Changhe Z-10
The Changhe Z-10 is a Chinese medium-weight, twin-turboshaft, attack helicopter built by the Changhe Aircraft Industries Corporation for the People's Liberation Army Ground Force Aviation. Designed by 602nd Aircraft Design Institute of Aviation Industry Corporation of China and Kamov Design Bureau, the aircraft is intended primarily for antitank warfare missions with secondary air-to-air combat capability.
The plan to develop a medium-weight helicopter program was initiated in 1994 with the attack helicopter program formally beginning in 1998. The preliminary design of the aircraft was provided by Kamov, while prototyping was conducted by the 602nd Aircraft Design Institute of Aviation Industry Corporation of China. The Z-10 first flew on 29 April 2003 and entered Chinese Army Aviation service in 2009.
Nicknames of characters in the Chinese classic novel Water Margin have been used to name Z-10 and its light-weight counterpart, the Harbin Z-19 by Chinese Army Aviation Corps; Z-10 is called Fierce Thunderbolt, the nickname of Qin Ming, while Z-19 is called Black Whirlwind, the nickname of Li Kui.
Development and history
Background
The People's Liberation Army Ground Force established its army aviation units in January 1988. The unit used helicopters transferred from People's Liberation Army Air Force, including Mil Mi-4, Harbin Z-5, Mil Mi-8, and Aérospatiale Gazelle. By the mid-1980s, the Chinese decided to field dedicated attack helicopters. The brief honeymoon period between China and the West provided China opportunities to evaluate Agusta A129 Mangusta, AH-1 Cobra, and BGM-71 TOW missiles. However, the 1989 Tiananmen Square protests and massacre and the ensuing arms embargo prevented many deals from going through. Nevertheless, China successfully imported or licensed aircraft types such as Changhe Z-8, Harbin Z-9, Sikorsky S-70, Mi-17, and Aerospatiale AS332 Super Puma.Also, debate had arisen in China about whether the PLAGF or PLAAF should operate attack helicopters. Eventually, the PLAGF won and began to induct armed helicopters based on the Harbin Z-9 design. The use of the Z-9WA modification helped China realize the requirement for a dedicated attack helicopter platform.
Development programs
A preliminary plan to develop an attack helicopter in China began in 1992. China began to develop the 6-ton class China Helicopter Medium program in 1994, headed by the 602nd and 608th Research Institutes. This program was later developed into Harbin Z-20. In 1995, China commissioned Kamov to develop a preliminary design for the 6-ton helicopter, known as Project 941 internally. Project 941 was a large departure from traditional Soviet design, focusing entirely on the CHM requirement. The concept was then handed to China for further development, in which Kamov did not participate. Based on the concept, Chinese engineers developed prototypes and iterate designs based on the testing results. The changes include modification on the airframe shapes to optimize radar cross section, changes on the engine bay shape to accommodate domestic engines, and the engine nozzle layout.China also secured assistance from Eurocopter France for the rotor system and AgustaWestland in 1997 for the transmission system in 1998. Pratt & Whitney Canada and Hamilton Sundstrand secretly provided PT6C-67C engines and digital engine control systems to aid the programs, leading to them receiving investigations and penalties from the United States government.
In 1998, the 602nd Research Institute proposed the Special Armed Project to develop the final design, which was designated the Z-10. Initially, the Z-10 project was planned to share its propulsion system with the CHM program, but the two programs were separated and the Z-10 was prioritized to be completed first. During the development in 2000, Denel also provided technical assistance to the project in the area of flight stability. After the US government cut off engine sources from Pratt and Whitney, China turned to domestic replacements with lower thrust ratings, leading to further weight-saving design changes. The replacement engine was the indigenous WZ-9 turboshaft.
David Donald of Aviation International News claimed the Z-10 had a universal engine bay capable of fitting various types of engines, including Ukrainian Motor Sich TV3-117. However, Chinese sources indicated the TV3-117 is incompatible with the Z-10's engine bay due to the driveshaft shape, and prototypes were fitted with either Pratt and Whitney PT6C-67C or Chinese-built Turbomeca Makila turboshaft engines, whereas the final version uses WZ-9 turboshaft engines due to its fully indigenous origin.
The Z-10 took its maiden flight on 29 April 2003 and entered PLA service in 2009 or 2010.
Further development
In March 2014, the Z-10 helicopter began deck trials with a People's Liberation Army Navy Type 072A-class landing ship. The purpose may be to qualify the helicopter on ships to provide air support for landing parties launched from the ship. Type 072A-class ships have a helipad, but no hangar or support facilities for the aircraft on board. The Z-10 may also be qualified on the larger Type 071 amphibious transport dock.The Z-10 was one of the contenders to replace Pakistan's Bell AH-1F Cobra attack helicopters. In 2015, Pakistan acquired three Z-10s for trials, but ultimately rejected the offer due to the inadequate WZ-9 engine. After the failed bid, Chinese engineers began to upgrade to the Z-10 platform to improve its competitiveness. A new prototype, designated Z-10ME, emerged in 2018 with a larger ammunition magazine size, new intake filtration systems, and a new missile approach warning system. In the same year, more equipment was added to the prototype, such as a more powerful WZ-9C turboshaft with power, new infrared signature-reducing engine exhaust nozzle, appliqué graphene-based armor plates, etc.
The PLAGF's domestic Z-10 fleet was upgraded to the Z-10ME standard with the engines, appliqué armor plates, and infrared suppression nozzles. The Pakistan Army eventually purchased the Z-10ME, as well.
Design
Overview
The Z-10 features a tandem cockpit compartment at the front section. The airframe bulges below the cockpit, extending backward and merging with the stub wings and tail boom, creating a distinctive ridge dividing the top and bottom half of the blended fuselage, which are both canted inward, creating a hexagon-shaped frontal profile. This slim, rhombic configuration ensures structural strength, increases internal volumes for equipment, and reduces the frontal projected area and overall radar cross section. The radar-absorbent material is applied to the fuselage, further reducing the radar reflection and providing a certain degree of low observability.The rotor system consists of a single semirigid, five-blade main rotor at the top and a four-blade tail rotor at the aft section. The airfoil of the primary 95KT rotor blade features a significant camber with swept tips, designed to reduce the blade length, vibration, and acoustic signature. The tail rotor consists of two sets of dual composite blades mounted in an angled, nonorthogonal arrangement designed to reduce noise generated by the wingtip vortices. All blades are made with carbon fiber-wrapped spars with layered honeycomb composite for the skin, capable of sustaining damage against rounds. A deicing device is fitted to the blades to increase flight safety in adverse weather.
The fuselage is primarily made of aluminum alloy, with 30% of the mass being composite materials. The cockpit compartment is wrapped inside carbon fibers, while the canopy is protected by bulletproof glasses of in thickness. Additional protection layers made of aluminum alloy and kevlar are applied to the bottom of the cockpit, side of the engine bays, and around the self-sealing fuel tank. The honeycomb composite layer is applied to the fuselage bottom, while the pilot seats, landing gears, and fuel tank are reinforced for improved crashworthiness. The early model of Z-10 prioritizes protection in critical areas for weight reduction without sacrificing structural integrity, range, and payload. In later serial production, appliqué graphene armor plates are mounted on the side of the cockpit and engine housing to further improve the protection level.
The Z-10's engine air intake is protected by a metal mesh to prevent foreign objects from being sucked in. Newer variants can be installed with integrated inlet particle separators for engine intake filtration, preventing harmful solid particulates such as sand and dust to damage the critical propulsion components. The Z-10's engine system is fitted with the Hover Infrared Suppression System, mixing in the engine exhaust with cold air to reduce the helicopter's infrared characteristic. Later serial production of Z-10s modified the engine nozzle from side-facing to the upward-facing direction, further reducing the signature from heat radiation. The upward-facing exhaust nozzle, albeit beneficial for suppressing the infrared signature, would lead to additional drag, To resolve this, the engine on the Z-10 was upgraded to from to to make up the loss.
Propulsion
The Z-10 prototype was powered by two Pratt and Whitney Canada PT6C-67C turboshaft engines, which is equipped with a Full Authority Digital Engine Control system and sports a maximum continuous power of. The early batches of Z-10 were powered by domestic Zhuzhou WZ-9 or WZ-9A turboshaft engines, providing of power. The reduced performance of WZ-9 turboshaft engines prevented Z-10 from carrying its maximum payload of 16 antitank guided missiles.Multiple engines were developed to upgrade the propulsion of the Z-10. China and European partners reportedly developed the WZ-16. The WZ-9 was upgraded to WZ-9C with of maximum power. The engine was originally designed for export, but subsequently used to upgrade early Z-10s batches. The WZ-9C provides 30% more power than the original version, providing the Z-10 with enough lift for a variety of payloads.
The Z-10 emphasizes extended-range operation. The WZ-9A turboshaft engine allows the aircraft to fly at a maximum speed of and a cruise speed of. The internal tank supports a range of.