What if the Germans had the Type XXI in production by Jan 1942

OK, a few responses.
The U-boats arent going to spend their entire time submerged. Charging with the schnorkel (especially the early versions) was not easy, it resulted in a lot of 'gasping' as the air cut off, on, off, on. You can probably get them to stay submerged in Biscay (after the aircraft start taking a toll), but I see it was very unlikely in mid atlantic. They dont know about centimetric radar, remember.
IN any case, any sort of issue or problem is going to make them want or need to surface, so they will still lose some boats to air attacks - not as many, though.

Squid isnt obsolete - if it was, the RN wouldnt have spent the time and money postwar developing Limbo to use against these sorts of boats.
Its better if you have a faster escort, and its better when you have more than one escort,but it will still happily sink elektroboots.
The homing torpedo was slow to reduce noise issues at speed, and probably to make it lighter too. Quite easy to get the speed up when intel shows Germany is developing a fast U-boat. It simply wasnt needed OTL

You cant use the pressure hull from the 9 for the 21, they were quite different sizes and shapes. You need to develop a new hull from scratch. Tank tests have limited use (they werent that sophisticated at the time), and in particular the analysis is slow, so it takes a long time. This isnt such a big deal normally (as you are rarely looking at a radicaly different hull design), but this time you are.
I was being generous to the Germans both for development times and build times.

Based on displacement (remember, no fancy electronics in WW2 ships, so there is a very close tie in between displacement and cost) the 21 will cost around 60% more than the 9. So thats either a lot more resources, or fewer boats.

I'm confused that convoys werent the U-boats main targets?? Precisely what were they doing in mid-atlantic then???

The high uw speed helps reaquisition a bit, but not that much - remember, they are only about as fast as they were OTL on the surface, and denial of reaquiring works pretty well then.

While the 21 is a better uw boat than the 7 or 9, I'm rather unconvinced its a miracle war winner. Indeed, looking at resources, numbers, and so on its possible to argue it would be LESS damaging to the convoys than in OTL.
Given the limitations of WW2 tech, there are certain advantages in numbers.
My personal feeling is that it would result in more sinkings at first, that the British will certainly be aware its coming (and I see no way its there before 1941 at the earliest, and late 41 is I think more realistic), resulting in faster development of some weapon systems, and taking a bit longer to grind the u-boat campaign to a halt, but its not going to have a huge effect on the war by that time.
 
Astrodragon said:
The U-boats arent going to spend their entire time submerged. Charging with the schnorkel (especially the early versions) was not easy, it resulted in a lot of 'gasping' as the air cut off, on, off, on. You can probably get them to stay submerged in Biscay (after the aircraft start taking a toll), but I see it was very unlikely in mid atlantic. They dont know about centimetric radar, remember.
To be clear, I wasn't suggesting they never surface, only that they can recharge udw as needed. It's also possible to recharge shallower, to avoid waves choking the mast.
Astrodragon said:
Squid isnt obsolete - if it was, the RN wouldnt have spent the time and money postwar developing Limbo to use against these sorts of boats.
My sense was, Squid & Limbo were too slow-reacting against fast boats because of the sink rate. If there's less success earlier, I imagine they'd be supplanted in favor of homing fish. I won't rule out Squid, tho.
Astrodragon said:
The homing torpedo was slow to reduce noise issues at speed, and probably to make it lighter too. Quite easy to get the speed up when intel shows Germany is developing a fast U-boat. It simply wasnt needed OTL
Even the Mk24 did have self-noise issues. Can you feature it working in combination with pingers from sonobuoys?
Astrodragon said:
You cant use the pressure hull from the 9 for the 21, they were quite different sizes and shapes.
Why not? USN used Gato, Balao, & Tench pressure hulls for GUPPYs OTL. It's the exterior form that's important, not the pressure hull. (It's not like you're really after the Albacore form.:rolleyes:) Even allowing they fit a hull plug to increase battery capacity, which USN did, the changes aren't necessarily large.
Astrodragon said:
I'm confused that convoys werent the U-boats main targets?? Precisely what were they doing in mid-atlantic then???
That's a statistical fact. It's a common belief U-boats scored most of their sinkings in convoy, but it's not true. Most sinkings were ships sailing alone, or ships roaming ahead of, or straggling behind, convoys. Only 0.7% of ships in convoy were sunk.
Astrodragon said:
The high uw speed helps reaquisition a bit, but not that much - remember, they are only about as fast as they were OTL on the surface, and denial of reaquiring works pretty well then.
Granted. I suggest the difference is, they can do it without being spotted, contrary to OTL Type VIIs.
Astrodragon said:
While the 21 is a better uw boat than the 7 or 9, I'm rather unconvinced its a miracle war winner. Indeed, looking at resources, numbers, and so on its possible to argue it would be LESS damaging to the convoys than in OTL.
Given the shocked Allied reaction to Type XXIs OTL, I seriously doubt it.
Astrodragon said:
its not going to have a huge effect on the war by that time.
I strongly disagree. In about June '43 OTL, with U-boats more/less under control, & after heavy losses in a convoy battle (IIRC biggest of the war), the Brits seriously considered abandoning convoys.:eek::eek: With *Type XXIs in '42 (I agree, sooner is very unlikely), it's probable the very same crisis arises, only this time, there's more merit in it. Do the Allies actually abandon convoys in response?:eek::eek::eek::eek: Or do they see technological responses can cope & hold on until the *Mk27 Mod 4:p is ready?
 
Squid and Limbo have very good sink rates - 42 ft/sec for squid
they'd got their act together by them and made them streamlined

You do need a completely different hull for the 21, you have to get the batteries in it! they were HUGE...

The reason the Type 21 was a shock for the allies is probably that they werent expecting it at the very end of the war (theyd got a bit complacent about the sub threat by 1944). Given that its during the war, its just another, better sub to fight, there wont be the same shock effect at all.

The whole issue with ho,ing torpedo speeds and noise for passive sonar is very complex.
However the U-boats also have a problem. The faster they go, the more noise, so the easier for the torpedo even if its degraded by its own speed. There isnt any simple answer to this particular problem, though, or a set solution.
 
Astrodragon said:
Squid and Limbo have very good sink rates - 42 ft/sec for squid
they'd got their act together by them and made them streamlined
Fair enough.
Astrodragon said:
You do need a completely different hull for the 21, you have to get the batteries in it! they were HUGE...
That's why I suggested a hull plug. Unless I'm mistaken, the difference wasn't so much design as capacity, & increased capacity can be handled within the existing hull plan.
Astrodragon said:
The reason the Type 21 was a shock for the allies is probably that they werent expecting it at the very end of the war (theyd got a bit complacent about the sub threat by 1944). Given that its during the war, its just another, better sub to fight, there wont be the same shock effect at all.
The real shock, as I understand it, was in the difference in capability of the Type XXI.
Astrodragon said:
However the U-boats also have a problem. The faster they go, the more noise, so the easier for the torpedo even if its degraded by its own speed.
True, but the Type XXI OTL was quiet even at fairly high speed compared to the Type VII. The Mk 24 would have been outrun by Type XXIs, so it didn't matter if they were noisy.
 
Fair enough.

That's why I suggested a hull plug. Unless I'm mistaken, the difference wasn't so much design as capacity, & increased capacity can be handled within the existing hull plan.

Sorry, the pressure hulls were completely different. And the 21 required far more internal volume for the required battery capacity.
IIRC, the US Gato mods were a hull plug, which could be done using the advanced US welding teqniques available at the time. But the changes for the 21 would have been way beyond that (and given the more-than-a-little-iffy quality of German shipbuilding welding, I wouldnt have wanted to go out in one!!
 
Astrodragon said:
Sorry, the pressure hulls were completely different. And the 21 required far more internal volume for the required battery capacity.
That presumes the exact same design is used. I see no reason that needs to be true, if the idea is to get them in service sooner...
 
Sorry, the pressure hulls were completely different. And the 21 required far more internal volume for the required battery capacity.
IIRC, the US Gato mods were a hull plug, which could be done using the advanced US welding techniques available at the time. But the changes for the 21 would have been way beyond that (and given the more-than-a-little-iffy quality of German shipbuilding welding, I wouldnt have wanted to go out in one!!

The GUPPY conversions of US fleet boats did not use any hull plugs to gain extra internal volume for additional battery capacity, but rather rearranged the storage and auxiliary machinery spaces located on the lower deck of the submarine below the control room, as well as occupying part of the after battery compartment (and were actually a couple feet shorter than unconverted fleet boats due to reshaping the bow.)

According to Friedman's, on a GUPPY conversion, the forward battery was rearranged so it could hold 168 cells of a new, more powerful type instead of the 126 normally found on a fleet boat, while the former magazine for deck gun ammunition & a couple freshwater tanks were converted into additional battery tanks that could hold 68 more cells; the aft battery tank was extended all the way to the bulkhead separating the aft battery compartment from the pump room located under the control room by moving a couple storerooms for provisions.

AFAIK, the only US fleet boats used operationally to have been fitted with hull plugs were the 9 GUPPY IIIs (converted from existing GUPPY IIs in the early 1960s as part of the FRAM program, & had a 15' section inserted to provide room for the extra sonar & fire control equipment and plotting space needed to use the Mk. 45 nuclear torpedo) & 6 Gato-class boats converted to radar pickets in the early 1950s under Project Migraine III (30' plug inserted to provide space for radar equipment & a CIC where air contacts could be plotted & fighters directed.)

Something else to consider is that if one's trying to build a fast submarine, length & wetted surface are things to be minimized as they create drag underwater, so a hull plug wouldn't be the best solution The Type XXI had a figure-8 pressure hull, as it used the hull designed for the Walther-cycle XXVI, which had the lower hull as a fuel tank for the volatile hydrogen peroxide fuel used by the Walther turbine, but as that technology was immature, the Type XXI was developed as a more conventional interim submarine, using the lower hull as a giant battery tank. However, the figure-8 isn't the most efficient hull form, & after analyzing it in model tests & operational trials of captured XXIs post war, the USN decided to go with a conventional circular hull for the Tang-class, as compared to the XXIs figure 8, it had greater usable internal volume & less wetted surface for the dimensions.

As for the viability of a 'GUPPYized Type IX' as some sort of interim solution, one'd have to look at some schematics for the class to see whether it'd be possible to increase battery capacity through internal rearrangements, & if so, by how much, ideally in concert with a more powerful type of battery & electric motors.
 
DD951 said:
The GUPPY conversions of US fleet boats did not use any hull plugs to gain extra internal volume for additional battery capacity
Didn't AFAIK, but "could not" is another matter.
DD951 said:
...the forward battery was rearranged so it could hold 168 cells of a new, more powerful type instead of the 126 normally found ...the aft battery tank was extended all the way to the bulkhead separating the aft battery compartment from the pump room located under the control room by moving a couple storerooms for provisions.
They were also smaller...& less "durable", needing to be replaced more often. Also, the magazine was deleted in some boats; these *Type XXIs could forego deck gun ammo, too.
DD951 said:
AFAIK, the only US fleet boats used operationally to have been fitted with hull plugs were the 9 GUPPY IIIs (converted from existing GUPPY IIs in the early 1960s as part of the FRAM program, & had a 15' section inserted to provide room for the extra sonar & fire control equipment and plotting space needed to use the Mk. 45 nuclear torpedo) & 6 Gato-class boats converted to radar pickets
That sounds right to me, too. (Where did I put my copy of Alden...:eek:)
DD951 said:
As for the viability of a 'GUPPYized Type IX' as some sort of interim solution, one'd have to look at some schematics for the class to see whether it'd be possible to increase battery capacity through internal rearrangements, & if so, by how much, ideally in concert with a more powerful type of battery & electric motors.
A lot of GUPPYs also deleted one of the main engines. Switching to a more compact engine (from the Type II?) could accomplish that, couldn't it? They could, in a pinch, delete the after torpedo tubes & use the space for something else.
 

Sumeragi

Banned
There seems to be an obsession with altering the Axis order of battle so that they win WWII. Yet there rarely seems to be any interest in the reverse, is "Souping up" the Allies for a faster victory. What if Coastal Command got 12 Squadrons of B-17s by 1939? What if 2 fleet submarines intercepted and sank several carriers on the 6th December 1941? What if, during the 30's Stalin shipped a bunch of generals off to Siberia instead?

No, these, some what foolish, ideas are nearly always skipped for "How can the Nazis win". Reminds of the re-enactors who dress up as the SS, maybe they should look at their motivations and look at what they are saying about themselves.
The Allies in OTL were pretty much a wank even by regular standards. It isn't fun to somehow get them even more wanked :p
 
Consider Henschel...

I sometimes think that Germany would have done better to use guided bombs from long-distance aircraft to a much greater extent.

And I'm glad they didn't.

Apropos my viewpoint, the dining table from my father's family home in Herne Hill had a scar from damage when the ceiling fell in. If that V-1 had been a bit closer, I wouldn't be alive. Herne Hill had the heaviest concentration of V-1 hits in London.

Types XXI and XXIII were examples of German engineering brilliance without the resources and time to deploy properly.

And the Schnorkel? First used by Cornelius Drebble in the 1640s, patented in 1910 by an ingenious Scottish engineer. So, yes, that does beat the Dutch.
 
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