• Document: US Nuclear Submarines: The Fast Attack
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Free ebooks ==> www.Ebook777.com New Vanguard OSPREY PUBLISHING US Nuclear Submarines: The Fast Attack Jim Christley • Illustrated by Tony Br yan www.Ebook777.com Free ebooks ==> www.Ebook777.com New Vanguard • 138 US Nuclear Submarines: The Fast Attack Jim Christley • Illustrated by Tony Br yan www.Ebook777.com Free ebooks ==> www.Ebook777.com US NUCLEAR SUBMARINES: THE FAST ATTACK INTRODUCTION his book constitutes a brief overview of the development of one T type of submarine over a period of 50 years. Much of the history of these boats is shrouded in secrecy, and consists of thousands of men spending endless days on patrol, preserving the peace by their presence. In the main, they were and continue to be successful in this mission. Here is not a story of heroic battles where ships are torpedoed and aircraft shot down, but rather a story of engineering trade-offs and technological advances. The heroics are in the work itself. THE PROPULSION PROBLEM Early submarine evolution is marked by a struggle to overcome the problem of how to propel the submarine efficiently both on the surface and submerged. This engineering challenge can be divided into two interrelated concerns – hull form and propulsion. The propulsion problem drives the hull form problem. The US submarine of 1945, embodied by the Balao and Tench classes, suffered from two serious shortcomings – limited underwater range and inadequate speed. To run completely submerged the submarine had to operate on its battery/electric motor combination alone. The range in Polar bears examine a Sturgeon Class boat surfaced in the Arctic. When surfaced in the ocean for a swim call, the boat crew posts an armed shark watch. When surfaced in the Arctic, the boat has a polar bear watch. Even though the person is armed, his main job is not to kill the bears but to warn personnel on the ice that a bear has been sighted. On the occasion of a sighting the ice is evacuated, leaving the bear in charge of the territory. 3 www.Ebook777.com Free ebooks ==> www.Ebook777.com this mode was 10 nautical miles (nm) at 8 knots or 50nm at 2 knots, the difference due to the batteries’ ability to supply a large quantity of amps (high discharge rate) for a short time before they were exhausted and had to be recharged. A smaller discharge rate meant the boat moved slower but could do so for a longer time. An answer to this range endurance problem was the snorkel, a small induction pipe that reached above the surface and supplied air to the diesel engines, allowing them to run while the boat was submerged. However, the snorkeling submarine is noisier by far than one running on the same number of engines on the surface, and quietness is part of the submarine’s underwater advantage. The speed issue involved a rethinking of the entire outer shell (hull) design. A first step was to remove all the things that caused flow resistance, thus wasting energy. This modification cut the flow resistance of the World War II fleet submarine by nearly 50 percent, and was one of the principal measures of the Guppy conversion of many World War II boats. (Guppy was the Greater Underwater Propulsion Program, which extended the useful postwar life of diesel-electric submarines by removing items such as deck guns so as to streamline their hulls, increasing battery capacity, and the addition of snorkel systems.) For a given hull design, however, an increase in speed is directly dependent on the amount of power put into the water, and equates directly to shaft horsepower (shp). Speed is related From left to right: a Skate Class, to a change in shp as the cubic function of the change. Thus to go from a Permit Class, and a Tang Class. The two outboard boats are 5 to 10 knots (doubling) requires an eightfold (two cubed) increase in nu

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