General Discussions
This is the place to discuss general issues related to the U-boat war or the war at sea in WWII.
XXI capabilities
Posted by:
SuperKraut
()
Date: December 19, 2000 08:27PM
<HTML>The Allies did a post war evaluation of U-boat courses and ASW patrol courses and found that the ASW planes missed snorkeling U-boats about 95% of the time. The find rate for surfaced U-boats must have been close to 100%. So we conclude that a U-boat with the big ball valve snorkel head was about 20 times harder to locate by radar than a surfaced U-boat. A well designed T-valve snorkel head is a lot smaller, rides lower in the water and is consequently more difficult to find. The issue is size and height above the water. The coatings used in WWII were not particularly effective.
I had an E-mail conversation with a retired US Navy ASW expert who tells me that snorkels were very hard to pick up with 1970s vintage analog radar. It was not until digital signal processing came along that the snorkel became relatively easy to spot.
The 3 cm radar came out about as fast as it was possible to do it. As mentioned above, it was no panacea against a well designed T-valve snorkel head. The truth is that the submarine (not the submersible) had the natural advantage vs. ASW until the advent of digital signal processing, both for radar and sonar. The caveat is that the U-boats had to become quieter with each generation and have appropriate weapons to shoot at escorts, i.e. wire guided acoustic torpedoes like Lerche. Given the current scenario, there is no reason why an improved XXI B could not be available in 1944 and an even better and quieter XXI C in 1945. The bottom line is that unless the Allies invent integrated circuits by 1945, the U-boat had the technical edge provided it used the appropriate tactics.
The top speed of the XXI was basically academic. The important issue was endurance at medium speeds. The correct way to march an XXI was to snorkel at 6 knots for about 4 hours at night to recharge the batteries and then go deep and run all day at 8 knots. Not a particularly fast way to travel, but relatively safe. The XXI was a complex weapon and required elite crews to be effective, so the safety of crew should have been of paramount importance. Fewer U-boats with elite crews can do a lot more damage than many U-boats with mediocre crews.
Actually, postulating what would have happened if the XXI had come out 2 years earlier is the wrong question. The XXI design was an unintended consequence of the Walter XVIII project and the hull was designed as a surface vessel. The XVIII was supposed to cruise on the surface until the time came to attack at which point it would submerge, go to Walter drive, make a high speed run at the convoy and escape. The concept only addressed the actual attack, but did nothing for the march to and from station, which was at least equally dangerous by 1943. The XXI was a workable solution to both problems, but it was far from ideal.
The real question to ask is what would have happened if the Kriegsmarine had recognized the theoretical danger of airborne radar back in the late 1930s. They would then have designed a real submarine, a single screw teardrop design. The theoretical advantages of such a design were known, and a bunch of such designs (types XXIX, XXX and XXXI) hit the drawing boards in 1944 when it was too late. Given a few years of development time, U-boats with at least twice the medium speed underwater endurance of the XXI could have been available, although their top speeds would not have been much higher. A U-boat which could run all day on battery at 10 - 12 knots was quite feasible with the available technology. If you throw in a thicker hull made from CM 351 steel, we can get a crush depth of 500 meters. In combination with wire guided torpedoes, a few hundred such boats would have closed the Atlantic.
Regards,
SuperKraut</HTML>
I had an E-mail conversation with a retired US Navy ASW expert who tells me that snorkels were very hard to pick up with 1970s vintage analog radar. It was not until digital signal processing came along that the snorkel became relatively easy to spot.
The 3 cm radar came out about as fast as it was possible to do it. As mentioned above, it was no panacea against a well designed T-valve snorkel head. The truth is that the submarine (not the submersible) had the natural advantage vs. ASW until the advent of digital signal processing, both for radar and sonar. The caveat is that the U-boats had to become quieter with each generation and have appropriate weapons to shoot at escorts, i.e. wire guided acoustic torpedoes like Lerche. Given the current scenario, there is no reason why an improved XXI B could not be available in 1944 and an even better and quieter XXI C in 1945. The bottom line is that unless the Allies invent integrated circuits by 1945, the U-boat had the technical edge provided it used the appropriate tactics.
The top speed of the XXI was basically academic. The important issue was endurance at medium speeds. The correct way to march an XXI was to snorkel at 6 knots for about 4 hours at night to recharge the batteries and then go deep and run all day at 8 knots. Not a particularly fast way to travel, but relatively safe. The XXI was a complex weapon and required elite crews to be effective, so the safety of crew should have been of paramount importance. Fewer U-boats with elite crews can do a lot more damage than many U-boats with mediocre crews.
Actually, postulating what would have happened if the XXI had come out 2 years earlier is the wrong question. The XXI design was an unintended consequence of the Walter XVIII project and the hull was designed as a surface vessel. The XVIII was supposed to cruise on the surface until the time came to attack at which point it would submerge, go to Walter drive, make a high speed run at the convoy and escape. The concept only addressed the actual attack, but did nothing for the march to and from station, which was at least equally dangerous by 1943. The XXI was a workable solution to both problems, but it was far from ideal.
The real question to ask is what would have happened if the Kriegsmarine had recognized the theoretical danger of airborne radar back in the late 1930s. They would then have designed a real submarine, a single screw teardrop design. The theoretical advantages of such a design were known, and a bunch of such designs (types XXIX, XXX and XXXI) hit the drawing boards in 1944 when it was too late. Given a few years of development time, U-boats with at least twice the medium speed underwater endurance of the XXI could have been available, although their top speeds would not have been much higher. A U-boat which could run all day on battery at 10 - 12 knots was quite feasible with the available technology. If you throw in a thicker hull made from CM 351 steel, we can get a crush depth of 500 meters. In combination with wire guided torpedoes, a few hundred such boats would have closed the Atlantic.
Regards,
SuperKraut</HTML>
| Subject | Written By | Posted |
|---|---|---|
type xxi
|
phil | 12/17/2000 12:41PM |
|
RE: type xxi
|
David W | 12/18/2000 06:36AM |
|
RE: type xxi
|
Dietzsch | 12/18/2000 09:12AM |
|
RE: type xxi
|
Rainer Bruns | 12/18/2000 01:35PM |
|
RE: type xxi
|
Nannia | 12/18/2000 02:37PM |
|
RE: type xxi
|
Takeo | 12/18/2000 03:16PM |
|
fallout?
|
Tom Iwanski | 12/18/2000 03:39PM |
|
RE: type xxi
|
kurt | 12/18/2000 05:43PM |
|
RE: type xxi
|
Rainer Bruns | 12/18/2000 03:40PM |
|
RE: type xxi
|
Steve Cooper | 12/18/2000 04:54PM |
|
RE: garbage?
|
Antonio Veiga | 12/18/2000 08:16PM |
|
RE: garbage?
|
Rick Mann | 12/19/2000 07:58PM |
|
RE: gaijin
|
kurt | 12/19/2000 11:47PM |
|
XXI and the 300 U-boats
|
SuperKraut | 12/18/2000 09:41PM |
|
Scary thought
|
J-E | 12/19/2000 01:27PM |
|
RE: type xxi
|
kurt | 12/18/2000 05:41PM |
|
RE: type xxi
|
MCE | 12/18/2000 06:00PM |
|
RE: type xxi
|
kurt | 12/18/2000 05:55PM |
|
You have missed the point
|
SuperKraut | 12/18/2000 09:30PM |
|
invisible snorkels at the XXI
|
Kurt | 12/18/2000 11:23PM |
|
XXI capabilities
|
SuperKraut | 12/19/2000 08:27PM |
|
RE: invisible snorkels at the XXI
|
Craig McLean | 12/20/2000 03:19AM |
|
Underwater speed and range
|
SuperKraut | 12/20/2000 09:39AM |
|
Snorkels and The Bismarck Add On
|
Fin Bonset | 12/20/2000 01:07PM |
|
Bismarck Fleet Add On
|
Fin Bonset | 12/20/2000 01:09PM |
|
RE: Bismarck Fleet Add On
|
Fin Bonset | 12/20/2000 01:10PM |
|
RE: type xxi
|
Steve Cooper | 12/19/2000 06:20PM |
|
RE: type xxi
|
Stewart | 12/19/2000 07:29PM |
|
Blair
|
SuperKraut | 12/19/2000 08:49PM |
|
RE: Blair
|
kurt | 12/19/2000 11:40PM |
|
RE: I meant 1950\'s
|
kurt | 12/19/2000 11:48PM |
|
RE: Blair
|
Jim, | 12/20/2000 01:35AM |
|
RE: mystery radar
|
kurt | 12/20/2000 10:10PM |
|
Radar and snorkels
|
SuperKraut | 12/20/2000 09:09AM |
|
Wilhelm Bauer Type XXI
|
Rick Mann | 12/20/2000 05:06PM |
|
RE: Wilhelm Bauer Type XXI
|
SuperKraut | 12/21/2000 10:08AM |
|
RE: Wilhelm Bauer Type XXI
|
Rick Mann | 12/25/2000 05:01PM |
|
RE: Wilhelm Bauer Type XXI
|
SuperKraut | 12/28/2000 12:41AM |