Pendulum-and-hydrostat control is a control mechanism developed originally for depth control of the Whitehead torpedo. It is an early example of what is now known as proportional and derivative control
The hydrostat is a mechanism that senses pressure; the torpedo's depth is proportional to pressure. However, with only a hydrostat controlling the depth fins, the torpedo tends to oscillate around the desired depth rather than settling to the desired depth. The addition of a pendulum allows the torpedo to sense the pitch of the torpedo. The pitch information is combined with the depth information to set the torpedo's depth control fins. The pitch information provides a damping term to the depth control response and suppresses the depth oscillations.
In control theory the effect of the addition of the pendulum can be explained as turning the simple proportional controller into a proportional-derivative controller since the depth keeping is not controlled by the depth alone anymore but also by the derivative (rate of change) of the depth which is roughly proportional to the angle of the machine. [1] The relative gain of the proportional and derivative functions could be altered by adjusting the linkages.
It was mainly used to control the depth of torpedoes until the end of the Second World War, and it reduced depth errors from ±40 feet (12 meters) to as little as ±6 inches (0.15 m).
The pendulum and hydrostat control was invented by Robert Whitehead. It was an important advance in torpedo technology, and it was nicknamed "The Secret".
A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. It is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as "boats" rather than "ships" irrespective of their size.
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and 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.
A torpedo boat is a relatively small and fast naval ship designed to carry torpedoes into battle. The first designs were steam-powered craft dedicated to ramming enemy ships with explosive spar torpedoes. Later evolutions launched variants of self-propelled Whitehead torpedoes.
A proportional–integral–derivative controller is a control loop mechanism employing feedback that is widely used in industrial control systems and a variety of other applications requiring continuously modulated control. A PID controller continuously calculates an error value as the difference between a desired setpoint (SP) and a measured process variable (PV) and applies a correction based on proportional, integral, and derivative terms, hence the name.
A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive hydraulic shock. Most depth charges use high explosive charges and a fuze set to detonate the charge, typically at a specific depth. Depth charges can be dropped by ships, patrol aircraft, and helicopters.
A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large Industrial control systems which are used for controlling processes or machines.
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the user. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. The purpose is to extend the breathing endurance of a limited gas supply, and, for covert military use by frogmen or observation of underwater life, eliminating the bubbles produced by an open circuit system. A rebreather is generally understood to be a portable unit carried by the user. The same technology on a vehicle or non-mobile installation is more likely to be referred to as a life-support system.
A spring is an elastic object that stores mechanical energy. Springs are typically made of spring steel. There are many spring designs. In everyday use, the term often refers to coil springs.
The Type 91 was an aerial torpedo of the Imperial Japanese Navy. It was in service from 1931 to 1945. It was used in naval battles in World War II and was specially developed for attacks on ships in shallow harbours.
Robert Whitehead was an English engineer who was most famous for developing the first effective self-propelled naval torpedo.
The G7a(TI) was the standard issue Kriegsmarine torpedo during the early years of World War II. It was a steam-powered design, using a wet heater engine burning decaline, with a typical range of about 7,500 metres (24,600 ft) while running at 40 knots. It was replaced beginning in 1942 by the electrically powered G7e torpedo, which did not leave a trail of bubbles in the water and thus did not reveal the location of the submarine. G7a's remained in service in other roles, including surface ships, until the end of the war.
The Mark 24 mine is an air-dropped anti-submarine warfare weapon (ASW) incorporating passive acoustic homing system and torpedo integration. It was used by the United States, the British and Canadian forces during the Second World War and entered service in March 1943 and remained in use with the US Navy until 1948. Approximately 4,000 torpedoes were produced, with 340 ultimately being deployed during the war. 204 torpedoes were launched against submarine targets, with 37 Axis submarines being sunk and a further 18 damaged. The deceptive name of "Mark 24 Mine" was deliberately chosen for security purposes, to conceal the true nature of the weapon.
The Howell Automobile Torpedo was the first self-propelled torpedo produced in quantity by the United States Navy, which referred to it as the Howell Mark I torpedo. It was conceived by Lieutenant Commander John A. Howell, United States Navy, in 1870, using a 60 kg (130 lb) flywheel spun at a very high speed to store energy and drive propellers.
The Mark 14 torpedo was the United States Navy's standard submarine-launched anti-ship torpedo of World War II. This weapon was plagued with many problems which crippled its performance early in the war. It was supplemented by the Mark 18 electric torpedo in the last two years of the war. Nonetheless, the Mark 14 played a major role in the devastating blow U.S. Navy submarines dealt to the Japanese naval and merchant marine forces during the Pacific War.
The Whitehead torpedo was the first self-propelled or "locomotive" torpedo ever developed. It was perfected in 1866 by Robert Whitehead from a rough design conceived by Giovanni Luppis of the Austro-Hungarian Navy in Rijeka. It was driven by a three-cylinder compressed-air engine invented, designed, and made by Peter Brotherhood. Many naval services procured the Whitehead torpedo during the 1870s, including the US Navy. This early torpedo proved itself in combat during the Russo-Turkish War when, on January 16, 1878, the Ottoman ship Intibah was sunk by Russian torpedo boats carrying Whiteheads, though this story has been disputed in one book.
The Schwartzkopff torpedo was a torpedo manufactured in the late 19th century by the German firm Eisengießerei und Maschinen-Fabrik von L. Schwartzkopff, later known as Berliner Maschinenbau, based on the Whitehead design. Unlike the Whitehead torpedo, which was manufactured out of steel, the Schwartzkopff was made out of bronze, enhancing corrosion resistance.
The Whitehead Mark 1 torpedo was the first Whitehead torpedo adopted by the United States Navy for use in an anti-surface ship role after the E. W. Bliss Company of Brooklyn, New York secured manufacturing rights in 1892. The US Navy made an initial acquisition of 100 Mark 1s, which, by the time they entered American service, were faster, had longer range and carried a larger warhead than Robert Whitehead's earlier models.
The Whitehead Mark 1B torpedo, designated as a Torpedo Type B, was a variant of the Whitehead Mark 1 torpedo adopted by the United States Navy for use in an anti-surface ship role after the E. W. Bliss Company of Brooklyn, New York secured manufacturing rights in 1892. The primary differences between the Mark 1 and the Mark 1B were that the Mark 1B was longer, carried a heavier guncotton charge in the warhead and included an improved guidance system.
The Whitehead Mark 2 torpedo was a Whitehead torpedo adopted by the United States Navy for use in an anti-surface ship role after the E. W. Bliss Company of Brooklyn, New York secured manufacturing rights in 1892. It was identical to the Whitehead Mark 1 torpedo, except for some mechanical details.
The Whitehead Mark 2C torpedo, also designated Torpedo Type C was a Whitehead torpedo adopted by the United States Navy for use in an anti-surface ship role after the E. W. Bliss Company of Brooklyn, New York secured manufacturing rights in 1892. It was probably based on the Whitehead Mark 1B, rather than a modification of the Whitehead Mark 2.