Helmet

For the band, see Helmet (band). For the post-Roman kingdom in north England, see Elmet.A helmet is a form of protective clothing worn on the head and usually made of metal or other hard substance, such as Kevlar, resin fiber, or plastic typically for protection of the head in combat, or in civilian life, from sports injuries, falling objects or high-speed collisions.

Helmets are common in the military, construction, mining, and some sports, including American football, baseball, ice hockey, equestrian sports, and rock climbing. Motorcycle helmets and bicycle helmets are compulsory headgear in some jurisdictions; in the United Kingdom only Sikhs are allowed to ride motorcycles without wearing motorcycle helmets. Bicycle helmet compulsion and even strong promotion has been a heated subject of debate amongst cyclists and scientists since at least the 1990's, lately focusing on alleged net protective effect at the population level.

Etymology

The English word "helmet" arose by Anglo-Saxon helm = "helmet" coalescing with a French diminutive of French heaume, Old French helme, from Frankish German helm. The origin is Proto-Germanic *khelmaz from PIE *kelmo- "a cover". The diminutive ending -et was to distinguish ordinary helmets from the knights' great helm.

Helmets' original military usage and symbolism

Helmets are among the most ancient forms of combat protection, and are known to have been worn by ancient Greeks, Romans, throughout the Middle Ages, and up to the end of the 1600s by many combatants. At that time they were purely military equipment, protecting the head from cutting blows with swords, flying arrows, and low velocity musketry. They were initially constructed from leather, but soon came to be made entirely from forged steel after about 950A.D. Military use of helmets declined after 1670, and rifled firearms, after 1700, ended their use by foot soldiers. 18th century cavalry units often wore steel body cuirasses, and frequently wore metal skull protectors under their hats, called "secrets". The often ridiculed Prussian spiked helmet did nevertheless save many soldiers by diverting sideways otherwise mortal sabre blows to the head; it was retained in the age of the machine gun merely for tradition.

The Napoleonic era saw ornate cavalry helmets reintroduced for cuirassiers and dragoons in some armies; they continued in use until the first year of World War I.

With World War I and the use of heavy artillery, the steel helmet made a quick comeback for foot soldiers. In the 20th Century it offered protection for the head from shrapnel and spent or glancing bullets. The use of protective helmets by millions of fighting men in the two world wars increased awareness of "hard hat" protection. By the 1950s, hundreds of new applications for helmets were found. The helmet offered an unexpected advantage: Symbolism. It can signify that, like a soldier, the wearer is someone qualified for or capable of a certain task or activity, such as construction, operation of heavy machinery, or participation in certain sports.

Today's militaries often use high-quality ballistic helmets made of materials such as Kevlar, which have excellent bullet and fragmentation stopping power. Some helmets also have good non-ballistic protective qualities, though many do not. Non-ballistic injuries may be caused by many things, including (but not limited to) concussive shockwaves from explosions, motor vehicle accidents, or falls. Operation-Helmet is a charity that provides non-ballistic upgrade kits to American troops.

Helmets' function and structure

Despite various designs and requirements, helmets always protect the user's head through a mechanical energy absorption process. Therefore their structure and protective capacity are altered in high energy impacts. Beside their energy absorption capability, their volume and weight are also important issues, since higher volume and weight increase the injury risk for the user's head and neck.

Classical helmets from the ancient Greeks to modern day treat the head uniformly and are currently tested on rigid headforms. Anatomical helmets adapted to the inner head structure were invented by neurosurgeons at the end of the 20th century. Since the materials are disposed according to the anatomical structure of the head, they are smaller and lighter than the classical helmets.

Images

Image: closed helmet.jpg|1500s helmet in forged steel (compatible Anachrome 3D).Image:Casque 501590 fh000009.jpg|Back of a SPECTRA helmet currently used in the French MilitaryImage:GordonCooperHelmetNasa.jpg|Gordon Cooper in Helmet and Pressure SuitImage:PithHelmetTrumann.jpg|Pith helmet of Harry S. TrumanImage:Bicyclinghelmet.saa.jpeg|A bicycle helmetImage:Climbinghelmet.saa.jpeg|A helmet used for rock climbingImage:Modern_day_Football_helmet.jpg|An American football helmetImage:Helmet.jpg|A helmet for riding horses (Riding helmet).Image:Aa workhelmet visor.jpg|Work safety helmet with visorImage:Aa motorcyclehelmet 00.jpg|Motorcycle helmet.Image:Riotsquad helmet.jpg|Riotsquad helmet with back-of-the-neck protectorImage:51479sweden_helmet.jpg|Pickelhaube of a Swedish Royal Guard soldier

Types of helmets

Helmets used for different purposes differ greatly in their design. For example, a bicycle helmet would chiefly need to protect against blunt impact forces. A helmet designed for rock climbing, however, would need to protect against objects (e.g. small rocks and climbing equipment) falling from above. Consequently, bicycling and rock climbing helmets little resemble each other. Practical concerns also dictate helmet design: a bicycling helmet would preferably be aerodynamic in shape and probably well ventilated, while a rock climbing helmet would be lightweight and with a minimum of bulk to reduce any detrimental effect on the climber's technique.

Goggles, face guards and ear plugs are other forms of protective headgear. Hard hats are typically preferred in modern times for construction workers. Helmets are often used by riot police.

Sometimes medical conditions need a helmet to be worn to protect the brain because of a gap in the braincase, e.g. because of cleidocranial dysostosis or in separated craniopagus twins.

Heraldry

As the coat of arms was originally designed to distinguish combatants on the battlefield or in a tournament, even while covered in armour, it is not surprising that heraldic elements were often also used for the decoration of knightly helmets, while it was also possible to use different elements than on the shield, but equally standardized.

Furthermore, it became common to use a helmet (or some other headgear, e.g. a crown) as part of the coat of arms, above the shield, a practice maintained long after her use in reality was ended by military technology and the demise of jousting. In some systems, the rank of the bearer was reflected in the model of the emblematic helmet, e.g. the metal and the number of bars in the visor, as in France. Anyway, the rank can be reflected by a coronet or wreath placed on the helmet (often instead of directly above the shield).

Helmet: Encyclopedia BETA

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