An even greater inter-Allied cooperation on the technical & tactical matter?

Compared to what the Axis were doing, Allied cooperation during the ww2 was probably a bed of roses Still, perhaps it could've been done on an even greater scale.

To start the ball rolling - the idea of mid-air refueling is made into a real thing. British impetus might've been in the (dire) need to shut down the Atlantic gap, while Americans might've wanted to extend the range/radius of their big aircraft, like the bombers, transports and MP aircraft. Both Americans and British were experimenting with such systems before the ww2, so it is not a far-fetched idea.

The Japanese, Italians and Swedes all made DB601 and DB605 engines under license. The Germans supposedly were considering the manufacture of some Italian aircraft. It was the people within the Nazi party who did not get along.

Merlins got manufactured in the USA because the British were trying to move production out of range of German bombers. As German bombers ceased effectively bombing British production, this all got less critical. Of course, every bit of production helped. It helped that the Merlin was a good engine that met all sorts of requirements. The Spitfire XVI puzzles me. Why not switch production over to Griffon engines? I suppose that there was a determination to not shut down production lines.

I have Alexander de Seversky's Victor Through Air Power here, and he claimed that the USA was stupid for making Merlins, rather than Napier Sabres. He would not have been aware of the Sabre's lack of reliability. The Sabre was not a good substitute for any engines that the Americans were using, particularly the Pratt and Whitney R2800.

The British installed R2800s in most of their Vickers Warwicks. The Warwick was big twin engined aircraft, and the Sabres and Centauruses simply were not available. I wonder how an R2800 would have worked on a Hawker Tornado or Tempest? The Fairey Barracuda was too big for its Merlin engine. Wright R2600 anyone? How about four R2800s on the Short Stirlings?

The Americans had difficulty manufacturing Hispano cannons.

Most early American turbojets were copies of British designs.

The British did much of the debugging on the Vought Corsairs for operations off of carriers.

The American tweaked some Spitfire IXs to increase range. I don't think they were serious. Without drop tanks, a P47 was not longer ranged than a Spitfire, but the Americans aggressively developed drop tanks. The British regarded the Spitfire primarily as an interceptor, not requiring range. When they wanted to escort their bombers, they used Mustangs. The Royal Navy installed P40 drop tanks on their Seafires out in the Pacific.

A team from North American visited Supermarine to get tips on the design of lightweight aircraft, which led to the P51H. Did Supermarine get tips on how to make things manufacturable?

Did the British manufacture any American designs?

re early-war IFR

The use of IFR (In-Flight Refueling) would not have been practical for the normal strategic bombing operations vs Germany - ie mass-formation bombing of targets/cities. The number of tanker aircraft (and associated airfields in the UK) would have been prohibitive to use, both in terms of the formation numbers, and in view of the flight times involved. Even topping up the bombers after they climbed to altitude would have been impractical given the fuel loads and numbers of the aircraft involved. Imagine the traffic patterns over Southern England.

However, for some missions, using small(er) formations (maybe for Ploesti?) if launched before daylight and striking at night, it might have been usable.

And as you mentioned above, long range operations over the Atlantic might have benefited, but I think entirely new patrol aircraft would have to have been developed in order to benefit enough to make it worthwhile.

The Flight Refueling Ltd method of the 'looped hose' type required at least a 2-man airframe, which would remove the possibility of using it for single-seat fighters. I would think the above mentioned factors for the bomber types would also prohibit the use of IFR for the escort fighters, with the additional problem of the relative small size and weight of the fighter airframes involved. Maybe an early push for high-performance twin-engine escort fighters would justify this method of range extension?

Having said the above, the idea of the probe & drogue method was already on someone's drawing board, somewhere in the UK, just before the war started. I think it was at Flight Refueling Ltd, but am not sure, but as with many other things it was put on a back burner until late in the war. The idea was passed along to the US during the Tizard mission(s), along with Flight Refueling Ltd's information on their pre-war 'looped hose' operations with the 'C' class flying boats for the trans-Atlantic crossings. Flight Refueling Ltd was (I think) the first to patent the idea in the early-1950s.

Late-war in the PTO & CBI areas it would seem (to me) that even a semi-efficient IFR system like the Flight Refueling Ltd 'looped hose' method would have been useful for some types of missions, but my understanding is that the UK looked quite seriously at the idea and concluded that overall it was not needed (enough) to justified the time and effort?? I have not been able to find clearly detailed reason for this conclusion.

It should also be mentioned that the probe & drogue system, while seemingly very simple, it is not that simple in terms of the engineering for reliability and safety. It also entails a significant weight and/or drag penalty for smaller aircraft. A fixed external probe would be too draggy for a P-51 or P-47 size airframe, while a retractable probe would be prohibitive due to the internal volume required. Larger aircraft, like the 4-engine bombers, would not notice the effect to any serious degree.

Howard Gibson said:

Merlins got manufactured in the USA because the British were trying to move production out of range of German bombers. As German bombers ceased effectively bombing British production, this all got less critical. Of course, every bit of production helped. It helped that the Merlin was a good engine that met all sorts of requirements. The Spitfire XVI puzzles me. Why not switch production over to Griffon engines? I suppose that there was a determination to not shut down production lines.

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Packard Merlin was basicaly free for the British. Griffon was not.

Howard Gibson said:

I have Alexander de Seversky's Victor Through Air Power here, and he claimed that the USA was stupid for making Merlins, rather than Napier Sabres. He would not have been aware of the Sabre's lack of reliability. The Sabre was not a good substitute for any engines that the Americans were using, particularly the Pratt and Whitney R2800.

The British installed R2800s in most of their Vickers Warwicks. The Warwick was big twin engined aircraft, and the Sabres and Centauruses simply were not available. I wonder how an R2800 would have worked on a Hawker Tornado or Tempest? The Fairey Barracuda was too big for its Merlin engine. Wright R2600 anyone? How about four R2800s on the Short Stirlings?

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Perhaps Sasha didn't put as much empasis on the limitations of the platform, together with the very real issues Sabre had? Merlin was as close as possible to a drop-in replacement to the main fighter's engine made for the USAAF - the V-1710 (bar the P-39/-63 installation), while providing the mature design for the fighters, together with a very important boost in the altitude performance.
That production of one Sabre would've meant two Merlins are not produced is also a thing. Then we have a thing that Sabre was to be installed in a small number of aircraft types in the UK, while everyone was craving for a Merlin.
The next most important fighter's engine for the USAAC - R-2800 - was a more mature design than the Sabre, the production about to begin in several factories in the USA at least 12 months before we can expect the Sabre to be made here.
Timing for the Sabre production is also too late.

tl;dr - Sabre made in the USA had a lot going against it, unlike the production of the Merlin.

R-2800 would've probably worked just fine on the big Hawkers, same for the R-2600 (or even the R-2800) on the Barracuda.

Howard Gibson said:

The American tweaked some Spitfire IXs to increase range. I don't think they were serious. Without drop tanks, a P47 was not longer ranged than a Spitfire, but the Americans aggressively developed drop tanks. The British regarded the Spitfire primarily as an interceptor, not requiring range. When they wanted to escort their bombers, they used Mustangs. The Royal Navy installed P40 drop tanks on their Seafires out in the Pacific.

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P-47 with the drop tanks was a much longer-ranged bird than the as-is Spitfire with the drop tanks. The bubbletop P-47Ds were long-legged enough to make it to Berlin, fight there, and return to the UK.
Unfortunately, British didn't saw the need for the real LR Spitfire until too late.

Howard Gibson said:

Did Supermarine get tips on how to make things manufacturable?

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Unfortunately, no. And too bad there was no such thing really and truly attempted for the Spitfire.

Something other that British can 'give' to the Americans - the APDS shot for the 75 and 76mm guns.

Howard Gibson said:

Merlins got manufactured in the USA because the British were trying to move production out of range of German bombers. As German bombers ceased effectively bombing British production, this all got less critical. Of course, every bit of production helped. It helped that the Merlin was a good engine that met all sorts of requirements. The Spitfire XVI puzzles me. Why not switch production over to Griffon engines? I suppose that there was a determination to not shut down production lines.

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Castle Bromwich Aircraft Factory produced the Spitfire II, V and IX in succession. The Mk.XVI was produced alongside the Mk.IX from 1944. The plan was was then to move to produce the Griffon engined Mk.21 & 22. Those latter models encountered development problems so delaying production.

I myself think Western Allied cooperation was really, really good as it was. Cargo ships and landing craft, Merlins, LL, Tube Alloys, the cavity magnetron and so on.

Things that Soviet can adopt for their needs, that originates from the West (bar just using the stuff as-is, like using whole tanks or aircraft)?
Soviet stuff interesting to the West?

tomo pauk said:

Things that Soviet can adopt for their needs, that originates from the West (bar just using the stuff as-is, like using whole tanks or aircraft)?
Soviet stuff interesting to the West?

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The T34 tanks. I am not a tank expert. I don't see any attractive Russian aircraft.

tomo pauk said:

Things that Soviet can adopt for their needs, that originates from the West (bar just using the stuff as-is, like using whole tanks or aircraft)?

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Since the title contains 'tactical' as well as technical, how about the Soviets learning that wasting your own men in pointless zerg rushes isn't useful? Or that shooting your own men en masse might not be the best thing for morale? Of course, given that Stalin a few years prior executed a large part of his officer corps, might be hard to apply in practice in the lower echelons.

Soviet stuff interesting to the West?

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AFAIU the Soviets were in general very tight-lipped about their own stuff and not willing to share much of that with their allies, but assuming that roadblock has somehow been overcome.

Soviet aircraft, while generally adapted to the style of fighting they were doing and to their own technical limitations, might not have much useful to teach the Western Allies?

And the Soviet navy, well the less said about it the better (of course, looking at a map and the war they were in, largely ignoring the navy was exactly the right decision for them).

But army stuff, tanks in particular, might have some useful lessons to the Western Allies. Britain, in particular. The Soviets were in desperate need of every single thing they produced themselves, so I don't see a scenario where the Soviets export a non-trivial amount of gear to the Western allies. Blueprints, maybe. So if getting T-34's as such is out of the question, more interesting is perhaps the doctrine and reasons behind it, and what kinds of tanks that lead to? From the blueprints the western allies could nick the torsion bar suspension and the idea of a three-man turret from the KV-1, the 76.2mm gun and the V-2 engine (in particular, the Soviet approach of using that one engine in most of their tanks instead of having a dozen mediocre engines?) from the T-34/KV-1. And the general idea of a heavily armored medium tank with a big gun from the T-34?

But for the doctrine & blueprint approach, timing will be an issue. Until the start of Barbarossa in mid-41 the Soviets are ostensibly allied with Germany, so even if the British receive a thick bunch of documents with tank blueprints and doctrine right in mid-41 when the tables turn, it would still take them years to turn that into a tank rolling out from their factories in volume?

Hi
Smaller items of co-operation between US and UK include ASV II, built in the USA as ASE by Philco equipping the USN with their first ASV operational radar. VHF radio, the SCR-522-A was based on and interchangeable with the British TR1143.
The British GM2 Reflector gunsight adopted by the USN as the Navy Mk 8, manufactured under licence by Bausch & Lomb and Bell & Howell. The British GM2 was also used by USAAF aircraft based in the UK as well as the P-51 (majority of production?). Also the later British gyro gunsight the GGS (Mk IID) manufactured in the USA as the Mk 18 for the USN and as the K-14 for the USAAF.
I am sure there are many other items from both sides of the pond.

Mike

Howard Gibson said:

The British installed R2800s in most of their Vickers Warwicks. The Warwick was big twin engined aircraft, and the Sabres and Centauruses simply were not available. I wonder how an R2800 would have worked on a Hawker Tornado or Tempest?

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I believe there is a Sea Fury flying (or being restored to flying order?) with a R-2800 today; Centaurus engines are apparently very hard to come by, difficulty getting spare parts etc.

In WWII, putting a R-2800 in a Tempest might have enabled the Tempest II to see service in the war, as opposed to the historical Centaurus powered Tempest II which missed the war.

The Americans had difficulty manufacturing Hispano cannons.

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Good point. A reliable Hispano rolled out in volume in US aircraft would have been a boon. 4 Hispanos would be only slightly higher weight than the US "standard" 6x.50 cal armament, but with a significantly heavier punch.

tomo pauk said:

That production of one Sabre would've meant two Merlins are not produced is also a thing.

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I think a Sabre engine was more like five times as expensive as a Merlin. Twice the number of cylinders and crankshafts, the sleeves were very expensive, but also AFAIU Napier manufacturing was much more artisanal handcrafted work than the Merlin which was (common trope notwithstanding) properly mass manufactured.

tl;dr - Sabre made in the USA had a lot going against it, unlike the production of the Merlin.

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Agreed. If there's a case for another British aero engine being produced in the US in addition to the Merlin, my vote would be on the Griffon. Even that case is relatively weak, there just weren't a large number of aircraft wanting Griffons. But with a bigger supply of Griffons, maybe some of the later Merlin Spitfire production could have switched over to the Griffon variants earlier? Or what about putting Griffons on a Lancaster? Or Mosquito?

z42 said:

From the blueprints the western allies could nick the torsion bar suspension and the idea of a three-man turret from the KV-1, the 76.2mm gun and the V-2 engine (in particular, the Soviet approach of using that one engine in most of their tanks instead of having a dozen mediocre engines?) from the T-34/KV-1. And the general idea of a heavily armored medium tank with a big gun from the T-34?

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In 1942 the US began looking at a successor to the M4 Sherman. That led to the M20 series of prototypes, some of which used a torsion bar suspension. Torsion bars were used in the M24 Chaffee light tank which arrived on the front line in Nov 1944 and the M26 Pershing that was beginning to arrive from spring 1945.

The British certainly didn't need to learn about the 3 man turret. Most of the cruiser tanks, even the early ones designed pre-war had 3 man turrets. (IIRC it was only the Crusader III that was forced into having a two man turret by virtue of squeezing in the larger 6pdr). The Matilda II infantry tank had a three man turret from the outset. Dig into the design history of the Valentine and you will find that Vickers originally designed the two man turret to carry their own gun with an autoloader, a concept rejected by the War Office which by the time the decision was taken to acquire it, was desperate for tanks, any tanks so was prepared to live with the two man turret. But even it was given an enlarged 3 man turret in Mk.III / V form.

In the USA, the T6 (The prototype for the M4 Sherman) had a 3 man turret when designed in early 1941, authorised on 19th June and trialled from Sept 1941. The Canadian Ram developed in the same timescale also had a 3 man turret.

As for engines, everyone wanted an engine with sufficient power, something that was not always available back in the day. In the US the multitude of engines arose from demand exceeding supply when those same engines were required by the aviation industry.

The T-34 didn't carry particularly heavy armour for the time but was able to benefit from it being heavily sloped. And I wouldn't say that the KV1 was the model to follow at 45 tons when most of the bridge infrastructure in Europe would struggle to cope with it.

EwenS said:

In 1942 the US began looking at a successor to the M4 Sherman. That led to the M20 series of prototypes, some of which used a torsion bar suspension. Torsion bars were used in the M24 Chaffee light tank which arrived on the front line in Nov 1944 and the M26 Pershing that was beginning to arrive from spring 1945.

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Indeed, this shows the timeline problem I mentioned in my post. Even if the Western allies were to receive a thick dossier with Soviet tank doctrine and blueprints in mid-1941 when Barbarossa kicks off, they'd be hard pressed to have any hardware resulting from that in volume use to make an impact in the war.

The British certainly didn't need to learn about the 3 man turret. Most of the cruiser tanks, even the early ones designed pre-war had 3 man turrets. (IIRC it was only the Crusader III that was forced into having a two man turret by virtue of squeezing in the larger 6pdr). The Matilda II infantry tank had a three man turret from the outset. Dig into the design history of the Valentine and you will find that Vickers originally designed the two man turret to carry their own gun with an autoloader, a concept rejected by the War Office which by the time the decision was taken to acquire it, was desperate for tanks, any tanks so was prepared to live with the two man turret. But even it was given an enlarged 3 man turret in Mk.III / V form.

In the USA, the T6 (The prototype for the M4 Sherman) had a 3 man turret when designed in early 1941, authorised on 19th June and trialled from Sept 1941. The Canadian Ram developed in the same timescale also had a 3 man turret.

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Good info, thanks. I wasn't saying the Western allies were unaware of the benefits of a 3 man turret, my point was to argue against making a clone of the T-34/76 with its two man turret.

The T-34 didn't carry particularly heavy armour for the time but was able to benefit from it being heavily sloped.

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Regardless of how it was achieved, the point was that it was able to withstand heavier fire than many other contemporary medium tanks.

And I wouldn't say that the KV1 was the model to follow at 45 tons when most of the bridge infrastructure in Europe would struggle to cope with it.

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I was saying to take the torsion bar suspension and the idea of a 3 man turret from the KV-1, and apply it to a medium tank in the T-34 weight class (25-30 tons) rather than cloning the T-34 as-is.

z42 said:

I think a Sabre engine was more like five times as expensive as a Merlin. Twice the number of cylinders and crankshafts, the sleeves were very expensive, but also AFAIU Napier manufacturing was much more artisanal handcrafted work than the Merlin which was (common trope notwithstanding) properly mass manufactured.

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Rolls Royce was an artisanal outfit too. Both Ford of England and Packard in the USA told Rolls Royce that their drawings were crap. Mass production needed way more precision than Rolls Royce was calling up. I recently did a presentation on Design for Manufacture and Assembly (DFMA) and documentation, and I pointed out that the complete drawings of the strategically critical Merlin engines were done at least three times.

Howard Gibson said:

Rolls Royce was an artisanal outfit too. Both Ford of England and Packard in the USA told Rolls Royce that their drawings were crap. Mass production needed way more precision than Rolls Royce was calling up. I recently did a presentation on Design for Manufacture and Assembly (DFMA) and documentation, and I pointed out that the complete drawings of the strategically critical Merlin engines were done at least three times.

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Calum Douglas has argued that RR was capable of, and did, mass production of Merlins. (Where the US was critical to enable this was not in teaching those backwards Brits how to do it, but by providing the necessary machine tools). A quick google turns up this post by him, by I recall he has argued that point elsewhere as well:
View: https://x.com/CalumDouglas1/status/1781728156681953664

tomo pauk said:

R-2800 would've probably worked just fine on the big Hawkers, same for the R-2600 (or even the R-2800) on the Barracuda.

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What about go whole hog and have the Brits build their own R-2800 under license and Hawker or Gloster or Boulton Pall or Morris Motors or whoever build P-47's. You get a lot better airplane than a Typhoon, one that will not terrify its pilots about crossing the Channel and leave British industry free to pursue jets. After all even the Tempest did not last after WW2 and the Sea Fury did not have a long life, because of the jets.

MIflyer said:

What about go whole hog and have the Brits build their own R-2800 under license and Hawker or Gloster or Boulton Pall or Morris Motors or whoever build P-47's. You get a lot better airplane than a Typhoon, one that will not terrify its pilots about crossing the Channel and leave British industry free to pursue jets. After all even the Tempest did not last after WW2 and the Sea Fury did not have a long life, because of the jets.

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While the Tempest V was withdrawn from some squadrons in Germany in 1946, two retained them until 1948 when they were replaced by Spitfire F.24 and the Vampire respectively. And some lived on beyond that in the target towing role.

The Tempest II remained in service in Germany until 1949 and in the Far East until June 1951. The last squadron, 33, swapped its Tempests for DH Hornet F.3 until disbanded in March 1955.

The last of the Tempest VI, which served in the Middle East, weren't replaced by Vampires until 1950.

As for the Sea Fury, it reached the front line squadrons in 1947, and remained in front line service with the FAA until the end of 1954, seeing service during the Korean War, and with other navies for several years after that.

The F4U Corsair was in USN service until after the Korean War and with France until the late 1950s.

z42 said:

Calum Douglas has argued that RR was capable of, and did, mass production of Merlins. (Where the US was critical to enable this was not in teaching those backwards Brits how to do it, but by providing the necessary machine tools). A quick google turns up this post by him, by I recall he has argued that point elsewhere as well:
View: https://x.com/CalumDouglas1/status/1781728156681953664

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Note how the conversation is with both Packard in the USA and Ford in England. In peacetime especially, manufacture of military aircraft is a boutique industry. The conversation was not between the USA and Great Britain. It was between car manufacturers accustomed to mass production, and aircraft manufacturers.

In mass production, you need interchangeable parts. To make interchangeable parts, you need precision. Packard USA and Ford of England explained this to Rolls Royce. Ford USA explained it to Consolidated. General Motors must have talked to somebody, somewhere. In the 1920s, Charles Sorensen and William Knudsen went through assembly shops and they threw away the hammers and files. Everything coming in from the vendors has to fit. I am sure Rolls Royce listened to the explanations. There must have been trial and error as well.

I love watching episodes of Forgotten Weapons on YouTube, where Ian shows us stuff made in the 19th century where a worker has obviously filed an iron or brass housing and the wooden grips to all line up perfectly.

MIflyer said:

What about go whole hog and have the Brits build their own R-2800 under license and Hawker or Gloster or Boulton Pall or Morris Motors or whoever build P-47's. You get a lot better airplane than a Typhoon, one that will not terrify its pilots about crossing the Channel and leave British industry free to pursue jets. After all even the Tempest did not last after WW2 and the Sea Fury did not have a long life, because of the jets.

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P-47 is one of my favorites, so the more the merrier
British-made P-47s would've been probably available by some time of 1943? Hopefully they don't jump on the P-47B bandwagon, that kinda showed the Brits how the Americans can make a combat aircraft - together with it's engine - that is more dangerous to it's own pilots than to the enemy.

British licence-producing Mustang would've probably been a much easier undertaking, though.

Howard Gibson said:

Note how the conversation is with both Packard in the USA and Ford in England. In peacetime especially, manufacture of military aircraft is a boutique industry. The conversation was not between the USA and Great Britain. It was between car manufacturers accustomed to mass production, and aircraft manufacturers.

In mass production, you need interchangeable parts. To make interchangeable parts, you need precision. Packard USA and Ford of England explained this to Rolls Royce. Ford USA explained it to Consolidated. General Motors must have talked to somebody, somewhere. In the 1920s, Charles Sorensen and William Knudsen went through assembly shops and they threw away the hammers and files. Everything coming in from the vendors has to fit. I am sure Rolls Royce listened to the explanations. There must have been trial and error as well.

I love watching episodes of Forgotten Weapons on YouTube, where Ian shows us stuff made in the 19th century where a worker has obviously filed an iron or brass housing and the wooden grips to all line up perfectly.

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The 'hald-built Merlin' myth is past it's sell date. British were mass-producing Merlins long before Ford of England was involved, let alone before Packard started out.