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Sunday, July 21, 2013

The American Stealth Helicopter

During the early 1980s, the U.S. Army began to calculate the helicopters need to replace the old ones, which then creates the light helicopters experimental program. In 1991, Boeing-Sikorsky team selected to make a prototype design that had not been tried before.  

RAH-66 Comanche is the world's first 'stealth' helicopter. The helicopter operates with an internal bay and is equipped with air to air and air to ground missile strikes. In an armed reconnaissance mission, the Comanche could recognise and identify targets and digitally transmit the information to the battlefield commander in near real-time, select the optimum force deployment and coordinate the attack.

Flight testing is done with two prototypes. The first Comanche prototype, serial 94-0327, which is completed 318 flight more than 387 hours before ending its career in January 2002. Having met the key criteria, the RAH-66 prototype enter the design development and manufacturing phase on June 1, 2000, which cost U.S. $3.1 billion.
RAH-66 Comanche, the American stealth helicopter. (Picture from: http://kaneblogpicz.blogspot.com/)
As the efforts to reduce the empty weight of approximately 200 lb (90.7 kg) or 2% to meet the target weight started later that year. The second prototype, serial 95-0001, has completed 93 flight hours and 103.5 raid mission in May 2001.
The Boeing Sikorsky RAH-66 Comanche armed reconnaissance helicopter was the centerpiece of the U.S. Army's aviation modernization plan. (Picture from: http://www.militaryaviation.eu/)
The second RAH-66 Comanche prototype received mission equipment and using two T800-LHT-801 turboshaft engines from LHTec with a maximum rated power of 1,432shp each, which is more powerful and continue its flight test on May 23, 2002, including the night vision and weapons systems test, until 2003. During the test, the Comanche could fly at a speed of 162 knots (186 mph; 300 kph), with a maximum speed of 172 knots (198 mph; 319 kph), and showed an ability to turn 180 degree within less than 5 seconds. The internal fuel capacity of the helicopter was 1,142 litres. The helicopters using rotor system with 5 blades and a small protected rotor on the tail, as well as French's Gazelle helicopters.

The Comanche has internal weapons storage facilities and wings that allow the addition of optional weaponry stability, with the risk if the optional wing mounted it will be detected by radar. The Comanche carried its weapons internally and had a weapons bay on each side of the fuselage. The missiles are mounted on the weapon bay doors which open sideways. The internal weapon bay could be fitted with Stinger, Starstreak or Mistral air-to-air missiles; TOW II, Hot II or Longbow Hellfire air-to-ground missiles; Sura D 81 mm, Snora 81 mm, Hydra 70 rockets; or the army counter air weapon system.

Cockpit interior of the RAH-66 Comanche. 
(Picture from: http://www.airforce-technology.com/)
The number of missiles on each door mounting varied, for example each door could hold three Hellfire or six Stinger missiles. The helicopter could be reconfigured with optional stub wings fitted with multiple weapon pylons which carried an additional four Hellfire or eight Stinger missiles. The helicopter's standard armament is three-barrel 20mm Gatling gun was capable of firing 750 or 1,500 rounds a minute. The gun was mounted on a Giat composite turret (weighing 127 kg) under the nose of the helicopter. The 500 round ammunition supply system could be reloaded in less than eight minutes by two crew members. Pilot and co-pilot (gunner) sits adjacent to the cockpit with good visibility in order to facilitate the firing system.

The Comanche had two identical cockpits for the pilot and the co-pilot, which were sealed and had a positive pressure air system for protection against chemical and biological warfare. The fly-by-wire flight control system was triple redundant. The cockpit was fitted with a pilot's night-vision system from Lockheed Martin and the pilots had a wide field of view (35° × 52°) Kaiser Electronics helmet-integrated display sighting system (HIDSS). HIDSS employed active matrix liquid crystal display (AMLCD) technology. The targets were designated and the weapons fired from collective and sidestick control push buttons. Each integrated cockpit had Harris Corp flat screen liquid crystal displays, a colour display for a digital moving map system, tactical situation and night operation display.
RAH-66 Comanche cutaway. (Picture from: http://www.militaryphotos.net/)
Northrop Grumman provided the Comanche's integrated communications, navigation and identification (CNI) suite. The CNI suite will feature secure multiwave, multiband multimode wireless communications, link 16, satellite communications and enhanced position locating reporting system (EPLRS) via the tactical internet.
On February 23, 2004, the U.S. Army announced their decision to cancel the RAH-66 Comanche helicopter program given the need to provide funding to renovate the aging helicopter fleets, utility, and reconnaissance aircraft. The U.S. Army also plans to use the Comanche program funds to accelerate the development of unmanned aerial vehicles (UAV).

The UAVs have provided surveillance during military operations in Afghanistan and Iraq. Approximately U.S. $6.9 billion invested in the Comanche program at the time of cancellation. Additional U.S. $450-680 million paid for the contract cancellation fee for the main program partners, Sikorsky and Boeing. What a pity, now the two units RAH-66 Comanche helicopter just be the displayed items in the museum.. *** [EKA | FROM VARIOUS SOURCES | SIKORSKY | BOEING | ARMY-TECHNOLOGY.COM]
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Specifications RAH-66 Comanche Helicopter

General Characteristics
  • Crew: 2 people
  • Length: 46.85 ft (14,28 m)
  • Wingspan: 39.04 ft (11,9 m)
  • High: 11.06 ft (3.37 m)
  • Wing area: 1,197 ft² (111,2 m²)
  • Empty weight: 8,690 pounds (3,942 kg)
  • Filled weight: 10,597 pounds (4,802 kg)
  • Maximum take-off weight: 17,175 pounds (7,791 kg)
  • Fuselage length: 43.31 ft (13.20 m)
  • Rotor systems: 5 blades on main rotor
  • Maximum speed: 175 knots (201 mph, 324 kph)
  • Cruise speed: 165 knots (190 mph, 306 kph)
  • Range: 262 nmi (without extra fuel tanks)
  • Reach the furthest distance: 1,260 nmi
  • Limit the maximum flight altitude: 14,980 ft (4,566 m)
  • Rate of climb: 1,418 ft/min
  • 1 unit of three-barreled 20 mm cannon XM301 with a capacity of 500 rounds of bullets
  • Internal Armament: 6 units of AGM-114 Hellfire missiles or 6 units of AIM-92 Stinger missiles or
  • 24 units Hydra 70 rocket

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