Earlier Type XXI - informed by Cold War developments

[Takao]

Mr. Takao apparently did NOT read my posting :

The Germans take one look at the design for the Snorkel, say, " Hey, that's a
wunderbar idea, but WE can make it even better! We will put a streamline casing
around it, reinforced and braced so that it can handle 17 knots of speed through
the water, add a few valves, make it extendable, and, Gott in Himmel ! have we
got a great idea !"

Yes, Mr. Ward...And if my grandmother had wheels she'd be a bicycle

Walter had put a snorkel in his boat design in 1933...Yet there was no "Gott in Himmel"

A Dutch naval officer patented a snorkel at the same time...Yet there was no "Gott in Himmel"

Sadly, there will be no "Gott in Himmel", only Deus Ex Machina.

Mr. Takao, you seem to have a problem: You apparently cannot conceive of the idea that what happened
historically was NOT the only thing that could have happened. History is fluid. Ideas, People, Events, all
COULD have occurred, NOT as they occurred historically, but in a different fashion.

No...No problem there...Anything is possible.

Your problem is not possibility, but probability.
It is possible the Germans could have "Gott in Himmeled" in 1937...It is possible the Germans could have "Gott in Himmeled" in 1933. However, it is not probable that they would have "Gott in Himmeled" earlier.

It is possible the Germans could have had nuclear submarines in 1937...However, it is not probable.

After WW2, in just two years, the USN developed, tested, and began installing Snorkels on the USN's Gato,
Balao, and Tench submarines that was capable of allowing the sub to run at 15 knots underwater while charging.
( This I got from a retired USN officer, who stated that, since the last of the GUPPYs was out of service, it wasn't
that big of a secret anymore ! )

Yes, I heard that too. I also heard that over 9 knots vibration was a problem with the snort and scopes...Not to mention noisy as hell.

If the Germans had started work in the summer of 1937, I am pretty certain that they could have at least equalled
the USN's efforts at building a High Speed Snorkel, and done so in less than a year. Hydrodynamics is just physics,

Pretty certain not...They couldn't do it in 2 years when they really needed to get it done.

If hydrodynamics is just physics, we should have had an "Albacore" hull type submarines much earlier than historically.

and like all engineering problems, all you have to do to solve it is throw money and steel at it.

Yeah...Where's my flying car, and power to cheap to meter, and SDI.

At the same time,
they work out the outer hull and conning tower design, fine tune the pressure hull and battery layouts, and spend
a little time on the wargaming floor developing a tactical doctrine to use high speed underwater attack subs to
destroy British Convoys.

Meanwhile, the British are working on high speed escorts, advanced sonar, advanced radar, autogyros with dipping sonar and MAD, better depth charges, ahead thrown weapons, even hunter-killer submarines.

After all, all the principals are there and the possibilities are, as you well know, endless.

However, there is that little thing with probability again.

Mr. Takao, with just a few tweaks here and there, history, and the world we live in, would be much different......

Yep, the possibilities are endless...Yet, somehow, someway, the Allies possibilities are not allowed
To happen. Why is it that the Germans get all the breaks, 1 in a billion chances, etc.

[Terry Duncan]

OK, guys, I get it. The Germans are a dull, stolid, unimaginative people, made even more so by their rigid practice of early toilet training. They never come up with new ideas, they have no flashes of intuition, there is zero initiative in their armed forces or their government, and they could never, EVER defeat the Allies.

Well, they did try twice and it ended badly for them both times. Both times they seemed to be running low on that thing known as Germans by the time the wars ended.

First of all, the Snorkel was NOT unnavailable. The Americans had tested them prior to WW1, the British patented it in 1916, the Italians tested a submarine with one in the early 1930s, and the Dutch were building a class of subs with Snorkels in the late 1930s. Guys, if the Germans had their heads so far up it in 1939 that they didn't know about Snorkels, then how the hell did they defeat France and bring Britain to it's knees in 1940 ? Remember who had the first air force to field a Jet Fighter, a Rocket Fighter, a Pulse Jet Cruise Missile, and a Short Range Ballistic Rocket, all in the space of one year !

The snorkel, rather like the hull form of the R class submarines, was something people dismissed entirely from the initial attempts right through until 1940 as being something that offered no practical benefit and was difficult to make work. The Dutch version was somewhat more practical iirc?

How did they defeat France? By being far more ready for war and having a far more attuned military-industrial base, and by unexpected tactics. They didn't win by having the best tanks. The first nation to field all those weapons you mention still lost the war and were still building the Pz IV as well as many wasteful different types of weapons for the same task.

All it takes is one, brief, blinding flash of intellect :

One that the Germans failed to have between 1914 and 1939 despite all the plans for U-boats and how best to use them.

Now guys, what if Doenitz, in 1937, gets on the phone to Admiral Canaris, and says, " Dude, send a couple of spies into Holland and see what they are doing in terms of Submarine development " Canaris complies, two agents
travel all the way around the world, end up in Holland, and three months later, after a little folding money changes hands with a couple of underpaid Dutch draghtsman, Doenitz has in his hot little greedys a full set of the blueprints for the new O-20 submarine.

I would ask why the Germans would decide to spy on the Dutch for naval weaponry advances? They would hardly be the most likely power to look to for anything, especially as they were ordering so much naval weaponry from Germany and without letting their snorkel design be known.

The Germans take one look at the design for the Snorkel, say, " Hey, that's a wunderbar idea, but WE can make it even better! We will put a streamline casing around it, reinforced and braced so that it can handle 17 knots of speed through the water, add a few valves, make it extendable, and, Gott in Himmel ! have we got a great idea !"

A similar leap will see them fielding Me 262s by 1942 also.

C'mon, Mr. Duncan, we are talking about the Germans here, NOT THE BRITISH ! If the Germans are so dull witted, then how was it that they were capable of beating the British like a Government Mule for two years until the United States stepped in and won the war ? All it would take would be Doenitz watching a group of swimmers running out of the water at a Baltic seaside resort, seeing the shark fin in the surf, and having that flash of intuition, " Hey, that's just vat vould happen to one of mine U-boats ! I vill haff to doo sumtink about that....."

The US didn't 'win the war', the war was won in the east. The US played a role certainly, but the idea they won the war ignores the massive losses inflicted on the Germans in the east.

Now, the design I came up with is NOT INCAPABLE of surface operations, with the caveat that it would have no deck guns.

Making it not very useful.

The USN's GUPPY III subs were fully capable of surface cruising, and in fact often did so. They would spend a lot of time on the surface, running on two diesels while the third kept the batteries topped of, and with their snorkels, they could do the same under water, two diesels driving and one charging.

During WWII they carried deck guns.

A Type XXI-1937, with same engineering plant as the Type X ( two supercharged GW F46a9pu nine cylinder, four-stroke diesel engines, (4,700 bhp) and two AEG GU720/8-287 electric motors, (1,100 shp ) would in fact be faster on the surface than under water. The difference is, with the greater battery capacity, it could run faster and longer under water on it's batteries. And, with the Snorkel, it could run underwater all day, with the conning tower just barely awash, the snorkel at full height, using one diesel to drive the boat and the other to top up the batteries. If aircraft are sighted, you dive the boat, shut down the diesels, retract the snorkel, and go electric until flyboy gets bored and goes home.

If you are going to operate on the surface a lot you do not need a massive battery power plant or a snorkel.

The true advantage conferred by the Type XXI-1937 is it's ability to combine tactically with Type VIIs and Type IXs in combined Wolf Pack operations. It is, in effect, a force multiplier. While the Type XXI-1937 engages the convoy escorts, relying on it's high speed and under water cruise ability, it can draw off the convoy screen, allowing the 'submersible boats' to engage and sink more members of the convoy, either underwater or on the surface.

How you work in any co-ordination between sub that works best by not surfacing and others that need to work mostly on the surface is a major problem, and what on earth happens if an Allied sub is working in the area is anyone's guess. It is all very much hindsight and overlooking that it took years of war experience to push certain elements forward.

It still doesn't solve the problem that one of the Type XXI's main advantages was supposed to be the mass production aspect, and that out of almost 120 boats assembled only 4 were seaworthy. Producing Type XXIs early in the same numbers as historical boats is not going to be enough.

[Terry Duncan]

Yes, Mr. Ward...And if my grandmother had wheels she'd be a bicycle

"So, your grandmother was also involved?"

[Takao]

Yes, Mr. Ward...And if my grandmother had wheels she'd be a bicycle

"So, your grandmother was also involved?"

Yeah, and she is long dead...Those darn Alien Space Bats again.

[Takao]

It can be seen that it would make use of the larger diameter hull of the Type X, but shortened and optimized for
high speed underwater attack.

You do realize that the pressure hull of a Type XB
Is only .5 meters greater diameter. The much larger outer hull of the XB was for mines and open to the sea.

The .5 meters does not give you much extra space to work with. So are you planning on storing the extra batteries outside the pressure hull? Or are you planning on widening the pressure hull into more of an oval shape?

If oval, how do you plan on strengthening and bracing the pressure hull so that it has the same resistance as a circular one?

You could enlarge the diameter of the pressure hull, but that opens a new can of worms.

[kfbr392]

Einsatzrichtlinien Typ XXI
--------------------------
Für die taktische Ausbildung waren im Sommer 1944 vom BdUop.Richtlinien für den Einsatz dieser neuen Boote ausgearbeitet worden,die in den >Überlegungen zum Einsatz des Typ XXI<(I/SKL Teil C 4/44 vom 10.Juli 1944) zusammengefaßt worden sind.Einige wesentliche Aussagen dieser Studie sind:

1. Der Typ XXI ist ein Boot mit ausgeprägt starken Unterwassereigenschaften,die geeignet sind, die durch Luftherrschaft und Überwasserortung erreichte Überlegenheit der feindl. U-Bootabwehr weitgehendst auszuschalten.

2. Das Uboot Typ XXI ist mit 6 Torpedorohren ausgerüstet,die in kurzer Zeit nachgeladen werden können (zweite Chargierung nach 5, dritte Chargierung nach 20 Minuten).Seine Kampfkraft ist,wenn sie zum Einsatz kommt,ausreichend,den stärksten Überwasser-Gegner bzw. mehrere feindliche Schiffe gleichzeitig zu vernichten.Seine Standkraft reicht jedoch nicht aus,die zum eigenen Einsatz seiner Torpedos erforderliche Entfernung über Wasser zu erzwingen,sie muß unbemerkt über oder unter Wasser "erschlichen" werden.

3. Grundsatz: Im Op-Gebiet vor dem Angriff unbedingt unbemerkt bleiben.(Typ XXI gestattet Erfüllung dieser Forderung im ungleich häheren Maße als die bisherigen Kampfboote.)
Hält das Boot Typ XXI,was es bisher verspricht,so bedeutet jedes Boot für den Gegner eine besondere Gefahr...Das Auftreten weniger Typ XXI bringt bereits eine weit stärkere Zersplitterung der Abwehr,als eine erheblich größere Zahl bisheriger Kampfboote.

4. Grundsatz: Der Einsatz des Bootes ist hoch,der erste Angriff muß daher zu einem lohnenden Erfolg führen.Dies gilt insbesondere bei Einsätzen in "Verkehrstrichtern" in Küstennähe.Gegenüber erhöhter Abwehr in diesen Bereichen sind die erforderlichen Eigenschaften lange Unterwasserausdauer und Robustheit gegenüber Waboverfolgungen durch die große Batteriekapazität und große Tauchtiefe beim Typ XXI gegeben.

5. Im Mai 1944 brauchte z.B. ein Typ IX C Boot beim Marsch zur Karibik 50 Tage.Beim Typ XXI wird dagegen mit 28 Tagen gerechnet,d.h. Typ XXI marschiert praktisch doppelt so schnell wie Typ IX C.
Verkürzungen der Anmarschzeiten bedeutet Verlängerung der Aufenthaltsdauer im eigentlichen Op-Gebiet.Große Räume,mehr Kojen,durch Klima-Anlagen gemäßigte Temperaturen,für jede Unternehmungsdauer ausreichende Proviantausrüstung,größere Kühleinrichtungen,bessere Raumluftverhältnisse bei langen Unterwassermärschen (führen zu einer geingeren) Beanspruchung der Besatzung...als bei früheren Kampfbooten.

6. Typ XXI ist kein Tauchboot,sondern ein Unterwasserboot.In seiner verhältnismäßig hohen Unterwassergeschwindigkeit und seiner Unterwasserdauer liegt seine Stärke.Sobald es an der Oberfläche ist,gleicht es mit seinen schwachen Überwasserkampfeigenschaften den bisherigen Kampfbooten.Es ist deshalb fraglich,ob das Boot nach Sichten oder Feststellen des Gegners über Wasser operierend in eine Angriffsposition kommt.
Daher gilt: Ist festgestellter Gegner auch unter rücksichtsloser Ausnutzung der Batteriekapazität in einem Unterwasseranlauf zu erreichen,ran,Angriff in einem Anlauf durchführen und notfalls erzwingen...Fällt der Schuß bei einem Batterie-Kapazitätszustand von nur 20 Prozent der Gesamtkapazität,so ist der Angriff richtig.20 Prozent Batteriekapazität genügen noch,um eine längere Wabo-Verfolgung (4-5 Stunden) durchzustemmen...

7. Nach letztem erfolgreichen Angriff noch einige Minuten mitlaufen,auf große Tiefe gehen,Schleichfahrt.Dann drehen,nach achtern seitlich ablaufen.Freisteuern (von) achtern Fegern nach eigener S-Ortung und Horchpeilung.
Bei einer Wabo-Verfolgung hat das Boot trotz seiner größeren Abmessungen bessere Chancen als die bisherigen Kampfboote,da hohe Unterwasserfahrt gezielten Wabowurf erhelbich erschwert,große Tiefe...und höhere Schleichfahrt...hervorragenden Schutz gewähren.

8. Sehr gute Horchgeräte und S-Geräte ermöglichen bessere Kontrolle des Verhaltens der U-Jäger,so daß keine Überraschungen mehr möglich sind.Mit Asdic sendenden Gegner kann mit Unterwasserhöchstfahrt weggelaufen werden.(Reichweite Asdic im Höchstfall 5000m.)
...

[kfbr392]

via google translate:
Type XXI application guidelines
--------------------------
Guidelines for the use of these new boats were drawn up by the BdUop. For tactical training in the summer of 1944, and these were summarized in the> Considerations for the Use of Type XXI <(I / SKL Part C 4/44 of July 10, 1944) Some key statements of this study are:

1. The type XXI is a boat with distinctly strong underwater properties, which are suitable for the superiority of the enemy achieved through aerial control and surface detection. Switch off submarine defense as much as possible.

2. The submarine type XXI is equipped with 6 torpedo tubes that can be recharged in a short time (second charge after 5, third charge after 20 minutes). Its combat strength, when used, is sufficient to be the strongest overwater opponent or to destroy several enemy ships at the same time. However, its stability is not sufficient to force the distance over water required for its own use of its torpedoes, it must be "sneaked" over or under water unnoticed.

Principle 3: Be absolutely unnoticed in the operating area before the attack (Type XXI allows this requirement to be met to a much greater extent than previous combat boats.)
If the Type XXI boat does what it promises so far, every boat poses a special danger to the opponent ... The appearance of fewer Type XXI already results in far more fragmentation of the defense than a considerably larger number of previous combat boats.

4. Principle: The use of the boat is high, the first attack must therefore lead to a rewarding success. This is especially true for missions in "traffic funnels" near the coast. Compared to increased defense in these areas, the required properties are long underwater endurance and robustness against wave tracking given by the large battery capacity and immersion depth in Type XXI.

5. In May 1944, e.g. a Type IX C boat during the march to the Caribbean 50 days, whereas Type XXI is expected to take 28 days, i.e. Type XXI marches almost twice as fast as Type IX C.
Shortening the approach times means lengthening the length of stay in the actual operating area: Large rooms, more berths, temperatures tempered by air-conditioning systems, sufficient provisioning equipment for each duration of the venture, larger cooling facilities, better indoor air conditions during long underwater marches (lead to less stress on the crew). .. as in previous combat boats.

Type XXI is not a submersible, but an underwater boat. Its strength is its relatively high underwater speed and duration. Once it is on the surface, it is similar to the previous combat boats with its weak surface fighting properties. It is therefore questionable whether the boat is after Sighting or detecting the opponent operating in water comes into an attack position.
Therefore, the following applies: If an opponent can be reached in an underwater start-up, even if the battery capacity is used ruthlessly, then run, carry out an attack in a start-up and force it if necessary ... 20 percent battery capacity is still enough to do a longer Wabo tracking (4-5 hours) ...

7. After the last successful attack, walk along for a few more minutes, go to great depth, creep speed. Then turn, run sideways to the back. Freely steer (from) aft sweeping after your own S-location and listening direction.
With a Wabo chase, the boat has better chances than the previous combat boats despite its larger dimensions, since high underwater travel makes targeted Wabowurf difficult, great depth ... and higher crawl speed ... provide excellent protection.

8. Very good listening devices and S devices enable better control of the behavior of the U-hunters, so that no more surprises are possible. With Asdic sending enemies, you can run away with underwater speed. (Range Asdic at maximum 5000m.)
...

[paulrward]

Hello All :

Mr. Takao wrote :

You do realize that the pressure hull of a Type XB Is only .5 meters greater
diameter. The much larger outer hull of the XB was for mines and open to the sea.

The .5 meters does not give you much extra space to work with. So are you planning
on storing the extra batteries outside the pressure hull? Or are you planning on widening
the pressure hull into more of an oval shape?

If oval, how do you plan on strengthening and bracing the pressure hull so that it has
the same resistance as a circular one?

You could enlarge the diameter of the pressure hull, but that opens a new can of worms.

First, Mr. Takao, you seem to be a ' problem generator ' rather than a ' problem solver '.As
a person who worked for most of his career as a professional engineer, I have frequently run into individuals like
yourself. Typically we engineers ignore them, roll up our sleeves, solve the problems, and then go on our way,
leaving the ' problem generator ' fussing and fuming in a futile display of intellectual inadequacy.

So, to solve the non existant problems: First, the pressure hull of a Type XB ( 4.75 M dia. ) is, in fact, only
0.05 m greater than that of the Type Vii ( 4.70 M dia ) - it is 0.35 m greater than the Type IX ( 4.40 M dia ) .
As for the Type XXI, it had a pressure hull profile formed like an ' 8 ' with an upper diameter of 5.3 m and a
lower diameter of 3.5 m. The enhanced battery was installed in the lower part of the pressure hull.

So, you see, Mr. Takao, the problems were not insurmountable. Now, if you wished to stick with the technology
of the early U boats, you would simply make the two hull bubbles of the Type XXI-1937 of equal size, for example,
they could both have a diameter of 4.75 M. This would give you approximately the same volume, and with a bit
of cutting and fitting, you could get all the equipment in the ' dubble-bubble' hull.

And, the advantage of this is that the 'dubble-bubble' hull is lighter than a similarly volumed cylindrical hull,
requiring less structure to achieve the same pressure resistance. Win-Win !

I have to admit, your suggestion about an OVAL sectioned hull gave me pause.... Mr. Takao, do you know NOTHING
of Physics or Engineering ? An oval is the WORST possible shape for a pressure hull. To the best of my knowledge,
it has NEVER been used. Now, if you had suggested a ELLIPTICAL cross section, that would be a different story, as
an ellipse has many elegant features would lend itself to a pressure hull design, namely the fact that certain
elliptical cross sections offer enhanced load carrying capacity with respect to their circular counterparts, due to
strain hardening in the section of low radius of curvature.


So, you see, Mr. Takao, there really are no insurmountable problems. Now, it must be admitted, that the fuel
bunker capacity of a Type XXI-1937 would be less than that of a comparable Type IX - however, this could be
alleviated by simply having three or four Type XXI-1937s 'teamed' with one or more ' Milch Cows ', which would
carry additional fuel and provisions. The Attack Boats could fuel up, go off to make their attacks, and then return
to refuel and prepare for another engagement, similar in practice to USAF fighters, who trail behind Tankers on
their way to combat, and go into their dogfights with full fuel tanks and no worries about getting home.


It must also be noted : Some of the WW2 USN subs, after the war, were converted to what was called the ' Fleet
Snorkel ' configuration. This involved removing one diesel, adding more batteries, fitting a Snorkel, and removing
useless excresences such as net cutters, deck guns, and false decking, and streamlining the hull, bow, and conning
tower

The result, with NO CHANGES to the pressure hull, and no revolutionary technologies, were boats that were faster underwater, and which could cruise with the conning tower barely submerged, drawing air through the Snorkel,
and cruising at about 14 knots while charging the batteries. Just like my proposed Type XXI-1937.

Mr. Takao, do you have any idea who the USN got this idea from ?


Respectfully :

Paul R. Ward

[Takao]

So, to solve the non existant problems: First, the pressure hull of a Type XB ( 4.75 M dia. ) is, in fact, only
0.05 m greater than that of the Type Vii ( 4.70 M dia ) - it is 0.35 m greater than the Type IX ( 4.40 M dia ) .
As for the Type XXI, it had a pressure hull profile formed like an ' 8 ' with an upper diameter of 5.3 m and a
lower diameter of 3.5 m. The enhanced battery was installed in the lower part of the pressure hull.

So, you see, Mr. Takao, the problems were not insurmountable. Now, if you wished to stick with the technology
of the early U boats, you would simply make the two hull bubbles of the Type XXI-1937 of equal size, for example,
they could both have a diameter of 4.75 M. This would give you approximately the same volume, and with a bit
of cutting and fitting, you could get all the equipment in the ' dubble-bubble' hull.

And, the advantage of this is that the 'dubble-bubble' hull is lighter than a similarly volumed cylindrical hull,
requiring less structure to achieve the same pressure resistance. Win-Win !

So, you are not actually using a Type XB hull then.
What you are using is the aft hull of the Type XI for the whole submarine then.

Wonderful...Except you said you were using the hull of a Type X.

I didn't know engineers were in the habit of saying one thing when they meant something different.

It must also be noted : Some of the WW2 USN subs, after the war, were converted to what was called the ' Fleet
Snorkel ' configuration. This involved removing one diesel, adding more batteries, fitting a Snorkel, and removing
useless excresences such as net cutters, deck guns, and false decking, and streamlining the hull, bow, and conning
tower

The result, with NO CHANGES to the pressure hull, and no revolutionary technologies, were boats that were faster underwater, and which could cruise with the conning tower barely submerged, drawing air through the Snorkel,
and cruising at about 14 knots while charging the batteries. Just like my proposed Type XXI-1937.

You neglected one very important fact about the Guppies Paul.

The original Fleet boats' submerged plant gave 2,740SHP...The Guppies increased this to 4,610SHP. The Type XXI had 5,000SHP

Your XB has 1,100SHP, while the unbuilt Type XI was to have 2,100SHP.

[paulrward]

Hello All :

Mr. Takao wrote :

Wonderful...Except you said you were using the hull of a Type X.

I AM using the pressure hull of the Type X - I am just mating two of them together in a fashion that the Germans
had every capability of doing, and using a technology they were familiar with - Electric Arc Welding. Mr. Takao,
for every piddling objection you come up with, the Germans had the full capability of solving in 1937 - they had
the structural and metalurgical knowledge, they had the installed industrial base to manufacture it, and they
had the grasp of the technical issues to make it happen.

Oh yes, since we are using the hull diameter of the Type X, we can VERY easily slip in two of the same diesels
that were scheduled for use in the Type X, ( two supercharged GW F 46 a 9 pu 9-cylinder, four-stroke diesel
engines, 4,700 bhp ) along with a pair of much larger electric motors to give you the desired underwater speed.

As for the underwater electric motors, you would simply have to either scale up the two 550 shp AEG GU 720/8-287 electric motors of the Type X, or put multiple motors on drive shaft. ( Scaling up electric motors is very easy, it merely means larger magnets, which are made of iron, and more copper wire. It has been done since the time of Edison and Westinghouse.... ) It would be very easy to scale up each electric motor by a factor of three, which
would give you a total underwater output of 3300 shp for a top underwater speed of appx. 14.8 knots.

Mr. Takao, this is NOT Rocket Surgery.......

That would be one of the main differences between the historical Type XXI and my Type XXI-1937 - the historical
boat had 5000 shp for a top speed of 17.2 knots - about 2.4 knots faster than my design - but if the Type XXI-1937
appeared in the early months of 1940, say in the darkest nights of January to March in the North Atlantic - it could
be a game changer for the Convoy System.

The sudden loss of a number of convoy escorts, followed by the massacre of a convoy similar to what happened to
PQ-17, and this sort of disaster being repeated on a weekly basis, might have a severe effect on Britain's morale....



Respectfully :

Paul R. Ward


Senator: " What I want to know is, How the Hell did they ( the russians ) get up there ahead of us ? Was it their
German Scientists ? "
Mysterious Figure speaking from the dark : " Nein ! My Germans are BETTER than their Germans..... "

[Takao]

Hello All :

Mr. Takao wrote :

Wonderful...Except you said you were using the hull of a Type X.

I AM using the pressure hull of the Type X - I am just mating two of them together in a fashion that the Germans
had every capability of doing, and using a technology they were familiar with - Electric Arc Welding. Mr. Takao,
for every piddling objection you come up with, the Germans had the full capability of solving in 1937 - they had
the structural and metalurgical knowledge, they had the installed industrial base to manufacture it, and they
had the grasp of the technical issues to make it happen.

Oh yes, since we are using the hull diameter of the Type X, we can VERY easily slip in two of the same diesels
that were scheduled for use in the Type X, ( two supercharged GW F 46 a 9 pu 9-cylinder, four-stroke diesel
engines, 4,700 bhp ) along with a pair of much larger electric motors to give you the desired underwater speed.

As for the underwater electric motors, you would simply have to either scale up the two 550 shp AEG GU 720/8-287 electric motors of the Type X, or put multiple motors on drive shaft. ( Scaling up electric motors is very easy, it merely means larger magnets, which are made of iron, and more copper wire. It has been done since the time of Edison and Westinghouse.... ) It would be very easy to scale up each electric motor by a factor of three, which
would give you a total underwater output of 3300 shp for a top underwater speed of appx. 14.8 knots.

Mr. Takao, this is NOT Rocket Surgery.......

That would be one of the main differences between the historical Type XXI and my Type XXI-1937 - the historical
boat had 5000 shp for a top speed of 17.2 knots - about 2.4 knots faster than my design - but if the Type XXI-1937
appeared in the early months of 1940, say in the darkest nights of January to March in the North Atlantic - it could
be a game changer for the Convoy System.

The sudden loss of a number of convoy escorts, followed by the massacre of a convoy similar to what happened to
PQ-17, and this sort of disaster being repeated on a weekly basis, might have a severe effect on Britain's morale....



Respectfully :

Paul R. Ward


Senator: " What I want to know is, How the Hell did they ( the russians ) get up there ahead of us ? Was it their
German Scientists ? "
Mysterious Figure speaking from the dark : " Nein ! My Germans are BETTER than their Germans..... "

Yes, hindsight is a wonderful thing.

[paulrward]

Hello All :

Mr. Takao wrote :

Yes, hindsight is a wonderful thing.

As Steve Jobs, founder of Apple put it so eloquently, shortly before his death, " You can only connect the
dots looking backwards - you have to trust that, going forwards, the dots are going to connect ! "

Respectfully :

Paul R. Ward

Welcome IBM.jpg

[paulrward]

Hello All :

In Posting # 91, by Mr. Takao, he stated :

...If hydrodynamics is just physics, we should have had an "Albacore" hull type
submarines much earlier than historically.....

Please, Mr. Takao, stop setting up such good straight lines.....

Holland Submarine 1901.jpg

Holland Submarine 1901 - no 2.jpg

Respectfully :

Paul R. Ward

[TheMarcksPlan]

Please, Mr. Takao, stop setting up such good straight lines.....

I always find it odd the extent to which people feel confident opining on ships and airplanes without knowing the very basics of fluid dynamics.

For a person with a decent quantitative education, the fundamentals can be learned in an evening of solid concentration. And these fundamentals explain so much of our modern world... Yet we have "technical" commentators who don't understand the difference between pressure and friction drag components and who couldn't explain the performance difference between wings that are short and fat versus long and skinny.

[TheMarcksPlan]

I would have voted for the sub-optimal solution to retrofit VIICs as "electro" boats instead of going for the perfedt solution of XXI.

It's interesting that the pre-war Type XII proposal had a submerged speed of 10kn, already faster than the 9kn provided for your first version of an upgraded VIIC:

The Type XII U-Boats were going to be fleet submarines based on the Type IX hull with a somewhat greater surface displacement, somewhere around 1,600 tons. The main propulsion was going to be the normal diesel and electric but the horsepower was to be 7,000 from the diesels and 1,680 from the electric motors. The increase in horsepower would propel these boats at 22 knots surfaced and 10 knots submerged. Hefty bunkers would provide a range of 20,000 miles at 8 knots. Armament would be six tubes forward, two tubes aft. There is no data on the gunnery provisions or the size of the crew. The Type XII U-Boat never even got to the drawing boards, and no provisions for building any were made. There were no Type XII U-Boats.

As you recognize, and as discussed in the USN's ASW manual that you linked, a sub's survivability against escorts relates to the square of its speed. A 10kn Type XII would have been ~twice as hard to kill as T7/9.

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IMO we have to look again at Donitz for a lot of the blame here - though not in a way that is quite fair to blame him. It seems that development of the Ubootwaffe was Donitz's own little domain, with little interest from the rest of the KM on a top-down development of tactics/strategy/technology. The record is replete with KM bigwigs denying that the Ubootwaffe was a potentially primary strategic asset.

Donitz's appears to have spent so much time and effort developing his preferred tactics that he didn't have the time or the mental bandwith to look beyond the tactical horizon to the strategic picture of ever-changing submarine warfare. He was, therefore, myopically concentrated on churning out as many T7's as possible while failing to push for a bigger, faster type of submarine that would have been more survivable. Donitz's preference for the T7 was rational in the context of pre-war resource/tonnage limitations, as the T9 and larger boats didn't pack as much punch per ton. Once the war started, however, and especially after the KM/Hitler focused more resources on the Ubootwaffe, Donitz should have re-evaluated his pre-war calculus to reflect the new strategic picture: A T9 cost only ~20% more than a T7 so a T12, had it been built, probably would have been on the order of 30% more expensive. For a sub that is twice as survivable and - due its range - can spend a longer time at sea, the T12 would have been far preferable in '41-'43.

In addition, had T12 been built, its larger size could have been better-adapted to an e-boat conversion a la Lars' proposal and the USN's GUPPY program.

This isn't a fair critique of Donitz in the sense that it shouldn't have been his responsibility to develop tactics, train the force in them, and lead the technological evolution of the force. But that's what happened historically: it took Donitz's initiative to instigate the process that led to T21's creation in November '42; the rest of the KM appears not to have been doing enough on the Ubootwaffe's behalf from a strategic/analytic perspective.