Could the Type XXI U-boat have won the war?

[RF]

Generally I find these counterfactual weapons arguments unenlightening.

Taken literally then all arguements and theoretical models used not just in historical debate but any academic discipline become purposeless. This forum would then not exist.

The methodology has to be used to consider matters otherwise you are unable to analyse anything.

I think the arguments here are productive - even the assumptions used in arguing that these subs were useless. I don't think they were useless - one sub did do a dummy attack on a convoy without the target knowing the sub was there, and it had to be a dummy attack because Germany had already surrendered and the sub was under orders to surrender itself.

[alecsandros]

In the real world the Kriegsmarine wanted 1170 Type XXI boats. What they got was 118. Because of horrendous quality control issues of those 118 only four were ever combat-worthy, the rest were floating scrap metal. .

... this was because the production system was constantly under attack... not because the model itself was flawed (or do you have evidence to the contrary ?)

With the type XXI in the water in large numbers in 1943, winning the war in the Atlantic would be highly problematic for the Allies.

[tommy303]

If you insist on two mulligans then I insist on one, that the Allies deploy a powerful millimeter airborne radar that can see even the stealthiest schnorkel at range.

My impression is the Allies did deploy such a radar set, hence the necessity of the Germans mounting a radar detector on top of the schnorkel so it could be lowered before the radar could pick up the schnorkel. I am just not sure at what range a useful return would be coming back to the sending unit, but the danger was already there.

The quality control issues concerning the Type XXI's is undeniable. Material shortages and shortages in skilled labour, together with a rush to get as many built as possible all conspired produce a high degree of faults in many of those boats which were built. I think, had Doenitz not placed all his eggs in one basket by chosing the type VII as the main battle U-boat supplemented by a smaller number of type IX's, it might have been possible to develope the type XXI earlier before the material and labour quality problems set in. As it was, the development of the XXI boats was left until the U-boat offensive had been decisively defeated in 1943 and represented merely a hope that it might return the U-boat arm to being on the offensive rather than the defensive. All this of course does not take into consideration that by the end of 1943, not much else could help Germany which was being defeated and ground down on land in the east, thus the chance of the XXI boats being able to alter the course of the war passed before any serious design work on them had begun.

[RF]

... this was because the production system was constantly under attack... not because the model itself was flawed

Not just under attack, but facing severe shortages of materials and skilled labour, as well as a lack of proper strategic planning at the top.

With the type XXI in the water in large numbers in 1943, winning the war in the Atlantic would be highly problematic for the Allies.

Agreed

[Dave Saxton]

If you insist on two mulligans then I insist on one, that the Allies deploy a powerful millimeter airborne radar that can see even the stealthiest schnorkel at range.

A powerful millimeter radar with range is not possible. By 1944 they had succeeded in producing millimeter waves at 10kw at 10% efficiency. The British gave up when it was realized that millimeter waves are absorbed by atmospheric humidy to such an extent that even megawatts of power could not yield worth while range attainments.

Effective Type XXI operation was a realistic possibility had the war taken a different course. Millimeter wave radar at sea is not realistic.

[ede144]

When memory serves, than the Walter boat development started in the 30. Dönitz found out as late as 1942 or 43and iimproved priority. It was decided in late 43 or 44 to replace the Walter turbine with electric drive

[RF]

What surprises me is that given the vulnerability of slow moving and shallow depth submarines to depth charging that no real thought orprority was given to the development of a faster moving submerged submarine in the late 1930's, particulary with the inception of the Z Plan and perhaps more pertinently the outbreak of war in 1939.

But again I suppose the focus was on the big battleships as prestige objects, rather than a critical evaluation of what was actually needed to win a war.

[Djoser]

One of the biggest advantages to stopping or slowing the Allied convoys would be slowing down the influx of trucks to the Red Army (the entire Studebaker run was designated for the Red Army). Without these trucks it would have been impossible both for the infantry to keep up with the armor and for the Red Army to keep the front line units fully and rapidly supplied (a la the Red Ball Express). Thus the pressure on the front line German units would have been lowered, and the Soviets unable to "blitz" at more than a local level, and the level of attrition increases.

The potential ramifications are interesting to ponder.

Precisely. Without all those trucks, the Soviets would have been forced to build way less tanks, or had the tank and mechanized armies slowed down to a fraction of their strategic speed.

If the US could not ship trucks, tanks, or armies to England safely, there would have been no Overlord either. Whole different ballgame on both fronts.

[delcyros]

Type XXI production and use table. Max. aviability was little over 120 type XXI submarine aviable early in 1945 with only a fraction in front flotillas.

Just keep one thing in mind:
The closest parallels to type XXI were the soviet ZULU-class Diesel-electric submarines and the US TANG class. The WHISKEY-class benefitted from some XXI technology but the soviets never considered it as a good aequivalent to the XXI. Similarely GUPPY-refitted US fleet boats benefitted from some experiences but never were considered the equal of a type XXI.

How many ZULU´s were ever commissioned? How many TANG´s?

[Dresden]

One of the biggest advantages to stopping or slowing the Allied convoys would be slowing down the influx of trucks to the Red Army (the entire Studebaker run was designated for the Red Army). Without these trucks it would have been impossible both for the infantry to keep up with the armor and for the Red Army to keep the front line units fully and rapidly supplied (a la the Red Ball Express). Thus the pressure on the front line German units would have been lowered, and the Soviets unable to "blitz" at more than a local level, and the level of attrition increases.

The potential ramifications are interesting to ponder.

Precisely. Without all those trucks, the Soviets would have been forced to build way less tanks, or had the tank and mechanized armies slowed down to a fraction of their strategic speed.

If the US could not ship trucks, tanks, or armies to England safely, there would have been no Overlord either. Whole different ballgame on both fronts.

To further expand on this it is my understanding that when the Soviet assault on Berlin was being prepared Stalin told Zhukov and Konev that this was it: the Soviets were at the bottom of the manpower barrel and there were no more troops to call up, etc. Now, take that real-world occurrence and then project it onto a "what-if" where the Soviets suffer heavier attrition and slower advances from '42 to March '45 due to lack of mechanical transport....

For implied evidence, look at the constant shrinking of the establishments of Soviet infantry divisions.

[RF]

The implication here is that if Manstein had his way from mid 1942 and had no interference from Hitler then he could have won the Russian campaign by attrition......

[fredleander]

Considering that the technology that the XXI, and the German homing torpedoes, were based upon were known long before the emergency building programs were started, a year earlier start would certainly have created serious problems for the Allies. Also because much of the production and quality issues of the XXI resulted from the steadily improved Allied bombing campaign as the end of the war approached.

Not to mention two years headstart.

The same could be said about the Heinkel 162 fighter. That product's main operational issue was its short range which could have been remedied by the simple means of a drop-tank. Started one yearlier, the quality issues could have been solved in half of that time, giving a half year more operational time. Of course, the German pilot problem was another matter.

Nice graph, delcyros!

Fred

[RF]

a year earlier start would certainly have created serious problems for the Allies. Also because much of the production and quality issues of the XXI resulted from the steadily improved Allied bombing campaign as the end of the war approached.

Not to mention two years headstart.

To be decisive it the XXI would have to be fully operational by March/April 1944 at the latest in order to make the D-Day landings questionable at least, cancelled altogether better still. They would need to be in sufficient numbers to attack not only the North Atlantic convoys but also the convoy routes to the USSR. Another area where a few of these subs could make an impact would be off the Pacific coast of Panama interdicting US shipping at a focal point and providing help to the Japanese.

[delcyros]

This is part of an excerpt I wrote to a friend in this matter:

The problem with an idea that type XXI would be feasable in 1943 is multifold.
As a matter of fact, the XXI benefitted by it´s late arrival (beeing introduced to production by late 43 and early 44) in one or the other form from advances in ASW technology and operation conducted by the allies meanwhile.
This allowed a significant number of technological responses to be incorperated in the design. Let me list some of them here:

[1] The Snorkel.
It seems simple but with an earlier introduction date, the need to ship Snorkels sinmply wouldn´t be there. The Snorkel was about refitted to german U Boats in the same time as it was incorperated to the XXI design. Without Snorkel, the submarine would have to surface to recharge it´s batteries.
The Snorkel greatly reduced the exposure to radar detection, it´s principal reason of existence. If an XXI would be avaiable in 1943 it means introduction in service 1941 latest, and there isn´t much Radar in play yet (particularely airborne search radar)

[2] The high degree of silentness.
The XXI was designed for 18kts submerged speed. The actual design as executed was somehow slower, beeing 16.25kts fast at the 1 hour discharge rate. This had three reasons: (a) a reduced high current discharge capacity of the choosen batteries, the choice of the number of flooding slits, and (c) a change in the prop design, which wasn´t as efficient at high rpm but allowed delayed cavitation at lower rpm (close to surface no cavitation up to 122rpm -which is roughly 6kts). This is a rather critical tradeoff as it allowed to operate more silently in all conditions. The RN rebuildt one S-class submarine for high underwater speed trials in 1944 and the listening trials suggested to the RN that an effective counter to high submerged speed submarines may be the use of hydrophone listening due to the large amounts of noise generated by HMS SERAPH at high underwater speed. SERAPH was equipped with special high rpm efficient props to allow for the high underwaterspeed which weren´t quited. It was suggested that XXI beeing substantially larger than SERAPH would be even noisier so that passive sound detection should in principle work and correspondingly, much of the wartime counter procedures were incorrectly centered on a wrongly anticipated noisyness of this type. This may have been the case had a faster XXI with 17-18kts at the 1 hour discharge rate appeared in 1943.
Historically, and as executed, type XXI submarines were drastically more silent both, at low and high underwaterspeed, rendering this "response" entirely ineffective.
When U-2513 was trialed in 1946, it was found to be as noisy at 15kts as a BALAO-class fleet submarine was at 8kts. In top of that, while running on creep engines (6kts), it couldn´t be detected at all with the period USN sound listening gears. This silentness is what frustrated so many approaches to the problem formulated by the advent of XXI-type submarine but it´s not clear that the very high degree of silentness would also have been present in an early XXI, particularely because it also evolved out of the need from experiences os U boats facing ever increasing levels of allied ASW.

Attached is a graph from Urich, R. Principles of Underwater Sound, p.338.
It´s not from wartime data but from 1946 trial data on U 2513, but so be it. As can be determined, at 100m operational depth, the boat may run 10kts at the same relative noise level as 6 kts at the surface, which would be close to undetectable. The noise optimised prop was a great deal in this types capabilities.

[3] Radar and radar detectors
Historically, XXI were fitted with a complete set of radar and radar detectors which weren´t yet avaiable in 1943.

[4] active/passive horizontal lot for FC
While the passive sound detection GHG array was -more or less- standart equipment in all U boats, active S devices were, unlike in USN boats uncommon prior to XXI. The horizontal active device Nibelung is broadly comparable with the attachment "SWORD" in 1945 RN ASDIC, but having up to 8 times the effective range of it. It was precise enough to attain firecontroll solutions against surface or submarine vessels with three pings, which could be detected but not measured due to the choice of amplitude modulation with 1945 equipment. This very powerful active set would not be avaiable in 1943.

[5] Kurier
HF/DF was effectively countered by using Kurier type burst encrypts with sending times in the ms range. It would not be possible to HFDF these short messages with the period technology. Kurier was introduced in march 1945 and wouldn´t be avaiable in 1943.

On top of that, what is an XXI even in 1943 supposed to do against russian tanks in the East? Removing Hitler from command of the Army would be more effective than any XXI ever could hope to be in that regard.


Additionally, I remain sceptical that the XXI is a good submarine platform for the confined waters of the Channel. The XXIII is probably a more reasonable platform, less technoclogically challanging (no S-device, no radar and radar detectors) and by the virtue of it´s tiny size stealthy enough.

addendum: Contrary to what You may read in many secondary sources, the He-162 didn´t had poor range or endurance by design. It´s endurance was quite good compared to other contemporaries on internal fuel (same as P80, slightly worse or better than Meteor III (depending on time and cleared capacity) and considerably better than P59, MiG-9, Yak-15 and Vampire F1). However, operational shortage of fuel meant that it was never flown with full capacity fuel load and it´s mission profile called JG1 to execute low level sweeps where fuel consumption is worst.

[pdunderhill]

Well since this a 'what if' type of question...
On the assumption that type 21s had extended the War in the Atlantic by two years, and assuming that the KM U-Boats had stayed in the Atlantic, there's no great history of the German Navy straying far from home, Southern Indian Ocean excepted.
I still believe the US would have continued, and possibly expanded the Manhattan project to produce a fourth, fifth or even sixth weapon. Trinity, Hiroshima and Nagasaki being one, two and three.
My point being Berlin and 'an other German City' could have been 2 and 3.
I apologize if I'm telling Gran about eggs, but the Axis loses, whether by an internal coup, wholesale revolution precipitated by the USAAF use of an Atomic Bomb or most likely an overwhelming force from the East.

Sure the XXis were good in fact very good but their reliance on RF coms would inevitably have given their locations and plans away.

I still believe that many people underestimate the role of GCCS at Bletchley Park, the staff there were an incredible mish-mash of people, we should be more aware and hold very great respect for them.

Anyway I'll prob get a b-king from the mods for irrelevancy!

Peter