Changgok Chk-18

Chk-18
File:Tsk-18 side colour.png
Chk-18
Role	V/STOL multi-purpose military utility aircraft
National origin	DSRA
Manufacturer	Changgok Design Bureau
First flight	25 November 1976
Introduction	28 August 1986
Status	In production
Primary user	DSRA Anikatia
Produced	1975–present
Number built	300+
Unit cost	Chk-18X: UR$78 million (estimated flyaway cost, 2014)

The Changgok Chk-18 is a Anikatian multi-mission, military, twin-engined tiltrotor, developed by the Changgok Design Bureau. It's unique configuration allows it to land vertically like a helicopter or operate as conventional aircraft with a short takeoff and landing capability. This give the design the functionality of a conventional helicopter with the long-range and higher speeds of a conventional aircraft. Originally developed as part of navy program interest from the air force led to a combined joint development which culminated in both battlefield and naval variants. The Chk-18 originated from an Anikatian Experimental Joint Army and Naval Vertical take-off/landing aircraft program started in 1960s. The programs ambitious and complex design led to many difficulties in reaching production, numerous design changes and alterations along with many years of development and testing were undertaken since the initial prototype first flew in 1968, but it was not until 1986 when a limited number entered operational and was later adopted by the armed forces of various nations, primarily serving in the battlefield utility, anti-armour, search and rescue and anti-submarine warfare roles. Anikatian Navy. It has been in continuous production since 1984, with the latest variants seeing significant upgrades to the avionics and flight systems, improved engines, glass cockpits, increased fuel capacity; and aerial refuelling.

History

In 1956 the Navy began work on the development of a prototype V/STOL aircraft that could provide helicopter type transport capabilities while large enough to replace existing light to medium-sized transport aircraft. The Navy also required a design that could operate and supply their vessels with the ability of the light transport aircraft. The program quickly gained interest from the Anikatian Army, and Air Force who joint the program making it a joint all-service program. All branches were specifically interested in designs with longer range and higher speeds than existing helicopters, which were considered inadequate with the Anikatian military doctrine which called for long range support operations. On 7 February 1962, a All-Service VTOL transport (ASVT) was launched. Design work started in 1963 by Changgok Design Bureau and Daesungkhu & Namkoong Manufacturing Company received a manufacturing contract and funding from the Ministry of Defence to build the four development prototypes initially known as the Changgok-Daesungkhu & Namkoong X-16A, but was known as the ASVT X-16A.

The first prototype made its first conventional flight on 9 December 1965, first hover on 2 January 1966, and first transition on 15 January 1966. The first X-16A was delivered to the Air Force test team in March 1967. During the X-16A ASVT program, a total of 480 hours were flown in 572 flights. The four X-16As were flown by 42 different military and civilian pilots. Tests included carrier operations, simulated rescues, paratroop drops, and low-level cargo extraction. During testing a number of problems were encountered including the crucial design fault in which the turboprop engines were not cross-linked, so the failure of one engine meant the aircraft would crash. Which tragically occurred on April 5 1968 leading to the loss of the aircraft and her crew. It was also revealed that the thrust control was through throttle changes, which were too slow for acceptable height and roll control. The crash nearly led to the cancellation of the project, however in the chaos following the 1967 revolution the program was left in limbo until 1972 when it was resumed with full state support.

File:Tsk-18.png

diagram of a Chk-18

The information learnt with the first four prototypes was critical in V/STOL development. While there was no issues with the initial ASVT X-16A design from a technical standpoint besides the lack of engine coupling. Concerns from the navy regarding the placement of propellers downwards on a confined naval vessel deck could lead to disaster, thus the design was changed from a system that utilized a tilting-propeller system, in which the two engines drove four bladed, contra-rotating propellers pusher propellers, that were capable of being tilted downwards to an angle of up to 90 degrees. The same engines from X-16 were used however the propeller blades were increased from 6.2 m (20.34 ft) diameter to 8 m (26.24 ft) to improve vertical flight profile.

By 1975 a new prototype with a revised tilting-propeller system, the design otherwise shared much with previous X-16A but was given a new designation as the the X-17A. It had the following changes, cross-shafting between the engines, direct propeller pitch control and a revised tilting-propeller system in which the engines remain in place while the rotors and drive shafts tilt upwards to an angle of up to 90 degrees, rather than downwards as was the case with the X-16A, this greatly reduced the risk of the blades coming into contact with personal, especially on naval vessels. The propeller blades were increased from 6.2 m (20.34 ft) diameter to 8 m (26.24 ft). The X-17A made its first conventional flight on 25 November 1976, first hover on 8 January 1977, and first transition on 28 January 1978. The X-17A's were flown by through the same rigorous tests the X-16s went through, it was able to successfully operate in both helicopter and normal aircraft flight modes and smoothly transition between the two. Acceptance testing for the design began in January 1986 with training units within the military, continuing for 36 months. Changes made in the design addressed structural strength, fatigue problems and reduced vibration levels. The production Chk-18 began to enter operational service in limited scale by elite SGRU military forces in 1986, although manufacturing difficulties kept it from appearing in strength until 1990. Experience gained with special forces operations led to the development of the Chk-18KTB and later MLR dedicated types for Special Operations missions.

Design

The Chk-18 is a large multi-purpose twin-engine tiltrotor aircraft. It's the most powerful and technologically advanced transport rotor-craft in the Anikatian military. Powered by two turboprop Daesungkhu & Namkoong DVT-03P-400 engines producing 11,033 kW (14,795 shp) each; in the event of single engine failure, either engine is capable of providing power to both prop rotors. Each engine drives a pair of contra-rotating propellers, a feature unique to this design the tilting-propeller system in which the rotors and drive shafts are able to tilt upwards to an angle of up to 90 degrees while the engines remain in place, for V/STOL operations. To save space on board naval vessels, the wing, rotors and tail fold. It is able to takeoff and land in a conventional way, or operate as a helicopter in take off and landing. On naval vessels it must operates as a helicopter with the nacelles vertical and rotors horizontal. Once airborne, the tilting-propeller system rotate back into the engine nacelles in as little as 12 seconds for horizontal flight, because of these abilities make the Chk-18 is far more fuel efficient than a helicopter and able to operate at higher speeds like a conventional turboprop aircraft. The Chk-18 can be equipped with stub wings at the top of fuselage to carry fuel tanks or various armaments.

Variants

ASVT X-16A

Initial prototype configuration. Only five build, one lost while testing.

ASVT X-17A

Redesigned prototype configuration. Only two build.

Chk-18

Pre-production version used as testbeds, entered service in 1983.

Chk-18T

Initial production for utility transport version.

Chk-18MT

Upgraded version with an upgraded flight/navigation system.

Chk-18K

Naval version military transport.

Chk-18KM

Upgraded naval version with an upgraded flight/navigation system.

Chk-18KPM

Anti-submarine warfare variant.

Chk-18AEW

Airborne electronic warfare variant.

Chk-18GBV

Version used as a gunship or direct air support platform. Airframe modifications add six external wing hard points and two side fuselage hard points for a total of eight, and mounts two 20mm cannons under the belly. Armament combination up to six 250 kg (550 lb) bombs and 4 x 57 mm UR-5P rocket pods or six ATG-4M anti-tank missiles.

Chk-18KTB

Assault transport variant. Features the advanced new avionics systems, glass cockpit and improved engines. Equipped with the in-flight refueling probe, terrain-following radar, color weather map generator, improved weapons capability, and various defensive systems.

Chk-18MLR

Special operations modification of the baseline Tsk-18KTB. Features the advanced new avionics systems, glass cockpit and quieter more efficient engines. In-flight refueling probe, extra wing fuel tanks forward looking infrared sensor, the terrain-following and terrain-avoidance radar, colour weather map generator, auxiliary fuel system, inertial navigation system, along with a projected map display enable the crew to follow terrain contours and avoid obstacles, making low-level penetration possible. It's main mission is to drop off, supply, and pick up special forces behind enemy lines. It also can engage in combat search and rescue missions. Low-level penetration was made possible by a state-of-the-art terrain following radar, as well as infrared sensors that allow the helicopter to operate in bad weather. It was equipped with armor plating.

Chk-18X

Export variant.

Chk-18KXB

Export variant based on the Chk-18KTB.

Chk-18GBX

Export variant based on the Chk-18GBV.

Operators

Current

Anikatia

• Anikatian Navy – Naval Air Arm Approximately 72.
• Anikatian Air Force Approximately 168.

Arthurista

• Commonwealth Army Approximately 84.

Template:Country data Estovnia

• Template:Country data Estovnia Royal Navy – Naval Aviation Corps Approximately 96
• Template:Country data Estovnia Estovnian Army – Army Aviation Corps Approximately 156

Template:Country data Ulthrannia

• Template:Country data Ulthrannia Whitestone Tactical Solutions Approximately 8.

Former operator

Template:Country data Democratic Socialist Republic of Anikatia

• Template:Country data Democratic Socialist Republic of Anikatia Anikatian People's Navy – Anikatian People's Naval Aviation Passed on to successor state.

Specifications (Chk-18)

diagram of a Chk-18MLR

General characteristics

• Crew: 4 Pilot, Copilot, Two flight engineers/specialists
• Capacity: 16,700 kg (8,818 lb) or up to 40 troops (55 with centerline seats installed)
• Length: 20.27 m (66.5 ft) ()
• Wingspan: 17.03 m (55.88 ft) ()
• Height: 5.28 m (17.32 ft) ()
• Empty weight: 23,100 kg (50,927 lb) ()
• Loaded weight: 36,820 kg (81,174 lb) ()
• Max. takeoff weight: 47,800 kg (105,381 lb) (STOL), 46,800 kg (103,176 lb) (VTOL) ()
• Powerplant: 2 × Daesungkhu & Namkoong DVT-03P-400M turboshafts, 11,033 kW (14,795 shp), () each

Performance

• Maximum speed: 675 km/h (364 knots, 419 mph)
• Cruise speed: 587 km/h (317 knots, 365 mph)
• Ferry range: 3,691 km (2,293 mi; 1993 nmi) ()
• Service ceiling: 8,200 m (26,903 ft) ()

Armament
Anti-Submarine: 4 x Torpedoes or 4x Anti-Ship Missiles or 8 x Depth charges.
Attack: 2 x 20mm Cannons, 6 x 250 kg (550 lb) bombs, 4 x 57 mm UR-5P rocket pods or 6 x ATG-4M Anti-Tank Missiles
General: 2 x 7.62mm Machine Guns

See also

• Aircraft of comparable role, configuration and era
  • Changgok Chk-6