Songrim SR-6
| Songrim SR-6 | |
|---|---|
| File:Sunglin SL 6.png Three-side view of the SR-6N | |
| General information | |
| Type | Strike bomber |
| Manufacturer | Songrim Aviation Factory |
| Designer | Sŏng-Lim Aviation Design Bureau |
| Status | In Service |
| History | |
| Manufactured | 1979-2003 |
| Introduction date | 1980 |
The Songrim SR-6 is a supersonic, all-weather strike bomber and interdiction aircraft developed in Menghe. Its notable features include variable-sweep wings, each with swiveling hardpoints, and a side-by-side cockpit. Currently, the main operator of the SR-6 is the Socialist Republic of Menghe, though it has also been exported to other countries such as Qusayn and Ummayah.
Development
During the late 1960s and early 1970s, the Menghe People’s Air Force relied primarily on the Daesŭngri DS-2B for its close air support missions. Though light and maneuverable, the DS-2B suffered from a small payload and a relatively limited range, constraining its effectiveness on the battlefield. It also lacked advanced navigation and radar systems, limiting it to daylight attacks in clear weather. Heavier tactical bombers met some of these requirements, but still lagged behind in others, and were not always appropriate for the CAS role.
Rather than fitting these improvements into the DS-2 airframe, which was deemed too light for the radical changes needed, Air Force High Command decided to procure a new aircraft altogether. The program, initiated in 1973, called for a "Large Tactical Attack Aircraft" with an 8,000-kilogram payload – four times that of the DS-2B.
Initial design attempts were hampered by the contradictory nature of the project requirements, which essentially called for mating a tactical bomber’s range and payload onto an airframe with the speed and performance of a light strike aircraft. The Sŏngrim design team was the first to meet the requirement. Its first proposal followed a delta-wing layout, with two high-power turbojets providing thrust and four smaller "lifting engines" providing additional power for short takeoffs and landings. This proposal never made it past the drawing board, however, as the secondary engines consumed valuable space and payload weight without contributing to in-flight performance.
Unimpressed with these delta-wing designs, the Songrim design team decided to start over with a new "swing-wing" prototype. This effort drew on experience the Daesŭngri design bureau had gained from its DS-5 fighter, which had already been approved for service, and the multiple variable-geometry attack aircraft in service with other nations. In addition to matching the speed, payload, and maneuverability requirements, this format also permitted shorter takeoffs and landings, thereby overcoming one major fault of the DS-2 family. The first variable-sweep prototype passed its trials in 1976, slightly exceeding the design requirements for payload and high-altitude speed. Impressed, the People’s Air Force ordered the aircraft into production as the Sŏngrim SR-6. Full-scale production began in 1977, with deliveries to front-line units beginning in 1980.
Design
Layout
The most central feature of the Songrim SR-6 is its variable-geometry wing arrangement. Adjusted by a hydraulic system in the upper fuselage, the outer wing sections can be set to a leading-edge angle of 71 degrees for supersonic sprints, 17 degrees for takeoff and landing, or 40 degrees for efficient cruising. Long leading-edge slats and double-slotted flaps on the trailing edge allow for a takeoff speed of just 235 kilometers per hour, allowing the SR-6 to be based from shorter fields than previous tactical bombers while retaining a large payload capacity. The tail elevators are all-moving control surfaces, while the rudder follows a conventional trailing-edge design.
Another unique feature of the SR-6 is its side-by-side cockpit, with the pilot sitting on the left and the copilot/WSO sitting on the right. This layout was chosen to give the WSO a wider field of view ahead of the aircraft, important when carrying out the gun and rocket attacks which designers initially considered important to the SR-6’s role. In addition to duplicated flying controls, the WSO station has a targeting scope which can be linked to hardpoint-mounted cameras or, on SR-6N variants, the built-in targeting system. The forward canopy is divided into four sections, unique for aircraft of this size, with two forward-folding hatches just aft of these allowing for entry and exit. Both crew members are provided with zero-zero ejection seats, particularly important given the aircraft’s reliance on low-level flight for ground-attack and interdiction.
Unlike previous Menghe aircraft, the SR-6 also pioneered a slightly different landing gear arrangement. Rather than pairing two wheels along the same axis, the rear two landing gear elements featured paired inline wheels. This arrangement was intended to maximize space for long hardpoint loads such as fuel tanks and large missiles; by folding directly forward and upward into fairings on either side of the intakes, the landing gear left a great deal of space beneath the centerline, and did not interfere with the innermost wing hardpoints. The forward covering for the rear landing gear wells also serves as an airbrake when opened, and can be deployed in flight independent of the side coverings and landing gear to slow the aircraft. The landing gear struts themselves proved simple, sturdy, and rugged, but they also concentrated contact with the ground close on either side of the aircraft’s center of gravity. Combined with the height of the landing gear, intended to leave more room for installing and servicing missiles and bombs, this increased the risk that a landing aircraft could tip left or right on landing.
External Payloads
Total payload for the SR-6 is listed as 8,500 kilograms, though it is possible to carry a payload of up to 9,700 kilograms by taking off with low fuel and refueling from a tanker aircraft once airborne. External payloads are carried on thirteen hardpoints: four under each wing, and five under the fuselage. Six of the eight wing hardpoints are fitted on the variable-geometry sections, and automatically swivel as the wings rotate to maintain a constant orientation in relation to the airflow. Those under the fuselage are arranged in an "X" shape, with two forward, two behind, and one in the center. Both of the innermost wing hardpoints are rated to a maximum weight of 4,000 kilograms each, allowing the SR-6 to carry large air-to-surface missiles.
Payload options were already diverse when the first aircraft entered service, and have only grown in number with subsequent upgrades. Options range from gun-pods and mine dispensers to long-range cruise missiles, with a variety of datalinks, jammers, and reconnaissance sensors available for special-purpose missions. The SR-6 is also compatible with short-range heat-seeking missiles, and often carries one on each of the outermost hardpoints for self-defense, but cannot target active or semi-active radar-guided missiles. Prior to 1989, payload options included nuclear bombs and missiles, making the SR-6 the lightest Menghe aircraft capable of carrying out a nuclear strike. With the introduction of more electronically advanced munitions, the SR-6N has increasingly been used to deliver standoff munitions, though unguided iron bombs remain a large and crucial element of Menghean Army Aviation's arsenal.
Gun Armament
The initial design requirement called for a powerful autocannon capable of engaging light armored vehicles, and Sŏngrim’s prototypes all included this feature. On the SR-6G, this consisted of a BGP-30-2 autocannon in a permanent centerline pod below the fuselage. Although it used the same 30mm electrically-fused cartridge as the KAP-30-2 (later used in the DGJP-230 Jaebŏngtŭl), and shared a gast-principle layout, it was a unique weapon in all other respects, relatively lightweight and compact for use on aircraft. Rate of fire was 3,000 rounds per minute, or 50 rounds per second. The ammunition compartment above the gun carried 400 30mm rounds in a mixed chain of armor-piercing and high-explosive, and could be reloaded through a slot on the underside.
Operational use during the Ummayan Civil War, however, found that the SR-6 was better-suited to standoff payloads and area bombing than strafing attacks. Additionally, pilots found the strike aircraft too clumsy to engage in gun-fights with air-superiority fighters, instead relying on heat-seeking air-to-air missiles and air-superiority escorts. When designing the SR-6N upgraded version, the design team removed the gun and replaced it with an integrated electro-optical targeting system, using the underline bulge and ammunition compartment to store the electronics. If gun-attacks are needed, 30mm and 22mm cannons can still be attached to the hardpoints in external gunpods.
Performance
Thrust is provided by two SRS-72 turbojets, each of which produces 110 kN thrust with afterburner and 78 kN without. Though squared off in its middle section, the rear fuselage gradually curves around the engines and exhaust tubes in an ovoid shape to reduce drag. The SR-6 can exceed Mach 2.4 at high altitude, but in low-level flight it can reach less than half of that; the high-altitude function, though mostly unnecessary for the Army, was included in the design as part of the Navy’s requirement for a long-range strike aircraft. To increase range further, a refueling probe is fitted within the nose. When extended, it protrudes vertically from the section behind the radar set, hooking forward at the end to catch refueling probes.
Electronics
All-weather strike capability was a major part of the SR-6's state requirements, and featured prominently in the design. An all-new navigation suite allows it to fly at night and under low-visibility conditions, and the addition of a Satellite Navigation system on the SR-6N further improved this capability. The surface-search radar in the nose is designed to pick up large ground targets, and a smaller radio antenna on the underside allows the aircraft to automatically maintain a low but safe altitude over terrain during low-level penetration flights.
The SR-6N variant built on these features considerably. One core upgrade was the addition of the new "Ranmu-1" targeting suite, installed in place of the centerline gun. This system consisted of a variable-zoom infrared camera and laser designator in a rotating "turret," allowing the WSO to observe and track ground targets independently of the aircraft’s bearing and angle of attack. Also included in the "Ranmu-1" system was a variable-frequency datalink antenna, capable of sending course updates to certain air-to-ground missiles. Both of these features eliminated the need for most external targeting and datalink pods, freeing up more space for other munitions. Other changes in the SR-6N included the addition of a radar-warning and jamming pod at the top of the tail fin and the installation of more advanced radar-warning antennas in the wing roots.
No variant of the SR-6 is capable of carrying or targeting radar-guided air-to-air missiles. The nose radar is only a surface-search set, not optimized for tracking and guidance against air targets, and the aircraft itself is not built for prolonged air-to-air combat. Its successor, the SR-8, has greater maneuverability as well as the ability to carry radar-guided AAMs.
Variants
- Songrim SR-6G: original service variant introduced in 1998. Armed with a built-in 30mm cannon, but fitted with older electronics. Most have been withdrawn from Menghean service, but they remain common in less-wealthy countries like Qusayn.
- Songrim SR-6N: upgraded Army variant first seen in 2008. Features a number of electronics upgrades, including a larger radar set and improved electronic warfare countermeasures. The 30mm cannon, originally mounted under the hull, was removed to make room for a built-in electro-optical system and laser designator.
- Songrim SR-6HG: purpose-designed variant for the Menghean Navy’s land-based wings, first entering service in 1982. Compared with the SR-6N, it features a wider nose with a more powerful surface-search radar.
- Songrim SR-6HM (Hanggong-Muham): carrier-based version, based on a 1979 proposal but only put into service in 1999. In addition to the electronics upgrades carried over from the SR-6N, it was fitted with a tailhook and reinforced landing gear, and made use of corrosion-resistant materials. These required high sacrifices in other areas, however, and as of 2014 all SR-6SKs have been removed from service in favor of the SR-8SK.
Service
Menghe
The first operational aircraft entered service with the Menghe People’s Air Force on June 15, 1980, as the Songrim SR-6G. The SR-6HG followed in 1982, assigned to the Navy’s coastal defense units. The Songrim SR-8 is intended as a replacement, but for the time being the SR-6N is being kept in service even as the SR-6G is withdrawn. It is estimated that roughly 1,200 SR-6 strike aircraft of all variants are currently in Menghean service.
The Menghean Navy also operates several wings of SR-6HGs, the navalized variant with a more powerful surface-search radar set in the nose. This variant can be used to carry anti-ship weapons ranging from the enormously heavy YDH-23 to the lighter YDH-28 and YDJ-82. In order to carry the full strike set of two YDH-23s and a large centerline fuel tank, the SR-6HG must launch with its internal tanks almost empty and refuel from a tanker aircraft once airborne, allowing it to launch below its minimum takeoff weight but exceed that level in flight.
Qusayn
Qusayn purchased 38 SR-6G attack aircraft from the Democratic People’s Republic of Menghe in 1985. From 1987 to 1989, one squadron equipped with SR-6Gs took part in the bombing of alleged secessionist strongholds in the south, a relatively low-scale operation compared to the borderline civil war fought over collectivization in the late 1970s. During the fighting, two SR-6Gs were damaged beyond repair by shoulder-launched heat-seeking missiles and one more was downed by anti-aircraft fire. The Menghean government refused to provide parts or technicians for repair until the Qusayni government, then still led by President Jamal Pasha, ended its bombing attacks on villages.
Specifications
General Characteristics
- Crew: 2 (pilot, copilot/WSO)
- Length: 22.64 meters overall
- Wingspan, extended: 20.14 meters
- Wingspan, swept:10.50 meters
- Height: 6.18 meters (on the ground, gear out)
- Wing Area: 61.04 square meters
- Empty Weight: 22,600 kg (49,800 lbs)
- Loaded Weight: 39,100 kg (86,200 lbs)
- Maximum Takeoff Weight: 45,150 kg (99,500 lbs)
- Powerplant: 2x SLS-72 turbojet
- Dry Thrust: 78 kN (17540 lbs-force) each
- Thrust with Afterburner: 110 kN (24728 lbs-force) each
- Fuel Capacity: 13,100 kg (28,880 lbs)
Performance
- Maximum Speed at Sea Level: Mach 1.1 (1348 km/h)
- Maximum Speed at High Altitude: Mach 2.4 (2812 km/h)
- Combat Radius: 974 km with 6000-kg payload in hi-lo-hi mission
- Ferry Range: 6,600km with external drop tanks
- Service Ceiling: 17,200 meters
- Rate of Climb: 155 meters per second
- Wing Loading: 370 kg/m2
- Thrust-to-Weight Ratio: 0.57
Armament
- Guns: 1x FZP-30-2 autocannon (SR-6G variant only)
- Payload: 8,500 kg on 13 external hardpoints
- 2x 4,000-kg hardpoint (wing root)
- 1x 2,000-kg hardpoint (hull centerline)
- 8x 1,000-kg hardpoint (hull sides and variable wing inner sections)
- 2x 500-kg hardpoint (variable wing outermost hardpoint)