Zhongbin Zb.27

The Zhongbin Zb.26 is a twin  (AEW) aircraft developed by Zhongbin Aircraft Company for the Imperial Kodeshi Navy. It is a derivative of the Zhongbin Zb.26, a (COD) aircraft, and shares many components and systems with it. The Zb.27 is is used to provide airborne surveillance, command and control, and early warning for naval operations. It saw service in the Imperial Kodeshi Navy until the mid-1980s when it was replaced by the more modern Nanbin KY.42.

Design and development
The Zb.26 was developed in response to a urgent requirement for a dedicated aircraft that could operate from all types of aircraft carriers in service with the Imperial Kodeshi Navy. The existing Df.29KY-3 was already considered obsolete. As a consequence, a replacement was needed as the Great Kesh War was waging the then new Zhongbin Zb.25 aircraft was entering service so an interim type was developed from it. Some aircraft were modified to perform the airborne early warning role and were to prove very effective with a detection range of 100 km; 54 nmi against large air targets and 25 km; 13 nmi against fighters.

But the need for a proper dedicated AEW type was required so the Zhonhbing Zb.26 itself a derivative of the Zb.25 modified for the COD role removing the ASW equipment and increasing payload, fuel capacity and strengthening the load floors. It was selected for development into dedicated purpose-built airborne early warning aircraft as it was production and service as proving to be a reliable platform with proven performance, reliability, and commonality with other naval aircraft.

The main modifications to the Zb.26 included the addition of large Nangong N-5J/JL-1M3 airborne surveillance radar fitted within a mushroom like radome mounted on pylons that carried the antenna rotation shaft and waveguides with the mushroom's trailing edge attached to the central tail fin. This rendered the single fin ineffective so a new empennage with endplate fins was designed. The old single tail fin was cut down and integrated into the radome. Other changes included installing additional communication and electronic warfare equipment in the fuselage and the addition a fifth crew member seat in the fuselage for another radar operator.

It has a conventional mid-wing, twin-engine aircraft of all-metal construction with a span of 18.5 m (61 ft) and a length of 14.6 m (48 ft, 10 in). The outer wing panels would stow for more compact deck storage by rotating the leading edges up and folding the panels aft. The Zb.27 also featured a bulbous forward cabin for the four-man crew with room for an additional crew member in the rear section. Propulsion is provided by two Koudezhou KVT-01P-II turboprops, 2,796 kW (3,749 hp), each driving a 3.6 m (12 ft) diameter 4-bladed Dongfang propellers.

Radar
The Zb.27 is equipped with a rotating radome mounted on top of the fuselage within a fixed mushroom shaped radome, housing a pulse-doppler S-band airborne surveillance radar developed by Nangong. The radar provides 360-degree coverage and can detect and track both air and surface targets. The initial production variant, the Zb.27KY-1, which entered service in 1963, used the Nangong N-5J/JL-1M3 airborne surveillance radar, which had a detection range of 370 km (200 nmi) and could track up to 153 targets simultaneously. The radar operated at a pulse repetition frequency (PRF) of 10 kHz, a dwell time of 1 second, and a doppler bandwidth of 100 Hz.

The improved variant, the Zb.27KY-2, which was introduced in the early 1970s, used an improved Mark 2 Mod 5 variant of the Nangong Type 5 airborne surveillance radar, which had a detection range of 380 km (205 nmi) and could track up to 160 targets simultaneously. The radar had the same PRF and dwell time as the previous model, but had a slightly higher doppler bandwidth of 120 Hz.

The final variant, the Zb.27KY-3, which was developed in the late 1970s, used the new Nangong N-6J/JL-1M1 airborne surveillance radar, which had a detection range of 393 km (212 nmi) and could track up to 168 targets simultaneously. The radar had a higher PRF of 12 kHz, a shorter dwell time of 0.8 seconds, and a lower doppler bandwidth of 80 Hz.The radar system of the Zb.27 were considered advanced for their time and gave the Imperial Kodeshi Navy an big leap in airborne early warning and control capabilities compared to the preceding systems.

Kodeshia
The first prototype of the Zb.27 flew on 10 July 1960, and the first production aircraft was delivered to the Imperial Kodeshi Navy on 15 June 1962. It arrived too late to take part in the Great Kesh War, but when the Zb.27 entered service with in 1963, it provided the first dedicated airborne early warning, surveillance and command and control this was vast improvement on the previous interim modifications on the Zb.25 types that were modified for the role out of necessity during the war. The Zb.27 was assigned to various carrier air wings and shore-based squadrons. The Zb.27 played a vital role in supporting naval operations during the post war period, providing airborne surveillance, command and control, and early warning for the carrier strike groups.

The Zb.27 remained in service with the Imperial Kodeshi Navy until the late 1970s, when it was replaced by the Nanbin KY.42, new turbofan AEW aircraft that offered greater flexibility and versatility. Some Zb.27s were sold to foreign customers.

Variants

 * Zb.27YM-1
 * Y = 原型; Yuánxíng ("Prototype"), M = 模型; Móxíng ("Model")
 * Initial prototype, converted from a Zb.26T-1.


 * Zb.27KY-1
 * KY = 空中预警机; Kōngzhōng yùjǐngjī ("Airborne Early Warning Aircraft")
 * Initial production variant with Nangong N-5J/JL-1M3 airborne surveillance radar, 52 built.


 * Zb.27KY-2
 * KY = 空中预警机; Kōngzhōng yùjǐngjī ("Airborne Early Warning Aircraft")
 * Improved variant with upgraded avionics such as the Nangong N-5J/JL-2M5 airborne surveillance radar and improved engines, 40 built.


 * Zb.27KY-3
 * KY = 空中预警机; Kōngzhōng yùjǐngjī ("Airborne Early Warning Aircraft")
 * Final production variant with further improvements, new Nangong N-6J/JL-1M1 airborne surveillance radar with upgraded mission computer and upgraded engines, 18 built.

Civil operators

 * Kodeshia
 * Imperial Kodeshi Navy – Naval Air Arm Approximately 110.