Demirkan-Yŏng'an DY-11

Demirkan-Yŏng'an DY-11 Galmaegi
Role	carrier-based utility aircraft
National origin	Menghe
Manufacturer	Demirkan-Yŏng'an Aircraft Corporation
First flight	2006
Introduction	2010
Primary user	Menghean Navy
Produced	2008-present
Number built	27

The Demirkan-Yŏng'an DY-11 (Formal designation: 데밀칸 영안 11호 다목적 함재기 / 데밀칸永安一一號多目的艦載機, Demilkan Yŏng'an iril-ho damogjŏk hamjaegi, "Demirkan-Yŏng'an No.11 multipurpose carrier plane;" Short designation 데영 11호 Deyŏng iril-ho "DY-11"), officially nicknamed Galmaegi (갈매기, "Seagull"), is a carrier-based twin-engine utility aircraft developed in Menghe during the 2000s. It has dedicated variants for airborne early warning, anti-submarine warfare, aerial refueling, and carrier onboard delivery.

The DY-11 is included in the carrier air wings of Menghe's three Sibiwŏl Hyŏgmyŏng class aircraft carriers, though only in its ASW and AEW variants. Menghean COD aircraft are typically based from land ports and leave the carrier after dropping off supplies. Menghe also exports a land-based DS-11 family, which includes a low-cost anti-surface-warfare variant.

Development

Menghean interest in a subsonic, carrier-based ASW platform stretches back to at least the late 1970s, when the two Haebang-class carriers were under construction. The Yŏng'an Aircraft Design Bureau conducted several design studies, but by the launch of Haebang in 1982 no working prototype existed, and both carriers took on an air defense complement of DS-5HG fighters. The chaos of the 1980s further delayed design work, especially after Menghe's priorities shifted to shore-based attacks against Dayashina rather than blue-water force projection.

Interest in carrier-based utility aircraft resumed in 1996 when Menghe laid down its first nuclear-powered aircraft carrier, the Sibiwŏl Hyŏgmyŏng. The Menghean Navy's long-term operational requirement called for a single airframe which would serve ASW, AEW, tanker, and COD roles, with room for expansion to other duties.

Yŏng'an initially made little progress, as it had laid off many of its leading designers following an agreement to end production of the Yŏng'an Y-4 bomber. In an effort to bring in more expertise, the Ministry of National Defense approved a merger between the reorganized Yŏng'an Aircraft Corporation and the Demirkan Aviation Group, a recently formed public-private corporation specializing in light civilian aircraft and turbine parts.

The first test flights with a cargo-variant airframe were conducted in 2006, and they left Navy evaluators impressed with the type's characteristics. Key contributions from Demirkan's team included upturned wingtips and more modern turbofan models, both of which resulted in increased fuel efficiency and longer patrol ranges. Production-made DY-11 aircraft were already leaving the assembly lines in mid-2009, but due to delays in commissioning, the carrier Sibiwŏl Hyŏgmyŏng was not ready to take them on until early 2010.

Description

All variants of the DY-11 share a common airframe which was designed to balance the demands of its upcoming composite roles. The wing has a high aspect ratio and a modest sweep, with upturned wingtips to counteract drag-inducing vortices. Power comes from two Demirkan D130 turbofans, each developing 45 kilonewtons of thrust. This arrangement, which Demirkan subjected to extensive wind tunnel testing and simulation, was found to maximize efficiency at a cruise speed of 650 kilometers per hour. A large fuel load of 6,000 kilograms allows for long travel distances and patrol times.

In an interesting departure from other carrier aircraft, the turbines were mounted on the body of the aircraft, behind the wings and forward of the tail. Demirkan advocated for this layout because it left more space under the wings for missiles, torpedoes, fuel tanks, and other payload options. This did necessitate a cruciform tail to keep the exhaust from the engines below the horizontal stabilizer, but total height remained under 7 meters, the hangar height on the Sibiwŏl Hyŏgmyŏng class.

To leave space for a radome above the fuselage, the designers opted for wings that fold backward along the fuselage, starting three meters away from each side. The wings fold with the lower surface facing outward, the flaps and ailerons facing downward, and the upturned wingtip facing inward, an arrangement Demirkan believed to be the most space-efficient. There is still enough space within the enclosed area to conduct maintenance on the turbines, including full turbine replacement, which requires the help of an overhead crane.

Variants

Carrier Onboard Delivery

The DY-11HS (Hwamul Susonggi) is a cargo variant used for delivering supplies to aircraft carriers at sea. Because Menghean aircraft carriers tend to operate on relatively short patrols closer to home waters, they take on most supplies while docked in port, leaving COD as a supplemental role. Thus DY-11HS squadrons are usually stationed on land bases and sent to carriers as needed, rather than being part of the carrier air wing.

In light of its less central role, the DY-11HS lacks a rear ramp, instead relying on a sliding door on the left-hand side of the fuselage to onload and offload cargo. It has a payload of 4,000 kilograms, and a crew of two (pilot and copilot) with the space for the rear seats used for storage. Though unable to carry bulk items such as replacement engines, it can deliver mail, spare parts, and stretchers with wounded personnel.

Anti-Submarine Warfare

The DY-11DJ (Dae-jamsuham) is a dedicated variant for anti-submarine warfare. It has a four-person crew, with the two additional electronics operators seated behind the pilot and copilot. In addition to a more capable surface-search radar, it carries a magnetic anomaly detector in a retractable tailboom, and has fifty ejector chutes for sonobuoys with an onboard computer to monitor their drift remotely. It also carries chaff and flare dispensers to defend against enemy aircraft and surface-launched missiles.

Anti-submarine weaponry on the DY-11DJ can be carried on four external hardpoints under the inner wing sections and four internal hardpoints in a bomb bay in the fuselage. Payload options include YDH-26 anti-ship missiles, lightweight homing torpedoes, and standoff anti-submarine weapons. The DY-11DJ can also be used in the anti-surface role, carrying four YDH-26 missiles, and the mine warfare role, carrying eight cylindrical mines (generally bottom-influence rising or homing mines).

Airborne early warning

This variant, designated DY-11GJ (Gongjung Jŏnpa), is an airborne radar platform for airborne early warning duties. It has a crew of 4, with two radar officers seated behind the pilot and copilot, and is capable of datalinking radar contacts to surface ships, friendly aircraft, and certain missiles.

The radar model used is designated GJ-200, and is the same type used by front-line Army AEW platforms. It consists of a narrow rectangular platform with mirrored active electronically scanned array antennas, providing a 150-degree field of view to either side. The nose-mounted radar covers the forward 30-degree blind spot, and a small radome in the tail covers the aft 30-degree blind spot, but neither of these has good tracking capability, so course adjustments would be used to provide a full scan. The GJ-200 radar has a claimed range of 300 kilometers in a dense electronic warfare environment and an instrumented range of 500 kilometers, and it can detect surface targets as well as airborne ones.

Concept art for the DY-11GJ produced in 2006 showed it carrying four YGG-7 Hwasal missiles on external pylons, a feature repeated on a model at a defense expo in 2008. This capability appears to be absent on production-version DY-11GJs, and since the type entered service none have been seen fitted with air-to-air missiles. Such an omission may reflect the Navy's judgment that the DY-11's low speed would limit missiles' kinetic energy, and a preference for retreating under threat rather than attempting to engage in beyond-visual-range combat.

Aerial refueling

The original DY-11 design requirement called for a carrier-based tanker aircraft with the ability to conduct probe-and-drogue refueling, extending the range and patrol time of naval combat aircraft. Transfer fuel capacity was to be between 8,000 and 10,000 kilograms, using tanks inside the fuselage. Ultimately, in the interest of saving space on board the carrier, the dedicated tanker idea was rejected in favor of letting other DS-9 and DY-11 aircraft conduct aerial refueling with buddy tanks.

Electronic warfare

This was a proposed variant, called DY-11JJ (Jŏnjajŏn), which would carry both active and passive electronic warfare systems to gather information on enemy communications and jam enemy radar and radio systems. Like the tanker concept, it was pulled from the Navy's requirements before any flying prototypes were produced in a bid to save hangar space. To fill the lost role, the DY-11GJ was given some signal interception equipment, and dedicated jamming pods were developed for the DS-9.

VIP Transport

A single DY-11YI (Yoin) serves as a VIP transport for the Menghean Navy. It is based on the DY-11HS cargo variant airframe, but with a refitted interior that includes interior wall paneling, upholstered seating, and noise-cancelling speakers near the engines. In addition to its pilot and copilot, it has interior seating for six people.

The sole VIP airframe, bearing the number 221, is stationed in Sunju. It is used to transport high-ranking officers, such as the High Admiral of the Menghean Navy and the Supreme Commander of the Armed Forces (currently Choe Sŭng-min), on inspection visits to carriers at sea.

Specifications (DY-11DJ ASW)

General characteristics

• Crew: 4
• Length: 16.23 m (53 ft 3 in)
• Wingspan:
  
  • Extended: 20.32 m (66 ft 8 in)
  • Folded: 8.41 m (27 ft 7 in)
• Height: 5.98 m (19 ft 7 in)
• Wing area: 60.64 m² (652.7 ft²)
• Empty weight: 12,570 kg (27,710 lb)
• Loaded weight: 19,210 kg (42,350 lb)
• Max. takeoff weight: 25,400 kg (56,000 lb)
• Powerplant: 2 × Demirkan D130 turbofan, 45.1 kN (10,140 lbf) each

Performance

• Maximum speed: 830 km/h (448 kts)
• Cruise speed: 650 km/h (351 kts)
• Combat radius: 1100 km (594 nautical miles) on internal fuel
• Ferry range: 3,600 km (1,940 miles) with two external tanks
• Service ceiling: 13,400 m (43,960 ft)
• Wing loading: 316.8 kg/m² (64.88 lb/ft²)
• Thrust/weight: 0.48

Armament

• Hardpoints: 4 hardpoints with a capacity of 4,000 kg and provisions to carry combinations of:
  • Missiles: YDH-26
  • Bombs: Bombs up to 1000 kg (2,200 lbs)
  • Other:
    
    • 40cm homing torpedo
    • Buddy refueling tank