Was the Elektroboat really a "wonder weapon"?

[davebender]

Prior to Hitler taking control of the military in mid 1930s, there was a long term strategic plan in place to rebuild Germany to mount an mechanized preventative war against the European powers by the early 1940s.

What makes you think Hitler had control over events in Austria, Czechoslovakia, Yugoslavia and Danzig? What makes you think Hitler had control over aggressive Marxist governments being installed in France and Spain? Those crisis would happen no matter who occupies the Reichskanzlei. Hitler's reaction to those events wasn't perfect but there's no guarantee Angela Merkel would muddle through any better.

 

[psteel]

What makes you think Hitler had control over events in Austria, Czechoslovakia, Yugoslavia and Danzig? What makes you think Hitler had control over aggressive Marxist governments being installed in France and Spain? Those crisis would happen no matter who occupies the Reichskanzlei. Hitler's reaction to those events wasn't perfect but there's no guarantee Angela Merkel would muddle through any better.

I was only speaking to the direction the german military was developing. It seemed to be well on track before he stuck his ore in.

 

[davebender]

In the case of 3/4 track vehicles that's absolutely correct. The German Army began research during the late 1920s and many of the basic vehicle specifications were written by 1933. Some models such as the Sd.Kfz.6 and Sd.Kfz.7 were in production during 1935. The entire 3/4 track fleet included advanced suspension. Pretty amazing Germany could develop such advanced vehicles while spending only 1% of GDP on national defense.

On the other hand 3/4 track vehicles were about the only equipment programs receiving substantial funding prior to 1935. Perhaps that's because artillery tractors were allowed under the Versallies Treaty.

 

[tyrodtom]

You don't say what year they were spending 1% of their GDP on national defense, but in 1935 Germany spend 10% of their GDP on the military.

That was more than any other country in Europe at the time, and it increased greatly every year thereafter.

 

[davebender]

What is your source for that data?

 

[tyrodtom]

The Devils Disciples by Anthony Read, Alternatehistory.com, Wiki. and others.

And what's your sources ?

 

[davebender]

Germany GDP. Billions of RM. (Rezessionen in historischer Betrachtung, Dr. Norbert Räth)
1930. 82.4
1931. 69.0
1932. 56.7
1933. 58.4
1934. 65.5
1935. 73.1
1936. 81.2
1937. 90.9
1938. 100.2
1939. 109.3

Germany Military Budget. Billions of RM. (Richard Gaettens).
1933. 1.9. 3.3% of GDP.
1934. 1.9. 2.9% of GDP.
1935. 4.0. 5.5% of GDP.
1936. 5.8. 7.1% of GDP.
1937. 8.2. 9.0% of GDP.
1938. 18.4. 18.4% of GDP.

1933 to 1938. per Niall Ferguson.
German GDP grew by an average of 11% per year. This was accomplished without significant inflation.
…..Austrian GNP rose 12.8% during 1938 and 13.3% during 1939.

 

[tyrodtom]

Looks like my 10 % is off a lot less percentage wise, than your 1%.

 

[delcyros]

I graphically tried to outline the approach problem for an XXI submarine versus a convoi:

By delcyros at 2012-06-12

To be shown here is a convoi made up from 28 M/V (6nm wide) in dark grey in the middle with three perimeters, each 10, 20 or 30nm distant from the convoi. The convoi is assumed to proceed with 10 kts maintening a steady heading (an HX-derivate).

Starting battery capacity of the XXI is assumed to be 70%, rather than 90% (legend) or 100% (full). Typical patrolling levels ranged from 90% to 60% at patrol station. A further 20% remaining battery capacity has to be kept as reserve when the boat achieved firing range (red, around the convoi) in order to be able to disengage.
Thus, only 50% of the full capacity can be used for the intercept.
The possible positions related to the convoi are given in the drawing for 14 kts sprint, 10kts submerged cruise and 6kts creep (silent speed).

 

[psteel]

Thanks Delcyros for the detailed diagram. I wonder for comparison could you show what a Type VII with Schnorkel could attempt in the same situation?

 

[delcyros]

Unfortunately, I have not (yet) enough information for type VII to outline a similar type of physical limit of approach analysis.

 

[psteel]

Thanks anyway. If you do find such info it would interesting to compare. I've read that the Type XXIII had a better schrnorkel than the XXI and could cruise at up to 12knots. I also gather that a new 12knot schnorkel was finished at the end of the war for the UBoat fleet. Any idea how that would change the above diagram with a XXI plus 12 knot schnorkel?

 

[delcyros]

Type XXI snorkel was cleared for 10 kts submerged cruise (10.42 kts in trials).
Type XXIII snorkel was cleared to 12 kts submerged cruise.

Note that at these levels of speed, no charging of the batteries is possible and there may even be electric motors switched on to augment the Diesels. Parctical recharging speeds varied between 6 and 7.5 kts for XXI and 5 to 7 kts for XXIII. At higher speeds than 6 kts, the improved sonar was disfunctional, too.

So my assumption is that nobody would dare to snort an extensive time at maximum submerged cruise speed on Diesels. The pume of smoke isn´t visually invisible, the amount of sound generated creates a noisy signal and can be detected from quite some distance. Another problem is the wave created by the snorkel. While the Wesh-coated snorkel head itselfe may be close to invisible (within the ground clutter return) to radar detection, the wave created at high snorting speed is not invisible and microwave radar sets could detect and discriminate wave signals, particularely at very calm Seas (in the 70´s it was seastate +1 kts and You are safe, indicating very slow snorting speeds).
Thus, I don´t expect a lot of change.

 

[psteel]

From what I can read Schnorkel and Periscopes are very difficult to detect visually. A notional detection range of 5-6nm is possible but sweep rates are based on 2nm width in calm seas and 1/2 nm wide in rough seas 10-40nm²/hr. In theory they are not visible to visual or radar, in sea state 4 or more. WW-II warship type radar is unlikely to get sweep rates of more than 6 miles wide against Schnorkel/periscope targets, suggesting sweep rates of only about 72 nm²/hr [12 knots cruise]. To completely cover the inner zone of a 12kt convoy is going to require over 1/2 dozen escorts. Sweeping for submerged targets over the same convoy zone for late war ASDIC is going to require about a dozen escorts. I've read that ideally 16 escorts were recommended to cover a convoy. I guess the last 4 escorts are for rapid investigating of possible contact and extended pursuit.

This should provide a zone about 6nm wide around a convoy where they can detect most submarine approaches and dispatch an effective counter attack force.

 

[psteel]

Sea Keeping - Battleship vs Heavy Cruiser in Battleship Vs Battleship Forum

At this site [post 10] shows how stormy seas effect merchant ships and a 10 knot convoy in heavy seas [force 7] is only going to be able to manage ~ 7-8 knots depending on how big the merchant ships are. Even a regular storm would result in convoy speeds of ~9 knots.

I have read that if submarines are diving deep , they are not effected by such weather and even at medium depth the speed loss is hardly noticable.

Based on Delcyros diagrames the heavier the seas the better the conditions for true submarine to catch a convoy.