[Submarine Design Ulrich Gabler Pdf Download
Tilo Chopin
Hans Saeger Howaldtswerke-DeutscheWerft AG (HDW)View Full Issue This paper addresses the German submarine technology and its evolution during the last 35 years. It concentrates on features integrated in the new submarine class 212 for the navies of Germany and Italy, like hydrogen/oxygen storage and energy generation by fuel cells, signature minimization, permanent magnet propeller motor, water ram weapon expulsion system. etc. The paper comments on the submarine-related maturity/suitability of different air-independent energy systems and the competitive situation of submarine designers and builders in Europe. It ends with information about the German submarine class 212 development, design, and construction costs.
The rearmament of the German armed forces, started in 1955, was subject to several political and technical conditions agreed upon between the Allies and Germany before that date and modified in the years thereafter and until the reunification happened. The conditions that were the origin of and reason for technologies and industrial structures and capabilities observed today in Germany have, to a large extent, been forgotten on both sides of the Atlantic.
For submarine-related research and development {R&D), Ingenieurkontor Luebeck (00.) was founded and operated by Professor Ulrich Gabler, who had experienced several war
missions on submarines during WWII as a chief engineer before he was called into the then naval design offices at Berlin for the design of the next types of submarines. Right up to today, the privately owned office ofIKL performs R&D and design work for all classes of German submarines for the MOD.
The industrial capability of delivering submarines under agreed specifications for the overall weapon system became attractive to several nations and navies that could not establish or maintain a full submarine R&D and detailed design capacity of their own.
Other conditions accompanying the rearmament phase had a significant influence on the development and the performance of German-designed submarines. Most significant was the tonnage limitation to 450, then 1000, then 1800 tons standard, which is no longer in effect today. However, of broader influence on submarine design was the allocation of the Baltic Sea and the Baltic approaches as the operational area of the FGN. The average depth of 40 and the maximum depth of 90 meters triggered not only the nickname flooded meadow for this area, but also developments deemed useful today in regard to littoral warfare requirements.
The necessary weight optimization also required the pressure hull to be designed and built to be as light as possible. The calculation methods applied had to be test verified. Consequently, the principle of scale 1: 1 testing was also applied to a complete bull of a class 205 submarine within a worldwide unique pressure dock of the naval arsenal at Kiel. This collapse test bad to prove that buckling of plates and instability of frames occur at the same outer load and that calculation methods and tolerances are in conformity with reality.
For coastal submarines, a shock and collision resistant steel with sufficient elasticity is the preferred choice. Mechanized production of high yield (HY) 100 hulls has been tested, but the application in designs offered is deferred until a customer insists on this material for his pressure hull.
All weight remaining within the maximum tonnage limitation after satisfying the requirements of sensors, data processing, manmachine interfaces, communications, weapons, propulsion, living conditions, etc. was used for energy storage and stability ballast. The German designs had between 16 and 24 percent of their surface weight in the form of active ballast which means battery. International submarine designs built so far achieve at the most half or two-thirds of this.
The maximum energy made available onboard has never relieved the submarine design engineer nor the subcontractors in their joint task of minimizing the required energy consumption for mobility, data acquisition and processing, living, etc., or, in other words, finding continuously more efficient and even multiple ways to use energy in its different forms and temperature levels. A most welcome side effect is the minimization of thermal effects in the water.
For about 30 years the most important operational area of German submarines has been the Baltic Sea. These waters are shallow and dominated on the surface and in the air by the Eastern opponent, more than suitable for mines with any kind of fuses and for bottom-moored acoustic sensors. Besides radiated noise, color selection, radar cross-section of the hoistable installations, sonar cross-section, etc., the magnetic signature of the boats was an additional and unique requirement of the German Navy. This feature of a magnetic design and construction has been transferred to the class 212.
The new class 212 is being built for the navies of Germany and Italy (Figure 1). The definition of the class 212, in U.S. Navy terms-the concept design, was finalized in July 1992. The construction contract, which includes in Germany the detailed design, was expected to be accepted in early 1993. The reshuffling of the federal budget due to reunification consequences delayed the signature of the contract to 1994 and the effective date of the contract to 1995.
The class 212 mission priorities are anti surface, antisub, and reconnaissance. These required a drastic increase in passive sensor ranges since surface targets as well as submarines have reduced their radiated noise levels significantly during the last decade. While passive detection ranges have more than doubled compared to submarines built a couple of years ago, the own noise radiation under comparable speed is now only a fraction of what it was. The 212 will displace approximately 1200 tons and be 56 meters in length. The power plant is a hybrid AIP fuel-cell plant with a diesel generator-battery base. Sonars will be an optimized flank array and a towed array. The propulsion motor is a permanent magnet motor with a low noise propeller.
Newly developed components of the boat are mainly the proton exchange membrane (PEM) fuel cell system, the permanent magnet propulsion motor (PMM), the towed array with low frequency detection and classification, several features of the combat management systems, and the torpedo launching system.
The oxygen is stored in two liquid oxygen tanks under the superstructure while the hydrogen is absorbed by metal-hydride, consisting of a mixture of titanium and ferrum with several additional ingredients, which is in hard-mounted tubes fixed around the pressure hull. The direct chemo-electrical energy conversion process has a high efficiency rate. The waste heat is partially used for releasing the absorbed hydrogen from the storage pipes in gaseous form.
The prototype of the permanent magnet propeller-motor has been driving a naval trial vessel since 1989. The availability of more powerful solid state switches triggered a redesign phase that was completed at the end of 1992. The low rpms and high efficiency of this PM are achieved over the full speed range without mechanical switches and generation of transient noises.
The Hydraulic Water Ram system consists of a piston in a water-tilled tube pulled back by hydraulic force. The water column is led to one of three weapon tubes. The prototype of the torpedo launching system was fitted into a towable section and operated during sea trials for shock and noise tests. It is a hydraulic water ram system that accelerates the weapon to be launched in the quietest way and allows weapon launches even if the boat is bottomed. The class 212 submarine bas two water ram systems and six weapon tubes in total.
The overall design of the submarine has been organized in a modular structure, both for technical reasons and for cost-efficient production. The CIC with its control consoles, etc. is arranged on a deck that is elastically connected to the pressure hull. Other electronic cabinets and complete storerooms, etc. are suspended under this deck without any uncontrolled noise-transferring contact to the hull.
Special emphasis was also given to the small but unavoidable noise of auxiliary engines, such as air conditioning, pumps, etc. They have all been fitted together in the encapsulated engine room, and their fittings and connections were optimized in regard to structure and airborne noise transfer to and through the pressure bull. Measurements were performed at sea on the engine room aft section of the submarine with critical equipment actually operating. The hull-mounted heavy hydrogen storage tanks were represented by corresponding weights.
Besides the noise signature, emphasis has also been given to minimizing the magnetic signature. The pressure hull is built of 1.3964 steel, an authentic magnetic and non-corrosive steel. The final compensation of a still remaining small magnetic effect (despite stray field-reducing design and magnetic materials used throughout) will require only a few kW, while for a boat of comparable size built of HY80 nearly 100kW would be consumed continuously without achieving the same signature reduction.
Subsystems developed for the class 212 can also be adapted for integration into other submarines, for example into class 209 boats. The submarine class 209 has outnumbered every other nonnuclear submarine family in the western world, with SO units contracted by 11 different navies. These boats have been continuously updated upon availability of platform improvements or of new sensors and weapons. Even an increasing number of U.S. suppliers is considering these boats as a potential market for their products.
It has been investigated to which extent an improved performance in deep submerged range could be achieved by adding the fuel cell system in a section with relevant storage capacities of liquid oxygen (LOX) and hydrogen stored in a metal hydride.
Also technical solutions introduced on the last copies of the class 209 have found their way, after further improvement, into the class 212. An elastically mounted frame is the foundation for the four diesel-generator sets of a class 209 and the auxiliary equipments. All together they are moved on the frame into the empty pressure hull.
795a8134c1