German destroyer Z51

The German destroyer Z51 was the only ship of the Type 1942 destroyer class built for the Kriegsmarine. She was the first destroyer designed or built by the Kriegsmarine to use diesel fuel, which would have given it a longer range and readier access to refueling compared to fuel oil. Z51 was ordered on 25 November 1942, and launched on 2 October 1944, far before being finished, likely to clear her slipway for U-boat construction. She was left floating outside Bremen and was sunk in an air raid on 21 March 1945. She was broken up between 1948 and 1949.

Class overview
Name: Type 1942 destroyer
Builders: Deschimag
Operators: Kriegsmarine
Preceded by: Type 1936C destroyer
Built: 1943–1944
Planned: Unknown
Lost: 1
General characteristics
Type: Destroyer
Displacement:
  • 2,014 tonnes (1,982 long tons; 2,220 short tons) (standard load)
  • 2,330 tonnes (2,290 long tons; 2,570 short tons) (design load)
  • 2,720 tonnes (2,680 long tons; 3,000 short tons) (full load)
Length:
Beam: 11 metres (36 ft)
Draught:
  • 3.72 metres (12.2 ft) (standard load)
  • 3.98 metres (13.1 ft) (design load)
  • 4.37 metres (14.3 ft) (full load)
Installed power: 57,000 electric horsepower (43,000 kW)
Propulsion:
  • 6 x 24-cylinder, two-stroke diesel engines
  • 3 x shafts
Speed:
  • 36 knots (67 km/h; 41 mph) (top speed)
  • 19 knots (35 km/h; 22 mph) (cruising speed)
Range: 5,500 nautical miles (10,200 km; 6,300 mi) at 19 knots (35 km/h; 22 mph)[lower-alpha 1]
Boats & landing
craft carried:
Complement: 12 officers and 335 enlisted
Armament:
  • 4 x 12.7-centimetre (5.0 in) QF guns (720 rounds of ammunition)
  • 8 x 3.7-centimetre (1.5 in) AA guns (16,000 rounds)
  • 12 x 2-centimetre (0.8 in) AA guns (24,000 rounds)
  • 2 x triple 53.3-centimetre (21.0 in) torpedo tubes (18 rounds)
  • 50 mines

Development

The Type 1942 destroyer class marked a major change from previous destroyer concepts produced by the Kriegsmarine, as it was the first design to be given diesel propulsion. This was done because of the longer endurance offered by diesel,[lower-alpha 2] and likely also because diesel fuel was more readily obtainable for Nazi Germany.[3] Between 1928 and 1935, MAN Augsburg built a light, double acting, two-stroke diesel motor, which met German navy specifications. The motors were then tested on the German cruiser Leipzig and the training ship Bremse. The motors encountered initial problems with teething, which although swiftly overcome, allowed those supportive of steam engines to deny diesel propulsion any research in the critical building period from 1935 on.[4][5] It was not until 1938 that the Kriegsmarine had a renewed interest in steam propulsion. However the advent of World War II largely led to the suspension of research, except for the Type 1942 destroyer class, which was to use six MAN type 12Z32/34 engines.[5]

Diesel engines

Six MAN type 12Z32/34 engines were ordered in 1943, but only four were completed by the end of the war in 1945. Test work on the engines was abandoned in February 1945, due to lack of fuel.[5] The type 12Z32/34 engine was 24-cylinder, placed in a 2 × 12 configuration, had a 320-millimetre (13 in) bore, a 440 mm (17 in) stroke motor, and was a 'V' form, fast-running, double-acting, two-stroke, diesel engine made of welded steel.[6] It had a maximum of 600 revs per minute, a piston speed of 8.8 metres per second (29 ft/s), maximum output of 12,000 horsepower (8,900 kW), medium effective pressure of 5.52 kilograms per square centimetre (78.5 psi), and a maximum fuel demand of 185 grams per horsepower per hour (2.43 oz/kW/ks). It had a dry weight of 67 tonnes (66 long tons; 74 short tons), including auxiliary machinery, but not the oil cooler. The six engines combined would give the Type 1942 destroyer class a range to match the pocket battleships and U-boats.[2]

Subdesigns

The Type 1942 design was expanded to three subdesigns as it was developed: 'A', 'B', and 'C'. The original plan had a six-diesel engine, three-shaft configuration, with an armament of four 12.7-centimetre (5.0 in) guns.[7] The design attracted much criticism,[8] thus a new sketch was drawn, 'A', with a twin 12.7 cm turret on the fore and aft, with a single 12.7 cm turret superfiring over both. This design also drew criticism. By December 1943, the Führer der Zerstörer (FdZ) demanded that the fore single superfiring turret be removed, in order to reduce length, improve speed, and reduce bow weight. They also mandated that the aft single 12.7 cm guns be able to elevate up to 75°. However, on 22 January 1944, after a meeting between the FdZ and Naval Group North, the FdZ dropped their demand for the fore single turret to be removed, after being informed that the speed loss due to it was marginal.[9]

At the same conference, the new 12.7 cm KM/41 naval gun was also discussed, as it was the best quick-firing gun design of the time. It was pointed out that the 12.7 cm KM/41 had a severe lack of anti-aircraft abilities, due to the fact that none of the mountings were tri-axial, and indeed, only the single turret guns were even bi-axial. Additionally, the twin turrets could only elevate to 52°, and the single turrets only to 75°. Because of this, questions on worth of stabilization for the directors and rangefinders were raised, whereupon it was decided that it would be up to the Shipbuilding Commission to decide if the stabilization would come with too great a weight penalty, and to omit if they felt it did. Due to the severe lack of flak defence, it was decided to replace the LM/44 2 cm (0.79 in) twin mounted AA guns with 3 cm (1.2 in) twin mount AA guns if possible, although the 2 cm AA guns were considered an acceptable interim measure. Another point of consideration was the matter of the new 5.5 cm (2.2 in) Gerät 58 AA gun, which was designed for U-boats. The idea of mounting these guns on the Type 1942 destroyer class was discussed at length, although it had major issues. One such issue was that the new 5.5 cm guns weighed between 6 tonnes (5.9 long tons; 6.6 short tons) and 7 t (6.9 long tons; 7.7 short tons), inclusive of directors and sights, which meant that the four 3.7 cm (1.5 in) guns could be replaced by only two 5.5 cm guns. Another issue raised was that room would have to be made for the new 5.5 guns. It was decided that the aft single 12.7 cm gun and two twin 2 cm guns would be removed to make room for two 5.5 cm guns, although it was noted that the 12.7 cm guns would likely arrive before the 5.5 cm guns, and thus the 12.7 cm guns would be allowed on a temporary basis. It was also decided that the remaining 3.7 cm AA guns would be replaced by 3 cm guns, in order to simplify ammunition supply.[9]

Another conference was held on 9 February 1944, to discuss the weight and trim of the design. at this conference, it was decided that the torpedo tube placement would follow that of its predecessors, with one set before and abaft the second funnel. Due to this, and the huge number of earlier changes, the design still being worked upon was dubbed the 'B' subdesign. However, yet further modifications were made, by 14 February the Shipbuilding Commission had convinced the other groups to change the design to have three twin main guns. This design, dubbed the 'C' subdesign, had two LM/41 twin turrets placed forward, and one aft, all of which were controlled by radar equipped directors. The number of 5.5 cm guns was increased to three, grouped about the after funnel. The hull length and displacement was slightly increased, and the engine machinery was moved further back on the boat, to balance out the weight of the added turret. The propulsion system was to be divided into four motor rooms, each containing two diesels (although only four were actually placed in Z51).[10]

Designs
Design Propulsion Main armament Other armament Torpedo tubes
Initial[8] Six × MAN type 12Z32/34 diesel engines 4 × 12.7 cm single naval guns, 2 forward, 2 aft Unknown 2 × 53.3 cm triple tubes, in unspecified locations
'A'[8] 2 × 12.7 cm twin naval guns, one forward, one aft
2 × 12.7 cm single naval guns, one forward, one aft		 8 × 3.7 cm AA guns
12 x 2 cm AA guns
Later 'A'[8] 2 × 12.7 cm twin naval guns, one forward, one aft
1 × 12.7 cm single naval gun, forward		 2 × 5.5 cm AA guns
12 × 3 cm AA guns
'B'[8][10] 2 × 53.3 cm triple tubes, before and abaft the second funnel
'C'[8][10] Eight × MAN type 12Z32/34 diesel engines 3 × 12.7 cm twin naval guns, two forward, one aft 3 × 5.5 cm AA guns
12 × 3 cm AA guns

Z51

Only one ship of the type was ever laid down, Z51.[3] Z51's design was modified heavily from the original ('A') design of the Type 1942 destroyer, and slightly modified from the final ('C') design. The original eight MAN type 12Z32/34 diesel engines, which were to drive two shafts via Vulkan gearing, were replaced by only four such engines, which were coupled to the centre shaft, with the wing engines being removed entirely.[11][7][2]

After 1944, Germany increasingly transmitted schematics and research for advanced science and weaponry to Japan using submarines, as they were the only method of transportation available to Germany that could hope to reach Japan.[12] One such transportation was attempted by German submarine U-234, carrying the material and designs for advanced weaponry, involving new torpedoes, two Messerschmitt Me 262 jet fighters with schematics to build them, and the designs for the Type 1942 destroyer class.[13] However, Germany surrendered on 8 May 1945, before U-234 could reach its target, and she therefore surrendered herself to USS Sutton, in the western Atlantic, on 14 May 1945.[14][13]

Characteristics

The Type 1942 destroyers were to be 108.0 metres (354.3 ft) long at waterline, and 114.3 m (375 ft) long overall. Their design gave them a breadth of 11 m (36 ft), and a freeboard of 6.5 m (21 ft). They would have a draught of 3.72 m (12.2 ft) at standard load, 3.98 m (13.1 ft) at design load, and 4.37 m (14.3 ft) at full load. They would displace 2,014 tonnes (1,982 long tons; 2,220 short tons) at standard load, 2,330 t (2,290 long tons; 2,570 short tons) at design load, and 2,720 t (2,680 long tons; 3,000 short tons) at full load. They were to have a complement of 12 officers and 335 crewmembers. They were to carry one motor pinnace and one torpedo cutter.[15]

Their armament was to be four 12.7-centimetre (5.0 in) quick firing guns, with 720 rounds of ammunition, and a range of 17.4 km (10.8 mi); eight 3.7 cm (1.5 in) anti-aircraft guns, with 16,000 rounds; twelve 2 cm (0.79 in) anti-aircraft guns, with 24,000 rounds of ammunition; two triple 53.3 cm (21.0 in) torpedo tubes, with 18 rounds of ammunition; and 50 mines.[15]

Their propulsion was made up of six MAN type 12Z32/34, 24-cylinder (in a 2 × 12 configuration), two-stroke, 'V'-form diesel engines, which had a 320-millimetre (13 in) bore, a 440 mm (17 in) stroke motor, and were made of welded steel, which were placed on three shafts of unknown diameter.[7][15] The two outer shafts were directly connected to one 5,620-shaft-horsepower (4,190 kW) diesel engine. The central shaft connected to four diesel engines, with each central engine producing 11,650 shp (8,690 kW). Their planned electricity plant is unknown.[15] This setup was designed to give a total output of 57,000-electric-horsepower (43,000 kW) or 57,120-brake-horsepower (42,590 kW), giving them a top speed of 36 knots (67 km/h; 41 mph).[16][15] They were to carry 533 t (525 long tons; 588 short tons) of diesel fuel, to give them a range of 5,500 nautical miles (10,200 km; 6,300 mi) at 19 knots (35 km/h; 22 mph).[15]

Construction and loss

Z51 was ordered from the German shipyard company Deschimag on 25 November 1942, and launched on 2 October 1944. She was sunk during a major air raid on Bremen, on 21 March 1945. She had just been moved away from a fitting-out quay at the Deschimag yard, although largely incomplete: she had only her forward and after shelter decks, no machinery was installed and her shaft tunnels had been welded up to make them watertight. From this it has been suggested that her launch was done only to clear the slip for U-boat building. She was lying abandoned, with her portside to the eastern end of Kohlenhafen, alongside Röchling wharf.[7]

During the air raid, she was hit by two bombs, although one may not have hit her directly; one struck the vicinity of the bulkhead, between compartments X1 and X11, breaking off the fore-end just behind her No. 2 gun pivot. A later bomb hit her aft, fracturing the stern aft of her No. 4 gun position and causing her quarterdecks to hang at an angle. At this point, numerous holes and cracks had formed in the hull, causing her to flood with water and sink to the bottom. Later on a crane from the nearby dockyard fell across her deck, above her after motor room. After the war, on 21 January 1948, the Weser Port Salvage Authorities called for tenders to assist in her breaking up. A number of quotations were given, ranging from 130,000 to 200,000 RM (Reichsmark), and from four to 13 months' duration. Eventually a contract was placed on 17 February 1948, with Deutsches Dampfschiffahrts Hansa, for 132,000 RM and eight months work.[7] Her breaking up was finished in February 1949.[15] Her four diesel engines were never installed due to the war and were left on MAN's testbeds in Augsburg. Two were later seized by the Allies during the postwar occupation of Germany. One surviving engine was retained by MAN and displayed in its company museum until it was transferred to the Auto & Technik Museum in Sinsheim in 1982.[17]

Notes
  1. The range would have greatly increased at a lower cruising speed.[1]
  2. Diesel propulsion gave the ship an extended range. The Kriegsmarine was particularly keen on developing a longer-range destroyer to compensate for its lack of light cruisers.[2]

References

Citations
  1. Koop & Schmolke 2003, p. 23.
  2. Koop & Schmolke 2003, p. 22.
  3. Whitley 1991, p. 40.
  4. Koop & Schmolke 2014, p. 12.
  5. Koop & Schmolke 2003, p. 21.
  6. Koop & Schmolke 2003, pp. 21–22.
  7. Whitley 1991, p. 41.
  8. Whitley 1991, pp. 41–42.
  9. Whitley 1991, p. 42.
  10. Whitley 1983, p. 49.
  11. Whitley 1983, p. 48 & 49.
  12. Boyd & Yoshida 2012, p. 162.
  13. West 2010, p. 313.
  14. Boyd & Yoshida 2012, p. 165.
  15. Gröner 1990, p. 210.
  16. Lenton 1976, p. 80.
  17. The Motor Ship 1982.

Works cited
  • Boyd, Carl; Yoshida, Akihiko (2012). The Japanese Submarine Force and World War II. Annapolis: Naval Institute Press. ISBN 978-1-61251-206-8.CS1 maint: ref=harv (link)
  • Gröner, Erich (1990). German Warships: 1815–1945, Major Surface Warships. I. Annapolis: Naval Institute Press. ISBN 978-0-87021-790-6.CS1 maint: ref=harv (link)
  • Koop, Gerhard & Schmolke, Klaus-Peter (2003). German Destroyers of World War II. Annapolis: Naval Institute Press. ISBN 978-1-59114-307-9.CS1 maint: ref=harv (link)
  • Koop, Gerhard; Schmolke, Klaus-Peter (2014). German Light Cruisers of World War II: Warships of the Kriegsmarine. Barnsley: Seaforth Publishing. ISBN 9781473850187.CS1 maint: ref=harv (link)
  • Lenton, H. T. (1976). German Warships of the Second World War. London: Macdonald and Jane's. ISBN 0356-04661-3.CS1 maint: ref=harv (link)
  • "New museum home for mint MAN warship engine". The Motor Ship. London: Temple Press. 63: 36. 1982. OCLC 457014193.
  • West, Nigel (2010). Historical Dictionary of Naval Intelligence. Lanham, Md.: Scarecrow Press. ISBN 978-0-81086-760-4.CS1 maint: ref=harv (link)
  • Whitley, M. J. (1983). Destroyer!: German Destroyers in World War II. London: Arms and Armour. ISBN 978-0-85368-258-5.CS1 maint: ref=harv (link)
  • Whitley, M. J. (1991). German Destroyers of World War Two. Annapolis: Naval Institute Press. ISBN 978-1-55750-302-2.CS1 maint: ref=harv (link)
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