This thread is more than just about Diesels but they are a central part so hence the thread title. Mostly this is about trying to undo as many of the construction and technical flaws as I think I can get away with.
Primary issues of the KM
1) Misguided and confused expansion program in mid 1930s on
2) Propulsion problems on multiple ships
3) Lack of escorts for raiders in early war as CLs & DDs didn’t have range
4) Problems with weapons, torpedo warheads not detonating, etc
Just about all of these problems can traced to the transition from the Kaiserliche Marine to the Reichsmarine. The entire design and building departments were let go and once the Germans started working on ships in the mid-1920s the CLs were all to one degree or another flawed as these departments were restored. Design problems continued into the 30s and this combined with rush for re-armament creates more than a bit of a mess.
In the interwar years Germany at once looked for ways to circumvent the restrictions of the treaty of Versailles. In the mid-1920s the Soviet and German military cooperation programs are perhaps best known but there were others. So, my thought is for Reichsmarine to have better continuity with the old Kaiserliche Marine in particular those builders and designers not to be lost. A possible answer is found within the Treaty of Versailles; Germany was required to surrender much of its merchant marine. Here let us have a new civilian office formed to help with the design of ships for a new merchant marine and the best of the designers from the Kaiserliche Marine design office go there along with a number of civilian designers.
***
The first major achievement was the salvage of the MAN 6-cylinder diesel 12,000 hp being constructed for dreadnoughts of the German Navy. MAN, first suggested this powerful engine back in 1909 but the engine had a long and somewhat tortured development. The first test occurred in 1911 and in 1912 a major redesign was required after an explosion killed 10 and wounded 14 others. By 1913 MAN was working on their 7th design and in 1914 a trial run produced 10,000 SHP. Once the fighting started design work slowed and then the fuel mixture was changed to coal tar oil / kerosene and the engine at last past its acceptance trial after a five-day run of 90% power, 10,800 SHP. Design maximum power was now 12,200 SHP. In October 1917 an overload power run was conducted on a single cylinder and it produced 3,573 SHP at 145 RPMs. Assuming all 6 cylinders had been run that would have produced 21,438 SHP.
The Inter-Allied Commission of Control ordered the MAN diesel destroyed as it was intended for the incomplete Dreadnought Battleship SMS Sachsen which was at Germaniawerft yard in Kiel. MAN, and the Naval Design office were not particularly interested in nearly 8 years of effort to end up cut into scrap with nothing to show for it. First MAN tried reason pointing out that the engine could be used for something else with no military application. The Commission was at first reluctant but after pointing out that Large Torpedo Boats of the 1918Mob class were being converted into merchant ships at last approval was granted.
The MAN diesel was installed in a newly designed bulk freighter, Wolf. Because of post war economic problems Wolf didn’t enter service till 1923, 14 years after the engine was first conceived of.
The engine was much larger than WOLF required so most of the time it was run 50% of its rated power of 12,200 SHP. Over the next several years a great deal was learned about the problems of running such a large and powerful diesel engine.
***
Emden was the first major warship that the new German worked on. A great many politicians thought that the cruiser was going to be a waste of money better spent on just about anything else. Knowing that the German navy would be out gunned in any war there were but two options for the new Reichsmarine, coastal defense which was the role that the victorious allied powers wanted or a commerce raiding force. The choice was fairly simple, raiders. Natural the German engineers looked back to the Koln Class of 1916 as the last built cruisers as a baseline. They also looked at the FK 16 series I to V.
Emden turned out to be a horribly compromised design. First there was the Treaty of Versailles that limited the cruiser to 6,000 tons. Also the Inter Allied Commission of Control outright vetoed certain design elements like using new 150mm L55 in twin gun houses. Instead forcing use of left over 150mm L45s from the Great War. Deciding that they couldn't build a design they wanted with these restrictions Emden ended up being a training ship with lots of space for cadets. To keep weight down to attempt to stay within treaty restrictions extensive use was made of welding on the hull.
Once in service a number of flaws were detected with the electrical welding, cracks in the hull and structural weakness of Emden. The design department looked deeply into the construction and design problems.
***
The Reichsmarine was in theory build five more light cruisers and six 10,000 ton armored ships as replacements for the pre-dreadnought battleships. The head of the Reichsmarine Admiral Hans Zenker had settled firmly on a raider model as the mission for the navy. This presented a number of challenges the most important was a lack of ports for resupply and repair. In the Great War living off prizes for resupply of fuel and supplies had proved a very uncertain proposition. As such range was key requirement. Only diesel offered the possibility for true global range without refueling. Based upon the experiences of Wolf some lessons were learned. Vibration in the engineering space of Wolf had proved to be a particular problem and the mounting for the engine had required reinforcement. Emden showed a need for better quality control on the wielding and structural reinforcement.
After range, the next key design requirement was speed, especially high cruise speed. The later requirement again pushed diesel as the propulsion choice. A large drawback of diesel was its relative weight and space inefficiencies per unit of power delivered compared to steam turbines especially the new high-pressure steam turbines. Most of this extra space and weight was the requirement for secondary motors to provide forced air to the primary propulsion motors. Despite the limitations in the end diesel engines won out for the larger ships. The new cruisers would be mixed steam and diesel propulsion plants.
One design change was the new hull form called a bulbous bow from the new liners for the Norddeutsche Lloyd. The liners besides having the most powerful engineering plants ever put on to German built ships, 135,000 shp, they also used bulbous bow. The new bow first to appear in American designs changed the flow of water around the ship and greatly reduced resistance. Many designers in the Reich Naval Design Office didn’t want to use the radical new hull form. Instead they wanted to let the Norddeutsche Lloyd’s liners act as test subjects. The problem was Germany could only build six large ships, if they were to gain the benefit of the hull form it was use it or not. In the end Zenker cast the deciding vote for to use the new hull form.
The last key design element of the new cruisers and armored ships was the Treaty of Versailles or rather responses to it. From the start, few Germans could say they supported the treaty that ended the war. After the experience of interference on the building of Emden and the rejection of allowing Germany to join the Geneva Naval Conference of 1927 the treaty was even less popular. As a result, it was decided to only make the vaguest pretentious of obeying the treaty restrictions. Deutschland ended up with a designed displacement of over 13,000 tons rather than her official 10,000 tons. The Konigsberg light cruisers ended up at over 8,000 tons rather than their official 6,000 tons. Both of these displacements were only in light condition at full deep draft their displacements were even higher. The withdrawal of the Inter Allied Commission of Control allowed these enlargements to the designs to occur.
MAN designed the diesel engines, 9 cylinder, double-acting, two-stroke diesel engines for Deutschland and 7 cylinder, double-acting, two-stroke diesel engines for Konigsberg. The engines for Konigsberg produced over 6,000 SHP per engine while Deutschland developed nearly 6,500 SHP per engine. When Deutschland conducted her builder’s trials she full just short of her designed power of 54,000 SHP and instead reached 52,000 SHP. Despite this slight lack of power Deutschland reached a speed of 29.3 knots with an impressive range of 17,000 nm at 13 knots. Konigsberg was less successful with a top speed of 32.5 knots and a range of 8,500 nm at 13 knots.
***
The appearance of the armored ships of the Deutschland class shocked the world. The combination of fire power, 2x3 11” main guns and 8x1 5.9” secondary guns, officially 27 knots and long range made them formidable weapons of war. The British Press at once coined the phrase ‘Pocket Battleship’ and others called them ‘Cruiser Killers’. The British and in particular the French started to consider replies to the new German Warships.
***
In 1928 Admiral Zenker was forced out because of a scandal. Some of the Reichsmarine’s hidden projects had become public in particular its investment since the end of the Great War in industry. What made it the shocking scandal was once the details got out was that the Navy was operating totally on its own outside of government control. Admiral Eric Raeder became the new chief of the Reichsmarine. With a new chief came new design priorities. Admiral Raeder with approval of the cabinet came up with a program of new warships, destroyers, more cruisers and even an aircraft carrier.
In 1930 a new naval disarmament talk was held in London. Once again Germany hoped to be involved but again would be disappointed. The shackles of Versailles remained even if imperfectly. For now, the new destroyers and other warships would remain paper studies. More data was collected as the Deutschland and Konigsberg Class ships sailed the globe. The light cruisers were capable of Northern Atlantic missions but only just as their range was just too short for anything else. Additional effort was put into creating even more powerful Diesel engines as escorts were needed, particularly long ranged destroyers. As the sister ships to Deutschland and Konigsberg entered service incremental improvements were made.
Admiral Raeder ordered consideration of larger ships in reply to the French Dunkerque class laid down in 1932. Armed with 13” guns, 29.5 knots and 26,000 tons in size made the new French Battleship a deadly threat to the Deutschlands. A series of design studies of battleships armed with 13”, 13.78”, 14”, 15” and even 16” guns were considered. Enlargement of the Deutschland class to 20,000 tons to allow for an 8” armored belt to provide protection from the French 13” guns. By 1932 the government had settled on a program of new warships. What was lacking was the political will to actually build any of the designs and overtly break the Treaty of Versailles
***
In 1933 Adolf Hitler became chancellor of Germany on a platform of rearmament and the destruction of the Treaty of Versailles. At first Hitler was reluctant himself to approve the naval program being suggested. A key concern was a desire to avoid antagonize the British whose cooperation he needed for his other revisionist ideas. Wanting to limit the new ships in size and gun power. Raeder and the designers were able to at last convince Hitler that a straight forward fast battleship design would be better than a progressive enlargement of the Deutschland class. The latest member had grown to over 16,000 tons base displacement and the design studies showed that at least 20,000 tons were required for the 8” belt but it was an unbalanced design. At least another triple turret was required for the 11” guns or better yet a larger main armament.
And so, Hitler reached out to the British and in 1934 negotiated the Anglo-German Naval Agreement where Germany could build up to 35% of the Royal Navy. In effect Germany became party to the Washington Naval Treaty system on same level as Italy and France. At once Germany laid down two Battleships of the Scharnhorst class. The ships displaced 35,000 tons, armed with 3x3 11” guns, 12 5.9” guns and 14 4.1” AAA guns. There was a strong push to use the new 128mm Duel Purpose weapons as a uniform secondary battery but the hitting power of the 150mm / 5.9” guns was impossible to ignore. With experience of the Deutschland class there was no debate over use of bulbous bow and they were part of all large German ships going forward.
By 1934 the German navy had a decade of experience with large marine diesels and the technology was mature. As such despite a lower top speed compared to steam propulsion, particular high-pressure steam plants again an all diesel propulsion plant was settled upon. MAN designed new 12-cylinder diesels, an enlargement of the Deutschland’s tried and tested units. Each engine developed 9,600 SHP and with 12 of these to drive the new battleship for a total rated power of 115,200 SHP. On her builder’s trial Scharnhorst achieved 29.75 knots. While it was hoped for a range of over 12,100 nm at 19 knots service trials showed a range of 10,600 nm, still an impressive achievement.
Various designs and proposals were considered for a new class of heavy cruisers. In the end the solution was to use the Deutschland Class Hull. Instead of two triple turrets of 11” guns there would be two quad turrets of 8” guns. Debate swirled around the secondary armament, use the same 8x1 150mm guns on the Deutschland class? By the 1930s the Deutschland anti-aircraft armament was looking very weak. The day had come for the 128mm DP guns and with their much lower weight the new heavy cruisers could mount two in place over every 150mm gun. Giving the cruisers an armament of 2x4 203mm and 8x2 128mm DP guns. Like the later Deutschland class ships the Admiral Hipper class had a 100mm armor belt, same range and top speed. The new heavy cruisers of the Admiral Hipper class like the Deutschlands before them turned heads around the world.
With the formal end of the Treaty of Versailles Germany was at last clear to build modern destroyers and an aircraft carrier. Both types of vessels ended up having very tortured design histories in the Kriegsmarine.
The ship that in the end became Graf Zeppelin went through multiple design cycles between 1932 and 1935 when she was finally laid down. First design series was 22,000 tons, then 19,500 tons to stay within the restrictions of the 1934 Anglo-German naval agreement and the final design jumped to 33,000 tons. All designs called for very high speeds and the final design called for not only cruiser scale protection but also cruiser scale weapons. Casement mount 5.9” weapons included. Most major sticking point was the engineering plant. There was a desire for the fastest possible speed, 35 knots. The required power densities to achieve 35 knots were simply impossible with Diesel engines. In the end German engineers resorted the Turbo-Diesel; a combination of a turbo charger with a Diesel engine. Up till Graf Zeppelin the Germans had use secondary Diesel engines to provide forced draft for the primary Diesel engines. Turbo Chargers on the same MAN engines as found in Scharnhorst produced over 13,000 HP. Providing a 40% increase in power during the engines endurance trial. This provided for Graf Zeppelin a propulsion plant capable of 160,000 HP and a theoretical top speed of 34 knots.
Many in the Kriegsmarine were worried what would happen once Graf Zeppelin was ready as there was no experience with operating the type. As a stop gap measure a bulk iron ore freighter normally used in the Baltic and Norwegian seas was converted. The upper works were raised and a primitive funnel system setup to vent engine gases. A very small hanger was provided for more to give experience to deck crews with moving aircraft to and from the flight deck than for increasing capacity.
Even with the advent of Turbo Diesels the reduced power density for diesels resulted in a Destroyer design with 60,000 SHP from six V24 diesels three on each shaft. The ship would have five single mount 128mm DP guns and twelve 533 torpedo tubes. Speed would be 33.5 knots and 5,500 NM range. Meanwhile a design using high pressure steam was developed to get maximum possible speed. Armament would be the same but the ship would have 70,000 SHP from boilers, speed of 36 knots and 1,900 nm range. Lavish use of automation in the boiler rooms allowed a reduced engineering staff. The arguments went back and forth between steam and diesel; in the end in truly Solomic Wisdom the decision was made to split production between the two types.
Between 1934 and 1939 when the war broke out the Kriegsmarine built no less than eight classes of destroyers. Each pair of classes following the split between high pressure steam and turbo-diesels found in the first class. In 1938 in a desperate attempt to gain even more firepower the 128mm DP guns were dropped in favor a 150mm main guns. Protest limited the 150mm weapons to only the steam destroyers and as feared once in service the larger weapons proved unworkable. Once reports of the problems returned no additional 150mm gun destroyers were built.
The last major class of warships built by the Kriegsmarine before war broke out was the Bismarck class. Possible main armament choices consisted of 13.78”, 15”, 16” and 16.5” main guns. In the end 15” main guns were settled upon. The big question was to continue the split between 150mm secondaries and 105mm anti-aircraft weapons first seen with Deutschland or adopt 128mm uniform secondary battery. At last a break with tradition was made and Bismarck was built with a battery of 12 twin 128mm guns 6 to a side. Four turrets on the main deck and two more raised one deck on each flank.
As the Hindenburg Class Battleships and Mainz Class Light cruisers ended up being broken up on the slipways once the war began little effort will be expended on discussion the last class of German warships.
***
***
Primary issues of the KM
1) Misguided and confused expansion program in mid 1930s on
2) Propulsion problems on multiple ships
3) Lack of escorts for raiders in early war as CLs & DDs didn’t have range
4) Problems with weapons, torpedo warheads not detonating, etc
Just about all of these problems can traced to the transition from the Kaiserliche Marine to the Reichsmarine. The entire design and building departments were let go and once the Germans started working on ships in the mid-1920s the CLs were all to one degree or another flawed as these departments were restored. Design problems continued into the 30s and this combined with rush for re-armament creates more than a bit of a mess.
In the interwar years Germany at once looked for ways to circumvent the restrictions of the treaty of Versailles. In the mid-1920s the Soviet and German military cooperation programs are perhaps best known but there were others. So, my thought is for Reichsmarine to have better continuity with the old Kaiserliche Marine in particular those builders and designers not to be lost. A possible answer is found within the Treaty of Versailles; Germany was required to surrender much of its merchant marine. Here let us have a new civilian office formed to help with the design of ships for a new merchant marine and the best of the designers from the Kaiserliche Marine design office go there along with a number of civilian designers.
***
The first major achievement was the salvage of the MAN 6-cylinder diesel 12,000 hp being constructed for dreadnoughts of the German Navy. MAN, first suggested this powerful engine back in 1909 but the engine had a long and somewhat tortured development. The first test occurred in 1911 and in 1912 a major redesign was required after an explosion killed 10 and wounded 14 others. By 1913 MAN was working on their 7th design and in 1914 a trial run produced 10,000 SHP. Once the fighting started design work slowed and then the fuel mixture was changed to coal tar oil / kerosene and the engine at last past its acceptance trial after a five-day run of 90% power, 10,800 SHP. Design maximum power was now 12,200 SHP. In October 1917 an overload power run was conducted on a single cylinder and it produced 3,573 SHP at 145 RPMs. Assuming all 6 cylinders had been run that would have produced 21,438 SHP.
The Inter-Allied Commission of Control ordered the MAN diesel destroyed as it was intended for the incomplete Dreadnought Battleship SMS Sachsen which was at Germaniawerft yard in Kiel. MAN, and the Naval Design office were not particularly interested in nearly 8 years of effort to end up cut into scrap with nothing to show for it. First MAN tried reason pointing out that the engine could be used for something else with no military application. The Commission was at first reluctant but after pointing out that Large Torpedo Boats of the 1918Mob class were being converted into merchant ships at last approval was granted.
The MAN diesel was installed in a newly designed bulk freighter, Wolf. Because of post war economic problems Wolf didn’t enter service till 1923, 14 years after the engine was first conceived of.
The engine was much larger than WOLF required so most of the time it was run 50% of its rated power of 12,200 SHP. Over the next several years a great deal was learned about the problems of running such a large and powerful diesel engine.
***
Emden was the first major warship that the new German worked on. A great many politicians thought that the cruiser was going to be a waste of money better spent on just about anything else. Knowing that the German navy would be out gunned in any war there were but two options for the new Reichsmarine, coastal defense which was the role that the victorious allied powers wanted or a commerce raiding force. The choice was fairly simple, raiders. Natural the German engineers looked back to the Koln Class of 1916 as the last built cruisers as a baseline. They also looked at the FK 16 series I to V.
Emden turned out to be a horribly compromised design. First there was the Treaty of Versailles that limited the cruiser to 6,000 tons. Also the Inter Allied Commission of Control outright vetoed certain design elements like using new 150mm L55 in twin gun houses. Instead forcing use of left over 150mm L45s from the Great War. Deciding that they couldn't build a design they wanted with these restrictions Emden ended up being a training ship with lots of space for cadets. To keep weight down to attempt to stay within treaty restrictions extensive use was made of welding on the hull.
Once in service a number of flaws were detected with the electrical welding, cracks in the hull and structural weakness of Emden. The design department looked deeply into the construction and design problems.
***
The Reichsmarine was in theory build five more light cruisers and six 10,000 ton armored ships as replacements for the pre-dreadnought battleships. The head of the Reichsmarine Admiral Hans Zenker had settled firmly on a raider model as the mission for the navy. This presented a number of challenges the most important was a lack of ports for resupply and repair. In the Great War living off prizes for resupply of fuel and supplies had proved a very uncertain proposition. As such range was key requirement. Only diesel offered the possibility for true global range without refueling. Based upon the experiences of Wolf some lessons were learned. Vibration in the engineering space of Wolf had proved to be a particular problem and the mounting for the engine had required reinforcement. Emden showed a need for better quality control on the wielding and structural reinforcement.
After range, the next key design requirement was speed, especially high cruise speed. The later requirement again pushed diesel as the propulsion choice. A large drawback of diesel was its relative weight and space inefficiencies per unit of power delivered compared to steam turbines especially the new high-pressure steam turbines. Most of this extra space and weight was the requirement for secondary motors to provide forced air to the primary propulsion motors. Despite the limitations in the end diesel engines won out for the larger ships. The new cruisers would be mixed steam and diesel propulsion plants.
One design change was the new hull form called a bulbous bow from the new liners for the Norddeutsche Lloyd. The liners besides having the most powerful engineering plants ever put on to German built ships, 135,000 shp, they also used bulbous bow. The new bow first to appear in American designs changed the flow of water around the ship and greatly reduced resistance. Many designers in the Reich Naval Design Office didn’t want to use the radical new hull form. Instead they wanted to let the Norddeutsche Lloyd’s liners act as test subjects. The problem was Germany could only build six large ships, if they were to gain the benefit of the hull form it was use it or not. In the end Zenker cast the deciding vote for to use the new hull form.
The last key design element of the new cruisers and armored ships was the Treaty of Versailles or rather responses to it. From the start, few Germans could say they supported the treaty that ended the war. After the experience of interference on the building of Emden and the rejection of allowing Germany to join the Geneva Naval Conference of 1927 the treaty was even less popular. As a result, it was decided to only make the vaguest pretentious of obeying the treaty restrictions. Deutschland ended up with a designed displacement of over 13,000 tons rather than her official 10,000 tons. The Konigsberg light cruisers ended up at over 8,000 tons rather than their official 6,000 tons. Both of these displacements were only in light condition at full deep draft their displacements were even higher. The withdrawal of the Inter Allied Commission of Control allowed these enlargements to the designs to occur.
MAN designed the diesel engines, 9 cylinder, double-acting, two-stroke diesel engines for Deutschland and 7 cylinder, double-acting, two-stroke diesel engines for Konigsberg. The engines for Konigsberg produced over 6,000 SHP per engine while Deutschland developed nearly 6,500 SHP per engine. When Deutschland conducted her builder’s trials she full just short of her designed power of 54,000 SHP and instead reached 52,000 SHP. Despite this slight lack of power Deutschland reached a speed of 29.3 knots with an impressive range of 17,000 nm at 13 knots. Konigsberg was less successful with a top speed of 32.5 knots and a range of 8,500 nm at 13 knots.
***
The appearance of the armored ships of the Deutschland class shocked the world. The combination of fire power, 2x3 11” main guns and 8x1 5.9” secondary guns, officially 27 knots and long range made them formidable weapons of war. The British Press at once coined the phrase ‘Pocket Battleship’ and others called them ‘Cruiser Killers’. The British and in particular the French started to consider replies to the new German Warships.
***
In 1928 Admiral Zenker was forced out because of a scandal. Some of the Reichsmarine’s hidden projects had become public in particular its investment since the end of the Great War in industry. What made it the shocking scandal was once the details got out was that the Navy was operating totally on its own outside of government control. Admiral Eric Raeder became the new chief of the Reichsmarine. With a new chief came new design priorities. Admiral Raeder with approval of the cabinet came up with a program of new warships, destroyers, more cruisers and even an aircraft carrier.
In 1930 a new naval disarmament talk was held in London. Once again Germany hoped to be involved but again would be disappointed. The shackles of Versailles remained even if imperfectly. For now, the new destroyers and other warships would remain paper studies. More data was collected as the Deutschland and Konigsberg Class ships sailed the globe. The light cruisers were capable of Northern Atlantic missions but only just as their range was just too short for anything else. Additional effort was put into creating even more powerful Diesel engines as escorts were needed, particularly long ranged destroyers. As the sister ships to Deutschland and Konigsberg entered service incremental improvements were made.
Admiral Raeder ordered consideration of larger ships in reply to the French Dunkerque class laid down in 1932. Armed with 13” guns, 29.5 knots and 26,000 tons in size made the new French Battleship a deadly threat to the Deutschlands. A series of design studies of battleships armed with 13”, 13.78”, 14”, 15” and even 16” guns were considered. Enlargement of the Deutschland class to 20,000 tons to allow for an 8” armored belt to provide protection from the French 13” guns. By 1932 the government had settled on a program of new warships. What was lacking was the political will to actually build any of the designs and overtly break the Treaty of Versailles
***
In 1933 Adolf Hitler became chancellor of Germany on a platform of rearmament and the destruction of the Treaty of Versailles. At first Hitler was reluctant himself to approve the naval program being suggested. A key concern was a desire to avoid antagonize the British whose cooperation he needed for his other revisionist ideas. Wanting to limit the new ships in size and gun power. Raeder and the designers were able to at last convince Hitler that a straight forward fast battleship design would be better than a progressive enlargement of the Deutschland class. The latest member had grown to over 16,000 tons base displacement and the design studies showed that at least 20,000 tons were required for the 8” belt but it was an unbalanced design. At least another triple turret was required for the 11” guns or better yet a larger main armament.
And so, Hitler reached out to the British and in 1934 negotiated the Anglo-German Naval Agreement where Germany could build up to 35% of the Royal Navy. In effect Germany became party to the Washington Naval Treaty system on same level as Italy and France. At once Germany laid down two Battleships of the Scharnhorst class. The ships displaced 35,000 tons, armed with 3x3 11” guns, 12 5.9” guns and 14 4.1” AAA guns. There was a strong push to use the new 128mm Duel Purpose weapons as a uniform secondary battery but the hitting power of the 150mm / 5.9” guns was impossible to ignore. With experience of the Deutschland class there was no debate over use of bulbous bow and they were part of all large German ships going forward.
By 1934 the German navy had a decade of experience with large marine diesels and the technology was mature. As such despite a lower top speed compared to steam propulsion, particular high-pressure steam plants again an all diesel propulsion plant was settled upon. MAN designed new 12-cylinder diesels, an enlargement of the Deutschland’s tried and tested units. Each engine developed 9,600 SHP and with 12 of these to drive the new battleship for a total rated power of 115,200 SHP. On her builder’s trial Scharnhorst achieved 29.75 knots. While it was hoped for a range of over 12,100 nm at 19 knots service trials showed a range of 10,600 nm, still an impressive achievement.
Various designs and proposals were considered for a new class of heavy cruisers. In the end the solution was to use the Deutschland Class Hull. Instead of two triple turrets of 11” guns there would be two quad turrets of 8” guns. Debate swirled around the secondary armament, use the same 8x1 150mm guns on the Deutschland class? By the 1930s the Deutschland anti-aircraft armament was looking very weak. The day had come for the 128mm DP guns and with their much lower weight the new heavy cruisers could mount two in place over every 150mm gun. Giving the cruisers an armament of 2x4 203mm and 8x2 128mm DP guns. Like the later Deutschland class ships the Admiral Hipper class had a 100mm armor belt, same range and top speed. The new heavy cruisers of the Admiral Hipper class like the Deutschlands before them turned heads around the world.
With the formal end of the Treaty of Versailles Germany was at last clear to build modern destroyers and an aircraft carrier. Both types of vessels ended up having very tortured design histories in the Kriegsmarine.
The ship that in the end became Graf Zeppelin went through multiple design cycles between 1932 and 1935 when she was finally laid down. First design series was 22,000 tons, then 19,500 tons to stay within the restrictions of the 1934 Anglo-German naval agreement and the final design jumped to 33,000 tons. All designs called for very high speeds and the final design called for not only cruiser scale protection but also cruiser scale weapons. Casement mount 5.9” weapons included. Most major sticking point was the engineering plant. There was a desire for the fastest possible speed, 35 knots. The required power densities to achieve 35 knots were simply impossible with Diesel engines. In the end German engineers resorted the Turbo-Diesel; a combination of a turbo charger with a Diesel engine. Up till Graf Zeppelin the Germans had use secondary Diesel engines to provide forced draft for the primary Diesel engines. Turbo Chargers on the same MAN engines as found in Scharnhorst produced over 13,000 HP. Providing a 40% increase in power during the engines endurance trial. This provided for Graf Zeppelin a propulsion plant capable of 160,000 HP and a theoretical top speed of 34 knots.
Many in the Kriegsmarine were worried what would happen once Graf Zeppelin was ready as there was no experience with operating the type. As a stop gap measure a bulk iron ore freighter normally used in the Baltic and Norwegian seas was converted. The upper works were raised and a primitive funnel system setup to vent engine gases. A very small hanger was provided for more to give experience to deck crews with moving aircraft to and from the flight deck than for increasing capacity.
Even with the advent of Turbo Diesels the reduced power density for diesels resulted in a Destroyer design with 60,000 SHP from six V24 diesels three on each shaft. The ship would have five single mount 128mm DP guns and twelve 533 torpedo tubes. Speed would be 33.5 knots and 5,500 NM range. Meanwhile a design using high pressure steam was developed to get maximum possible speed. Armament would be the same but the ship would have 70,000 SHP from boilers, speed of 36 knots and 1,900 nm range. Lavish use of automation in the boiler rooms allowed a reduced engineering staff. The arguments went back and forth between steam and diesel; in the end in truly Solomic Wisdom the decision was made to split production between the two types.
Between 1934 and 1939 when the war broke out the Kriegsmarine built no less than eight classes of destroyers. Each pair of classes following the split between high pressure steam and turbo-diesels found in the first class. In 1938 in a desperate attempt to gain even more firepower the 128mm DP guns were dropped in favor a 150mm main guns. Protest limited the 150mm weapons to only the steam destroyers and as feared once in service the larger weapons proved unworkable. Once reports of the problems returned no additional 150mm gun destroyers were built.
The last major class of warships built by the Kriegsmarine before war broke out was the Bismarck class. Possible main armament choices consisted of 13.78”, 15”, 16” and 16.5” main guns. In the end 15” main guns were settled upon. The big question was to continue the split between 150mm secondaries and 105mm anti-aircraft weapons first seen with Deutschland or adopt 128mm uniform secondary battery. At last a break with tradition was made and Bismarck was built with a battery of 12 twin 128mm guns 6 to a side. Four turrets on the main deck and two more raised one deck on each flank.
As the Hindenburg Class Battleships and Mainz Class Light cruisers ended up being broken up on the slipways once the war began little effort will be expended on discussion the last class of German warships.
***
***