Stealth helicopter

An OH-6 Cayuse, similar to the Hughes 500P

Efforts to develop helicopters which possessed low observability characteristics commenced during the Cold War period. It was during this time that several different stealth helicopters would first emerge.[6][7] The Central Intelligence Agency (CIA) was one such party seeking such rotorcraft, during the early 1970s, a single modified Hughes 500P was produced for the agency; it had a reduced noise operation capability, leading to its nickname of "The Quiet One". It was reportedly used in at least one operation by the CIA, to deploy a wiretap during the Vietnam War.[8]

Such helicopters were considered advantageous by several military planners. The United States Army sought to develop a stealth helicopter for aerial reconnaissance missions; between 1996 and 2004, work on 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] 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.[14] 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.[15] 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.[15] 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.[15]

A French Army NHIndustries NH90

Westland's stealth helicopter research subsequently influenced its other programmes; the NHIndustries NH90 was one such beneficiary via the application of stealth profiling techniques into its fuselage design.[15] The AgustaWestland AW159 Wildcat, an advanced development of the Westland Lynx, also incorporated several stealth features, such as infrared exhaust suppressors; such devices have been installed on other platforms by the company, including the AgustaWestland Apache.[16][17] Such measures augment the effectiveness of its defensive aids suite, which includes missile warning sensors and countermeasures dispensers.[17]

Several production helicopters, including the HAL Light Combat Helicopter and Eurocopter Tiger, reportedly feature presence-reduction measures or "stealth". The use of advanced composite materials on the airframe has commonly resulted in reductions in an aircraft's radar cross-section (RCS).[18] In the case of the Eurocopter Tiger, numerous measures were incorporated in its design so that it would possess minimal visual, radar, infra-red and acoustic signatures, which enhances the Tiger's battlefield survivability.[19][20] HAL's Light Combat Helicopter is reported to feature a digital camouflage system.[21]

During October 2018, leaked images of a future as-of-yet unnamed Kamov helicopter that possessed stealth features appeared online.[22] The footage was displayed in a meeting chaired by Sergei Mikheyev, General Designer of the Kamov Design Bureau, in front of Russian officials. The stealth technology used to decrease the RCS of this helicopter and to avoid its detection includes infrared heat suppressing systems and various stealthy fuselage contour constructions, in addition to an internal weapons bays.[23] Alternative design proposals have since emerged, one harnessing an unorthodox canard configuration that was allegedly capable of great manoeuvrability and a high top speed along with its stealth features.[24]

During the 2010s, China has been working on developing stealth helicopters. The Harbin Z-19 attack helicopter, which was derived from the Eurocopter AS365 Dauphin, had reportedly integrated several stealth features to enhance its survivability.[25] In 2013, rumours circulated that China had reverse engineered its own stealth helicopter using knowledge gained from the Osama bin Laden raid;[26] China has issued strong denials that it has ever had access to the stealth helicopter's wreckage.[27] During late 2015, reports emerged that a new Chinese attack helicopter with stealthy characteristics was being actively developed.[28]

• Stealth aircraft
• Black helicopters
• Unmanned aerial vehicle

• Stealth helicopter design speculation via theaviationist.com