using the same defence forces/population ratio as the contemporary UK - in fact part of the setup was that at the time of each of the interwar naval treaties the ATL country accepted exactly the same per-capita tonnage for each class as the UK. Secondly, like the other advanced South Pacific economies of NZ and Australia, the ATL country has had very high GDPs per capita. Some sources say that Australia had a higher GDP per capita than the USA for some of the '30s and in the WW1 era Australia was close to the USA in per capital GDP and comfortably ahead of the UK. So we're looking at a small but wealthy maritime nation that, like the UK for much of its history, looks to the navy for its defence and needs flexible forces.

By calculating GDP per capita budgets, Royal Navy and RAF purchase and operating cost (ie those given by Chatfield and to Inskip) and the WW2 forces of the UK, NZ and Australia and other factors I'm confident that the ATL nation could afford a small carrier, largely because it's not trying to raise anywhere near as many divisions as other countries because of its geographical location and history.

You have to be careful with raw GDP numbers: The UK was historically making money buy selling manufactured goods in return for raw material. As a result, their manufacturing is extremely efficient. Which skews the numbers. Looking at it the other way, HMAS Albatross was designed to cost £ <400k, but cost £ >1.2M as built at Cockatoo. So, Australia would have needed 3X UK GDP to match (I know I'm cherry picking but you get the concept).

Remember NZ finally paid off HMS NZ in '44; 22 years after she was disposed of. (And NZ never had to pay for the crewing/maintenance and received "most preferred nation" rates on the loan).

I love a good what-if but IMHO, a good story is somewhat plausible. Which is why I was trying merely to comment about the carrier, while providing alternatives for your Sea Hurricane.

 

[Onslow]

The issue with Allison: Production doesn't really ramp up until '41...

You have to be careful with raw GDP numbers: The UK was historically making money buy selling manufactured goods in return for raw material. As a result, their manufacturing is extremely efficient. Which skews the numbers. Looking at it the other way, HMAS Albatross was designed to cost £ <400k, but cost £ >1.2M as built at Cockatoo. So, Australia would have needed 3X UK GDP to match (I know I'm cherry picking but you get the concept).

Remember NZ finally paid off HMS NZ in '44; 22 years after she was disposed of. (And NZ never had to pay for the crewing/maintenance and received "most preferred nation" rates on the loan).

I love a good what-if but IMHO, a good story is somewhat plausible. Which is why I was trying merely to comment about the carrier, while providing alternatives for your Sea Hurricane.

I thought Allison may have come in too late but US engine production is not something I'm familiar with at all. Thanks.

I understand the economies the UK had, but they also had some outdated yards and practises (as noted in Buxtons (?) "The battleship builders", D K Brown and other sources) as well. I can't find the detailed piece on the debate about building Albatross or the cruisers at Cockatoo but most papers of the time reported her quoted cost at 800k before construction, and the actual cost at 1.2m. The papers also indicate that it was believed the cruisers would cost 23% more if built at Cockatoo. Austtralian wages were higher and there was a big jump during Albatross' construction, but it also seems that the stop-start programmes imposed extra costs so a properly-scheduled long-running construction programme would have addressed the cost issue to a certain extent.. However, in this ATL the country has a longer history of shipbuilding, is in a joint venture with Vickers*, may get major ships built in the UK if desired, and is therefore almost certainly more efficient than Cockatoo if not up with the UK yards (or Vickers in Spain).

For some reason I can't find the detailed paper on the construction of Albatross, but

An 18,500 ton carrier along the lines of a slightly larger Unicorn (which cost 2.5 mill GBP with wartime inflation) with more power and 27.5 knots could come in at 3 million just before the war in capital cost. That's very conservative since Illustrious was 4 million. Such a ship would be halfway between the two carriers Chatfield gave annualised costs to the Australian government in 1938. That annualised coat would be about 750,000, including ship and aircraft repair and replacements, all pay, fuel, maintenance etc. For comparison, the RAF agreed that 44 bombers could be run for about the same amount. So the carrier is not cheap, but also arguably much better value than say 44 Blenheims or Whitleys, without a system of airports to operate from.

For comparison, Australia spent 97.2 million pounds on its contribution to the EATS up until March 1943. A nation of three million and a comparable per capita contribution to EATS would have spent about 40 million on EATS during that period. So instead of joining EATS, it could have bought and run two carriers each year for the same funds and had cash left over. Add to that the fact that the ATL nation has very little interest in the very expensive game of heavy bombers and is happy to run a comparatively small army*, and the sums seem to indicate that the cash would be there.

 

[Onslow]

a.
b. The small country has enough money and engineering talent to build an aircraft carrier. WNT says no one can sell them one, so this has to be an in-country effort. If you can build a carrier, you can bore an engine give all the original engineering data.

Article XV of the WNT is;

"No vessel of war constructed within the jurisdiction of any of the Contracting Powers for a non-Contracting Power shall exceed the limitations as to displacement and armament prescribed by the present Treaty for vessels of a similar type which may be constructed by or for any of the Contracting Powers; provided, however, that the displacement for aircraft carriers constructed for a non-Contracting Power shall in no case exceed 27,000 tons (27,432 metric tons) standard displacement."

So a Contracting Power can build a carrier for a non-party to the WNT as long as it's under 27,000 tons. Or, of course, it could be built in the country of ownership or in by Vickers/Amstrong etc in Spain, which was not a signatory to the WNT.

 

[Geoffrey Sinclair]

Australian Archives Series Number A5954 Control Symbol 1024/10 page 38, readable online, if you use control symbol 1024* a number of pre war documents come up and are available to read. See also pages 11 and 12 of A5954 1005/8 naval expenditure comparison between UK and Australia, 1928/29 and 1933/34

The British naval estimates bottomed out at around £50,200,000 in 1932/33 up to around £81,000,000 in 1936 and 1937.

Australian naval expenditure bottomed out at £1,444,000 in 1931/32, then by fiscal year £1,496,000, £1,646,000, £1,998,000, £2,371,000, £2,577,000 and £2,960,000 in 1937/38

Australia's defence spending in dollars, $2 = 1 pound. 1301.0 - Year Book Australia, 2001

Australia's actual aircraft carriers https://seapower.navy.gov.au/sites/default/files/2023-02/PIAMA04_0.pdf

As the table in A5954 1024/10 shows aircraft cost, for the same money as a battleship you can have 58.5 naval aircraft, a large cruiser 26.1 aircraft, small cruiser 17.6 aircraft, a destroyer 5.7 aircraft, the non aircraft part of a carrier capable of using 36 aircraft equals 41.7 naval aircraft. Assuming no other build, maintenance etc. costs Ark Royal with 72 aircraft would cost almost twice as much as Nelson per year over their lifetimes. Ark Royal would require almost all RAN expenditure per year in the 1930's. Triple that and it is two Ark Royals plus the actual 1939 RN.

Thanks to the way costs work depending on airbase costs you can have your mobile airbase and
15 aircraft, or land based about 150% more aircraft
36 aircraft, or land based about 100% more aircraft
72 aircraft, or land based about 50% more aircraft

As the US conclusively proved in WWII ships are complex enough you need to have a working industry that avoids one only construction, even then when it came to Liberty ships for the yards that built more than 50 costs per ship varied between $1,544,000 and $2,099,000, the yard that built 10 averaged $3,923,000 each, the yard that built 1 cost was $7,161,000

Australia is reported to have had the highest standard of living in the world end of the 1800's thanks to the gold rushes and wool, it then declined. It meant Australian wages tended to be higher than British and that feeds through to costs, similar for the higher US wages relative to Britain.

 

[don4331]

Article XV of the WNT is;

"No vessel of war constructed within the jurisdiction of any of the Contracting Powers for a non-Contracting Power shall exceed the limitations as to displacement and armament prescribed by the present Treaty for vessels of a similar type which may be constructed by or for any of the Contracting Powers; provided, however, that the displacement for aircraft carriers constructed for a non-Contracting Power shall in no case exceed 27,000 tons (27,432 metric tons) standard displacement."

So a Contracting Power can build a carrier for a non-party to the WNT as long as it's under 27,000 tons. Or, of course, it could be built in the country of ownership or in by Vickers/Amstrong etc in Spain, which was not a signatory to the WNT.

Article XVIII
Each of the Contracting Powers undertakes not to dispose by gift, sale or any mode of transfer of any vessel of war in such a manner that such vessel may become a vessel of war in the Navy of any foreign Power.

Which really overrides Article XV (one of the contractions of the treaty). And we will note that none of the contracting powers did build and cruiser/battleships/carrier for a non-contracted power.

Yes, Vickers/Armstrong/etc assisted in construction in Spain of cruisers, but we will also note, it took 8 years to build them. And Battleship/Aircraft Carriers are much more complex.

 

[Onslow]

Australian Archives Series Number A5954 Control Symbol 1024/10 page 38, readable online, if you use control symbol 1024* a number of pre war documents come up and are available to read. See also pages 11 and 12 of A5954 1005/8 naval expenditure comparison between UK and Australia, 1928/29 and 1933/34

The British naval estimates bottomed out at around £50,200,000 in 1932/33 up to around £81,000,000 in 1936 and 1937.

Australian naval expenditure bottomed out at £1,444,000 in 1931/32, then by fiscal year £1,496,000, £1,646,000, £1,998,000, £2,371,000, £2,577,000 and £2,960,000 in 1937/38

Australia's defence spending in dollars, $2 = 1 pound. 1301.0 - Year Book Australia, 2001

Australia's actual aircraft carriers https://seapower.navy.gov.au/sites/default/files/2023-02/PIAMA04_0.pdf

As the table in A5954 1024/10 shows aircraft cost, for the same money as a battleship you can have 58.5 naval aircraft, a large cruiser 26.1 aircraft, small cruiser 17.6 aircraft, a destroyer 5.7 aircraft, the non aircraft part of a carrier capable of using 36 aircraft equals 41.7 naval aircraft. Assuming no other build, maintenance etc. costs Ark Royal with 72 aircraft would cost almost twice as much as Nelson per year over their lifetimes. Ark Royal would require almost all RAN expenditure per year in the 1930's. Triple that and it is two Ark Royals plus the actual 1939 RN.

Thanks to the way costs work depending on airbase costs you can have your mobile airbase and
15 aircraft, or land based about 150% more aircraft
36 aircraft, or land based about 100% more aircraft
72 aircraft, or land based about 50% more aircraft

As the US conclusively proved in WWII ships are complex enough you need to have a working industry that avoids one only construction, even then when it came to Liberty ships for the yards that built more than 50 costs per ship varied between $1,544,000 and $2,099,000, the yard that built 10 averaged $3,923,000 each, the yard that built 1 cost was $7,161,000

Australia is reported to have had the highest standard of living in the world end of the 1800's thanks to the gold rushes and wool, it then declined. It meant Australian wages tended to be higher than British and that feeds through to costs, similar for the higher US wages relative to Britain.

The page you gave in the image is the Chatfield information I'm going off, and mentioned earlier.

I agree that you need a shipbuilding industry that avoids stop-start construction; that is arguably one reason why Albatross cost so much. Tradesmen were laid off while waiting for it to start and therefore had to be re-hired later. While I'm not sure whether a carrier would be built (or partly built) in country because of its complexity, the countr's shipyards would be be running a continuous stream of escorts, rebuilds, support vessels and some merchant vessels to maintain its workforce and therefore if a carrier was built or partly built there, it could be done more efficiently than was the case at Cockatoo.

For a small island nation west of New Caledonia and with some outlying possessions, I think the flexibility of a carrier would be more valuable than 36 extra aircraft (or 44 twin engined aircraft if going off the RN/RAF agreed facts at the CID) sitting on one location. Higham's "Bases for air power" notes that the cost of a bomber field was about

Extensions alone to Fighter Command fields in one year (1943) alone cost as much as a new fleet carrier and runways, hardstands and taxiways for each bomber field coat about 1.1 million pounds. So by the time one gives one's 40 or so extra land-based aircraft some decent mobility by building a network of bases, ignoring the issues of ground crew, fuel and armamant and airfield buildings, the carrier looks like pretty fair value, apart from the fact that without a carrier any naval forces are going to be at a major disadvantage against an IJN detachment as minor as a few 8" cruisers and Hosho or Ryujo and therefore the entire nation's reach is largely restricted to about 150m off the coast where there is a convenient airfbase.

Australia and NZ both had high wages, but as far I understand that is compensated to a considerable degree by the fact that the higher GDP per capital can finance more defence than if the wages were lower. Australia was hit heavily war debts of 50% of GDP, by the Depression and the need to pay back loans such as the 30 million GBP that the state of NSW alone had spent around the early '30s on Sydney urban transport. Another country could have reduced or avoided many debts of that sort.

The vast sums spent on the EATS seem to indicate a lot of money that was available to be spent elsewhere. NZ spent about 21.5 million on EATS and had a smaller population at the time than "ATL-land", so even if "Atland" spent half as much as NZ on the EATS then the savings could pay for a carrier and more.

So in general while fully recognising the cost of a carrier, and the problems of being a smaller nation, a carrier could be afforded by either cutting back on ground forces or simply by not joining the EATS or halving a nation's pro-rata contribution.

One thing I have been looking for is a comparison cost for running army formations compared to naval and air force ones. Do you know of any sources from the CID or elsewhere? If I even try to roughly calculate costs it seems that the pay cost alone of a single division makes the other arms look like good value!