Italian Carrier Aircraft

[Darthtabby]

Here's a good page that covers the Aquila, the Italian carrier design process and the R2001 in detail (including carrying torpedoes).

Aircraft carrier Aquila

Naval Encyclopedia has lots of interesting info that often isn't included in other sources, but I don't 100% trust it. I don't have access to all the sources it cites, but I'll note this segment from the the Quora Write Up it cites.

The storage of aircraft in the Roma was actually rather high-capacity for a conversion. Aircraft could not only be carried on the flight deck and soil of the hangard, but could also be suspended to the hangar's ceilling to make use of as much space as possible. The aircraft which was adapted to be used in the Aquila was Reggiane's Re.2001 fighter, a rather slow but smaller and more robust fighter in comparison to the Macchi C.202; 51 of the first carrier model, the Re.2001OR, could be operated from the Aquila, with 10 sitting on the deck and the rest in the hangar; if a folding wing model of the Re.2001 could be produced, the number of aircrafts used could be risen to 66, and all could be stored within the hangar when needed. The Fiat G.50 has also been considered as a carrier fighter, but the Re.2001 offered superior armament (two 12.7mm and two 7.7mm on the Reggiane, just the two 12.7mm on the G.50) and performance. It was reportedly even better than the German Bf 109T; a German delegation arrived in Italy in March of 1943 to help train the fighter group that was to be operated from the Aquila on carrier operation, and reportedly reported that the Re.2001 had more potential than the Messer for carrier operation. It could also be modified into a decent naval fighter-bomber (Re.2001GV), and a torpedo bomber model, the Re.2001G, was in trials by September of 1943.

The mention of the fighter bomber and torpedo bomber variants in that paragraph seems like an aside/afterthought, and most of what I've read on the Re.2001 leads me to believe the G and G/V models were strictly land based and built in small numbers (three G/Vs and one G). They didn't have tail hooks, which the Quora response even directly pointed out in the caption of a photo depicting a G model.

The Re.2001G prototype, modified to fit a 600kg torpedo under the fuselage and featuring a raised tailwheel. It did not have an arrestor hook and was therefore not adapted to carrier operation, though it is not inimiginable that a torpedo-bomber Re.2001 may be able to be fitted with a tail hook.

Again, I have my suspicion that people have attributed the capabilities of highly specialized land based Re.2001 variants to the navalized Re.2001 variant Aquila was intended to carry. As far as I can tell most Re.2001s carried bombs of 250kg or less if they were equipped to carry bombs at all.

The Italians desperately need folding wing. Instead of 27 fighters Aquila could have a CAG of 40 plus. Though will the "usually" calm Mediterranean weather, deck parking would be more feasible.

View attachment 634418

I've seen much larger air wing figures attributed to Aquila, so maybe they did intend to use a deck park? While I don't 100% trust Naval Encyclopedia its article on Aquila states that "The hangar measured 160 by 18 meters, initially large enough to house only 26 planes" which suggests the hangar may have been expanded. Alternately perhaps when it says 41 in the hangar and 15 suspended from the roof later in the article what it really should say is 41 including 15 suspended from the roof to save space since 26+15=41. Add the ten aircraft on deck and you have the 51 planes commonly attributed to Aquila. Alternately 41+15 suspended on the roof + 10 on deck would match the figure of 66 planes I've seen associated with a notional folding wing variant.

 

[MikeMeech]

Naval Encyclopedia has lots of interesting info that often isn't included in other sources, but I don't 100% trust it. I don't have access to all the sources it cites, but I'll note this segment from the the Quora Write Up it cites.



The mention of the fighter bomber and torpedo bomber variants in that paragraph seems like an aside/afterthought, and most of what I've read on the Re.2001 leads me to believe the G and G/V models were strictly land based and built in small numbers (three G/Vs and one G). They didn't have tail hooks, which the Quora response even directly pointed out in the caption of a photo depicting a G model.



Again, I have my suspicion that people have attributed the capabilities of highly specialized land based Re.2001 variants to the navalized Re.2001 variant Aquila was intended to carry. As far as I can tell most Re.2001s carried bombs of 250kg or less if they were equipped to carry bombs at all.



I've seen much larger air wing figures attributed to Aquila, so maybe they did intend to use a deck park? While I don't 100% trust Naval Encyclopedia its article on Aquila states that "The hangar measured 160 by 18 meters, initially large enough to house only 26 planes" which suggests the hangar may have been expanded. Alternately perhaps when it says 41 in the hangar and 15 suspended from the roof later in the article what it really should say is 41 including 15 suspended from the roof to save space since 26+15=41. Add the ten aircraft on deck and you have the 51 planes commonly attributed to Aquila. Alternately 41+15 suspended on the roof + 10 on deck would match the figure of 66 planes I've seen associated with a notional folding wing variant.

Hi
Numbers of aircraft to be carried by the Aquila vary in different sources, probably because it never went into service and therefore rather speculative. Details from 'Aircraft Carriers of the World, 1914 to the present' (1992 edition of 1984 original) by Roger Chesneau, page 153:

And pages 290-291 of 'Conway's All the Worlds Fighting Ships 1922-1946' (1980) Editorial Director Robert Gardiner and Editor Roger Chesneau (it appears his earlier work differs from his later work reference aircraft numbers, change of mind?):

Mike

 

[Schweik]

Exactly right, as simplistic as that sounds. Italy was a threat from the sea, not the air. The Luftwaffe's presence was entirely unexpected over the Med (I believe the Germans couldn't believe their luck when they succeeded in invading Western Europe so quickly) and German intervention in North Africa was a response to Italy getting its backside kicked by the British Army and RAF.

The Italians certainly didn't have any fighters in service at the outbreak of war that was better than the Gladiators based in Malta in 1939 (it did have a few Fiat G.50s, but not many in 1939) that could reach its carriers at sea and it had the Fulmar entering service on those. Why would the British expect anything else?

I think you might be overstating that. What about the Fiat G.50? MC. 200 was coming online too. Both a lot better than a Gladiator.

 

[Schweik]

Hi
Numbers of aircraft to be carried by the Aquila vary in different sources, probably because it never went into service and therefore rather speculative. Details from 'Aircraft Carriers of the World, 1914 to the present' (1992 edition of 1984 original) by Roger Chesneau, page 153:
View attachment 634454
And pages 290-291 of 'Conway's All the Worlds Fighting Ships 1922-1946' (1980) Editorial Director Robert Gardiner and Editor Roger Chesneau (it appears his earlier work differs from his later work reference aircraft numbers, change of mind?):
View attachment 634455
View attachment 634456

Mike

Neat! Wasn't the big problem with the Italian fleet in general the lack of fuel?

 

[Schweik]

Yes it was, but at what power levels?
The mid 30s R-1830 engines gave about 950hp for take-off and were limited to 2550rpm.
By 1938-39 they were turning 2700rpm.
An early R-1830 weighed about 1235lbs.
The early R-1830 engines made a fair amount of power at sea level but they used small superchargers and had FTH well under 10,000ft. Great for getting transport planes out of small airfields and cruising at heights that passengers would be comfortable without oxygen. Not so good for a fighter intended to operate at over 10,000ft.

I think this is pretty misleading. Obviously the R-1830 could and did scale up to higher altitude (2 stage) version (see R-1830-76 and 86 on the F4F). They even had a turbocharged version on the P-43. You are implying it could only be made in low-altitude version for some reason.

R-1830 seems like it would have been a good choice, it started out better than the Mercury with the potential to get a lot better. The only problem would have been Nationalist or the administrative logistics of arranging a production license (and / or shipping engines over).

 

[nuuumannn]

I think you might be overstating that. What about the Fiat G.50? MC. 200 was coming online too. Both a lot better than a Gladiator.

Not overstating the situation at all. Better than a Gladiator they might have been, but if they were not in use, that makes the Gladiator's rival the CR.42. The G.50 was available in very small numbers only, we are talking a handful, the first unit was still working up to serviceability and was in no way ready for combat operations in 1939. The MC.200 was the same and entered service with a unit in North Africa first, again in very small numbers, but it was not looked on very well by the pilots, so they actually re-equipped with Fiat CR.42s again. In 1940 when the Italians began attacking Malta with their bombers, the Gladiators and Hurricanes were able to match them because they had no fighter escort, despite both types being in service for a year or so, in fact, the first SM.79 shot down over Malta was by a Gladiator.

Over Britain in late 1940 the Fiat G.50 was available, but again in much smaller numbers, double figures only in total service with the RA, whereas the CR.42 was the most numerous fighter in RA service with over 200 available. It's worth noting that the MC.200 was not used in Belgium at all, despite its performance.

 

[nuuumannn]

Grant, that's the stern.

Oh good, thanks for that. It is deceiving because it is so narrow.

 

[GrauGeist]

Oh good, thanks for that. It is deceiving because it is so narrow.

I agree.
It appears to have been built up from the original design, eliminating that classic raised "fantail" style that passenger liners used back in the early 20th century.

Here's an image that shows the SS Roma's stern:

 

[Schweik]

Not overstating the situation at all. Better than a Gladiator they might have been, but if they were not in use, that makes the Gladiator's rival the CR.42. The G.50 was available in very small numbers only, we are talking a handful, the first unit was still working up to serviceability and was in no way ready for combat operations in 1939. The MC.200 was the same and entered service with a unit in North Africa first, again in very small numbers, but it was not looked on very well by the pilots, so they actually re-equipped with Fiat CR.42s again. In 1940 when the Italians began attacking Malta with their bombers, the Gladiators and Hurricanes were able to match them because they had no fighter escort, despite both types being in service for a year or so, in fact, the first SM.79 shot down over Malta was by a Gladiator.

Over Britain in late 1940 the Fiat G.50 was available, but again in much smaller numbers, double figures only in total service with the RA, whereas the CR.42 was the most numerous fighter in RA service with over 200 available. It's worth noting that the MC.200 was not used in Belgium at all, despite its performance.

Well, the context of the discussion was British war planning, right? Or did I miss something? And you said that the Italians didn't have anything which would outclass the Gladiators based on Malta in 1939.

In that case, it doesn't really matter that much that only a few G.50s and MC 200s were deployed in 1939 or how fast they were being produced, (there weren't that many Gladiators on Malta either). The issue is more that they were there and they clearly outclassed the Gladiator (as the British were to learn in North Africa once MC.200s started arriving in significant numbers). So on a Strategic level, they actually did need something better than a Gladiator (or for that matter a Skua, a Roc, or a Fulmar) and they should have been able to extrapolate that need based on the extant enemy fighters which were already flying. G.50 was flying since 1938.

Also, given the fact that Germany and Italy were already very chummy in 1939, had fought together in Spain from 1936, specifically had fought with and developed their aircraft and air combat tactics in Spain. So I don't think it's a huge stretch to expect (and plan for) German aircraft to be flying from Italian bases in say, Sicily or Sardinia.

The fact that fighters in general at that time tended to have very short range was lucky for the RAF and RN, because it meant that a lot of the bomber raids were unescorted, at least initially.

 

[Shortround6]

I think this is pretty misleading. Obviously the R-1830 could and did scale up to higher altitude (2 stage) version (see R-1830-76 and 86 on the F4F). They even had a turbocharged version on the P-43. You are implying it could only be made in low-altitude version for some reason.

R-1830 seems like it would have been a good choice, it started out better than the Mercury with the potential to get a lot better. The only problem would have been Nationalist or the administrative logistics of arranging a production license (and / or shipping engines over).

Sorry if I rained on your parade.
I was trying to show what was available from the US engine makers in 1937-38 when the decision to make the F.5/34 would have to be made.
The First production Gladiator was accepted by the RAF in Feb 1937. The 830-840hp at 14,000ft Mercury was in production in 1937. Bristol got caught up in the sleeve valve cool-aid fest and didn't put much research and development into the Mercury.

The power levels I gave for the American radials was pretty typical of what could be expected in 1937-38. The high altitude engines came later.
There were 2 two stage R-1830s at the US army fighter trials in Jan 1939 and they did not quite reach the power levels of the -76 engine. Not to mention that the 7th production R-1830-76 was not built until Aug of 1940.

The use of the P-43 is a bit misleading itself.
While the YP-43s were ordered in March of 1939 the first were not delivered until Sept 1940. They used R-1830-35 engines.
The Army ordered 54 P-43s in Oct 1940 with R-1830-47 engines. Which was followed by the P-43A (80 ordered) with R-1830-49 engines. First ones delivered in Sept of 1941.
A bit before that the US ordered 125 P-43As in June of 1941 using R-1830-57 engines for lend lease to China. Last ones were delivered in March of 1942.
It was only the -49 and -57 engines that could deliver 1200hp at 25,000ft.
Including the prototype at the Jan 1939 fighter trials the P-43 went though 5 different R-1830s and quite likely more than one different version of turbocharger let alone other details in the powerplant. The Army was none too happy with the turbo controllers in use at this time (designed by the army and not P & W or GE)

The R-1830 also gained several hundred pounds between the low powered/low altitude versions I gave and the later versions offering 1200hp for take-off.


Now if you think the British should have adopted and tooled up for an aircraft on the basis of what the Americans might be able to offer in an engine 2-4 years in the future , that may be a different discussion.

BTW, Wiki is wrong in the Gloster F.5/34 entry or gives a wrong impression.
"The Perseus was still under development and although it was expected - accurately - that the sleeve valve powerplant proffered much greater potential horsepower, the more conventional Mercury was deemed acceptable for the purposes of developing the prototype airframe, with a view to restoring the Perseus in the production version."

The much greater potential horsepower never materialized. They did get a Perseus (Mark X) up to 880hp at 15,500ft but if an additional 40hp ten percent higher in altitude is "Much greater" then somebody has some pretty low standards.

 

[Schweik]

You didn't rain on my parade, you are just doing your usual bit of trying to shut down lines of discussion for reasons I won't speculate on. The original context of this was "what engine could they have put in a Bristol 146", which got inferior performance to the Gloster F.5 on the same (Mercury) engine. I was idly speculating as to what kind of other engine they could have used. A Taurus maybe? And R-1830? You wrote:

"The Taurus XVI was rated at 1130hp at 3500ft at 3100rpm at 4.75lbs boost using 100/130 fuel.
One might estimate a bit over 800hp at 14,000ft from that and the only advantage the Taurus has is smaller diameter.
It never got a two speed supercharger.

The Japanese Zuisei engine was 1702 cu in (9.8% larger than the Taurus) the Japanese only used it to power the first two A6M prototypes before changing engines to the Sakae.
It was used in other aircraft.
The engine used in the Brewster Buffalo was 19.7% bigger in displacement than Mercury/Perseus.

The British simply have no path forward for a radial engine fighter in the late 30s no matter how well some of the prototypes performed.

Obviously, when planning for future aircraft development, there is always a certain amount of guesswork involved. Engine development was often disappointing, took longer than expected, ran into problems, ran into impassable dead ends. I don't think, however, that your bolded statement above holds water. Obviously they did have a path forward if they wanted to, but they chose to go with the Merlins at least initially because those were performing quite nicely and better than their radials. And maybe for other reasons. In the long run as we know the British developed both air cooled and liquid cooled engines for their fighters. Whether the Bristol Hercules or Centaurus lived up to the 'sleeve valve hype', they did become effective engines, albeit probably too big for the Bristol 146.

But probably not too big fir any radial engine fighter. The Hercules available in 1939 was already producing 1290 hp.

There is no reason, IMO, to assume they couldn't use American engines. The US sent plenty of engines to Britain. Engines were being lent (license built etc.) from both the US and Britain, and from wherever you want to put the epicenter of Hispano Suiza, to half of the developed world. It might be hard to predict that it was possible to develop a two stage or two speed supercharger for certain engines, but there were certainly many options, and it was obvious that ~840 hp wasn't the upper limit.

The P-43 is a bit of an outlier, since it used a turbo, but the two stage engine for the Wildcat came fairly early.

 

[Graeme]

Ease of storage and transportation.

Nice example of that here - for £595 you can own a Moth in 1925 and tow it from garage to airfield.

 

[MikeMeech]

The fact was, there was no need for them to ever do so. The concepts you are thinking of didn't exist back in the day. Carrier aircraft were for either attacking ships with torpedoes or bombs, fleet reconnaissance or shooting down enemy recon aircraft or bombers out at sea threatening the fleet. Attacking ground targets from the air was either the RAF's job or in a naval context what big guns were for. Naval air was not responsible for attacking land targets (other than dockyard facilities, cos it's the navy and ships, 'n stuff).

Joint operations came via WW2, very rarely beforehand and each of the services in peacetime had their own agendas. This is why that quaint British term "Army Co-operation" comprised of Westland Lysanders and Hawker Hart variants carrying teensy bombs flying straight and level over a target area at height. Close support was a very different beast to what it became as a result of WW2 or even what it had been during the Great War.

Hi
Why do you think that "Army Co-operation" is a 'quaint' term? It is descriptive of what the aircraft in army co-operation squadrons were involved in doing up to the beginning of WW2. This involved artillery spotting, tactical reconnaissance (close and medium recce, with and without cameras), liaison (flying staff and documents around), inter-communications including message pick-up, ground attack (along with fighters) and supply dropping. Indeed in 1940 we see the Hawker Hectors of 613 Sqn. 'dive-bombing' German forces around Calais and dropping supplies to the allied garrison. These AC squadrons basically were undertaking the roles of the Corps squadrons on WW1. During WW2 the various roles were split amongst different types of aircraft (the bigger wartime budgets helped in this specialisation), for example light aircraft such as the Auster undertook artillery spotting (although some fighters also were involved in this task in certain circumstances), liaison and inter-communication. Larger transports were used for aerial re-supply. Fighter reconnaissance aircraft (eg Mustang I) undertook tactical photo reconnaissance, and fighters also undertook both Close Air Support and Armed Reconnaissance (Typhoon, Tempest, Spitfire etc) . All this was classed as 'Air Support' ( hence AP 3235 'Air Support' that gives the WW2 RAF history of these tasks) for the ground forces during WW2, 'Close Support' would only cover part of this so, in my opinion, the term Army Co-operation could be seen as less "quaint" to use than close support.

Mike

 

[Shortround6]

for

Obviously, when planning for future aircraft development, there is always a certain amount of guesswork involved. Engine development was often disappointing, took longer than expected, ran into problems, ran into impassable dead ends. I don't think, however, that your bolded statement above holds water. Obviously they did have a path forward if they wanted to, but they chose to go with the Merlins at least initially because those were performing quite nicely and better than their radials. And maybe for other reasons. In the long run as we know the British developed both air cooled and liquid cooled engines for their fighters. Whether the Bristol Hercules or Centaurus lived up to the 'sleeve valve hype', they did become effective engines, albeit probably too big for the Bristol 146.

But probably not too big fir any radial engine fighter. The Hercules available in 1939 was already producing 1290 hp.

There is no reason, IMO, to assume they couldn't use American engines. The US sent plenty of engines to Britain. Engines were being lent (license built etc.) from both the US and Britain, and from wherever you want to put the epicenter of Hispano Suiza, to half of the developed world. It might be hard to predict that it was possible to develop a two stage or two speed supercharger for certain engines, but there were certainly many options, and it was obvious that ~840 hp wasn't the upper limit.

The P-43 is a bit of an outlier, since it used a turbo, but the two stage engine for the Wildcat came fairly early.

Ok, what path forward did Britain have in 1937-38 for a useable radial engine fighter using a British engine that would arrive in time to do anything in the first few years of the war?
Like by even the end of 1941.

Now as far as foreign engines go there are several problems.
As I tried to point out above, without using Mr. Peabody's wayback machine The American radials don't offer much over the Bristol Mercury for a fighter engine in 1937-38, They get better latter while the Mercury stagnates as Bristol tries to sort out the sleeve valve engines.

If the US won't export the turbo until late summer of 1940 why do you think they would do so earlier?
The Hispano is a red herring, Buying early 30s (or 1920s?) technology didn't prepare anybody for WW II.

I tried to show that the P & W two stage supercharger wasn't ready at the time. As far as the British using it, why bother, especially after Hooker is working at RR.
The R-1830 two stage engines needed two stages and intercoolers to do what RR was doing with a single stage in 1940.
Unless you had designed a fairly fat fighter plane the two stage R-1830 was not a drop in conversion. You need 10-15 cubic feet of space for the supercharger, the intercoolers and most importantly the ducts leading the air to and from the inlets and the different components/stages.
Would the US allow the exportation of the mechanical two stage engines before the war or in the first year?
The Martlet II & III got two speed single stage R-1830s.
The Martlet I & IV got two speed single stage R-1820s
The Martlet V got the 2 stage superchargers. But the Martlet V doesn't show up until the end of 1942.

US superchargers were pretty poor specimens in the late 30s. P & W and Wright were both divorcing themselves from buying GE designs and starting inhouse supercharger development. They got there, it just took a while. Most other countries weren't any better.

Yes the Hercules was making 1290hp in 1939, But it was a lousy engine to use in a fighter in it's 1938-40 form.
That was take-off power (a very lousy way to compare engines) and it's max power was actually 1375hp.
But that was at 4,000ft. Now subtract 2% for every 1000ft above that you want to fly.
1100hp at 14,000ft isn't that impressive for an 1800lb engine. It won't get better with 100 octane unless you redesign or at least re-gear the supercharger.
I will assume, for the sake of argument, that the Hercules could have been fitted with an up draft carb so you don't have the honking big airscoop right in front of the pilots windscreen.

The British certainly sketched out a number of proposals using Taurus and Hercules engines in single engine aircraft and fighters. None came to anything, mainly because of other work but the historical path/outcome of the histories of the Taurus and Hercules do not indicate a rosy picture for a single engine fighter using either one in the early part of the war.
Bristol did eventually turn the Hercules into a reliable, long lasting engine that made good power. It just took an awful lot of work.

 

[Schweik]

1375 hp at 4,000 ft and 1100 hp at 14,000 ft, with room to improve- is a lot better than what the Mercury was making. It is a lot heavier, granted. But fighters did tend to get a lot heavier from 1936-45.

The low altitude Martlets going to the FAA were not necessarily due to the original export restrictions, from what I understand, but were also in line with the FAA's only preferences for low-altitude optimized aircraft. British made naval aircraft like the Fulmar, Firefly, Barracuda, Skua, Roc were also made with engines that peaked at low or relatively low alttidue. From the FAA's point of view, chasing U-boats, SM.79s and FW 200s didn't require very high altitude flying. If UK really wanted F4F-3 type engines they could have had them IMO.

And a two speed engine will still probably get you decent performance at your specified 14,000 ft.. Better than the Mercury.

New engines (especially bigger ones) might not just drop into small aircraft like the Bristol 147, but that is a far cry from saying that the British had no path forward for air cooled engine fighters. Probably more accurate to say they had more promising liquid cooled engines.

As for Hispano Suiza, their 12Y was the basis for the Soviet Klimov M-105 engines (used in the Yak fighters), and it and the Gnome Rhone Mistral series were the powerplants for the engines of many aircraft of smaller nations around the world (including powerplants for the Romanian IAR 80, the Italian Re 2000, CANT Z.1007, Sm 84 etc., and the Soviet Il-4 and SU-2 bombers).

For that matter the Bristol mercury and other British types, and the R-1820 / 1830 were also the basis of several foreign engines for fairly important aircraft.

 

[Shortround6]

The Martlet I's were ex French aircraft. Ordered in Oct 1939.
The Martlet IIs were British ordered with single stage R-1830s
During 1940 and 41 the US took delivery of 65 F4F-3A aircraft with single stage superchargers due to low production of two stage engines.
P & W only built 98 two stage engines in 1940
The R-1820 engines in the Martlet I's were good for 1000hp at 13,500ft in high gear and weighed 1315lbs
The R-1830 engines in the Martlet II's were good for 1000hp at 14,500ft in high gear and weighed 1495lbs.

The US engines used the 2nd speed to boost take-off/low altitude performance. The 1830 in the Martlet II being good for 1200hp to just under 5000ft for example.

I would also note (as I have before) that the R-1820 went through 3 complete and total redesigns between the engine used in the early Buffaloes and the engine used in the Grumman FM-2 (Wildcat VI) for four different versions, versions in this case referring to the basic construction, like crankcase and crankshaft and cylinder design. Changes in reudcution gear ratio, supercharger gears, different carbs or magnetos not counted.

Yes better than the Mercury but hardly dominating performance.
None of these radials made much use (or any) of exhaust thrust at this point in time. British radial cowlings were poor, US cowlings were better but still nowhere near what they would be latter.

The 840hp Mercury was good for 725hp for take-off. Much like the Merlin III was good for 1030hp at 16,250ft but only rated at 880hp for take-off.
The 880hp Perseus was good for 750hp for take-off.
The FAA for some reason rarely got 2 speed engines (early in the war) so they had to get engines that gave enough take-off power which then limited altitude performance.
Engine in the Skua being good for 905hp at 6,500ft but gave 850hp for take-off.
Perhaps Bomber Command was sucking up all the two speed Pegasus engines?

The no path forward with British engines is because the Taurus, unknown at the time, was a dead end for several reasons and the Hercules was just a bit too big to put in anything designed for a Mercury or Perseus and too small to give enough power to be competitive for much of the war even if given a special airframe. It was about 92% of the size of the BMW 801. It took until the MK VI to be a competitive engine.
Sleeve valve engines seemed to have trouble using higher boost when better fuel became available.
In May of 1942 there is a test of Beaufighter in which they measure the performance difference going from 7lbs boost to 8lbs boost for high speed and from 5lbs boost to 6lbs boost (both at 2400rpm) for climb. No filling the tank with 100 octane and cranking the boost limit screw from 6lbs to 12 lbs or from 9lbs to 14lbs like on the Merlins.

The French had a reputation they didn't deserve in the 1930s. The M-105 gained several hundred pounds over the parent H-S engines and even reduced the bore by 2mm to help beef things up. The Gnome Rhone Mistral series was another engine that crashed into a development wall. There is only so much you can do with a 14 cylinder 2 row radial with no bearing on the crankshaft between the rows. Just ask Armstrong Siddeley.

 

[Schweik]

Well, for an abject failure, the Gnome Rhône Mistral powered a lot of aircraft, some of them pretty successful ones: IAR 80, SM 79, Cant Z.1007, PZL 24, Re 2000, Su-2, IL-4. Maybe not the best aircraft of the war, but hardly the worst either.

Gnome-Rhône Mistral Major - Wikipedia

en.wikipedia.org

As for the 12Y and the M-105, sure they hacked it - that is one of the traits of good designs- they lend themselves to hacks! And some quie good planes came out of it. Dewoitine D.520, Bloch MB 170, Latecoire 298, Pe-2, Pe-8, Yak-1, Yak 7, Yak 9 etc. I'd call that one of the more successful engine designs of the war.

Hispano-Suiza 12Y - Wikipedia

en.wikipedia.org

And lets not forget, they came up with some not perfect, but highly influential cannon designs too, right?

Also, I'm not sure you can call Hispano-Suiza precisely a French company.

 

[Schweik]

The Wright R-1820 was of course the basis for the Shvestov ASh-82 of Lavochkin La 5 fame...

 

[Skua]

Very interesting information on a possible Italian carrier; plus the radar/Fulmar experiments, thanks.
Oh...I am glad that, like me, a few people like the Buffalo.....

 

[Shortround6]

Well, for an abject failure, the Gnome Rhône Mistral powered a lot of aircraft, some of them pretty successful ones: IAR 80, SM 79, Cant Z.1007, PZL 24, Re 2000, Su-2, IL-4. Maybe not the best aircraft of the war, but hardly the worst either.

The war ended in 1945, ALL of those aircraft would have been little more than targets in the last 1/2 of the war. With a war lasting nearly six years picking best and worsts gets difficult.
There were basically 3 Gnome Rhône Mistrals

The K, which wide licensing from the early 30s on and which powered most of the non-French aircraft. Sometimes it was developed somewhat in the various countries.

However, from Wiki
"IAR realized that the Mistral Major was at the limits of its development potential even by the middle of 1941."

The Russians never got more that 1100hp from the M-88 which was a developed version of the K.
The N, coming into service in 1938-30, Pretty much used by the French in the Bloch 152 and other newer French aircraft.
Got to around 1180hp.
The R, used in one or more prototypes in 1940, failed as a post war commercial engine. It got the center bearing and weight went up several hundred pounds.
The Mistral Major was a useful engine in the 30s, it had no future in the 1940s or after 1940-41 for most nations.

As for the 12Y and the M-105, sure they hacked it - that is one of the traits of good designs- they lend themselves to hacks! And some quie good planes came out of it. Dewoitine D.520, Bloch MB 170, Latecoire 298, Pe-2, Pe-8, Yak-1, Yak 7, Yak 9 etc. I'd call that one of the more successful engine designs of the war.

Well, the Ford flathead V-8 lent itself to all kinds of hacks. Didn't stop the design from being toast when the small block Chevy came out. And by the way, strengthing the weakest pieces, increasing the boost and accepting shorter service/over

The Russians were not happy with the 12Y when they bought it in 1933-34 and it required a number of modifications to meet Soviet standards. Having the crankshaft break 11 hours into a 100 hour test was not a good start. The engine went from 966lbs to 1047lbs by the time all the modifications were done. Some of the modifications had been incorporated in the license built Czech engines.
At this point in time the French-Soviet relations were pretty good, It was assumed that the production technology of the French engines was closer to Soviet industrial capability than British engines. The Drawings were already metric and the Soviets had already dealt with the French when they licensed the G-R 9A which became the M-22. All of these were considerations when evaluating a license deal, not just the technical merits of the engine itself. And in 1933 there were few competing engines.

You are also confusing the engine with the aircraft. Were those planes successful because of the 12Y (and derivatives) or in spite of the 12Y?
BTW the PE-8 only used a single M-100 engine (early Russian built 12Y) in the fuselage to power a supercharger which supplied air to the four engines out in the wings which were
Mikulin AM-34FRN's, only the first four planes built had this arrangement.

Soviets were working on two highly modified 12Y designs before the German invasion, the M-106 and the M-107. The M-106 didn't go very far and the M-107 was still giving problems post war.
Russians limited the armament of some of their aircraft in order to keep up performance with lower powered than desired engines.

The Wright R-1820 was of course the basis for the Shvestov ASh-82 of Lavochkin La 5 fame...

In a rather convoluted way you are correct.

However the path went from the R-1820-F3 of 1933 (712hp at 1950rpm for take off and a weight of 1050lbs) through the licensed copy M-25 (during 1935 the Russians were using US valve springs, piston rings and bearings) to the M-62 which used a two speed supercharger based on the R-1820-G103 and on to the M-63 9 cylinder radial. Then came the M-80 a 14 cylinder engine using the same cylinders as the M-25 which was followed by the M-81 which a lot of parts from the M-63 and finally the M-82 (ASh-82) showed up using a shorter stroke. Russians also tried to build 18 cylinder engines using the same cylinders. That went through four versions (the last used the short cylinders).

However trying to take a R-1820-F3 and modify it to make 1200hp is quite an undertaking. The story has been told before. It also took 7-8 years. Where you pick to use it in it's development arc may require quite the crystal ball to predict where it would end up, 1350hp for take off in later FM-2s and 1525hp post war with 115/145 fuel but that took 4-5 years after hitting 1200hp.

This is what bedeviled the Two French engines. They were very good for 1933, they were pretty good for 1936, they were good enough for 1939 (barely), and became progressively more hopeless after that. They never got (or didn't get in time) the massive updates the R-1820s got or they weren't as good to begin with as the Merlin (or at least the Merlin II/III, some of the real early ones were a bit dubious). The Russians increase the weight of the 12Y design from 1036lbs on the M-100 to 1323lbs on the M-105PF. Which is Allison/early Merlin (II/III) territory. Basically a M-105PF in May of 1942 could do what a Merlin III (with better fuel) could do in the summer of 1940, except the M-105PF had a shorter time to overhaul.