A copy of the He-111

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Does anyone know why the Russians didn't build a copy of the He-111 the way they did the A-20, B-25, B-29, Do-17, C-47, yadda yadda? Or did they, and it's very obscure?
The Tu-4 was a reverse-engineered copy of a captured B-29 and first flew several years after WWII.

The only U.S. aircraft that the Soviets considered "copying" (without licence) during the war, that I'm aware of, was the P-39 by Belyayev.

His proposed design, the Ol-2 was to be a twin fuselaged fighter (like the P-82, Bf109Z, etc.) but never left the drawing board.
Copied, built, same difference
Practically speaking? In the 1940s the difference between reverse engineering and license production was huge.

To reverse-engineer an aircraft, the factory is going to need a few examples of the plane. They're going to need to measure damn near everything, and they're going to need to measure those same dimensions on multiple aircraft.

And then they're going to run into problems. Say they find a bolt that's .05" larger than standard. Is it like that for a reason? Did the people who designed the original determine that there's a little more stress there and they needed to beef it up? Did the capitalist pigdogs simply run out of standard-sized bolts? Did a worker make a mistake?

And what about this funny extra bend in panel #358 on the port wing? Engineer comrade Alexi thinks it's to compensate for spiral wash from the prop, but engineer comrade Sergei thinks it's just a mistake the lofters department made. Sure would be handy to be able to go to the draftsman's office and just ask, but on a reverse engineering job that's not happening.

And just what alloy of aluminum is this thing made out of exactly? Obviously, the metallurgists in 1940 could give you an analysis out to the fourth decimal point if that's what you really needed, as well as a microstructural evaluation of the material, but that doesn't mean that the home industry can replicate the stuff. Will it be safe to substitute something similar? Suddenly, this whole reverse-engineering project is looking nearly as hard as just engineering the thing from scratch.
My point is that reverse-engineering aircraft was not the fastest way to get aircraft into service at all. The practical problems caused by not having access to the original blueprints and engineers are quite significant. Aircraft technology was moving very, very fast in WWII. Reverse-engineering a design would generally be a good way to have a second-rate design by the time it actually reached production.

The TU-4 was a bit of an exception because it was dramatically more advanced than anything the Soviets even had on the drawing board (or at least that's what Stalin was convinced of), and because it was such a radically advanced design for the time, it was likely to still be competitive once it got into the air, especially given the drawdown caused by the end of the war.
In the event, it took the Soviets about two years to get their first TU-4s in the air.

If the Soviets had taken, say, a captured HE-111H in mid 1941 and bolt-for-bolt copied it and gotten it into production just in time for, say, the Battle of Kursk, would there have been any advantage to it vs. the Tu-2 already in series production by then?
There is also the licensing aspect. The builder paid the original manufacturer for the right to build the aircraft (such as the Soviet's DC-3/Li-2).

The reverse engineered B-29 was not done with Boeing's permission nor did they ever receive compensation.

Big difference here! Exactly, Dave.

It's worth noting that the DC-3 and Li-2 were different in several respects and the Soviets themselves also received DC-3s direct from Douglas, and in military service the DC-3s were favoured because they had better performance overall and were more reliable. I can't say I know whether or not the Tu-4 was more reliable than the B-29, but it did not suffer the same engine issues as the B-29, and it lasted longer in service, although that was more because of operational differences. US technology that went into the B-29 was well in advance of what the Soviet industry was producing at the time, for example single cast main undercarriage barrels, the Soviets had never cast such big legs before. That technology advanced Soviet aircraft design in so many ways.
Back to the original premise of the thread, the Soviets did not put the He 111 into service because they thought it fell short of twin engined bomber expectation at the time they got to evaluate the type. The Soviets got their first opportunity to examine an He 111, a B model in 1938 during the Spanish Civil War. One was captured by the Republican forces, but the Spanish decided it should go to France for evaluation (why, I don't know), but the Soviets did get it eventually to Russia and it went to Moscow for evaluation, where they commented favourably on build quality, serviceability and reliability, but stated that they did not believe it fulfilled their expectation of modern twin-engined bombers. The aircraft was flown in mock combat against Polikarpov biplane and monoplane fighters to gain perspective on its defensive armament.

The next He 111 that came into Soviet evaluation was an H-6 model captured on the Eastern Front in 1943. This time the Soviets were not impressed with its performance at all. Criticisms were levelled at its defensive armament and lack of armour plating, but they praised its constant speed propellers. A few of the type made it to the SU as bounty.

It seems the type did not inspire the Soviets to build it, but one unit (the 132nd Bomber Regiment) was going to operate the type using captured examples, but this plan was rescinded in 1943 and it eventually received the Tu-2. It is intriguing to note that in 1940 the Soviets enquired about buying Ju 88s, of which they were very impressed and two were delivered to the SU in April 1940. There is some conjecture that aspects of the Ju 88's technology that the Soviets were impressed with went into the Petlyakov Pe-2 aircraft and a Ju 88 was in fact used as a test subject for Pe-2 components. The Ju 88's dive recovery mechanisms were copied by the Soviets however.

Information from German aircraft in the Soviet Union and Russia by Yefim Gordon and Sergey Kommissarov.
The difference to me is in one case you are buying the blue prints and in another you are drawing them yourself. In the end you're still building an aircraft.
yes and no.

When the Canadians were building Hurricanes and Blenheims they had quite a few problems trying to source items in the US.
We joke about Whitworth but in actuality the US and British/Canadians didn't always use the same tubing/pipe wall thickness. They sometimes didn't even use the same sheet metal gauge thickness. Or tubing joints/connectors or............................. a lot of their stuff may have been common but sometimes it wasn't. And now you have to decide to use the next larger/thicker standard dimension or see if the smaller one will work or see if rolling mill XYZ will custom roll out the thickness you want for LMNQ amount of metal rolls.

If the US and Canada had occasional problems then going from metric to imperial could be a huge problem.

Remember that a "stress skin" aircraft uses the skin of the aircraft as part of it's strength so the thickness and the alloy/heat treatment are part of the stress calculations.
If the Soviets had taken, say, a captured HE-111H in mid 1941 and bolt-for-bolt copied it and gotten it into production just in time for, say, the Battle of Kursk, would there have been any advantage to it vs. the Tu-2 already in series production by then?
To be honest, the He111 had nothing on several of the Red Airforces' twins and was closer in performance profile to the Tupolev ANT-40 than any other types.

The Soviets also had the Yermovlev Yer-2, Petlyakov Pe-2 and the rarely mentioned Arkhangelsky Ar-2.

So creating their own copy of the He111 really wouldn't be worth the effort.
Article here on the Catalina & GST in Soviet service. Note the work involved in setting up Soviet licence production including redrawing all the plans in metric measurements. Only 27 GST produced at end of the day.

ISTR reading a story, probably apocryphal, that when the Soviets reverse engineered the Tu-4 they even copied some graffiti left by a US worker somewhere on the interior of the aircraft they were copying from!
They were instructed by Stalin to make exact copies of the B-29, which they did including a skin patch over a shrapnel hole and the Boeing logo on the control yoke. The problems were in the very slight differences of the three airframes they had as subjects.
very slight differences of the three airframes
Or not so slight. I don't know what they got but B-29s were built in several factories so even with everything going very well there are going to be a few differences.
If the Soviets got their hands on a B-29A they may have done a bit of head scratching.

"The B-29 had employed a two-piece wing center section that was bolted together at the center line and which was installed as a single unit passing entirely through the fuselage and supporting the engine nacelles. The B-29A used a very short stub center section that did not project beyond the fuselage sides, being only 47.75 inches wide on either side of the center line or almost eight feet in total. Each pair of engine nacelles was fitted to a separate short section of wing. The outer wing panels were attached at the same point on B-29s and B-29As alike."

From Joe Baugher.

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