Earlier Type XXI - informed by Cold War developments

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Re: Earlier Type XXI - informed by Cold War developments

Post by T. A. Gardner » 16 Jul 2020 16:34

I posit it is still vulnerable. As we know, at full speed on a fully charged battery--the later being a rarity going into action as the boat would be off snorkel and submerged well prior to the actual engagement--it has something like 10 to 15 nm of range at 15 to 17 knots. That's not much distance to get away from pursuers, particularly aircraft.

On those, sonobuoys would still be effective contrary to TMP's assertion. The AN/CRT-1 series has a working range of about 300 to 6000 yards depending on sea state and water conditions. A plane laying down a pattern of these takes between 8 and 15 minutes to do so depending on the model of aircraft and the pattern chosen to deploy. The standard 5 or 6 buoy circular pattern takes about 12 minutes to lay down and assuming that the center buoy is directly on top of the Type XXI when dropped and the boat immediately recognizes the sonobuoy is there, and goes to top speed to evade, can't escape the search area of the pattern before it is laid. That's a lot of 'if's' to meet. Worse, if the aircraft maintains contact it will be able to run the Type XXI's battery down in a high speed chase it can't get out of to a point where it becomes vulnerable to attack or forced to snorkel to recharge its battery.

Even surface escorts with a 20 knot speed would be sufficient to hound a Type XXI into impotence. The German boat doesn't have sufficient high speed endurance to run any really safe distance. Instead, it's high speed is really only useful for evading immediate attack with then extant weapons, particularly depth charges. Against Squid, not so much as this has a sink rate of 44 fps or about 7 seconds at 300 feet depth. Hedgehog would take 13 seconds to get that deep.
The problem with depth charges is the boat has warning as the attacker moves over it and laying a full pattern of charges will take several minutes on its own to complete, plenty of time for the boat to evade at 15 or 17 knots.

To beat a Type XXI, the Allies need a 25 knot escort. They have that. They need ahead thrown weapons with fast sink rates or guided ones. They have those. They need a scanning sonar versus a searchlight sonar. They got those late in the war. Aircraft with ASW weapons. They have those.

The British problem for much of the war is they are using the 'poor man's' escort ships like the Flower class. The US by 1943 isn't. They are using the destroyer escort with a 25 to 28 knot top speed. Both the US and British have the weapons and sensors in place with the exception of a scanning sonar. Aircraft can and would be effective against a Type XXI just as they were against postwar electric submarines with higher submerged speeds.

Yes, the Type XXI is a big improvement on the earlier Type IX, but it isn't revolutionary so much as evolutionary. It is the nuclear sub with unlimited underwater performance that's the game changer and Germany isn't getting those.

What Germany needed to really up their game in the Battle of the Atlantic was a fully committed Luftwaffe with aircraft that had the range and weapons to attack ships in 1940 along with a system in place to allow them to cooperate with U-boats at sea. The planes supplement the boats in attacking merchant shipping and act to greatly, massively, increase the search area and rate for the U-boats that become more effective because they have more target data available.

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Re: Earlier Type XXI - informed by Cold War developments

Post by TheMarcksPlan » 16 Jul 2020 17:03

T.A. Gardner wrote:Even surface escorts with a 20 knot speed would be sufficient to hound a Type XXI into impotence.
Yeah I get your position. What you haven't explained is why your analysis of the existing escorts' chances should be valued over that of every ASW expert in the Royal Navy.
T.A. Gardner wrote:To beat a Type XXI, the Allies need a 25 knot escort. They have that.
Again, they couldn't use asdic above 20 knots, not even in 1946.
And even at 20kn asdic detection range is quite low.
20+kn speed is useful in getting the escort to the datum quickly, thereby reducing the search area. But the T21's speed escalation over T7/9 is far greater than a 25kn escort's over a 20kn escort - meaning the search area remains exponentially larger than before.
T.A. Gardner wrote:sonobuoys would still be effective contrary to TMP's assertion.
I haven't made any assertions about sonobuoys...

But let's look at what the RN thought in '47-'48:
once a submarine submerged
the only means aircraft had of detecting it was by using sonobuoys, but these only
worked effectively when the submarine’s acoustic output was high enough to be
recognized against the background noise. Thus the sea had to be relatively calm, the
submarine travelling at high speed and not too deep. Training continued in the use
of sonobuoys into the immediate post-war period, but JASS reminded its students
that the buoys were not suitable for searching large areas, in part because relatively
few buoys could be monitored by an aircraft, but also because the detection range of
individual buoys was short, and only limited stocks of these heavy buoys could be
carried in each aircraft (especially in naval types).
RNASW49 at 134.

So the buoys have some utility but they aren't a game-changer either. They can't be used in close proximity to a convoy-escort-sub battle because background noise will be too high for detection. Outside of such battles, the sub isn't likely to be travelling fast enough to register on the buoys.
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Re: Earlier Type XXI - informed by Cold War developments

Post by Lars » 16 Jul 2020 18:49

An XXI-prototype was skipped to save time. Otherwise the XXI was not operational before 1946. I don't precisely remember how much time was saved by skipping a prototype but I believe it was in the order of 18 months. Building an XXI without a prototype was like building a B-29 without a prototype. Bugs could be ironed out in the end but it would take time.

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Re: Earlier Type XXI - informed by Cold War developments

Post by T. A. Gardner » 16 Jul 2020 21:15

TheMarcksPlan wrote:
16 Jul 2020 17:03
Yeah I get your position. What you haven't explained is why your analysis of the existing escorts' chances should be valued over that of every ASW expert in the Royal Navy.
You are making your rebuttal in the form of an appeal to authority, a logical fallacy.
Again, they couldn't use asdic above 20 knots, not even in 1946.
And even at 20kn asdic detection range is quite low.
20+kn speed is useful in getting the escort to the datum quickly, thereby reducing the search area. But the T21's speed escalation over T7/9 is far greater than a 25kn escort's over a 20kn escort - meaning the search area remains exponentially larger than before.
There's sprint and drift. There is also working in pairs or with aircraft. Everybody doesn't have to be a sensor platform. Aside from that, given that realistically, a Type XXI couldn't use more than about 10 to 12 knots, if that, to escape a determined pursuer given its endurance on battery at full charge being about 1 hour at 17 knots, means that the ship is going to be able to catch up at speeds where it can use its sonar.
I haven't made any assertions about sonobuoys...

But let's look at what the RN thought in '47-'48:
once a submarine submerged
the only means aircraft had of detecting it was by using sonobuoys, but these only
worked effectively when the submarine’s acoustic output was high enough to be
recognized against the background noise. Thus the sea had to be relatively calm, the
submarine travelling at high speed and not too deep. Training continued in the use
of sonobuoys into the immediate post-war period, but JASS reminded its students
that the buoys were not suitable for searching large areas, in part because relatively
few buoys could be monitored by an aircraft, but also because the detection range of
individual buoys was short, and only limited stocks of these heavy buoys could be
carried in each aircraft (especially in naval types).
RNASW49 at 134.

So the buoys have some utility but they aren't a game-changer either. They can't be used in close proximity to a convoy-escort-sub battle because background noise will be too high for detection. Outside of such battles, the sub isn't likely to be travelling fast enough to register on the buoys.
Roughly 40% of all U-boats were sunk by aircraft in WW 2, the bulk of those beginning in 1943. Sonobuoys became available about the same time. They were a game changer.
Before sonobuoys were available, once a sub submerged, it had pretty much evaded air attack as aircraft had no means to find it. The US introduced MAD early on, but it was found to be too short-ranged to find and track a sub almost every time. Sonobuoys were the first sensor introduced that an aircraft could use to find and track a submerged submarine successfully.
Sonobuoys proved capable of detecting submarines in most conditions and generally at ranges of 1 to 3 miles. When combined with MAD, the two proved very effective at tracking and allowing an aircraft to successfully attack a submerged boat, something that previously had not been possible.

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Re: Earlier Type XXI - informed by Cold War developments

Post by Terry Duncan » 18 Jul 2020 10:58

TheMarcksPlan wrote:
16 Jul 2020 16:29
Terry Duncan wrote:However, if we assume the supply of these boats is possible it is not going to happen early on in the war due to the design process taking years to arrive at the Type XXI, they did not spring from thin air, they are the product of war experience and so you need actual time at war before they even become possible, somewhere like the end of 1942 just for the idea!
Were the KM competently invested in submarine R&D, they likely would have come up with the idea earlier. The motive was already there: Donitz had briefly to cease all night-time surface attacks in May 1941 due to radar. That's 1.5 years earlier than OTL T21 genesis.

Within the KM, it took inordinately long for the Walther types to get strategic-level discussions and for KM engineers to be invited to discuss the proposal. When this finally happened in Fall '42, one of the engineers made the obvious point that maybe we should just fill the extra hull space with more batteries instead of hydrogen-peroxide.

All that has to happen is that some competent, higher-level engineers/designers see the Walther proposals earlier and the obvious idea would have taken hold.

Donitz bears a lot of the blame here as well. He made basically zero efforts from '38 onwards to invest in submarine design.

As with all things, a strategically-better Hitler would have made a difference also. Had he stuck to his original anti-big-fleet position and refused Raeder's Plan Z scheme and its strategic drift, the KM would have focused earlier and better on submarine development.
A major hitch is going to be the lack of war experience that will be available to contribute to the final product. The Germans cannot deploy countermeasures to an Allied technology or tactic they have not seen yet, it takes actual war experience which I would say makes a Type XXI unlikely to be any earlier than maybe 6 months at best.

The British have the WWI R class submarines that showed the way forward, yet they proved to have little influence on British subs between the wars. Simply enlarging such a design and fitting more modern technology could see a very effective WWII weapon with the knowledge we have today, but as of 1939, they looked to be a dead-end in most respects.

https://en.wikipedia.org/wiki/British_R-class_submarine

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Re: Earlier Type XXI - informed by Cold War developments

Post by Ружичасти Слон » 20 Jul 2020 20:27

Terry Duncan wrote:
18 Jul 2020 10:58
TheMarcksPlan wrote:
16 Jul 2020 16:29
Terry Duncan wrote:However, if we assume the supply of these boats is possible it is not going to happen early on in the war due to the design process taking years to arrive at the Type XXI, they did not spring from thin air, they are the product of war experience and so you need actual time at war before they even become possible, somewhere like the end of 1942 just for the idea!
Were the KM competently invested in submarine R&D, they likely would have come up with the idea earlier. The motive was already there: Donitz had briefly to cease all night-time surface attacks in May 1941 due to radar. That's 1.5 years earlier than OTL T21 genesis.

Within the KM, it took inordinately long for the Walther types to get strategic-level discussions and for KM engineers to be invited to discuss the proposal. When this finally happened in Fall '42, one of the engineers made the obvious point that maybe we should just fill the extra hull space with more batteries instead of hydrogen-peroxide.

All that has to happen is that some competent, higher-level engineers/designers see the Walther proposals earlier and the obvious idea would have taken hold.

Donitz bears a lot of the blame here as well. He made basically zero efforts from '38 onwards to invest in submarine design.

As with all things, a strategically-better Hitler would have made a difference also. Had he stuck to his original anti-big-fleet position and refused Raeder's Plan Z scheme and its strategic drift, the KM would have focused earlier and better on submarine development.
A major hitch is going to be the lack of war experience that will be available to contribute to the final product. The Germans cannot deploy countermeasures to an Allied technology or tactic they have not seen yet, it takes actual war experience which I would say makes a Type XXI unlikely to be any earlier than maybe 6 months at best.

The British have the WWI R class submarines that showed the way forward, yet they proved to have little influence on British subs between the wars. Simply enlarging such a design and fitting more modern technology could see a very effective WWII weapon with the knowledge we have today, but as of 1939, they looked to be a dead-end in most respects.

https://en.wikipedia.org/wiki/British_R-class_submarine
For to summary

Imagination story was write for to make Germany submarines mostest deadly for maximum period for to change result of war.

1. Since 80 years on hindsight must to change persons what was make decisions long times before and must to change many decisions what was made long times before.

2. Must to assume imaginations persons and imaginations decisions was be perfect for to get result what imaginations storys was want for to happen.

3. Must to assume imaginary persons and imaginary decisions are most good for to have technologies many years before real history.

4. Must to assume Britain and Amerika navys was be to stupid for to change operations from real history on imaginations storys for to make difference. Imaginary story was have no value when Britain and Amerika navies make quick changes for to combat.

For to conclude

Imagination story can to be interest for fiction and hollywood but not good for to help understand history.

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Re: Earlier Type XXI - informed by Cold War developments

Post by Lars » 21 Jul 2020 10:56

Normally I would agree with this statement BUT the Germans were looking for a true submarine with high underwater speed from the late 1930s onwards. They looked to the Walter boats to do this.

it is not rocket science to go:

"Maybe we could do what the Walter boat promises with a large enough conventional submarine, plus a schnorkel and quadrouple the batteries. It is known technology, safer, and faster to develop".

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Re: Earlier Type XXI - informed by Cold War developments

Post by T. A. Gardner » 21 Jul 2020 17:12

Lars wrote:
21 Jul 2020 10:56
Normally I would agree with this statement BUT the Germans were looking for a true submarine with high underwater speed from the late 1930s onwards. They looked to the Walter boats to do this.

it is not rocket science to go:

"Maybe we could do what the Walter boat promises with a large enough conventional submarine, plus a schnorkel and quadrouple the batteries. It is known technology, safer, and faster to develop".
Walter was looking into this at Germaniawerft along with H2O2 rocket motors as a potential propellant system for torpedoes. The KM was paying scant attention at the time. This only became of serious interest to the KM when the Allies started their smack down of the Type VII and IX. The Walther H2O2 engines were short ranged and dangerous so there was little interest until the choices became desperate.

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Re: Earlier Type XXI - informed by Cold War developments

Post by Lars » 21 Jul 2020 17:22

The Kriegsmarine ordered the Walter V-80 in 1939. True, the urgency wasn't there but the argument still stands. If the German had come up with the Elektroboot concept then and had ordered an experimental "Elektroboot V-80" instead they would have been on the right track in 1939 instead of November 1942.

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Re: Earlier Type XXI - informed by Cold War developments

Post by kfbr392 » 21 Jul 2020 18:18

for all who can read German, SKL ideas on the operational deployment of the Type XXI:
„Überlegungen zum Einsatz des Typ XXI“, dated 1944-07-10. Written by Erich Topp and Gerd Suhren, with a foreword by Dönitz.
http://www.mediafire.com/?88qafi83saaffs1

you may want to base your assumptions regarding German actions on it.

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Re: Earlier Type XXI - informed by Cold War developments

Post by Lars » 21 Jul 2020 20:50

Thanks, I did try to slug my way through the document perhaps 15 years ago but it too technical for me as well as difficult to read due to the photo copy/micro film quality.

Have you (or anyone else) read it and what is your conclusion?

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Re: Earlier Type XXI - informed by Cold War developments

Post by kfbr392 » 21 Jul 2020 21:22

well, one needs to read the whole thing to get the total picture. but one key section:

chapter V, section B. Night attack (on a convoy):
[paraphrasing here:] The XXI should attack surfaced, use eyes, FuMB, FuMO (Hohentwiel), and Balkon-GHG to get a picture of the situation. Stay surfaced as long as possible. Use FuMO to detect approacing escorts. Use FuMO to get firing solution for T5 Zaunkönig homing torpedo launch against escorts. Try to stay surfaced after launching the Zaunkönig, since it has a longer arming run. Dive when you must, close in at convoy at high underwater speed, make frequent course changes. Escorts at night cannot follow due to risk of friendly collisions. Fire torpedos when close to convoy if you can, else get under the convoy and shoot based on sonar data from below.
The last sentence: "Below the convoy the (u)boat is as safe as in a concrete bunker"

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Re: Earlier Type XXI - informed by Cold War developments

Post by Takao » 21 Jul 2020 22:18

Lars wrote:
21 Jul 2020 10:56
Normally I would agree with this statement BUT the Germans were looking for a true submarine with high underwater speed from the late 1930s onwards. They looked to the Walter boats to do this.

it is not rocket science to go:

"Maybe we could do what the Walter boat promises with a large enough conventional submarine, plus a schnorkel and quadrouple the batteries. It is known technology, safer, and faster to develop".
The Walter boat promised 24-27 knots underwater...your not going to do that with a large conventional submarine with quadruple the batteries.

Maybe it is rocket science? Such Walter speeds required nuclear power or a completely new hull form(USS Albacore).

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Re: Earlier Type XXI - informed by Cold War developments

Post by TheMarcksPlan » 21 Jul 2020 22:20

kfbr392 wrote:
21 Jul 2020 21:22
well, one needs to read the whole thing to get the total picture. but one key section:

chapter V, section B. Night attack (on a convoy):
[paraphrasing here:] The XXI should attack surfaced, use eyes, FuMB, FuMO (Hohentwiel), and Balkon-GHG to get a picture of the situation. Stay surfaced as long as possible. Use FuMO to detect approacing escorts. Use FuMO to get firing solution for T5 Zaunkönig homing torpedo launch against escorts. Try to stay surfaced after launching the Zaunkönig, since it has a longer arming run. Dive when you must, close in at convoy at high underwater speed, make frequent course changes. Escorts at night cannot follow due to risk of friendly collisions. Fire torpedos when close to convoy if you can, else get under the convoy and shoot based on sonar data from below.
The last sentence: "Below the convoy the (u)boat is as safe as in a concrete bunker"
Re below the convoy... this document - or its tactical content - appears to be that to which Ashbourne was referring in the quote provided upthread - that T21 would defeat all current countermeasures.

The reason T21 would be safe below the convoy should be obvious: escorts can't meaneuver effectively against it in the midst of dozens of ships. Plus the noise of all those propellers would make detection extremely difficult. For a 9-knot fast convoy, T21 has the endurance to remain underneath for hours but needs only ~35min to shoot 18 torpedoes.

The tactic of engaging the escorts first also revealing. It shows that the quick reloads would be used, after penetrating the screen, to sink merchants. As a convoy had usually around 8 escorts, a couple T21's might seriously devastate its protection quickly.
Last edited by TheMarcksPlan on 21 Jul 2020 22:33, edited 1 time in total.
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Re: Earlier Type XXI - informed by Cold War developments

Post by TheMarcksPlan » 21 Jul 2020 22:30

Re the economic attrition picture, I've been trying to find cost figures for Allied escorts. Does anyone have a source?
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