Stealth helicopter

Stealth helicopters are helicopters that incorporate stealth technology to decrease an enemy's detection ability.^[1] There are a diverse range of technologies used to achieve this decreased detectability; these have largely involved the reduction of several different signatures typically generated by a rotorcraft, including those of noise, radar, and infrared.

In many ways, helicopters are less suitable for stealth technology than fixed-wing aircraft are; one such area is their

It is known that some nations have used such rotorcraft operationally, albeit in a limited scope, since the 1970s; a

wiretap during the Vietnam War.^[8]

Such helicopters were considered advantageous by several military planners. The

Boeing/Sikorsky RAH-66 Comanche entered the prototype stage with an eye towards production. However, the Comanche programme was ultimately cancelled, both due to rising costs and the considerable technical issues which had been experienced.^[4] However, other efforts continued. It is known that a number of Sikorsky UH-60 Black Hawks have been outfitted with stealth technologies; these features reportedly include the use of specialized materials, along with numerous harsh angles and flat surfaces across the exterior fuselage, techniques that had previously been employed upon other stealth aircraft.^[9]

It is believed that one or multiple of the UH-60 Black Hawks used in the

raid upon Osama bin Laden's compound on 1 May 2011 featured stealth technologies.^[9][10][11] Prior to the raid, the existence of such helicopters had been unknown. One of the UH-60s had crashed during the raid, leading to the remains being recovered and studied by various authorities, revealing the existence of this type to the public.^[12][13] The helicopter's most notable features are the extreme modifications to the nose, the "doghouse" where the engines and main gearbox are situated, as well as the engine intakes and exhausts. It also has a heavily modified rotor hub. All of these features appear to be designed to reduce its radar signature, especially from the critical forward hemisphere aspect.^[14] According to F. Michael Maloof, a former Pentagon senior policy analyst, identical stealthy UH-60s have been supplied to Israel and used for intelligence gathering missions inside Iran.^[15]

Maloof’s claim, however, is not supported by any evidence.

Various other nations have worked on stealth helicopter technology. During the 1980s, British company Westland Helicopters undertook a top secret research programme towards developing a stealth attack helicopter.^[16] Being based on the Westland Lynx, the proposed design was internally designated WG 47; its configuration included a faceted fuselage with internally stored weapons, twin canted tail rotors and the routing of engine, environmental and cooling system exhausts into a side-exiting infrared suppressor.^[16] It featured a tandem cockpit, the glazing of which was specifically angled outward to eliminate optical glint towards the horizon. The programme was concluded during 1987.^[16] Westland's stealth helicopter research subsequently influenced its other programmes; the

HAL Prachand (LCH)

Bell 360 Invictus, is a reconnaissance and attack helicopter that is being is offered to the US Army's Future Attack Reconnaissance Aircraft (FARA). It is currently under development and incorporates a smooth, rounded fuselage, single rotor, back tail rotor and internal weapons bay, intended to reduce radar signature. While the exact extent of the 360s stealth properties may not be available for security reasons, the visible external shape and internal weapons bay do seem to exhibit radar signature reducing capabilities.^[23]