Haigao Hg.37

The Haigao Z.37 is a twin-engine, multi-role, utility helicopter developed by Central Haigao Aircraft Works.

Origins
The Z.37 was derived from the earlier prototypes by the Central Haigao Aircraft Works for a utility helicopter during the 1960s. The early designs were cancelled during the 1964 Xuanyi Restoration. But after the new Imperial Government re-established control there was interest reviving the plans to form the basis for a new light helicopter, as part of new army requirements. The Central Haigao Aircraft Works submitted their concept to the program and order placed for an experimental prototype to test the suitability of the platform for testing a new helicopter design. This became the Z.37, initially powered by a pair of CAIC C9T-300A turboshaft engines driving 3-bladed main rotor and single tail shaft. This arrangement would provide increased reliability and improved performance.

The first Z.37s prototype designs were built and flown in February 1972, at the Haigao factory in Shangyu in Dachuan province. Initially, the Z.37s were fitted with an upgraded version of the engine, the CAIC C9T-322. By the end of that year, the program was renamed Utility Transport Helicopter (通用运输直升机; Tōngyòng yùnshū zhíshēngjī; TYZ), and the design goal was to produce a highly capable utility and transport helicopter. Further development included redesigning the aft fuselage, using strengthen materials. The first flight of the production aircraft, occurred on 16 February 1977. It was officially introduced into the Imperial Kodeshi Air Force in 1979, It would enter service with the Imperial Kodeshi Army in 1980.

Design
The Hg.37 is a general-purpose utility helicopter based on a conventional fuselage and tail design with a relatively large, tandem engine installation. It uses a dual-crown, three-blade main rotor that incorporates a single-bladed tail rotor and a single-fuselage, tail mounted two-bladed cycloidal, single-tail rotor. The main rotor is suspended between the fuselage and tail booms with the blades arranged on a circular array with an overall diameter of 15.8 m. Each main rotor blade features a special coating with the central complex consisting of a strengthened rotor head with the addition of a reinforcing plate. The fuselage is strengthened with a single-piece vertical bulkhead. The cabin was made larger to accommodate two crew and up to 18 passengers in its standard configuration.

Operational history
The Z.37 entered service with Imperial Kodeshi Air Force in 1979, It would enter service with the Imperial Kodeshi Army in 1980 and the type has since undergone many modifications over the course of its service. It currently has an array of different engines in the form of both gas turbines. It has also featured various different airframe configurations. The main differences are in its fuselage and tail, in addition to the modifications. Its current form is in service with the Imperial Kodeshi Air Force, based at the Zhengzhou Flying University Air Force Base in Dazhong province. It's main operational military deployment has been on operations against rebel forces in the northern Kodeshia since it's introduction until the end of major operations in 1987. The type was one of major air units deployed by the Imperial Kodeshi Army and Imperial Kodeshi Air Force units. Additionally the Hg.37 helicopter is a general-purpose utility helicopter and the type has seen use by many civilian organisations from law enforcement, fire service to search and rescue and general transportation.

Prototype Models

 * Hg.37YM-TYZ
 * F = 原型; Yuánxíng ("Prototype"), M = 模型; Móxíng ("Model")
 * Company model number for basic prototype, one built. Powered by the CAIC C9T-300A turboshaft engine.


 * Hg.37FM-TYZ
 * F = 发展; Fāzhǎn ("Development"), M = 模型; Móxíng ("Model")
 * Pre-production series powered by CAIC C9T-322 turboshaft engine, five built.

Production Models

 * Z.37DS
 * D = 多用途; Duō yòngtú ("Multi-purpose"), S = 搜救; Sōujiù ("Search & Rescue")
 * General utility helicopters for the Imperial Kodeshi Air Force used for search and rescue, utility or transport, 72 built.


 * Z.37Y
 * Y = 运输; Yùnshū ("Transport")
 * Utility transport helicopter variant adopted by the Imperial Kodeshi Army, Royal Theykan Airforce and Interservice Special Forces Command. 598 built.

Civilian Models

 * Hg.37D
 * D = 多用途; Duō yòngtú ("Multi-purpose")
 * Commercial transport helicopter. The Hg.37 can be fitted out as an all-passenger, all-cargo, or cargo/passenger transport helicopter.


 * Hg.37G
 * G = 贵宾; Guìbīn ("VIP")
 * Civilian VIP transport version, with accommodation for 8 passengers.


 * Hg.37S
 * S = 搜救; Sōujiù ("Search & Rescue")
 * Search and rescue version.

Operators
 Kodeshia  Theyka
 * Imperial Kodeshi Air Force operates 72 Z.37DSs with the rotorcraft units.
 * Imperial Kodeshi Army operates around 550 Z.37Ys, with more ordered.
 * Royal Theykan Airforce: operates 40 license built Z.37Y in 2 Air Assault Groups.
 * Interservice Special Forces Command: operates 8 license built Z.37Y.