Naval helicopter

A military helicopter is a helicopter that is either specifically built or converted for use by military forces. A military helicopter's mission is a function of its design or conversion. The most common use of military helicopters is transport of troops, but transport helicopters can be modified or converted to perform other missions such as combat search and rescue (CSAR), medical evacuation (MEDEVAC), airborne command post, or even armed with weapons for attacking ground targets. Specialized military helicopters are intended to conduct specific missions. Examples of specialized military helicopters are attack helicopters, observation helicopters and anti-submarine warfare helicopters.

Military helicopters play an integral part in the sea, land and air operations of modern militaries. Generally manufacturers will develop airframes in different weight/size classes which can be adapted to different roles through the installation of mission specific equipment. To minimise development costs the basic airframes can be stretched and shortened, be updated with new engines and electronics and have the entire mechanical and flight systems mated to new fuselages to create new aircraft. For example, the UH-1 has given rise to a number of derivatives through stretching and re-engining, including the AH-1.

Modern helicopters have introduced modular systems which allow the same airframe to be configured for different roles, for example the EH-101 in Royal Navy service can be rapidly configured for ASW or transport missions in hours. To at the same time retain flexibility and limit costs, it is possible to fit an airframe for but not with a system, for example in the US Army's AH-64D variants are all fitted to be able to take the Longbow radar system, but not enough sets have been brought to equip the whole force. The systems can be fitted to only those airframes that need it, or when finances allow the purchase of enough units.

...
Wikipedia