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Contra-rotating Marine Propellers
Contra-rotating propellers have benefits when providing thrust in marine applications. Contra-rotating propellers are used on torpedoes due to the natural torque compensation and are also used in some motor boats. The cost of boring out the outer shafts and problems of mounting the inner shaft bearings are not worth pursuing in case of normal ships. Advantages and disadvantages Advantages *The propeller-induced Sailing#Heeling, heeling moment is compensated (negligible for larger ships). *More power can be transmitted for a given propeller radius. *The propeller efficiency is increased by recovering energy from the tangential (rotational) flow from the leading propeller. Tangential flow does not contribute to thrust, conversion of tangential to axial flow increases both thrust and overall system efficiency. Disadvantages *The mechanical installation of coaxial contra-rotating shafts is complicated and expensive and requires more maintenance. *The hydrodynamic gains are partiall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contra-rotating Propeller
Aircraft equipped with contra-rotating propellers (CRP) coaxial contra-rotating propellers, or high-speed propellers, apply the maximum power of usually a single engine piston powered or turboprop engine to drive a pair of coaxial propellers in contra-rotation. Two propellers are arranged one behind the other, and power is transferred from the engine via a planetary gear or spur gear transmission. Although contra-rotating propellers are also known as '' counter-rotating propellers'', the term is much more widely used when referring to airscrews on separate non-coaxial shafts turning in opposite directions. Operation When airspeed is low, the mass of the air flowing through the propeller disk (thrust) causes a significant amount of tangential or rotational air flow to be created by the spinning blades. The energy of this tangential air flow is wasted in a single-propeller design, and causes handling problems at low speed as the air strikes the vertical stabilizer, causing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such a device was called an automotive, automobile, locomotive, or fish torpedo; colloquially, a ''fish''. The term ''torpedo'' originally applied to a variety of devices, most of which would today be called mines. From about 1900, ''torpedo'' has been used strictly to designate a self-propelled underwater explosive device. While the 19th-century battleship had evolved primarily with a view to engagements between armored warships with large-caliber guns, the invention and refinement of torpedoes from the 1860s onwards allowed small torpedo boats and other lighter surface vessels, submarines/submersibles, even improvised fishing boats or frogmen, and later light aircraft, to destroy large ships without the need of large guns, though somet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ships
A ship is a large vessel that travels the world's oceans and other navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity and purpose. Ships have supported exploration, trade, warfare, migration, colonization, and science. Ship transport is responsible for the largest portion of world commerce. The word ''ship'' has meant, depending on the era and the context, either just a large vessel or specifically a ship-rigged sailing ship with three or more masts, each of which is square-rigged. The earliest historical evidence of boats is found in Egypt during the 4th millennium BCE. In 2024, ships had a global cargo capacity of 2.4 billion tons, with the three largest classes being ships carrying dry bulk (43%), oil tankers (28%) and container ships (14%). Nomenclature Ships are typically larger than boats, but there is no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailing
Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, Windsurfing, windsurfer, or Kitesurfing, kitesurfer), on ''ice'' (iceboat) or on ''land'' (Land sailing, land yacht) over a chosen Course (navigation), course, which is often part of a larger plan of navigation. From prehistory until the second half of the 19th century, sailing craft were the primary means of maritime trade and transportation; exploration across the seas and oceans was reliant on sail for anything other than the shortest distances. Naval power in this period used sail to varying degrees depending on the current technology, culminating in the gun-armed sailing warships of the Age of Sail. Sail was slowly replaced by steam as the method of propulsion for ships over the latter part of the 19th century – seeing a gradual improvement in the technology of steam through a number of developmental steps. Steam allowed schedul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torpedoes
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such a device was called an automotive, automobile, locomotive, or fish torpedo; colloquially, a ''fish''. The term ''torpedo'' originally applied to a variety of devices, most of which would today be called Naval mine, mines. From about 1900, ''torpedo'' has been used strictly to designate a self-propelled underwater explosive device. While the 19th-century battleship had evolved primarily with a view to engagements between armored warships with naval artillery, large-caliber guns, the invention and refinement of torpedoes from the 1860s onwards allowed small torpedo boats and other lighter surface combatant, surface vessels, submarines/submersibles, even improvised fishing boats or frogmen, and later light aircraft, to destroy large ships wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bliss-Leavitt Torpedo
The Bliss-Leavitt torpedo was a torpedo designed by Frank McDowell Leavitt and manufactured by the E. W. Bliss Company of Brooklyn, New York. It was put into service by the United States Navy in 1904 and variants of the design would remain in its inventory until the end of World War II. History The E. W. Bliss Company secured manufacturing rights to the Whitehead torpedo in 1892 and thereafter supplied the US Navy with this weapon. In 1904, an engineer with E. W. Bliss, Frank M. Leavitt, designed a torpedo with a "single-stage vertical turbine engine" that utilized compressed air preheated by alcohol. This design became the Bliss-Leavitt Mark 1 torpedo, the first non-Whitehead design after the Howell torpedo. The Mark 1 had a tendency to roll on its axis, affecting its directional stability. This was remedied by Lieutenant Gregory C. Davison who proposed a two-stage turbine design that drove contra-rotating propellers. This cancelled the torque effect of the single-stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volvo Penta
Volvo Penta is a Sweden, Swedish marine and industrial engine manufacturer, a joint stock company within the Volvo, Volvo Group. Volvo Penta evolved from a foundry in Skövde 1907, when the first marine automobile engine, marine engine, the B1, was manufactured. The name Penta was created about 1916.https://everythingaboutboats.org/volvo-penta, retrieved 18 October 2024. The Penta company soon became an established internal combustion engine manufacturer, which in 1927 delivered the engine for Volvo's first passenger car. Volvo acquired Penta in 1935 and Volvo Penta has been part of the Volvo Group since then. It now provides internal combustion engines (ICEs) and complete power systems to the marine industry, power generation, power-generating equipment, and similar industrial applications. The business also manufacturers sterndrive and inboard drive systems such as the Volvo Penta IPS. The engine program comprises petroleum fuel (diesel engines, diesel and petrol engine, gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury Marine
Mercury Marine is a marine engine division of Brunswick Corporation headquartered in Fond du Lac, Wisconsin. The main product line is outboard motors. It also produces the MerCruiser line of sterndrives and inboard engines, as well as a lineup of electric outboard motors. Utilizing modular and portable 48V lithium-ion batteries and transverse flux motor technology, these yield high torque with optimum efficiency. Some manufacturing is in Fond du Lac, while 40-60 HP engines are made in China. Smaller engines are Tohatsus that have been rebadged. History Founding The Kiekhaefer Mercury company began in 1939 when engineer Carl Kiekhaefer purchased a small outboard motor company in Cedarburg, Wisconsin. Kiekhaefer's original intention for the Kiekhaefer Corporation was to make magnetic separators for the dairy industry. The purchase included 300 defective outboard motors. Kiekhaefer and a small staff of employees rebuilt the motors and sold them to Montgomery Ward, a ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asea Brown Boveri
ABB Group is a Swedish-Swiss multinational electrical engineering corporation. Incorporated in Switzerland as ABB Ltd., and headquartered in Zurich, it is dual-listed on the Nasdaq Nordic exchange in Stockholm, Sweden, and the SIX Swiss Exchange in Zurich. ABB was ranked 340th in the Fortune Global 500 list of 2020 and has been a global Fortune 500 company for 24 years. ABB was formed in 1988, when Sweden's Allmänna Svenska Elektriska Aktiebolaget (ASEA) and Switzerland's Brown, Boveri & Cie merged to create Asea Brown Boveri, later simplified to the initials ABB. Both companies were established in the late 1800s and grew into major electrical equipment manufacturers, a business in which ABB remains active. Its traditional core activities include power generation, transmission and distribution; industrial automation, and robotics. Between 1989 and 1999, the company was also active in the rolling stock manufacturing sector. Throughout the 1990s and 2000s, ABB acquired hundreds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azimuth Thruster
An azimuth thruster is a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder redundant. These give ships better maneuverability than a fixed propeller and rudder system. Types of azimuth thrusters There are two major variants, based on the location of the motor: # Mechanical transmission, which connects a motor inside the ship to the outboard unit by gearing. The motor may be diesel or diesel-electric. Depending on the shaft arrangement, mechanical azimuth thrusters are divided into L-drive and Z-drive. An L-drive thruster has a vertical input shaft and a horizontal output shaft with one right-angle gear. A Z-drive thruster has a horizontal input shaft, a vertical shaft in the rotating column and a horizontal output shaft, with two right-angle gears. # Electrical transmission, more commonly called pods, where an electric motor is fitted in the pod itself, connected directly to the propeller without ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azipod
Azipod is a trademarked azimuth thruster pod design, a marine propulsion unit consisting of a fixed pitch propeller mounted on a steerable gondola ("pod") containing the electric motor driving the propeller, allowing ships to be more maneuverable. They were developed in Finland in the late 1980s jointly by Wärtsilä Marine, Strömberg and the Finnish National Board of Navigation. Although "Azipod" is a registered trademark and brand name owned by ABB, it is sometimes used as a generic term for podded propulsion units manufactured by other companies. Concept In the conventional azimuth thrusters such as Z-drive and L-drive thrusters, the propeller is driven by an electric motor or a diesel engine inside the ship's hull. The propeller is coupled to the prime mover with shafts and bevel gears that allow rotating the propeller about a vertical axis. This type of propulsion system has a long tradition throughout the 1990s and today such propulsion units are produced by a n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
