WZ-YY - Stealth Medium Transport Helicopter

After China broke through the stealth technology in fighter jets, military designers turned their attention to the other two battlefields: bombers and helicopters. Whether they could see these two aircraft using stealth technology, no one would have thought that stealth helicopters appeared immediately. In a certain exhibition, on 28 May 2021 CCTV exhibited a model of a stealth helicopter that resembled the American stealth Black Hawk that the United States dispatched to kill the terrorist Osama bin Laden in early May 2011.

On 1 May 2011, the United States announced that it had launched an operation into Pakistan from Afghanistan to apprehend Al-Qaeda leader Osama bin Laden. Bin Laden was killed during the operation. During the raid, it was reported that one of the force's MH-60 helicopters was damaged and had to be destroyed in place. Subsequent pictures of the wreckage suggested that the helicopter might have in fact been a new type or a highly modified existing type, incorporating stealth technology. By one account, the remnants of the RUH-60 helicopter were later recovered and moved from the site by the Pakistani military, and surely shared with appreciative Chinese engineers. Probably Pakistan not only allowed Chinese military engineers to take photos of the wreckage of the plane, but also allows them to take some samples for research. The Pentagon refused to discuss whether Pakistan rejected the request of the United States to return the wreckage of the helicopter.

The stealth technology of helicopters is slightly different from the stealth technology of fixed-wing aircraft, because radar is not the main threat. If the helicopter is flying close to the ground at low speed, terrain clutter can better cover the helicopter, which is the advantage of helicopter stealth. However, the low speed of the helicopter also allows enough time for the radar to call the defense. This is the disadvantage of stealth helicopters. Technology required includes reducing the size of the helicopter; adopt a swept-tip rotor to reduce its noise; adopt a plane-type small reflective cockpit cover; adopt composite materials to reduce radar reflection on the fuselage; paint the surface of the helicopter with non-reflective camouflage materials; apply engine infrared suppression technology, etc.

To improve the stealth performance of helicopters, it is mainly considered from the aspects of maneuvering concealment, the use of stealth materials and various stealth technologies. From the perspective of stealth technology, it mainly includes: visual stealth, radar stealth, infrared stealth and acoustic stealth.

Invisible at a glance. That is, by reducing the size of the body, reducing the diameter of the rotor, and adopting a narrow body design with a single seat or a stepped tandem double seat, the body is slender and the probability of being discovered by the enemy is reduced; camouflage is painted on the body Paint, make the helicopter color close to the background, so as not to be detected by the enemy when flying in the jungle, grassland and desert Gobi and other special terrains.

The second is radar stealth. That is, the use of stealth shape design, such as a narrow body design composed of polyhedrons and curved surfaces, retractable landing gear, built-in bomb bays, extensive use of radar absorbing materials and composite materials, and additional installations on the hub and blade roots The fairing, concealing the engine in the fuselage, and designing the air inlet to be prismatic, effectively reduces the radar reflection cross-sectional area of ??the helicopter and reduces the probability of being detected by the radar.

The third is infrared stealth. That is, an infrared suppression device is installed to reduce the infrared characteristics of the helicopter. It is mainly to install an infrared baffle at the tail nozzle to shield infrared radiation; spray a radioactive isotope on the tail nozzle to absorb infrared; use a special-shaped tail nozzle to change the wavelength of infrared radiation; use a new type of atomizing nozzle to make fuel Fully burn and reduce infrared radiation, etc., to reduce the possibility of being discovered by the enemy's infrared detection system and being hit by the enemy's infrared guided missiles.

The fourth is acoustic stealth. Minimizing helicopter noise is the basic requirement for acoustic stealth. The main purpose is to improve the acoustic stealth effect of helicopters by using multiple main blades with large cross-section root-to-tip ratio, low-noise rotor system with the blade tip swept back, low-noise power unit, and tail-less design. It is not easy to achieve radar stealth for helicopters. The technical difficulty is very large, and it is even more difficult to achieve silence. It is not easy to achieve this technically.

The flapping noise of modern helicopter rotor blades is caused by the "blade vortex interaction". This noise can be heard from two miles or more away. This is related to the ability of humans to distinguish different sounds. People may not The sound of the lawn mower next door will be heard, but the sound of the airplane is easy to hear. It is more frequent and sounds very annoying. It allows the enemy to prepare ahead of time. History shows that 90% of helicopters were shot down by infantry weapons, and 80% of helicopters shot down by infantry weapons did not find an attacker on the ground. These elusive threats force the US military to need stealth helicopters that "quietly take off and pick up people over enemy territory".

Generally speaking, in addition to reducing noise and suppressing infrared features, stealth helicopters must also reduce the radar reflection cross section. The usual way to reduce the radar reflection cross section is to wrap the parts that can generate echoes. For example, the original exposed landing gear is changed to a retractable type, the original external antenna is buried in the fuselage, and the cabin glass is coated. Wait. And because special operations helicopters often fly in the blind zone of the radar, even if they are found, they are difficult to track due to the stealth design.

Before the first use of stealth helicopters in the hunt for bin Laden, there were no real stealth helicopters in use in the world. The AH-64, A-129 and "Tiger" helicopters only adopted some partial measures to reduce the helicopter's capacity Visibility, reduce infrared characteristics, and improve its survivability with the help of active confrontation. The "Aerospace" issue of March 1, 2018 revealed that the WG.44~WG.48 series of fully stealth helicopters designed by Westland in the United Kingdom in the 1980s. This report has brought the initial development of modern stealth helicopters closer to the time. The RAH-66 "Comanche" being developed by Boeing/ Sikorsky also applied the stealth principle as a whole to carry out a comprehensive and comprehensive stealth design.

By 2015, reports in China of domestically-made stealth helicopters attracted widespread attention. Such news really excited people who are concerned about the development of China's army aviation power. The English version of China’s official media "China Daily" quoted Lin Zuoming, president of the Aviation Industry Corporation of China, saying that the stealth capability of the armed helicopter will "reshape" the combat mode of the Chinese People's Liberation Army, and so on. For a time, news of China's 4th generation stealth gunship was overwhelming. The media even compared the American RAH-66 "Comanche" stealth attack reconnaissance helicopter, which was terminated in 2004, with my country's new generation of stealth armed helicopters.

It can be seen from the public model that the aircraft body is very wide, adopting a conventional single-rotor and tail rotor design. The overall size is similar to a WZ-20 general transport helicopter [a Blackhawk with Chinese charateristics]. The aircraft body is very special and adopts the unique slope design of a stealth fighter. The nose edge extends back to the fuselage and then to the tail beam. The fuselage forms a sharp ridge at the lower edge of the porthole. The upper and lower parts are inclined inward. The fuselage has a smooth surface without the exposed structure of a traditional helicopter, or the holes or bulges formed by equipment.

It is worth noting that the main landing gear of the helicopter adopts a kneeling design. There is a landing gear diagonal support point on the outside of the bottom of the fuselage. The connection point of the landing gear pillars, to maintain the perfect stealth, should be retracted inward Hidden into the fuselage, this design should also appear on the tail landing gear.

The machine’s unique intake and exhaust grille are impressive. The aircraft uses a 5-blade high-speed propeller, the tip of the blade adopts a longer sweeping short, the length is particularly long, about 6 times the width of the blade, this is the first time that a Chinese helicopter adopted this design. The design is more suitable for high-speed flight, using a large sweep to reduce the sound barrier resistance, this is an out-and-out high-speed helicopter!

The body design of the helicopter is similar to the stealth Black Hawk of the United States, but the most interesting is the infrared stealth design. This is caused by the unique working environment of the helicopter. The biggest threat is the infrared-guided shoulder-launched missile when flying at low altitude for a long time. The air intake of the machine adopts a flat and slender grille design, and the exhaust port also cancels the traditional large cylindrical exhaust port. It is placed on the back of the tail beam and uses 2 rows of several meters long. Grille design, it can also be seen that this is a twin-engine helicopter. This design has dual functions. On the one hand, it can prevent radar from entering. On the other hand, it benefits particularly from infrared stealth, with a large exhaust area. The exchange circumference is also large, and the infrared characteristics are particularly small. The downward high-speed airflow caused by the rotation of the rotor can be used to quickly cool the hot air from the tail nozzle, so that it can achieve good stealth characteristics.

Taken together, there is an impression that this is a 10-ton medium-sized helicopter with excellent high-altitude plateau performance. It is very likely to borrow the experience gained in the development of the Zhi-20 attack helicopter, including high-power turboshaft engines, transmission systems, and advanced fly-by-wire flight control system. Based on the Z-20, this new design has been carefully crafted to create a more advanced stealth helicopter than the American stealth Black Hawk helicopter. The overall shape is more like an F-117 attack aircraft, and the nose and fuselage are adopted With a prismatic design, the engine air intake adopts a grille design, which is protruding outside the fuselage, which is not as good as the built-in design of a Chinese helicopter, and the exhaust design is relatively old.

If designers want to achieve perfect stealth, the aircraft must install two weapon bays in the aircraft body and open them during use. The disadvantage of this design is that due to the limited space of the aircraft body, large auxiliary fuel tanks and sufficient numbers cannot be mounted. The weapon has a huge negative impact on the range and ammunition of the helicopter. If a large auxiliary fuel tank is installed, a large hanging pylon must be added. The stealth performance is greatly reduced, and it can be used for long-distance transitions.

In any case, this is huge progress made by China’s aviation industry. Encouraged by the success of the J-20, there are no fundamental obstacles to overcome in the development of new stealth helicopters. Therefore, in the next few years, China may get advanced stealth helicopters, and there may be more than one. This one is more suitable as a special forces infiltration and sneak attack model, and China also needed at least one new stealth reconnaissance helicopter and a heavy stealth attack helicopter.