Questions about B-29 operational range, VVS, VVS intercept capability if Operation Unthinkable happen.

[bf109xxl]

I think you underestimate the effects. An atomic bomb punches a brutal hole into the city.: 1.82 square kilometers has suffered heavy blast damage, everyone in a 5.1 square kilometer area has suffered a fatal or severe dose of radiation, fires burn widely, massive numbers of people need immediate medical attention, the strain on civil services would be enormous.

I think you far overestimate the effect.

NUKEMAP estimates such an attack on current-day Moscow would kill some 89,000 and injure over 245,000 people. No city could cope with that level of carnage inflicted on a single day; even a nation would face difficulties mustering the amount of resources needed to respond to a sudden disaster of that magnitude.

In my opinion, these are completely unrealistic figures for Moscow in 1945. Moscow remembered the bombings of 1941, the air defense was equipped with radar - at least the Soviets could spot a bomber and sound the alarm.

 

[Peter Gunn]

Just to back up a bit, I find it quite humorous to even list the Soviet Pacific (or the entire) "navy" in the same breath as the U.S. Navy circa summer/fall of 1945.

They would have been blotted out with little more than a shrug from Spruance and/or Halsey's forces. Hell, there were enough ships to actually have a Third and Fifth Fleet by then, no need for the TF 38 / TF 58 ruse any longer.

Also I'm not convinced Moscow would just shrug off an atomic bomb attack.

 

[GrauGeist]

Also I'm not convinced Moscow would just shrug off an atomic bomb attack.

Especially if Red Square was ground zero.

Also, conduct a concerted attack, striking several cities at the same time, like Moscow, Leningrad, Sebastopol, etc.

Regarding the bombs themselves, as the Mark 3 was produced, they progressively got stronger in yield, too - going from 21kt to 23kt.

As far as AA defenses go, Fat Man was released over Nagasaki at an altitude of 29,000 feet (and detonating at about 1,650 feet) which is within range of the Soviet M1939 85mm, but at an altitude of 30,000 feet, it's accuracy will not be as great, especially if the guns were radar directed and pathfinders deployed a version of "window" ahead of the strike force.

 

[33k in the air]

Source of the numbers? According to Ellsberg the US possessed 9 bombs by June 30, 1946. That seems much closer to reality to me

General Groves. See the link kindly provided by EwenS in post #145.

Absolutely. But for a city like Moscow, it is not fatal. That's why the American plans from 1945 required 5-6 bombs - according to the same Ellsberg.

Depends on what you mean by fatal. Is the city permanently gone? Of course not. Hiroshima and Nagasaki recovered; so would Moscow. But it takes time and resources. Until such recovery the city's ability to function as an administrative and control hub is going to be significantly impaired.

 

[EwenS]

With the end of WW2 the US could afford to scale back production of A-bombs and begin a programme to improve the design.

"The Army Air Forces wanted improvements to the design to make it easier to manufacture, assemble, handle, transport, and stockpile. The wartime Project W-47 was continued, and drop tests resumed in January 1946."​

A Mk 3 Mod 0 appeared in mid-1946. By then there were some 50 Mk 3 casings etc but only 9 plutonium cores. Eventually about 120 Mk 3 were produced by 1949, but only 53 cores. The outcome of further redesign was the Mark 4 that entered service in 1949.

The 393rd BS 509th CG remained the sole nuclear bomber unit until mid-1948. IIRC its strength peaked at 22 Silverplate B-29 in early 1946.

 

[33k in the air]

I think you far overestimate the effect.

If NUKEMAP is not to your liking, then try Nuclear Bomb Blast Simulator. The results are similar, which shouldn't be surprising since it's just physics.

In my opinion, these are completely unrealistic figures for Moscow in 1945. Moscow remembered the bombings of 1941, the air defense was equipped with radar - at least the Soviets could spot a bomber and sound the alarm.

The casualty figures are for the present day, as stated, since an online simulator is not going to be using period city data. The physical effects in terms of building damage and radiation exposure are applicable since these are driven by the physics of the detonation.

I don't think you properly grasp the scale involved. 20 kilotons is equal to 20,000 tons of TNT. That's 40,000,000 lbs of TNT. The U.S. 500-lb GP bomb contained about 267 lbs of TNT. To equal 20 kilotons would require some 150,000 such bombs. Dropping that many 500-lb bombs in a single raid would need 3,760 Superfortresses each carrying 40 bombs or 12,500 Flying Fortresses each carrying 12 bombs.

To put 150,000 into perspective, 8th Air Force heavy bombers dropped a total of 1,365,387 of the 500-lb GP bomb during its wartime operations. Thus the power of one atomic bomb is equal to 11% of all the 500-lb bombs dropped; 9 atomic bombs would equal the entire 500-lb bomb effort of the 8AF for the entire war.

That is the destructive efficiency of atomic weapons.

 

[Dimlee]

And this is a comparison of B-29 kill/loss ratios in WWII vs Korea against MiG-15s. Note that even in the Korean war the B-29, against MiG-15, was very slightly positive. Rewind to 1945, when the USSR is fielding Yak-9s and -3s, and La-7s.


View: https://www.youtube.com/watch?v=Uq_epYQLKPY&ab_channel=WWIIUSBombers

If I'm not mistaken (it was discussed on this forum a few years ago), the B-29s loss ratio in the Korean War was less than in WWII.

 

[Dimlee]

Just to back up a bit, I find it quite humorous to even list the Soviet Pacific (or the entire) "navy" in the same breath as the U.S. Navy circa summer/fall of 1945.

They would have been blotted out with little more than a shrug from Spruance and/or Halsey's forces. Hell, there were enough ships to actually have a Third and Fifth Fleet by then, no need for the TF 38 / TF 58 ruse any longer.

Also I'm not convinced Moscow would just shrug off an atomic bomb attack.

The Soviet Navy was pathetically ineffective in the European theatre in WWII. Just one example: its submarine fleet was the largest in the world before the war and its results were minuscule until 1945 when the opportunity arose in the Baltics to hunt and sink German transports in the period of massive evacuation.
I assume that in the backwaters of the Far East region, the quality of personnel and maintenance was even worse. Probably, with one exception: the teams and equipment trained in the USA in 1945.
Should the campaign last until 1946, the Soviet Navy in the Far East would be in big trouble. The Strait of Tartary is covered with ice, La Perouse Strait will be certainly blocked by US forces. Everything in the north of Okhotsk Sea and in Kamchatka will be cut from supplies that were possible only by sea from Vladivostok and several smaller ports in the south of the region. Most of the bays will be frozen so the movement of the ships will be slow, require the assistance of the icebreakers and become problematic in the coastal areas at night time, - even without the mine blockade which certainly will be implemented.

 

[Thumpalumpacus]

If I'm not mistaken (it was discussed on this forum a few years ago), the B-29s loss ratio in the Korean War was less than in WWII.

It was news to me when I saw that video. That channel's very good imo, official documentation given in support.

 

[bf109xxl]

If NUKEMAP is not to your liking, then try Nuclear Bomb Blast Simulator. The results are similar, which shouldn't be surprising since it's just physics.

I perform simulations in semiconductor physics by myself and perfectly know that it is a big mistake to overestimate the precision of the simulations.

The casualty figures are for the present day, as stated, since an online simulator is not going to be using period city data. The physical effects in terms of building damage and radiation exposure are applicable since these are driven by the physics of the detonation.

And it's no longer just physics if you're trying to model the effects of destruction or population casualty rates. You have to average, "reasonably" estimate the coefficients in the models, use some empirical "engineering" formulas, as a result you will get some numbers, but without experimental confirmation their value will be extremely low. Numerical stability of such models may also be extremely low - a small variation of a parameter will lead to a huge difference in the result. Yes, you can very accurately calculate the size of the crater after the explosion, the size of the area where the shock wave will cause buildings to collapse with a certain probability, etc. But these factors will play a much smaller role in estimating casualties than the percentage of the population not in shelters. And in Moscow it will be extremely small, unlike in Hiroshima or Nagasaki. So I am extremely skeptical of such estimates.

I don't think you properly grasp the scale involved. 20 kilotons is equal to 20,000 tons of TNT. That's 40,000,000 lbs of TNT. The U.S. 500-lb GP bomb contained about 267 lbs of TNT. To equal 20 kilotons would require some 150,000 such bombs. Dropping that many 500-lb bombs in a single raid would need 3,760 Superfortresses each carrying 40 bombs or 12,500 Flying Fortresses each carrying 12 bombs.

I think they would do far more damage than one equivalent atomic bomb. They would spread the effect over a much larger area.

That is the destructive efficiency of atomic weapons.

Which is estimated from two rather atypical experiments and incorrectly extrapolated to completely dissimilar conditions.

 

[bf109xxl]

General Groves. See the link kindly provided by EwenS in post #145.

There are estimates of capabilities given there, and they can be overly optimistic. 9 bombs on June 30, 1946 is a reality.

Depends on what you mean by fatal. Is the city permanently gone?

Infrastructure breaks down, military production ceases. One 20 kt bomb in Moscow won't do that. It is too big a city with stone construction and protected subway tunnels. A 1000 bomber raid with less TNT equivalent would be more dangerous, I think.

Of course not. Hiroshima and Nagasaki recovered; so would Moscow. But it takes time and resources. Until such recovery the city's ability to function as an administrative and control hub is going to be significantly impaired.

Moscow is much larger and has a completely different type of building construction. You cannot blindly extrapolate from the experience of Hiroshima and Nagasaki.

 

[bf109xxl]

If I'm not mistaken (it was discussed on this forum a few years ago), the B-29s loss ratio in the Korean War was less than in WWII.

1. The motivation of Soviet pilots was lower than in World War II - they were not fighting directly for their country.
2. Soviet MiG pilots had many limitations in Korea, which reduced the effectiveness of MiGs against the B-29s.
3. The B-29s had an escort. In raids on the USSR it would be absent or inadequate.
4. The USSR could not organize a reasonable rotation of pilots in the Korean War. As a result, the units arriving for replacement had no combat experience and were ineffective suffering heavy losses.
In case of a war against the USSR, the effectiveness of the MiG-15s against the B-29s could have been much higher. But during night raids, most likely, the effectiveness of MiGs would drop much stronger than that of the B-29s.

 

[EwenS]

There are estimates of capabilities given there, and they can be overly optimistic. 9 bombs on June 30, 1946 is a reality.

Firstly Gen Groves was not a man to promise more than he believed could be delivered. Having been in charge of the Manhattan Project since late 1942 he knew better than most what was involved.

Secondly, I don't think you appreciate just what production facilities were becoming available in 1945 and the effect that would have on the number of plutonium bombs becoming available for use in late 1945. Events after that, that Groves could not have predicted when he wrote his Memo on 1 July 1945 then affected the 1946 position. This was after all cutting edge science.

Plutonium Production
The Hanford B Reactor, whose purpose was to generate Plutonium from Uranium metal, began to be loaded with Uranium "slugs" in Sept 1944 and went critical that same month. As the first such reactor it took time to get up to full operational speed with charging not complete until Dec, and didn't achieve full power until Feb 1945 (5 months). It was Plutonium from this reactor which, after processsing (see below) was first sent to Los Alamos in Feb 1945 and was used in both the Trinity Test and the Nagasaki Fat Man bomb.

Hanford D Reactor took 2 months (Dec 1944-Feb1945) to achieve the same.

Hanford F Reactor took 3 weeks (Feb-Mar 1945) to achieve the same.

So by mid-late March all 3 reactors were churning out Plutonium, in addition to the less powerful X-10 reactor at Oak Ridge Tennessee, that had delivered the first few microgrammes of Plutonium back in early 1943.

Processing the reactor output to produce Plutonium for the A-bombs
The first processing plant at Hanford, 221-T, started processing the output from B Reactor in Dec 1944 and was able to sent the first batch to Los Alamos in Feb 1945. By April shipments were in kilogram quantities. These were 98+% pure Plutonium. (Fat Man used 6.2kg of Plutonium). A second processing plant became operational in Spring 1945, and a third was built but not needed before the end of the war, so became a training facility.

Polonium 210
Another essential component of both Little Boy and Fat Man was Polonium 120, which also came out of Hanford. Needed as an initiator for the chain reaction. Problem is that while Plutonium has a very long half life (24,100 years), that of Polonium is only 138 days and it decays into a stable element. And the decay begins as soon as it is produced. So very quickly your A-bomb will simply "fizzle", if it goes off at all, rather than produce a nice big nuclear explosion.

So, if I understand the physics correctly, there is no point in producing a lot of Fat Man bombs after the war ended if you do not intend to use them in the next few months. So that generation of atomic weapons cannot be kept on the shelf for a significant period of time like an HE bomb. Everything relies on producing enough Polonium 210 on an ongoing basis to rebuild the bombs you have every few months.

Postwar rundown
Several things happened after the end of WW2 to slow down production.

Because the 3 reactors at Hanford had been run so hard in 1945 the scientists, who of course had very limited experience of operating these reactors, became worried in early 1946 that the reactors were showing signs of wear (Wigner Effect) and might therefore become inoperable in the not too distant future if high level production continued. And as Polonium 210 was needed on an ongoing basis just to maintain the limited nuclear stockpile let alone expand it, it was decided in March 1946 to place B Reactor at Hanford on standby, and to significantly curtail power on the other two in an effort to conserve their useful lives.

DuPont who had the contract to run Hanford decided to pull out and GE were appointed in their place, taking over the running of the plant at the end of Sept 1946.

Following the end of the war, morale at Los Alamos fell dramatically and there was apparently a lack of direction from the top. Many of the scientists involved in implosion weapon left the Army for civilian life, so adding to the difficulties of maintaining & expanding the stockpile. As a result the Army apparently turned more towards the Uranium Little Boy weapons that relied on Uranium coming out of the Oak Ridge Tennessee facilities. BUt that still relied on Polonium from Hanford.

Finally at the end of 1946 the whole Manhattan Project was wound up and responsibility for everything nuclear passed to the civilian controlled Atomic Energy Commission.

 

[bf109xxl]

Firstly Gen Groves was not a man to promise more than he believed could be delivered. Having been in charge of the Manhattan Project since late 1942 he knew better than most what was involved.

I have a pretty good idea who Leslie Groves was. However, the technology was brand new, some of the effects were not well understood, and any predictions - even by Groves himself - were only predictions.

Secondly, I don't think you appreciate just what production facilities were becoming available in 1945 and the effect that would have on the number of plutonium bombs becoming available for use in late 1945. Events after that, that Groves could not have predicted when he wrote his Memo on 1 July 1945 then affected the 1946 position. This was after all cutting edge science.

New plants won't necessarily be operating at full capacity because the technology is not mature. I work in the high-tech industry (R&D) and have an idea of how problems arise out of nothing simply because the impact of some unimportant factor was not considered.

Polonium 210
Another essential component of both Little Boy and Fat Man was Polonium 120, which also came out of Hanford. Needed as an initiator for the chain reaction. Problem is that while Plutonium has a very long half life (24,100 years), that of Polonium is only 138 days and it decays into a stable element. And the decay begins as soon as it is produced. So very quickly your A-bomb will simply "fizzle", if it goes off at all, rather than produce a nice big nuclear explosion.

So, if I understand the physics correctly, there is no point in producing a lot of Fat Man bombs after the war ended if you do not intend to use them in the next few months. So that generation of atomic weapons cannot be kept on the shelf for a significant period of time like an HE bomb. Everything relies on producing enough Polonium 210 on an ongoing basis to rebuild the bombs you have every few months.

Not exactly. The problem of the polonium neutron initiator was never recognized as limiting factor - it can be replaced that required a complete disassembly of the bomb. However, there were other problems required bomb disassembly, moreover, you should keep the core away from the explosives - the latter degrades due to core heating. The amounts of polonium necessary to cover a 2cm beryllium sphere of the initiator were extremely low.

Postwar rundown
Several things happened after the end of WW2 to slow down production.
Because the 3 reactors at Hanford had been run so hard in 1945 the scientists, who of course had very limited experience of operating these reactors, became worried in early 1946 that the reactors were showing signs of wear (Wigner Effect) and might therefore become inoperable in the not too distant future if high level production continued.

You contradict yourself: the reactors were operating at full capacity, but only 9 cores were produced. So how can you be so sure that more plutonium could have been produced if the capacity was already at its limit?

9 cores in mid-1946 was the reality.

 

[EwenS]

You contradict yourself: the reactors were operating at full capacity, but only 9 cores were produced. So how can you be so sure that more plutonium could have been produced if the capacity was already at its limit?

9 cores in mid-1946 was the reality.

No. From the information I have read over the years was that the US nuclear stockpile in mid 1946 was 9 bombs. To me that reads bombs available for use. It does not mean that there were not more Plutonium cores sitting in storage. As I noted the problem is that the Polonium elements need regular replacement.

Edit:- And it doesn't mean that all the Plutonium produced by Hanford in 1945 actually found its way into completed bombs by mid-1946. Hanford produced the Plutonium. Los Alamos manufactured the bombs themselves. The immediate need for more available A-bombs evaporated with the end of WW2.

 

[bf109xxl]

No. From the information I have read over the years was that the US nuclear stockpile in mid 1946 was 9 bombs. To me that reads bombs available for use. It does not mean that there were not more Plutonium cores sitting in storage. As I noted the problem is that the Polonium elements need regular replacement.

electrical and mechanical components for about 50 bombs were stockpiled at Kirtland Army Air Field by August 1946, but only nine plutonium cores were available

Wiki, ref.

Edit:- And it doesn't mean that all the Plutonium produced by Hanford in 1945 actually found its way into completed bombs by mid-1946. Hanford produced the Plutonium. Los Alamos manufactured the bombs themselves.

I don't see a fundamental difference. It does not matter which stage was the bottle neck.

The immediate need for more available A-bombs evaporated with the end of WW2.

And where did they vaporize to? Did the USSR suddenly become friendly and democratic? Did the Chinese Communists change their faith? But okay, I'm ready to agree if I see a document with direct instructions to reduce the production rate.

 

[33k in the air]

And where did they vaporize to? Did the USSR suddenly become friendly and democratic? Did the Chinese Communists change their faith?

"How can you be so obtuse?" -- Andy Dufresne

If you can't see how the end of a six-year-long shooting war would lead to the sharp curtailment of military production then I don't know what to tell you.

 

[bf109xxl]

"How can you be so obtuse?" -- Andy Dufresne

I hope the blatant insult doesn't go ignored by the moderators.

If you can't see how the end of a six-year-long shooting war would lead to the sharp curtailment of military production then I don't know what to tell you.

All I need are links to the documents. And for Soviet industry such direct orders to reduce military production are known. But not all types of military products were subject to reduction after the end of the war, especially the newest ones. It was either what was already in excess or what could be easily produced. This did not concern atomic bombs in any way.

 

[Thumpalumpacus]

3. The B-29s had an escort. In raids on the USSR it would be absent or inadequate.

You might want to brush up on these:

In case of a war against the USSR, the effectiveness of the MiG-15s against the B-29s could have been much higher. But during night raids, most likely, the effectiveness of MiGs would drop much stronger than that of the B-29s.

What MiG-15s were present in 1945, when this scenario is unfolding? That's right -- none. You can't cherry-pick your years to make your case.

 

[bf109xxl]

You might want to brush up on these:
What MiG-15s were present in 1945, when this scenario is unfolding? That's right -- none. You can't cherry-pick your years to make your case.

The point was made above about the insufficient effectiveness of even the MiG-15 against the B-29 based on the Korean War. But from my point of view direct extrapolation is incorrect. No one mentioned 1945.