WW2 Fantasy Aircraft

[tomo pauk]

I was wondering about availability of Merlins for the "Torbattle". Use V-1710s?

From the British perspective, Merlin was probably more easily available.
OTOH - British were also using the Bristol Taurus on the Albacore, so having that powering the "TorBattle" would've not been a long shot. Also makes the aircraft lighter and shorter a bit. Use the R-1830 on it, too?

 

[tomo pauk]

• Select a country and an air service.
• Select dates to start design, and introduce the aircraft into service. It should take three years to design a new aircraft, but blind, screaming panic mode over three months has had good results.
• Consider available resources. The Germans and Japanese fantasized about bombing the USA, but it was not happening. If your proposal is resource heavy, describe what other activity will be discontinued. Forget about not invading Russia. The whole point of WWII in Europe was to invade Russia.
• Select an aircraft manufacturer and engine(s).
• In context of WWII, new engine design from scratch takes too long. According to writer Bill Gunston, it takes five or six years to design a new engine and get it working. All the important engines of WWII were running prior to or very early in the war. You may propose upgrades of existing engines.
• Understand doctrine, design practise, and available technology of the nation and manufacturer. For example, the Russians did not see a requirement for high altitude combat. They did not make aircraft out of metal, and they did not have turbochargers. The Soviet P-47 Thunderbolt was not happening.
• Discuss how the aircraft will work, and justify your design decisions.
• You may design from scratch, or modify something that already exists.

• Italian AF
• 1938, in service in 1941
• Check
• Caproni; Isotta-Fraschini Asso L.122 of 1000 HP
• Check
• Check
• A fast 1-engined bomber, max speed of 530 km/h clean, 500 km/h bombed-up (shown with a 1000 kg bomb). Two HMGs in the wing. Italians can afford it.
• A spin-off from the Ca.335 design. wing area of 265 sq ft.

 

[tomo pauk]

• Select a country and an air service.
• Select dates to start design, and introduce the aircraft into service. It should take three years to design a new aircraft, but blind, screaming panic mode over three months has had good results.
• Consider available resources. The Germans and Japanese fantasized about bombing the USA, but it was not happening. If your proposal is resource heavy, describe what other activity will be discontinued. Forget about not invading Russia. The whole point of WWII in Europe was to invade Russia.
• Select an aircraft manufacturer and engine(s).
• In context of WWII, new engine design from scratch takes too long. According to writer Bill Gunston, it takes five or six years to design a new engine and get it working. All the important engines of WWII were running prior to or very early in the war. You may propose upgrades of existing engines.
• Understand doctrine, design practise, and available technology of the nation and manufacturer. For example, the Russians did not see a requirement for high altitude combat. They did not make aircraft out of metal, and they did not have turbochargers. The Soviet P-47 Thunderbolt was not happening.
• Discuss how the aircraft will work, and justify your design decisions.
• You may design from scratch, or modify something that already exists.

De Havilland-Percival fighter

• UK, RAF
• Start in 1936, in service in 1940
• Check
• De Havilland and Percival cooperation; RR Merlin
• Check
• Did
• A fighter whose airframe is mainly wooden 'composite' material. Both the companies knew how to make a sleek A/C, and wood 'composite' was DH's bread and butter come 1930s. Less gaps and leakage = lower drag = higher speed. Merlin in the nose, 8 .303s initially in the wings; later two cannons + 4 .303s. A lot of fuel to cover North Sea and for over-seas service.
• Percival and DH racers fell in love, and this is the child of that love.

 

[tomo pauk]

• Select a country and an air service.
• Select dates to start design, and introduce the aircraft into service. It should take three years to design a new aircraft, but blind, screaming panic mode over three months has had good results.
• Consider available resources. The Germans and Japanese fantasized about bombing the USA, but it was not happening. If your proposal is resource heavy, describe what other activity will be discontinued. Forget about not invading Russia. The whole point of WWII in Europe was to invade Russia.
• Select an aircraft manufacturer and engine(s).
• In context of WWII, new engine design from scratch takes too long. According to writer Bill Gunston, it takes five or six years to design a new engine and get it working. All the important engines of WWII were running prior to or very early in the war. You may propose upgrades of existing engines.
• Understand doctrine, design practise, and available technology of the nation and manufacturer. For example, the Russians did not see a requirement for high altitude combat. They did not make aircraft out of metal, and they did not have turbochargers. The Soviet P-47 Thunderbolt was not happening.
• Discuss how the aircraft will work, and justify your design decisions.
• You may design from scratch, or modify something that already exists.

• USSR, VVS
• Start in 1964, service entry 1968
• Check
• Northrop/Yakovlev; Mikulin copy of the Bristol/RR Viper
• Check
• Check
• A fail-safe bet against the problems with the new generation of fighters, and as a replacement for the MiG-15s and -17s in the world; guns being the left-over 1-barreled 23mm types
• Soviet moles get the blueprints from Northrop, while Yugoslavia makes an easy access to the small and light engine, that Soviets improve by adding an afterburner

Yak-31:

 

[SaparotRob]

• USSR, VVS
• Start in 1964, service entry 1968
• Check
• Northrop/Yakovlev; Mikulin copy of the Bristol/RR Viper
• Check
• Check
• A fail-safe bet against the problems with the new generation of fighters, and as a replacement for the MiG-15s and -17s in the world; guns being the left-over 1-barreled 23mm types
• Soviet moles get the blueprints from Northrop, while Yugoslavia makes an easy access to the small and light engine, that Soviets improve by adding an afterburner

Yak-31:

View attachment 813488

 

[z42]

By 1940, Bristol had finished with the Beaufighter. It would have been nice if they had focussed on updating the Hercules and getting the Centaurus into production.

I don't know (yet) what the bottlenecks were for Hercules production.

IIRC Bristol spent a lot of time getting the Hercules into decent shape, largely due to the valves. Due to this the Centaurus got pushed further and further into the future, to the point it missed the war.

As far as bottlenecks, one issue was the Hercules used a lot of ball bearing which were supplied in small lots from Sweden with either fast aircraft or fast boats.

 

[tomo pauk]

The Yak-31 prototype in the workshop after the 6th flight:
(historically, an ex-Vietnamese F-5E at Sukhoi's)

 

[bf109xxl]

But they did. Russians as Polikarpov, for example, with his I-200. Then some Armenians as Mikoyan, Jews as Gurevich... Probably, "the Soviets" is a better term.

The I-200 was initially designed as a high speed front-line fighter. The altitude characteristics of the AM-35 were just a bonus which was not used properly - above 8000 m it had certain difficulties with oil cooling. The real attempts to build a high altitude fighter in the USSR were the "100" by Petlyakov and the I-28 (Yak with M-105PD). even the I-135 (Su-1) with turbocharger was not.

If you look for an ideal design for the Eastern Front, it was the I-185. May be, it was the highest _available_ technological level for the Soviets during the war - at the edge of the acceptability due to a higher demand on the aluminum. I don't think that even now anyone can suggest anything better taking into account all the limitations of the Soviet industry.
I don't see much point in fantasizing airplanes that couldn't be built under the available conditions. And this requires accurate knowledge of the capabilities of the industry. If for the USA/UK you can fantasize almost anything, then for the USSR the inspiration will be sharply limited.

 

[Zmauky]

Here's some of my recycling from previous threads.

The Rules
- service - Luftwaffe
- start of designing in 1937
- resources - instead OTL Until 17
- everything else - story


The story of Dornier Do 117

As the performance of Messerschmitt's Bf 110 with jumo engines was not even up to the knees of the Focke Wulf Fw 187 Falke RLM decided during 1937 to accept Tank's private initiative for the single-seater Zestorer as a cheaper variant. Acknowledging the fact that the Fw 187 is still a very small twin engine, the Bf 110 remained in limited production and the reason was partly that it shared a good part of the construction with the more famous Bf 162 Jaguar. This later proved to be a good decision as the Bf 110 turned out to be a good night fighter. Of course, Willi wanted to make up for the lost orders, so he concentrated on the licht schnellbomber variant of the Bf 110, known as the Bf 162. The Jaguar, powered by Jumo 211 engines, shone later during the BoB terrorizing the airfields of the Fighter Command. During that 1937 the Dornier design team was finalizing the Do 17Z variant but they realized that (even if they got permission for the DB 601 or Jumo 211 engines) it would not come close to the performance of the announced Bf 162C powered by the Jumo 211. The only way to continue production of the Do 17 is some radical change. And so in the end, the Do 117 was born. In order for the project and production to be ready during 1938, the existing parts of the Do 17 were used to the maximum, to which a new central part was designed that encompassed the bomb bay and a central part of the wings on which were and additional engines. Existing wings and existing parts of the fuselage - cabin and tail - are attached to it. The new four-engine plane had a greater payload and radius of action than the heaviest bomber of the time, the He 111. RLM found itself in a situation where it did not want to accept a worse plane (Do 17Z vs Bf 162C) but also did not want to lose the Dornier production capacity. The new Bf 162C had the same payload (Max 1000 kg) as the intended (and never produced) Do 17Z over almost the same distance, with a significantly higher speed, so the KG did not feel disadvantaged by the change.
Meantime RLM reluctantly agreed to the production of Do 117A, while in KG they replaced the older Do 17 models with the new Bf 162. By the beginning of the war in 1939, approximately 150 Do 117A powered by 4 Bramo 323 engines (vs 380 OTL Do 17Z) were produced, which was enough for a full Kampfgeschwader . The Luftwaffe command was not sure how best to use that Kampfgeschwader 4 "General Wever" so, oddly enough, it had its own Luftflotte status. So with that status (relying primarily on Abwehr intelligence) KG 4 already carried out a couple of significant strategic attacks in Poland and during the Battle of France. Although the most famous actions were the night bombings of Rolls-Royce's Merlin engine factories in Crewe and Derby. Of course the Luftwaffe could not have carried out the Sealion alone, but they still managed to almost eliminate the British Isles as an Allied base (for attacking Europe) until late winter 1944.
Some historians later put forward the theory that the liberation of Europe would have been easier and faster if the British Isles could have been used as a launching pad with landings in Pas-de-Calais or Normandy rather than across the mountainous Balkans from Africa.

Grey are new components on OTL Do 17Z.
Maybe it will be 3d followed by 3d print but I have to make time for that.

Second episode - how the Kriegsmarine and Luftwaffe made the best schnell / torpedo ww2 bomber.

 

[Admiral Beez]

I'd like to see Armstrong-Siddeley receive funding, resources, talent and govt interest to create a sodium-cooled poppet valve pre-war engine series equal to the P&W R-1830 Twin Wasp. Have Hawker acquire A/S and then Camm has an in-house engine to power our fantasy Hawker, Gloster and A/W aircraft.

 

[tomo pauk]

• Select a country and an air service.
• Select dates to start design, and introduce the aircraft into service. It should take three years to design a new aircraft, but blind, screaming panic mode over three months has had good results.
• Consider available resources. The Germans and Japanese fantasized about bombing the USA, but it was not happening. If your proposal is resource heavy, describe what other activity will be discontinued. Forget about not invading Russia. The whole point of WWII in Europe was to invade Russia.
• Select an aircraft manufacturer and engine(s).
• In context of WWII, new engine design from scratch takes too long. According to writer Bill Gunston, it takes five or six years to design a new engine and get it working. All the important engines of WWII were running prior to or very early in the war. You may propose upgrades of existing engines.
• Understand doctrine, design practise, and available technology of the nation and manufacturer. For example, the Russians did not see a requirement for high altitude combat. They did not make aircraft out of metal, and they did not have turbochargers. The Soviet P-47 Thunderbolt was not happening.
• Discuss how the aircraft will work, and justify your design decisions.
• You may design from scratch, or modify something that already exists.

• Luftwaffe
• 1944 for both
• You know me
• Heinkel, Jumo 004/BMW 003
• Doh
• Ditto
• Heinkel's project, that has gotten the wing from the Me 163 in order to a) speed up the construction of the prototype, b) so it can hold more fuel, c) to give favorable wing loading, and d) to behave better at high speeds. Against the 2-engined fighters, the limited engine production still alows for a good number of fighters produced. Also less fuel needed.
• Basically, He 162 with the wings from the Me 163

(historical example is to the right)

 

[Zmauky]

The Rules
- service - Marinefleger / Luftwaffe
- start of designing (OTL version) 1935 fantasy version changes 1937
- resources - instead OTL Bf 110 / Hs 126 and latter Me 210/410
- everything else - story


Marineflieger lead the way.

Story of Bf 162 Jaguar / Schwertwal


After Raeder had a car accident in 1924, Chef der Marineleitung Hans Zenker embraced as his successor Wolfgang Wegener, who succeeded him in 1928. Wegener was the one who struck the foundations of naval aviation even before with the naval counterpart of the aviation school in Lipetsk.
One of the basic attack components for naval aviation is of course the torpedo bomber. And so, after a couple of biplanes and early constructions during 1930-1936, it was time for a successor. Heinkel offered the He 111J variant. Apart from the fact that the Marinefleger command was not entirely happy with the performance of the Heinkel (as it was expected to operate in the North Sea and within range of land-based fighters), the unavailability of the DB 601 engine sealed the project's fate. On the other hand, the fate of the Bf 110 was also (due to the Fw 187) hanging in the balance.
In this situation, Messerschmitt was very happy to accept the Marineflieger delegation.
Unlike the (historical) first variant of the Bf 162, the navy required a large enclosed bomb bay in which a torpedo could be placed. The simplest solution was to raise the wings by about fifty cm ( in inline with top of the fuselage but below cockpit) and so that the space under the wing spars could be used for a bomb bay long enough for a torpedo or alternatively 4x250 kg bombs. The cockpits of the pilot and navigator/torpedo gunner in the nose were separated from the radio operator/machine gunner with enclosed space. For self-defense, two 20 mm MG FF (with drums of 96 shells) were placed in the wing root and two 7.9 mm MG 17 each in the nose and rear cabin. The slightly reduced tanks in the wing roots are supplemented by tanks between the cabins above the wing spars. Results looked somehow like later japanese Ki-45. Everything sounded great, but of course (again) no DB 601 engines were available. So the whole project almost fell into the water.
But very quickly, Messerschmitt realized that he had in his hands a project of a light and fast (and in terms of payload better than the Do 17E and P ) bomber ideal for deep, fast penetrations. And so it happened that Messerschmitt managed to push the concept of licht schell kampfzestorer (light fast bomber destroyer ie fighter bomber) to the Luftwaffe. Of course, he was practically forced to do so, because orders for the Bf 110 were hanging by a thin thread because of the Fw 187B. The RLM (with the Kriegsmarine's promise of co-financing) agreed to allocate the first 800 Jumo 211 engines that were intended for the Ju 87 to the joint project, because by canceling the Hs 126, they used the same number of Bramo 323s for the Ju 87S, which in terms of performance was somewhere between the Ju 87A and B variants.
The first naval variant of the Bf 162C Schwertwal (Orca) flew in late 1938, and differed from the DB 601 project in that the fairing of the Jumo engines was at first modeled like those of the He 111 (in fact production version used Heinkel motor gondolas because Heinkel switch to radial variants but that is another story) with cooler below engine in nacelle, thus freeing up additional space (previously occupied by the coolers ) in the outer parts of the wings, which was used for additional tanks.
The biggest success of the Bf 162 Schwertwal is the support for the invasion of Norway and the subsequent complete interruption of the Arctic convoys to Russia. Namely, after the successful execution of plan R (that is, the UK and French landings in Norway), the Bf 162C Schwertwal practically stopped the supply of landed troops via ships.
The Bf 162D Jaguar first variant for the Luftwaffe was similar to the naval one but the nose gunner was removed making it two crew aircraft. Aiming was performed by the pilot, using fighter type of gun sight and he was assisted by a partially glazed nose with a slanted downward view. Two more 20 mm MG FFs were pushed into the space previously occupied by the navigator/gunner for a total of 4 pieces. Of course, the Bf 162D could not be used as a classic medium bomber in large groups (even if they had a payload like the Do 17Z), but the Luftwaffe used (especially during the BoB) attack tactics in small groups of the maximum size of a staffel, i.e. 12 planes. If the target was more important (such as the airfields of the Fighter Command), several staffels would carry out a coordinated attack. Similar to the OTL tactics for the Do 17, the planes would reach the target in a long, shallow descent (we are talking about an angle of a few degrees), so that they would be practically uncatchable over the target at speeds exceeding 700 km/h. As their speeds (after dropping the bombs) were almost identical to the fighter Bf 110, they were quite successful in avoiding the fighters. And even with the formidable armament of 2x7.9 and 4x20 mm, they were more than capable of defending themselves.

Pictures tomorrow

 

[Dimlee]

The I-200 was initially designed as a high speed front-line fighter. The altitude characteristics of the AM-35 were just a bonus which was not used properly - above 8000 m it had certain difficulties with oil cooling. The real attempts to build a high altitude fighter in the USSR were the "100" by Petlyakov and the I-28 (Yak with M-105PD). even the I-135 (Su-1) with turbocharger was not.

If you look for an ideal design for the Eastern Front, it was the I-185. May be, it was the highest _available_ technological level for the Soviets during the war - at the edge of the acceptability due to a higher demand on the aluminum. I don't think that even now anyone can suggest anything better taking into account all the limitations of the Soviet industry.
I don't see much point in fantasizing airplanes that couldn't be built under the available conditions. And this requires accurate knowledge of the capabilities of the industry. If for the USA/UK you can fantasize almost anything, then for the USSR the inspiration will be sharply limited.

That particular engine came as a bonus, indeed. My comment was the reaction to the claim that the Soviets did not have the requirement of high-altitude fighter. Polikarpov did see such a requirement as the others you mentioned. Some brains in VVS saw it as well, despite it did not materialise later in WWII. It was even popularised in the literature and the "infotainment" media of that period, as technical magazines and documentaries. The ubiquitous slogan vyshe, bystreye, dalshe (higher, faster, further) was not only a declaration but also an instruction, as many slogans in the USSR.

I share the sentiments towards I-185.

Should I think about the Soviet WWII "fantasy" aircraft, I'd start with this pre-condition: Lend-Leased engines.

 

[bf109xxl]

That particular engine came as a bonus, indeed.

The AM-37 was originally intended to be installed on the I-200, the AM-35 was rather a forced and provisional solution, which, due to circumstances, remained permanent. I do not know any documents according to which the I-200 was designed as a high-altitude fighter. The only objective of Polikarpov was superiority in terms of maximum speed - it was important for him to achieve a higher speed than that of the competitors, even at altitudes where air combat was supposed to be unlikely.

My comment was the reaction to the claim that the Soviets did not have the requirement of high-altitude fighter.

I would say that in the USSR the development of a high-altitude fighter had a low priority until the middle of the war.

Polikarpov did see such a requirement as the others you mentioned.

Polikarpov installed the AM-35 not because he wanted to build a high-altitude fighter, but because he hoped to obtain finally the AM-37, which should allow to outperform the competitors even in the altitude range up to 5000 meters.

(from the book by A.Medved')

Some brains in VVS saw it as well, despite it did not materialise later in WWII. It was even popularised in the literature and the "infotainment" media of that period, as technical magazines and documentaries. The ubiquitous slogan vyshe, bystreye, dalshe (higher, faster, further) was not only a declaration but also an instruction, as many slogans in the USSR.

Neither the USSR nor its potential opponents had bombers at the time that would have required high-altitude fighters for escort or interception. The fact that even Petlyakov's "100" was converted into a bomber is an unequivocal evidence of a low priority of the development of high-altitude fighters.

 

[Shortround6]

The problem is looking 3-4 years down the road, or more.

It was even popularised in the literature and the "infotainment" media of that period, as technical magazines and documentaries.

This was world wide and the US experimental aircraft got a lot of "press"/newsreel footage. Likewise record setting aircraft of all kinds including altitude records of various kinds (not just altitude but weight lifted to XXXX height). With the rapid progress in many areas of aviation many people expected progress to keep going at the same rate that had occurred in the mid to late 1930s.
The need for pressure cabins and not just oxygen masks for crews to operated for several hours at over 30,000ft was unforeseen. Many of difficulties with pressure cabins were also unforeseen. Compressibility problems were either unforeseen or not noticed outside of a few researchers? Even variable pitch propellers were only a few years old let alone figuring out what actually worked in higher thinner, air.
The answers were not as easy to come by as going from under 200 mph biplanes to over 300 mph monoplanes. It took a lot more work to get smaller increases in performance.
What had been a high altitude airplane in 1938-40 was NOT a high altitude airplane in 1942-43.
I would note that even the turbocharged American aircraft were not rated at 25,000ft in the late 30s. What they wanted and what they got were not the same. A lot of the late 30s turbo charged airplanes had critical altitudes of around 20,000ft.
For example the YP-43s had been ordered in March of 1939, they started being delivered in Sept 1940. A few months after at the First P-40s. The engines in the YP-43 was good for 1200hp for take off and 1100hp at 20,000ft. Which for a turbo is not all that great. But in Sept 1941 they were delivering P-43A's with new powerplant that gave the same 1200hp for take-off but also gave 1200hp at 25,000ft. Roughly 20% more power at 25,000ft than the YP-43 had.

The PE-8 bomber was envisioned as a high altitude aircraft.
"These requirements specified a bomber that could carry 2,000 kg (4,400 lb) of bombs 4,500 km (2,800 mi) at a speed greater than 440 km/h (270 mph) at an altitude of 10,000 metres (32,808 ft)."
This required the installation of a Klimov M-100 engine driving a central supercharger to supply to the four Mikulin AM-34FRN engines.

Now if your government is looking at a 10,000 meter bomber it kind of stands to reason that they would be looking for a 10,000 meter interceptor in case their enemies came up with their own 10,000 meter bomber. How much (what percentage of effort) was put into these projects compared to the lower altitude planes may not have been large.
My own impression of Soviet engine development is that they tried to turbo-charge just about every large aero engine they had at some point. They had less luck than the US had in the late 30s (turbo explosions were common in both countries).

 

[bf109xxl]

The PE-8 bomber was envisioned as a high altitude aircraft.

How many Pe-8 were built?

"These requirements specified a bomber that could carry 2,000 kg (4,400 lb) of bombs 4,500 km (2,800 mi) at a speed greater than 440 km/h (270 mph) at an altitude of 10,000 metres (32,808 ft)."
This required the installation of a Klimov M-100 engine driving a central supercharger to supply to the four Mikulin AM-34FRN engines.
Now if your government is looking at a 10,000 meter bomber it kind of stands to reason that they would be looking for a 10,000 meter interceptor in case their enemies came up with their own 10,000 meter bomber. How much (what percentage of effort) was put into these projects compared to the lower altitude planes may not have been large.

How many Pe-8s could be produced per year by Plant No. 124 in Kazan, where serial production was deployed? The Pe-8 was a terrible airplane from the technological point of view - their production in appreciable quantities was completely unrealistic. The USSR leadership was well aware of this and prioritized aircraft design and production accordingly.

My own impression of Soviet engine development is that they tried to turbo-charge just about every large aero engine they had at some point. They had less luck than the US had in the late 30s (turbo explosions were common in both countries).

The Soviets lacked suitable heat-resistant alloys to provide the required blade reliability. The same problem that plagued the turbines of early Soviet jet engines. Soviet experiments with turbochargers were largely driven by concerns about the German high-altitude reconnaissance aircraft.

 

[Dimlee]

The AM-37 was originally intended to be installed on the I-200, the AM-35 was rather a forced and provisional solution, which, due to circumstances, remained permanent. I do not know any documents according to which the I-200 was designed as a high-altitude fighter. The only objective of Polikarpov was superiority in terms of maximum speed - it was important for him to achieve a higher speed than that of the competitors, even at altitudes where air combat was supposed to be unlikely.

I would say that in the USSR the development of a high-altitude fighter had a low priority until the middle of the war.

Polikarpov installed the AM-35 not because he wanted to build a high-altitude fighter, but because he hoped to obtain finally the AM-37, which should allow to outperform the competitors even in the altitude range up to 5000 meters.
View attachment 813550
(from the book by A.Medved')

Neither the USSR nor its potential opponents had bombers at the time that would have required high-altitude fighters for escort or interception. The fact that even Petlyakov's "100" was converted into a bomber is an unequivocal evidence of a low priority of the development of high-altitude fighters.

This spontaneous discussion shows how the same information can be interpreted.
Yes, everything "high altitude" was a low priority as you said.
No, the low priority didn't mean the lack of requirement or interest (referring back to the original argument, not yours).
No, probably, there is no documented evidence that Polikarpov ever thought about the I-200 as a high-altitude type.
Yes, Polikarpov experimented with high-altitude aircraft before I-200.
Yes, there was no immediate need to intercept high-altitude bombers when the idea of I-200 was born.
Yes, Polikarpov and other designers (and GRU, NKVD, GUGB) were aware of the high-altitude programs of other nations.
Yes, Petlyakov's VI-100 was converted into a bomber. And yes, it was designed first as a "high altitude fighter = Vysotny Istrebitel". The state order was given in 1938 (!) and requested 12,500 m of max altitude.
Etc..

 

[Dimlee]

By the way, the Pe-8 deserves a separate thread. Its story was so "Soviet" in many respects.
Now, back to the topic...

 

[Shortround6]

• USSR, VVS
• Start in 1964, service entry 1968
• Check
• Northrop/Yakovlev; Mikulin copy of the Bristol/RR Viper
• Check
• Check
• A fail-safe bet against the problems with the new generation of fighters, and as a replacement for the MiG-15s and -17s in the world; guns being the left-over 1-barreled 23mm types
• Soviet moles get the blueprints from Northrop, while Yugoslavia makes an easy access to the small and light engine, that Soviets improve by adding an afterburner

Yak-31:

View attachment 813488

A lot depends on exactly when and which versions of the engines are available.
In 1962-63 the Viper II was offering about 2500lbs of thrust, earlier versions offered less, the Viper 20 was supposed to offer more. Confusingly the the MK numbers are often modifications of basic engines. Like the MK 22-6 used in the Soko J-2 Galeb is a modified, licensed Viper 11.
In the early 60s the US J-85 engine was only good for 2850lbs without an after burner. But they already had an after burner.

The Viper was small, the J-85 was miniscule.
engine....................Viper 9......................J-85-7................J-85-5 (after burner)
Diameter................617mm....................445mm...............513mm
Length..................1703mm....................998mm...............2650mm
Weight....................239kg.......................148.4kg..............244.6kg
Thrust......................2500lbs....................2450lbs..............3850lbs

Both engines increased in power substantially in later models.
The Viper 600 series was rated at 4000lbs thrust in the early 70s without afterburner, weight had grown to 376kg.
The J-85-21 was rated at 3500lbs dry in 1972 and 5000lbs with afterburner, weight was 306kg.
Both engines had changes to the compressors and other changes.

 

[bf109xxl]

• USSR, VVS
• Start in 1964, service entry 1968
• Check
• Northrop/Yakovlev; Mikulin copy of the Bristol/RR Viper
• Check
• Check
• A fail-safe bet against the problems with the new generation of fighters, and as a replacement for the MiG-15s and -17s in the world; guns being the left-over 1-barreled 23mm types
• Soviet moles get the blueprints from Northrop, while Yugoslavia makes an easy access to the small and light engine, that Soviets improve by adding an afterburner

Yak-31:

View attachment 813488

There was no need, as the Soviets had something better.