G7es torpedo

The G7es (TV) "Zaunkönig" (wren in German) was an acoustic torpedo employed by German U-boats during World War II. It was known as the GNAT (German Navy Acoustic Torpedo) to the British.

Description

The forerunner of the TV was the G7e/T4 Falke, codename "Falcon," which was introduced in March 1943, but only fired by three U-boats by September of that year when the G7es (which was faster, had more range, possessed a magnetic exploder and could also be equipped with a percussion pistol) became available.

The torpedo was electric and had an effective range of 5700 metres at a speed of 24 knots (44 km/h). This torpedo employed passive acoustic homing to find its target, becoming active after a straight run of 400 metres. The homing mechanism consisted of two hydrophone receivers which sensed the sound waves of ship propellers and altered the direction of the rudder via an electropneumatic device.

There were three variants:

Gnat

A gnat /ˈnæt/ is any of many species of tiny flying insects in the Dipterid suborder Nematocera, especially those in the families Mycetophilidae, Anisopodidae and Sciaridae.

In English, the term applies particularly to Nematocerans of the family Culicidae (mosquitoes). The common gnat is the species Culex pipiens.

Male gnats often assemble in large mating swarms or ghosts, particularly at dusk.

Gnat larvae are mostly free-living and some are aquatic. Many feed on plants, though some are carnivorous. Larval plant feeders (such as the Hessian fly larva) cause root, stem, or leaf galls to be formed by the host plant. Some species of fungus gnats (families Mycetophilidae and Sciaridae) are pests of mushrooms and roots of potted plants in homes and greenhouses.

Some South American Pleurothallid orchids are pollinated by tiny gnats and have correspondingly small flowers.

See also

References

GNAT3

Guanine nucleotide-binding protein G(t) subunit alpha-3, also known as gustducin alpha-3 chain, is a protein that in humans is encoded by the GNAT3 gene.

Gustducin alpha-3 chain is a subunit of the heterotrimeric protein gustducin that is responsible for basic taste.

References

Further reading

General Atomics GNAT

The General Atomics GNAT is a reconnaissance UAV developed in the United States in the late 1980s and manufactured by General Atomics Aeronautical Systems Inc. (GA-ASI). As initially designed, it was a simplified version of the LSI Amber intended for foreign sales. The GNAT 750 made its first flight in 1989.

Design and development

The GNAT 750's configuration was similar to that of the Amber, except that the GNAT 750's wing was mounted low on the fuselage, instead of being mounted on a pylon on top. The GNAT 750 was somewhat larger than the Amber, but weighed less and could carry a heavier payload. Even though the name "GNAT" can be thought of as a contraction of GeNeral ATomics, the original name of the developing company before its acquisition by General Atomics was Leading Systems Incorporated (LSI). The idea of the name was more probably related to the fact that a gnat is small. The "750" part of the name stands for the distance in millimeters from the leading edge to trailing edge of the wing near the wing root.

Torpedo

The modern torpedo is a self-propelled weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with its target or in proximity to it.

Historically, it was called an automotive, automobile, locomotive or fish torpedo; colloquially called a fish. The term torpedo was originally employed for a variety of devices, most of which would today be called mines. From about 1900, torpedo has been used strictly to designate an underwater self-propelled weapon. The original torpedo is a kind of fish: an electric ray.

While the battleship had evolved primarily around engagements between armoured ships with large-caliber guns, the torpedo allowed torpedo boats and other lighter surface ships, submersibles, even ordinary fishing boats or frogmen, and later, aircraft, to destroy large armoured ships without the need of large guns, though sometimes at the risk of being hit by longer-range shellfire.

Naval mine

A naval mine is a self-contained explosive device placed in water to damage or destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel. Naval mines can be used offensively—to hamper enemy shipping movements or lock vessels into a harbour; or defensively—to protect friendly vessels and create "safe" zones.

Description

Mines can be laid in many ways: by purpose-built minelayers, refitted ships, submarines, or aircraft—and even by dropping them into a harbour by hand. They can be inexpensive: some variants can cost as little as US$1000, though more sophisticated mines can cost millions of dollars, be equipped with several kinds of sensors, and deliver a warhead by rocket or torpedo.

Their flexibility and cost-effectiveness make mines attractive to the less powerful belligerent in asymmetric warfare. The cost of producing and laying a mine is usually anywhere from 0.5% to 10% of the cost of removing it, and it can take up to 200 times as long to clear a minefield as to lay it. Parts of some World War II naval minefields still exist because they are too extensive and expensive to clear. It is possible for some of these 1940s-era mines to remain dangerous for many years to come.

Torpedo (genus)

Torpedo is a genus of rays, commonly known as electric rays, torpedo rays, or torpedoes. They are slow-moving bottom-dwellers capable of generating electricity as a defense and feeding mechanism.

The naval weapon known as the torpedo was named after this genus, whose own name is derived from the Latin word meaning "numb" or "paralysed", presumably the sensation one would feel after experiencing the ray's electric shock.

Electricity

The largest species is the Gulf torpedo, Torpedo sinuspersici, which can grow to a weight of 13 kg (29 lb). Electric rays have patches of modified muscle cells called electroplaques that make up an electric organ. These generate an electric gradient, similar to the normal electric potential across most cell membranes, but amplified greatly by its concentration into a very small area. The electricity can be stored in the tissues, which act as a battery. The battery can be discharged in pulses. A ray can emit a shock into the body of a prey animal to stun it and make it easier to capture and eat, or into the body of a predator.