The idea of creating a promising helicopter appeared in the minds of the Pentagon representatives back in the early 1980s. At that time, the Cold War, after some detente in the 70s, was able to find a second wind. At the same time, probable opponents were identified: the Soviet Union and its closest allies. In those years, the Warsaw Pact countries had an overwhelming superiority in the quantitative and qualitative composition of armored vehicles over the NATO countries. Naturally, it was profitable for the American military to get an effective means of fighting armored vehicles, primarily tanks. At the same time, one of the most effective means of fighting tanks was seen as an attack helicopter armed with anti-tank guided missiles (ATGM).
In December 1982, a report was prepared, called "Research in the field of the use of US Army aviation", in this report the inability of the outdated Bell OH-58 and Bell AN-1 helicopters to solve combat missions in the face of opposition from the air defenses of the Warsaw Pact states was proved. The following year, the US Department of Defense announced the start of work on a new light multipurpose helicopter under the Light Helicopter Experimental - LHX program. The new combat vehicle was planned to be developed in two versions - multipurpose (UTIL) and reconnaissance and strike (SCAT).
The terms of reference issued by the American military contained a number of complex and difficult tasks at that time. The helicopter was supposed to successfully carry out combat missions in all climatic zones, day and night, in flat and mountainous terrain. The key point was the requirements for the maximum flight speed, which was 180 km / h higher than the speed of any helicopter in operation. The machine, created as part of the LHX project, was supposed to reach a speed of about 500 km / h. The second very important task was to reduce the visibility of the helicopter in the radar, infrared and acoustic ranges.
The creation of a rotorcraft under the LHX program was to take place on a competitive basis. From the standpoint of today, the then appetites of the American generals can boggle the imagination. In the interests of the army alone, it was supposed to order almost 5 thousand helicopters: 1100 in the SCAT version to replace the AH-1 "Cobra" attack helicopters, another 1800 to replace the OH-6 "Hughes" and OH-58 "Kiowa" and 2000 machines in the UTIL version for replacement of the multipurpose UH-1 "Huey". In addition, orders for a helicopter could follow from the Marine Corps and the Air Force, and the total order volume could be 6 thousand vehicles. The total development cost of the helicopters was estimated at $ 2.8 billion, and the cost of their production would be $ 36 billion, which would automatically make the LHX program the largest helicopter program ever in existence.
A firm that would have secured a victory in this competition would have received orders, and hence profit for the next 20-25 years. In a rather fierce competition for the right to create a new attack helicopter, four large US aircraft companies - Boeing-Vertol, Sikorsky, Bell and Hughes - have entered. At the same time, the projects presented by these companies were very different from each other. So the company "Sikorsky" offered a coaxial helicopter with an additional pusher propeller installed in the annular fairing. It was assumed that such a project is the most technically advanced, but also has a high degree of risk, in particular, due to the use of a coaxial scheme, which is almost never used in the West.
Bell Company, which had extensive experience in the creation of aircraft with rotary propellers, promoted a project based on an experimental tiltrotor XV-15. Hughes offered a light winged helicopter based on a single-rotor design without a tail rotor. In this project, a jet of reactive gases from the engine was used to balance the reactive moment of the main rotor and create additional thrust in the longitudinal direction. A similar project, but with a tail rotor in an annular channel, was demonstrated by the Boeing-Vertol company. At the same time, the only common place in all projects was the placement of weapons on the internal sling.
In 1984-1987, the projects submitted were evaluated in the USA. It resulted in a revision of key requirements. This mainly concerned flight speed. Special studies have shown that at altitudes of about 15 meters and speeds of more than 320-350 km / h, it will be extremely difficult for the crew to simultaneously drive and perform the tactical tasks facing them. Especially if it happens in bad weather or at night. It turned out to be completely impossible to fight in a helicopter developing a speed of 500 km / h. This conclusion made it possible to abandon the most exotic projects, the implementation of which was associated with a significant share of risk. At the same time, due to a decrease in funding, it was decided to abandon the creation of a multipurpose version of the UTIL helicopter. For the helicopter, only reconnaissance and strike functions were left, and the total number of supposed machines was reduced to 2096 pieces.
Despite the reduction in tasks to be solved, further work within the framework of the LHX project still required unexpectedly high costs. Financial and technical problems led to the fact that the bidders were combined into two groups: Bell-McDonnell-Douglas (the latter took over Hughes) and Boeing-Sikorsky. The companies presented their projects in 1990. But at that time, the Soviet Union had significantly surrendered its positions, and the likelihood of a major war in Europe had significantly decreased. Against this background, a possible order was once again envisaged, which was reduced to 1292 helicopters.
In January 1991, it was announced that the Boeing-Sikorsky tandem had won the competition. At the same time, the unnamed vehicle received the official name - RAH-66 "Comanche". Traditionally, American helicopters are named after the tribes of the North American Indians - "Apache", "Chinook", "Kiowa" - after all, "air cavalry". At the same time, the designation RAH (reconnaisence and attack helicopter) was assigned to an American helicopter for the first time in history. In the American army, attack helicopters were designated AN (attack helicopter), and light vehicles intended for observation and reconnaissance OH (observation helicopter). At the same time, the new helicopter was not inferior in its capabilities to attack vehicles and was the first truly reconnaissance helicopter in the American army, so the presence of the letter R in its name is no coincidence.
The Boeing-Sikorsky association was awarded a contract for the development and construction of two RAH-66 Comanche helicopters. It was about demonstration copies. At the same time, they tried to test all the most complex and "critical" technologies on flying laboratories or stands. The helicopter's airframe was made entirely of composite materials. To check it, the Sikorsky S-75 helicopter was built and tested, on which the change in the shape of the airframe was also checked by the value of EPR - the effective scattering surface. Apparently, it was the S-75 helicopter that became the first in the world to use the elements of stealth technology.
The main elements of the fuselage of the new RAH-66 Comanche helicopter were a box-shaped girder, which was made of composite materials. A central fuel tank with a capacity of 1142 liters was located inside this beam. From the outside, all the main units of the helicopter were installed on the beam, which were covered with special large-sized panels that formed the outer contour of the machine. The casing of the helicopter was unloaded and when combat damage appeared - holes from 23-mm shells and 12.7-mm bullets, there was no loss of its strength. There was no armor as such on the helicopter, only the pilot's seats had light protection. The cockpit floor consisted of safely damaged panels, which were supposed to absorb impact energy in a possible accident. For access to various components and systems when performing maintenance, about 40% of the fuselage surface was made in the form of removable panels. Due to the peculiarities of the installed landing gear, the helicopter could "squat" on it in order to reduce the height during transportation by air.
The layout of the helicopter was traditional, but had a bright twist. It consisted of a crew accommodation that was different from other helicopters. The pilot was in the front seat, and the weapons operator was in the back. As a result, the pilot had excellent visibility, which was especially important when flying close to the ground, as well as during air combat. At the same time, the weapons operator retained all his ability to search for targets. This was achieved through the implementation of the “eyes outside the cockpit” concept. The Comanche was equipped with thermal and infrared systems for viewing the front hemisphere, belonging to the second generation of such devices. They made it possible to see 40% farther and produce 2 times clearer images than similar systems on the Apache attack helicopters.
Guided missiles were not created specifically for the new helicopter. The available weapon bays were suitable for the existing air-to-air Stinger missile and Hellfire ATGM. On the inner surface of the compartment doors there were 6 weapons suspension nodes (3 on each door), on any of them it was possible to install 2 Stinger missiles, one Hellfire ATGM or a container with an NAR. In addition, the helicopter was equipped with a three-barreled 20-mm cannon, the ammunition of which ranged from 320 to 500 rounds. The gun had a variable rate of fire. When firing at air targets, it was 1500 rds / min, when firing at ground targets - 750 rds / min. In the case of using an attack helicopter in conditions of a relatively weak enemy air defense, the armament could be significantly strengthened by using additional hardpoints mounted on small attached wings. These wings could be delivered in the field in just 15 minutes. In this configuration, the helicopter was able to carry up to 14 ATGM "Hellfire", only 2 missiles less than the "Apache". True, the maximum flight speed in this mode was reduced by 20 km / h due to the increase in the drag of the vehicle.
Particular attention was paid to reducing the helicopter's radar signature. The achievement of this goal was facilitated by the convex shape of the fuselage with flat surfaces, the use of a rotor hub fairing, a retractable landing gear, a radio-absorbing coating of the blades and fuselage, and even a cannon retracted into a special fairing by turning 180 degrees. All these measures significantly reduced the vehicle's visibility.
In reducing the visibility of the helicopter, the Americans achieved a real triumph. The RCS value of the RAH-66 Comanche was 1/600 of the RCS of the Apache helicopter and 1/200 of the RCS of the Kiowa helicopter. This allowed the helicopter to remain unnoticed by the enemy radar for longer. The main rotor noise was also significantly reduced - 2 times compared to the Apache, which allowed the helicopter to sneak up to enemy positions 40% closer. Another success was the reduction of the thermal radiation of the power plant to 25% of the usual level. For the first time, it was on the Comanche that an infrared suppression system was used (previously, various nozzles on engine nozzles were used to reduce infrared radiation), in which hot exhaust gases from engines were mixed with ambient air and then thrown down through two special flat slots that ran along the ledge along the entire length of the tail boom of the machine. Thanks to these solutions for air defense radars, as well as missiles equipped with radar and infrared guidance heads, the RAH-66 Comanche was a difficult target.
Of course, the tests carried out revealed a number of serious problems with the machine, primarily with the electronics. It also turned out that the weight of an empty helicopter is significantly greater than the calculated one. Because of this, all the flight characteristics of the helicopter, in particular its rate of climb, were lower than those originally stated. In fairness, it should be noted that the manufacturer eliminated all the shortcomings at a fairly rapid pace. The first 6 RAH-66 Comanche combat helicopters were to enter service in 2002, and by 2010 the number of helicopters in combat units was to be 72. However, even such a significant reduction in the order did not help. On February 23, 2004, the US Congress decided to close the program. By this time, the development carried out had already consumed more than $ 7 billion. Thus, the program for the creation of the Comanche helicopter was disrupted, becoming one of the most expensive programs with such an unenviable fate.
It is believed that such a difficult decision was also made on the basis of a detailed analysis of modern military operations, the use of helicopters and their losses in Afghanistan, Iraq and Chechnya. In all these conflicts, most of the rotorcraft were shot down with the help of MANPADS equipped with a combined guidance system (including a thermal imaging channel), small-caliber anti-aircraft artillery, or even with the help of conventional small arms. Against these short-range weapons, none of the stealth technologies used on the RAH-66 Comanche and costing a lot of money did not help. Moreover, the helicopter had no armor. Based on this, many American generals decided that RAH-66 was not at all suitable for use in the conditions of those military conflicts that are common in the modern world. With the disappearance of the global confrontation in Europe, the conditions for use in which this helicopter was created have disappeared.
Flight technical characteristics of the RAH-66 Comanche:
Overall characteristics: length - 14, 28 m, fuselage length (without cannon) - 12, 9 m, maximum fuselage width - 2, 04 m, height to the main rotor - 3, 37 m, rotor diameter - 12, 9 m, the diameter of fenestron is 1.37 m.
The area swept away by the rotor is 116, 74 m2.
Normal takeoff weight - 5601 kg, empty weight - 4218 kg, maximum takeoff weight - 7896 kg.
The volume of fuel tanks is 1142 liters (only internal).
The power plant is a turboshaft LHTEC T800-LHT-801 with a capacity of 2x1563 hp.
The maximum speed is 324 km / h.
Cruising speed - 306 km / h.
Combat radius - 278 km.
Crew - 2 people (pilot and weapons operator).
Armament - three-barreled 20-mm cannon (500 rounds), internal compartment - up to 6 ATGM Hellfire or 12 SAM Stinger. External suspension - up to 8 ATGM Hellfire, up to 16 SAM Stinger, 56x70-mm NAR Hydra 70 or 1730 liters in PTB.
