RAH-66 Comanche
Encyclopedia
The Boeing-Sikorsky RAH-66 Comanche was an advanced five-blade armed reconnaissance and attack helicopter
Attack helicopter
An attack helicopter is a military helicopter with the primary role of an attack aircraft, with the capability of engaging targets on the ground, such as enemy infantry and armored vehicles...

 designed for the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

. The RAH-66 program was canceled in 2004, before mass production began, after nearly $7 billion was spent on the program.

During the early 1980s, the U.S. Army began formulating a requirement for a replacement of its helicopters then in service, resulting in the Light Helicopter Experimental
Light Helicopter Experimental
The Light Helicopter Experimental program was a 1980s United States Army helicopter procurement project to replace the AH-1 Cobra and OH-58 helicopters.-Background:...

 program. In 1991, the Boeing-Sikorsky
Sikorsky Aircraft
The Sikorsky Aircraft Corporation is an American aircraft manufacturer based in Stratford, Connecticut. Its parent company is United Technologies Corporation.-History:...

 team was chosen to produce prototypes. The Comanche would incorporate stealth technologies
Stealth technology
Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...

, featuring a number of designs previously untried. It was to employ advanced sensors in its reconnaissance role, and was intended to designate targets for the AH-64 Apache. The aircraft was also armed with missiles and rockets to destroy armored vehicles. Two RAH-66 prototypes were built and conducted flight testing from 1996 to 2004; since the cancellation the prototypes have been placed on display.

Origins and LHX

In 1982 the U.S. Army started the Light Helicopter Experimental
Light Helicopter Experimental
The Light Helicopter Experimental program was a 1980s United States Army helicopter procurement project to replace the AH-1 Cobra and OH-58 helicopters.-Background:...

 (LHX) program to replace UH-1, AH-1, OH-6, and OH-58
OH-58 Kiowa
The Bell OH-58 Kiowa is a family of single-engine, single-rotor, military helicopters used for observation, utility, and direct fire support. Bell Helicopter manufactured the OH-58 for the United States Army based on the 206A JetRanger helicopter. The OH-58 has been in continuous use by the U.S...

 helicopters. It took six years, until 1988, before the request for proposal
Request for Proposal
A request for proposal is issued at an early stage in a procurement process, where an invitation is presented for suppliers, often through a bidding process, to submit a proposal on a specific commodity or service. The RFP process brings structure to the procurement decision and is meant to...

 (RFP) was issued, in which the requirement was changed to a reconnaissance helicopter. In October that year, the Boeing-Sikorsky and Bell-McDonnell Douglas teams received contracts for their designs. The program's name was changed to Light Helicopter (LH) in 1990. In April 1991, the Boeing-Sikorsky team was selected as the contest winner and received a contract to build four prototypes for a demonstration and evaluation phase. Also that month the helicopter was designated RAH-66 Comanche by the Army.

In November 1993, the first prototype began assembly at Sikorsky's Stratford and Boeing's Philadelphia plants, before the sub-assemblies were transferred to the former location for final assembly. The following year the number of prototypes was cut to two. The first Comanche prototype was rolled out of the Sikorsky Aircraft
Sikorsky Aircraft
The Sikorsky Aircraft Corporation is an American aircraft manufacturer based in Stratford, Connecticut. Its parent company is United Technologies Corporation.-History:...

's helicopter production facility on 25 May 1995, before being transferred to West Palm Beach, Florida
West Palm Beach, Florida
West Palm Beach, is a city located on the Atlantic coast in southeastern Florida and is the most populous city in and county seat of Palm Beach County, the third most populous county in Florida with a 2010 population of 1,320,134. The city is also the oldest incorporated municipality in South Florida...

, for flight testing. The prototype, piloted by Bob Gradle and Rus Stiles, made its 39-minute maiden flight
Maiden flight
The maiden flight of an aircraft is the first occasion on which an aircraft leaves the ground of its own accord. This is similar to a ship's maiden voyage....

 on 4 January 1996. The flight was originally planned for August 1995, but was delayed by structural and software problems. The second prototype made its first flight on 30 March 1999.

Design aspects

The RAH-66 was intended to be a stealth helicopter
Stealth helicopter
Stealth helicopters are helicopters that incorporate stealth technology to avoid detection. In recent years, designs for blades have emerged that can significantly reduce the noise, which is a major issue for clandestine use of helicopters...

; it incorporated multiple techniques in order to reduce its radar cross-section (RCS) and other areas of viability. Radar-absorbent material (RAM) was used on the Comanche, as well as having infrared-suppressant paint applied on its faceted surface; with these measures, the Comanche's RCS was 360 times smaller than the AH-64 Apache attack helicopter. The Comanche's noise signature was noticeably quieter than comparative helicopters; this was partly achieved through the all-composite 5-blade main rotor and tail rotor assembly.
|style="text-align: left;" |"This platform is not just another system – it's an asset with a multirole-ability to gain information dominance and then pass on that information to the critical command and control people, the intelligence people, to the manoeuvre elements and guys in fire support."
|-
|style="text-align: right;" | — Brigadier General Joseph Bergantz,
US Army RAH-66 program manager>


The Comanche was equipped with sophisticated navigation and detection systems intended to allow operations at night and in bad weather. Each of the two crew-members had two LCD multi-functional displays in addition to the Helmet-Integrated Display and Sight System (HIDSS). It has a digital fly-by-wire
Fly-by-wire
Fly-by-wire is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires , and flight control computers determine how to move the actuators at each control...

 flight control system. Its primary mission was to use its advanced sensors to find and designate targets for attack helicopters, such as the AH-64. The RAH-66 also had its own light armament – it could carry six AGM-114 Hellfire
AGM-114 Hellfire
The AGM-114 Hellfire is an air-to-surface missile developed primarily for anti-armor use. It has multi-mission, multi-target precision-strike capability, and can be launched from multiple air, sea, and ground platforms. The Hellfire missile is the primary 100 lb-class air-to-ground precision...

 and twelve FIM-92 Stinger
FIM-92 Stinger
The FIM-92 Stinger is a personal portable infrared homing surface-to-air missile , which can be adapted to fire from ground vehicles and helicopters , developed in the United States and entered into service in 1981. Used by the militaries of the U.S...

 missiles split evenly between the two retractable weapons pylons. The Comanche was also to be fitted with the three-barrel XM301
XM301
The XM301 Cannon is an externally-powered, three-barrelled 20mm gatling gun made by General Dynamics for the U.S. Army. Developed for use with the RAH-66 Comanche stealth helicopter, it is the world's lightest 20mm gatling cannon. The XM301 was designed to be a versatile and accurate lightweight...

 20 mm cannon under its nose. More armament could be accommodated externally but would reduce the effectiveness of the stealth technologies.

The RAH-66 was powered by two LHTEC T800
LHTEC T800
-External links:* *...

 turboshaft
Turboshaft
A turboshaft engine is a form of gas turbine which is optimized to produce free turbine shaft power, rather than jet thrust...

 engines. Its fuselage was 43 feet (13.1 m) long and made of composite material
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...

. The F-22 Raptor-derived airframe was designed to fit more easily onto transport ships, enabling it to be deployed to hot spots quickly. If transport assets were not available, the Comanche's ferry range
Range (aircraft)
The maximal total range is the distance an aircraft can fly between takeoff and landing, as limited by fuel capacity in powered aircraft, or cross-country speed and environmental conditions in unpowered aircraft....

 of 1200 nmi (2,222.4 km) would allow it to fly to battlefields overseas on its own. The Comanche was specifically tailored to the role of armed scout, replacing the U.S. Army's current armed scout helicopter, the OH-58D Kiowa Warrior, which is an upgraded version of a Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

-era observation helicopter. The Comanche was smaller and lighter than the AH-64.

Prototype testing

Flight testing was conducted with the two prototypes. After meeting key criteria, the RAH-66 entered the $3.1 billion engineering and manufacturing development (EMD) phase on 1 June 2000. An effort to reduce the Comanche's empty weight
Manufacturer's Weight Empty
Manufacturer's Weight Empty Manufacturer's Weight Empty (MWE) Manufacturer's Weight Empty (MWE) (also known as Manufacturer's Empty Weight (MEW) is the weight of the aircraft "as built" and includes the weight of the structure, power plant, furnishings, installations, systems and other equipment...

 by approximately 200 lb (90.7 kg) or 2.1% to meet its target weight was started later in 2000. Through the early 2000s, the U.S. Army planned to purchase over 1,200 Comanches to fill the scout and light attack roles, with deliveries of operational RAH-66s scheduled to begin in 2006. The first Comanche prototype, serial 94-0327, completed 318 flights over 387 hours before ending its testing career in January 2002. The second prototype, serial number
United States military aircraft serials
In the United States, all military aircraft display a serial number to identify individual aircraft. Because these numbers are located on the aircraft tail, they are sometimes referred to unofficially as "tail numbers"...

 95-0001, had accumulated 93 flight hours and 103.5 sorties by May 2001.

The second RAH-66 received mission equipment and more powerful T800-LHT-801 engines and continued flight testing from 23 May 2002, including testing of night vision and weapon systems, until 2003. During testing, the Comanche cruised at 162 kn (197.3 mph; 317.5 km/h), a "dash speed" of 172 kn (209.5 mph; 337.1 km/h), as well as demonstrating an ability to make a 180° turn in under 5 seconds.

In 2002 the program was restructured and the number of Comanches to be purchased was cut to 650. Production of this fleet had a projected total cost of $26.9 billion. The EMD phase was planned to last six years with five Comanches built for testing. Production on the third RAH-66, the first EMD helicopter, began in 2003. Subsequently eight RAH-66s were to be built for operational testing. The initial production RAH-66s were to be completed to a Block I configuration with most of the planned weapons and sensors. The 16th and later helicopters would be to the Block II standard and have all the planned capabilities.

Cancellation

On 23 February 2004, the U.S. Army announced their decision to cancel the RAH-66 Comanche program. The Army determined upgrades would be required for the RAH-66 to survive current anti-aircraft
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 threats and decided to put the funding toward renovating its existing helicopter fleet of attack, utility, and reconnaissance aircraft. The Army also planned to use the program's funds to speed up development of unmanned aerial vehicle
Unmanned aerial vehicle
An unmanned aerial vehicle , also known as a unmanned aircraft system , remotely piloted aircraft or unmanned aircraft, is a machine which functions either by the remote control of a navigator or pilot or autonomously, that is, as a self-directing entity...

s (UAVs). The Comanche program had spent US$6.9 billion at the time of its termination. Contract termination fees were estimated to total US$450–680 million for the main program partners Sikorsky
Sikorsky Aircraft
The Sikorsky Aircraft Corporation is an American aircraft manufacturer based in Stratford, Connecticut. Its parent company is United Technologies Corporation.-History:...

 and Boeing. The Army subsequently pursued the Bell ARH-70 to replace the OH-58D, but the ARH-70 was also canceled in October 2008, due to cost overruns.

Many reasons led to the ultimate cancellation of the RAH-66 program; according to author James Williams, efforts to speed up the program by cutting risk-mitigating measures and continuous adjustments for yearly budget cuts formed a deadly cycle that would greatly extend development schedules. Over the course of the Comanche's development, multiple government agencies would cut the number of helicopters to be ordered, especially on the basis that the Cold War had ended (the Peace Dividend
Peace dividend
The peace dividend is a political slogan popularized by US President George H.W. Bush and UK Prime Minister Margaret Thatcher in the early 1990s, purporting to describe the economic benefit of a decrease in defense spending. It is used primarily in discussions relating to the guns versus butter...

), and this caused unit cost projections to rapidly climb, while led to the program encountering critics such as the Army Acquisition Executive James Ambrose, who had declared that the Army would not have an aircraft "costing a dollar over $7.5 million". By only 1995, the Comanche was facing complete cancellation as a choice between which defense development programs were to be scrapped. In mid-1999 the Comanche came under governmental scrutiny, the Government Accountability Office
Government Accountability Office
The Government Accountability Office is the audit, evaluation, and investigative arm of the United States Congress. It is located in the legislative branch of the United States government.-History:...

 (GAO) reported "serious doubts" about the program and noted that it would "consume almost two thirds of the whole Aviation budget by Fiscal Year 2008". Army experiences from the Kosovo War
Kosovo War
The term Kosovo War or Kosovo conflict was two sequential, and at times parallel, armed conflicts in Kosovo province, then part of FR Yugoslav Republic of Serbia; from early 1998 to 1999, there was an armed conflict initiated by the ethnic Albanian "Kosovo Liberation Army" , who sought independence...

 had led to senior figures placing greater emphasis on unmanned platforms to conduct many of the same roles the Comanche was being developed to do. By 2000, Williams postulates that the main reason for keeping the program was out of concern for the state of the helicopter industry, Sikorsky's production and employment figures were at their lowest for decades and the contract was considered critical.

Author Fred Brooks
Fred Brooks
Frederick Phillips Brooks, Jr. is a software engineer and computer scientist, best known for managing the development of IBM's System/360 family of computers and the OS/360 software support package, then later writing candidly about the process in his seminal book The Mythical Man-Month...

 criticized the need for the Comanche to ferry itself across the Atlantic as an example of excess requirements in a project's design phase and their repercussions. Williams notes that the Comanche's weight requirements were unachievable due to poor management, no party was aware or in control of the aircraft's final weight; there were concerns that, when outfitted with actual equipment required for operations, the Comanche's engines would be incapable of lifting the total weight of the helicopter. Additionally, it was difficult to convince the Army that the development program had serious troubles, as key individuals failed to realize the existence of insurmountable technical problems. Prized elements of the program, such as software capability and integration, failed to foster confidence with Army overseers; capabilities were seen as unproven and risky while the consumption of up to 40% of the aviation budget on some years was considered extreme. In the end, it was concluded that its budget would be better spent delivering less risky and more critical needs.

The GAO recorded that an Army spokesperson stated that "the program's costs could no longer be justified". Author Cindy Williams said of the Comanche: "The rationale for cutting Comanche... is twofold. First, the doctrinal niche that the Comanche occupies is unnecessary in the near term and probably not viable in the longer term. Secondly, as with all rotary-wing aircraft, the Comanche is a voracious consumer of strategic airlift."

Specifications (RAH-66A)

See also

External links

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