Daesŭngri DS-9

Daesŭngri DS-9
DS-9G, the initial Army production model, and DS-9N, its twin-seater variant.
Role	Multirole combat aircraft
National origin	Menghe
Manufacturer	Daesŭngri Aircraft Corporation
First flight	1998
Introduction	2002
Primary user	Menghean Army
Produced	2002-present
Number built	925 (2019)

The Daesŭngri DS-9 (Formal designation: 대승리 9호 전투기 / 大勝利九號戰鬪機, Daesŭngri Gu-ho Jŏntugi, "Daesŭngri No.9 Fighter;" Short designation 대승-9 Daesŭng-gu "Daesŭng-9"), officially nicknamed Biho (비호/飛虎, "Flying Tiger") is a lightweight multirole combat aircraft developed and produced by the Daesŭngri Aircraft Corporation in Menghe.

With its single-engine powerplant, close coupled canards, and fly-by-wire controls, the Biho is a highly maneuverable fighter, aerodynamically optimized for low-level flying and close-range dogfighting. Its rugged undercarriage and thrust reversal system make it ideal for operating off of short, damaged, or unpaved runways, allowing it to be dispersed around the front lines in response to enemy attacks. It also retains a respectable 6,000-kg payload for strike missions and an AN/APG-73 derived radar for beyond-visual-range combat. Subsequent variants of the DS-9 feature improved electronics, more powerful engines, thrust vectoring, and reduced-RCS materials and features. There are also carrier-based variants of the DS-9, with folding wings, revised landing gear, a refueling probe, and other changes.

The DS-9 is one of the most widely produced fighter aircraft in Septentrion, with over 2,000 airframes manufactured as of 2020. It is the most numerous aircraft in active service with the Menghean Army and the Menghean Navy, serving in both branches' aviation wings alongside the Songrim SR-8 in a hi-lo mix. The DS-9 has also been widely exported abroad, serving in all Namhae Front member states and several other countries around the globe.

Development

DS-08

The origins of the DS-9 can be traced back to the early 1980s, when the Daesŭngri aviation design bureau began preliminary design work on a fighter designated "DS-08." This was a twin-engine design using the Songrim SR-7's Gokchŏn Gi-15 turbojets in a lighter, shorter-ranged airframe. The resulting design would have a high thrust-to-weight ratio and good agility, making it more suitable for air-to-air combat than the SR-7, which was a dedicated interceptor. Tailed delta and canard delta configurations were both considered, the latter drawing on experience from failed SR-7 prototypes. The canard-delta proposal was deemed more maneuverable on paper, and work on a prototype airframe began in 1984, but the political turmoil and economic hardship of the Ryŏ Ho-jun era stalled development, and no flight tests were conducted.

After the Decembrist Revolution, the stringent export restrictions imposed on Menghe in response to its nuclear weapons program were relaxed, and the national economy began to recover. Daesŭngri resumed work on the DS-08 project, this time proposing a single-engine design with the Gokchŏn Gi-17 turbojet, still in the early stages of development.

MoND Light Fighter Project

Further opportunities for improvement came in 1992, when the Ministry of National Defense issued a requirement for a Fourth-generation jet fighter. While Songrim looked into licensing a ready-made foreign aircraft, Daesŭngri responded by pouring more resources into its existing program, in the hopes of producing a working prototype by 1994. The MoND initially sought to pit the two programs against one another, but Choe Sŭng-min suggested that both go forward simultaneously, allowing domestic manufacturers to gain experience in aircraft design. It was also anticipated that Daesŭngri's plane would be cheaper and more reliable than a foreign aircraft, making it a good fallback option if the SR-8 program failed.

A stroke of luck for the DS-08 program came in 1993, when Ostland shipped a single OVAG Greif light fighter to Menghe for evaluation. Daesŭngri's engineers feared the new fighter would outperform the still-struggling DS-08, so they pushed the Army to evaluate it in the same competition as the Super-Mirage, Or-27, and Iolar, where it quickly lost in the range and payload assessments. The Greif was then flown to Daedong, where it was disassembled, reassembled, and thoroughly inspected. The airframe proved to be a treasure trove of information for the Daesŭngri team, which did not copy the Greif entirely, but did draw on aspects of its design to address persistent issues with the prototype.

By the mid-1990s, the Menghean Navy was also expressing interest in Daesŭngri's project. The nuclear aircraft carrier Sibiwŏl Hyŏgmyŏng was laid down in 1996 with the understanding that it would eventually support a new-generation fighter, and while the Or-27 had a naval variant, the Iolar did not. To meet the Navy's request, Daesŭngri began simultaneous work on a carrier-capable version of the new fighter, modifying the basic design so that naval compromises could be easily integrated.

The Gi-17 turbojet proved to be a severe source of problems, failing to start entirely on some ground tests and performing well below target when it did run. Menghe's political leadership had hoped for an entirely domestic aircraft, but before long the engine-related delays were becoming unacceptable. In November 1996, Daesŭngri's design team decided to drop the problem-ridden Gi-17 and instead modify the airframe to accept the Glasic TF-530 turbojet, which Songrim was already licensing for the Songrim SR-8. Prototype DS-09-02, carrying the new engine, made its first flight on April 3, 1998, impressing Army evaluators with its performance.

Testing and Improvement

The initial DS-08 project from the 1980s called for either one or two 23mm revolver cannons of an as-yet-unspecified design. By the early 1990s, the Army was calling for a 27mm or 30mm weapon, which could be used against the side and rear armor of enemy tanks. For some time, Daesŭngri's design team was divided on the issue, with old cadres insisting on a 30mm weapon to keep capability constant over the SR-3 and DS-5D and new staff favoring the minimal weight and higher rate-of-fire of a small-caliber weapon. DS-09-01, the first prototype, carried a Rajian 27mm revolver cannon, but it never took off due to problems with the Gi-27 engine.

The first two prototypes carried the AN/APG-67B radar with an enlarged antenna and increased power, the same model carried by late variants of the Daesŭngri DS-5. This was intended as a placeholder until newer radar systems were approved for export. Initially Daesŭngri planned to use the Rajian AN/APG-68 radar, carried by the Jalohaukat fighter, and in 1997 a single AN/APG-68 was installed in a modified DS-5. Tests with this airframe apparently concluded that the AN/APG-68 was not as effective as its marketers had claimed, and its wide, flat antenna shape was not optimal for the DS-9's side-intake configuration.

Tír Glas intervened by authorizing sales of the AN/APG-73, which was more capable and made better use of the space in the prototype's nose. The AN/APG-73 also shared parts and programming commonality with the AN/APG-70 used on the SR-8, which was already entering production. The second fully operational prototype, DS-09-03, took to the air in February 1999, and impressed pilots with its radar's capability. Its slightly redesigned nose also housed a Glasic 23mm revolver cannon; the air-to-air and air-to-ground factions had settled on the compromise that 30mm weapons could be mounted on the hardpoints in gun pods.

Meanwhile, development in other areas stalled over reliability problems. The previous flyable prototype crashed in October 1998, and though the pilot was able to safely eject, the airframe had to be written off. Subsequent investigation attributed the crash to problems with the fly-by-wire control system. Adjustments were applied to the DS-09-03, but the lack of a flyable test airframe slowed down approval, and concerns over safety added new delays. It soon became apparent that the original goal of mass production before the end of 2000 was overly optimistic.

Production

After two more airframes had made a rigorous demonstration of reliability, the Ministry of National Defense approved the design for mass production, granting it the official designation DS-9. Three publicity names were considered: Biho (Flying Tiger), Bŏngae (Lightning), and Taepung (Typhoon). In the end, Biho won out, while Bŏngae was used for the GH-32 helicopter and Taepung was used for a rocket artillery system.

The Army leadership decided to procure the DS-9 alongside the SR-8 in a 3:1 ratio, as it was cheaper and more reliable but also less effective. The Navy received its first delivery of DS-9MNs in 2006, but did not order land-based Bihos until 2009.

Initial production took place at Daesŭngri's main assembly center in Daedong, which rolled out its last DS-5M in 1999. As with the SR-8, it was agreed that the first 60 engines would be delivered from Banbha in knocked-down assembly kits, and subsequent engines would be built entirely in Menghe, as the Donghae 74/124.

Navalization

The development of the navalized Biho variants was a source of major contention within the Menghean Navy. Operational trials with the DS-5M variants on the Haebang in the early 1990s revealed a number of drawbacks with the fighter, which was not properly adapted to maritime conditions and suffered reliability problems as a result. The DS-5M also fell short of the Navy's mission requirements due to its short combat radius and limited payload. Many officers in the Navy's upper ranks feared that they would suffer the same problems if they relied on another navalized Army light fighter as the successor model, and argued for a fully independent carrier fighter program.

Unfortunately, during the same period, the Menghean Armed Forces were working under severe budgetary constraints. As part of its focus on economic growth, the Menghean government made steep military budget cuts after the Decembrist Revolution, and the real value of the Naval budget declined in the late 1990s due to a monetary policy that tolerated moderately high inflation. Under these circumstances, the Ministry of National Defense was unwilling to finance a second, independent light fighter program, as any money allocated to the project would require cuts elsewhere. The MoND was also generally favorable to the Army in Army-Navy political disputes, as most of its higher staff came from Army posts and Choe Sŭng-min himself was a former Army officer.

The Navy's options were also limited by more practical concerns. Because the recently-commissioned Haebang would remain in service for another thirty to forty years, the new fighter would have to be reverse-compatible with her cramped facilities. The forward inboard elevator, which measured just 8.84 meters across, was a particularly severe bottleneck, as practical sortie rates would fall off dramatically if aircraft could only enter and exit the hangar one at a time on the aft outboard elevator. New carrier aircraft would also have to be capable of taking off from the Haebang's forward ski-jump, which had a run-up distance of 85 meters from the nosewheel position to the lip of the flight deck and ended at a modest angle of 4 degrees.

For several years, the Navy's design staff urgently searched for foreign aircraft which they could import or license, but the options were limited. The F-16N, Septentrion's most widely-used carrier fighter, was too wide to fit through the forward elevator and was not rated for ski-jump takeoffs. The Navy also considered the GIA Goshawk, a high-performing STOVL fighter, and even drew up a few draft proposals for STOVL light carriers. Banbha, however, blocked exports of the Goshawk over human rights concerns and concerns over the newness of the Goshawk's technology. Letnia aggressively lobbied to secure a deal for the joint design of a navalized MiG-29; but because Mikoyan had no prior experience designing carrier aircraft, Daesŭngri would have to handle all navalization work while also replacing the radar and avionics with Menghean systems, nearly matching the cost of a newly-developed airframe. Ostland offered a navalized version of the JAS 39 Gripen, which faced the same problems. Domestically, Songrim conducted initial design work on a navalized SR-8, designated SR-8M, but its size and weight would have entirely restricted it to future CATOBAR carrier classes and nothing beyond a 1/8 scale model was produced. Staunch opponents of a joint Army-Navy development process pushed for a series of increasingly marginal options, including modified lead-in fighter trainers and licensed last-generation aircraft from foreign navies, but many of these were inferior even to the DS-9 when measured against the Navy's mission requirements. The MoND's General Directorate for Procurement, which had the final say in all major development programs, stated that it would not give the green light to any alternative aircraft unless the Navy demonstrated that it would satisfy program requirements better than the DS-9 prototype to a degree which justified any increases in development cost, a clear signal that the Army-dominated institution was impatient with the Navy's efforts to secure a separate program.

Faced with growing pressure from the MoND and mounting problems with the DS-5, the Navy's upper leadership eventually conceded that a navalized version of the DS-9 would be the least bad practical option. As a result of reduced input from the Navy during the separate procurement debate, the Army was able to exert greater influence on the design of the DS-9, and shaped the default G/N model to suit its priorities: short-field operation, high ruggedness, and a moderate emphasis on visual-range engagements, with reduced emphasis on combat radius and radar search range.

Originally, the Navy had planned to fully convert the Haebang's air wing to DS-9s during the ship's mid-life overhaul in the early 2000s. But because of delays in developing the naval variant, the Haebangwent to sea in 2004 with her original complement of DS-5MG and MN fighters.

Design characteristics

Airframe

Modeled after an amended version of Daesŭngri's fighter design doctrine, the DS-9 Biho is a lightweight multirole designed for dogfighting combat at relatively low altitudes and relatively close ranges. It uses a delta wing design with a dog-tooth leading edge and close coupled canards on the engine intakes, with all changes carefully tailored to maximize aerodynamic performance at low altitudes. The airframe is designed to be inherently unstable to allow rapid changes in roll and pitch, with a fly-by-wire system to maintain stability in level flight. If the onboard computer detects that the pilot is unconscious or has lost control of the aircraft, it automatically recovers into a level, slightly climbing trajectory at full military thrust.

In 2002 a DS-9 prototype successfully entered an 80-degree angle of attack on agility trials and recovered, making it one of a handful of aircraft able to conduct the Pugachev's Cobra. Menghean pilot training officially discourages using this maneuver in combat, as it bleeds energy and comes with a risk of losing control, but DS-9 aircraft have performed it in airshows.

One of the main requirements of the DS-9's design was that the aircraft be able to operate from short, damaged, or improvised runways. The close-coupled canards and fly-by-wire system help the pilot retain control of the aircraft at low speeds and high angles of attack, and on "D/R" models the radar can map out the runway during approach to identify bomb-damaged patches and plot an optimal landing course. The landing gear struts are very sturdy, designed to cushion the aircraft during a high rate of descent and withstand rolling on a rough surface.

Army models come with bucket-type thrust reversers on either side of the rear fuselage, and all models have large airbrakes on the rear fuselage. The canards can also be pointed sharply downward to serve as additional airbrakes. In service, DS-9s would have to operate off 800-meter runways if dispersed, though prototypes were recorded making landings as short as 400 meters.

Performance

The base powerplant consists of a single TF-530 turbojet, with 73.8 kN thrust at military power and 124.5 kN thrust with afterburner. This is a close relative of the turbojet used on the Songrim SR-8G, with plumbing and supports modified for a single-engine mounting. Thrust-to-weight ratio at loaded weight is 0.9, but this rises to 1.12 once half the internal fuel has been exhausted, giving the Biho good climbing and acceleration characteristics. Likewise, constructive interference between the canards and wing surfaces results in better maneuverability than the wing loading figure would suggest on paper.

Internal fuel capacity is 4,800 kilograms on single-seat variants and 4,600 kilograms on twin-seat variants. This can be augmented with two under-wing 1200kg and one centerline 750kg drop tanks, increasing total fuel storage to 7950 or 7750 kilograms. Land-based models have a port on the upper fuselage spine for flying boom refueling, the standard Menghe adopted with the introduction of the SR-8. Carrier-based models, and some export models, have a fixed, non-retractable refueling probe on the right side of the nose.

Sensors

The main radar on the Biho is the AN/APG-73. This system has a number of data bus components in common with the SR-8's AN/APG-70, allowing commonality in production and maintenance. In search-while-track mode, the radar can track up to 10 targets, display up to 8, and guide active-seeker missiles toward 4. Resolution, resistance to jamming, and ability to distinguish multiple nearby targets are greatly improved over the AN/APG-67, and performance is superior to the AN/APG-68 considered in development. In ground-search mode it can produce high-resolution returns for 3D reconnaissance mapping and terrain contour matching. Menghean sources claim the Biho can identify a fighter-size target from 120 kilometers away, though as in Tír Glas, the actual characteristics of the radar are classified.

Above the nose and offset to the left, the Biho carries the same IRST sensor as the SR-8. This has an air-search mode capable of tracking an enemy fighter or missile's warm skin against the non-reflective background sky, and a ground-search mode capable of locating ships or vehicles. It can also plot a wide-view infrared image onto the heads-up display, allowing the pilot to see the terrain up ahead when conducting a low-level flight at night or in bad weather.

Another feature borrowed from the SR-8 is integral terrain-following capability, achieved with a radio altimeter and a special radar mode. Both of these sensors can maintain a vertical angle to the ground through up to 45 degrees of bank and anticipate curved trajectories, allowing the Biho to conduct sharp turns without losing its terrain-following solution. This capability eliminates the need for a separate under-fuselage terrain-following pod, like the AN/AAQ-13.

In combination with the IRST's imaging feature, the modified AN/APG-73 radar can support assisted landings. In this mode, the radar maps out the approaching runway to identify rough or damaged sections and calculates the optimum trajectory for a safe landing. It then feeds course markers to the heads-up display, and can control the throttle directly in assisted autopilot mode. This allows the DS-9 to use shorter runways by making the greatest use of the available tarmac, and is also valuable when landing in fog or total darkness.

ECM antennas mounted on the wingtips, vertical stabilizer, and nose side-bulges provide passive radar warning alerts to the pilot, and a limited ability to jam incoming missiles. Jamming capability was improved on the DS-9G/N/MG/MN-1 and on the DS-9D/R. When operating in an area with high SAM threats, the DS-9 can be fitted with an external jamming pod, either under one wing or in place of the Maenun targeting pod.

Avionics

The DS-9's electronics are based on the sensor fusion principle, with data from multiple systems fed into a single central computer. A datalink allows the plane to receive flight path and targeting information from other platforms, including airborne early warning platforms, land-based radars, and other combat aircraft. The entire system is modular in design, allowing easy replacement of modules and programming sections for mid-life upgrades, and 40% of computing capacity was reportedly left unused in early models to allow room for growth. System data can be continuously recorded during a mission and offloaded after landing, a useful feature for training, debriefing, and troubleshooting.

Information from the sensors and avionics is presented on three multi-function liquid-crystal displays, part of a glass cockpit system intended to simplify operation and presentation. A reflective heads-up display in front of the pilot provides targeting and course information, as well as airspeed, altitude, and other indicators. All displays can be managed with HOTAS controls, and on the DS-9D/R some non-combat functions can be activated by voice command.

Early models supported the Shchel-3UM helmet-mounted display, which allowed pilots to fire the YGG-5 Dando at targets far off the plane's pointing direction. After 2016, DS-9s were integrated with the Keikō helmet-mounted display, which can also project sensor data onto the pilot's field of view for greatly improved situational awareness. Refitted Keikō-capable models were the refit iterative designator "2" (DS-9G2/N2 for early Army, HG2/HN2 for Navy), and all "D/R" variants were built with wired-in Keikō integration.

On two-seater N, HN, and R variants, the rear WSO has four LCD screens and a fully duplicated set of flight controls, allowing recovery if the pilot is incapacitated. The two display systems can show different output at once, allowing the pilot to focus on flying the aircraft while the WSO watches video feed from a targeting pod or TV-guided bomb or missile. Either crew member can also relay screen output to the other, or keep screens synced in regular flight.

Armament

The "G" and "N" variants of the Biho, as well as their carrier-based cousins, have a total of ten external hardpoints. These are divided between one on each wingtip, three under each wing, one centered under the fuselage, and one under the right-side intake. The latter is used to mount a targeting pod for guided air-to-ground munitions, usually PDL-CT or the smaller, newer Maenun.

Early service versions of the Biho were designed for compatibility with the YGG-7 Hwasal air-to-air missile, which was under development but had not yet entered service. Other air-to-air munitions include the YGG-5 Dando and the YGG-6 Skybolt, which was later discontinued. It would later be adapted for compatibility with the YGG-8 medium-range infrared homing missile and the YGG-110 Chŏn Chang.

With seven air-to-ground-compatible hardpoints and a payload of 6,000 kilograms, the DS-9 can take on a wide variety of ground-attack missions, including anti-shipping strikes. The bomb trajectory predictive computer, based on a Sieuxerrian design, allows for accurate delivery of unguided bombs if a targeting pod is not fitted. The fighter can even be equipped with camera and signals intelligence pods, turning it into a reconnaissance platform, or passive EW and jamming pods, turning it into a SEAD platform.

Close-range armament consists of a single 23mm revolver cannon, in the lower-left "cheek" of the fuselage. It has a rate of fire of 1,700 rounds per minute, with 220 rounds stored. As on the SR-8, this weapon is formally designated "JP-24/3" in Menghe, and its rounds are designated as 24mm ammunition. This is done to avoid confusion with the shorter, smaller 23mm cartridge used by earlier Menghean aircraft.

Reliability

The Menghean Army demanded high reliability of the DS-9 during its design process, as it has done for all of its previous aircraft models. The single-engine powerplant complemented these concerns, as a DS-9 would be unable to return home at half power if it suffered an engine failure. Daesŭngri's careful attention to reliability concerns resulted in a surprisingly rugged design with good maintenance requirements.

Many of the onboard electronics systems are modular in design, and can be easily replaced in the field, either for repair or upgrading. A built-in system health program alerts ground crews to any electronic or physical components in need of replacement. The fly-by-wire system is quadruple-redundant, as are some other electronic systems, to allow continued operation in the case of a failure. Careful attention to quality control along the supply chain also led to major strides in mean-time-between-failures from the DS-5 to the DS-9, with continued improvements in part quality over the course of the 2000s and 2010s.

Like the modified SR-8, the DS-9 includes folding filter grills just inside the intakes, though they are attached to the outer sides of the intake walls rather than the floors. These swing across the intakes during takeoff and landing to prevent ingestion of rocks, debris, and other loose objects when landing. In flight, they fold flush with the intake walls, allowing full airflow to the engines. This feature is not present on Navy variants, which deleted it to counterbalance the added weight of the tailhook and reinforced landing gear.

As a result of this emphasis on reliability, the Biho can operate off of damaged airfields, unpaved airfields, and straight sections of highway, where runway quality is poor and available logistics are sparse. With the help of a skilled ground crew, a DS-9G with an air-to-air loadout can land, refuel, and re-arm in under 15 minutes, allowing for fast turnaround times on defensive air patrol missions.

Variants

Since the first orders were placed in 2002, the DS-9 has been produced in a wide and sometimes bewildering array of major variants, which differ in their seating arrangement, engine, and electronics. Beginning in 2015, a number of existing G and N airframes were rebuilt to an improved standard, resulting in different performance characteristics. The table below summarizes the performance of the major variants, allowing easier comparisons in areas like thrust-to-weight ratio.

Single-seat variants
Characteristic	DS-9G	DS-9MG	DS-9G1	DS-9D (clean)	DS-9D (CFTs)	DS-9MD	DS-9G2
Year introduced	2003	2004	2015	2018	2018	2019	2020
Empty mass	8,970 kg	9,103 kg	9,010 kg	8,514 kg	8,968 kg	8,750 kg	8,719 kg
Fuel capacity	5,638 L	5,630 L	5,638 L	6,020 L	7,770 L	4,815 L	4,510 L
Payload	4,500 kg	4,500 kg	5,800 kg	6,500 kg	4,500 kg	6,000 kg	6,500 kg
Radar	AN/APG-73	AN/APG-73	AN/APG-73	Samsan GJ-16	Samsan GJ-16	Samsan GJ-16	Samsan GJ-16
Engine	F110-GE-100	F110-GE-100	F110-GE-129+	F110-GE-129++ TV/TR	F110-GE-129++ TV/TR	F110-GE-129++ TV/TR	F110-GE-129++
Dry thrust	74 kN	74 kN	84.5 kN	89 kN	89 kN	89 kN	89 kN
Wet thrust	124 kN	124 kN	151 kN	160 kN	160 kN	160 kN	160 kN
TWR*	0.920	0.911	1.115	1.196	1.053	1.176	1.205
A2A combat radius**	940 km	940 km	940 km	1040 km	1180 km	1020 km	950 km
A2G combat radius***	1,330 km	1,330 km	1,330 km	1,450 km	1,700 km	1,450 km	1,350 km
Ferry range****	6,700 km	6,700 km	6,700 km	7,400 km	7,900 km	7,200 km	6,800 km
Tandem-seat variants
Characteristic	DS-9N	DS-9MN	DS-9N1	DS-9R (clean)	DS-9R (CFTs)	DS-9MR	DS-9N2
Year introduced	2003	2004	2015	2018	2018	2019	2020
Empty mass	9,405 kg	9,538 kg	9,445 kg	8,939 kg	9,393 kg	9,185 kg	9,154 kg
Fuel capacity	5,038 L	5,038 L	5,038 L	5,419 L	7,169 L	5,419 L	5,038 L
Payload	4,500 kg	4,500 kg	5,800 kg	6,500 kg	4,500 kg	6,000 kg	6,500 kg
Radar	AN/APG-73	AN/APG-73	AN/APG-73	Samsan GJ-16	Samsan GJ-16	Samsan GJ-16	Samsan GJ-16
Engine	F110-GE-100	F110-GE-100	F110-GE-129+	F110-GE-129++ TV/TR	F110-GE-129++ TV/TR	F110-GE-129++ TV/TR	F110-GE-129++
Dry thrust	74 kN	74 kN	84.5 kN	89 kN	89 kN	89 kN	89 kN
Wet thrust	124 kN	124 kN	151 kN	160 kN	160 kN	160 kN	160 kN
TWR*	0.916	0.908	1.110	1.192	1.050	1.171	1.200
A2A combat radius**	835 km	835 km	835 km	935 km	1095 km	915 km	850 km
A2G combat radius***	1,180 km	1,180 km	1,180 km	1,325 km	1,570 km	1,300 km	1,200 km
Ferry range****	6,200 km	6,200 km	6,200 km	6,800 km	7,400 km	6,600 km	6,300 km

*TWR is reported in lbs-force of thrust divided by loaded weight, and uses an "airshow configuration" with no external weapons and full internal fuel.
**1000 kg payload (6 AAMs), cruise at Mach 0.9 at 13,000 m, 50% of fuel reserved for combat, no drop tanks.
***2000 kg payload, cruise at Mach 0.9 at 13,000 m, 33% of fuel reserved for combat, no drop tanks.
****2× 1300L tank and 1× 800L centerline tank, cruise at Mach 0.9 at 13,000 m, no fuel for side missions.

DS-9G/N Biho

Major land-based variants of the DS-9 in service with Menghean Naval Aviation.

DS-9G is the designation given to the original single-seater variant introduced in 2001. It is most easily recognizable for its large target-type thrust reverser plates, which are located on either side of the jet engine nozzle. When activated, these plates swing backward and close end-to-end, forming a bucket shape in the path of the engine exhaust.

The DS-9N is the twin-seat counterpart of the DS-9G. The rear position has a duplicate set of flight controls, allowing the weapon systems officer to take over if the pilot is incapacitated; this feature also allows the "N" variant to be used as an operational conversion trainer when new pilots are brought into the unit. Visibility from the aft cockpit is poorer, however, and certain non-essential controls and indicators are omitted to free up more space and weight for other systems. The WSO's main duty is to manage the plane's sensors, communications, and combat systems, both in the air-to-air and air-to-ground roles, thus freeing up the pilot to focus on the task of flying the aircraft.

The DS-9N has the same fuel capacity as the DS-9G; on the DS-9G, the space aft of the cockpit is left empty to reduce weight and improve agility. Due to its increased weight, however, the DS-9N has slightly reduced range and performance characteristics. It is typical practice in the Menghean Armed Forces to assign DS-9Gs to air-to-air missions where agility is more decisive, and DS-9Ns to ground-attack missions where the weapon systems officer is able to target guided munitions, but both variants are capable of undertaking a full spectrum of air-to-ground and air-to-air missions.

DS-9MG/MN Haeho

Variants with an "M" suffix, denoting hanggong moham (aircraft carrier) are navalized versions of the DS-9. They are used on the Menghean aircraft carrier Haebang and on the Sibiwŏl Hyŏgmyŏng and Choe Sŭng-min-class aircraft carriers. As with the baseline Army variants, the DS-9MG is a single-seat model, and the DS-9MN has a tandem cockpit for a weapon system officer or flight instructor. Sometimes DS-9M is used to denote both variants collectively.

The most visible change, compared with the land-based Army variant, is the absence of thrust reversers around the engine nozzle. Above the engine, the drogue chute was omitted and replaced by a receptacle for a towed decoy. When deployed, the decoy trails 100 meters behind the fighter on a Kevlar cord, replicating the fighter's radar signature and luring radar-guided missiles away from it. Beneath the tail, DS-9M variants have a tailhook to catch the arrestor wires on an aircraft carrier's deck, and the fuselage is reinforced where the tailhook is attached to the airframe.

The forward landing gear section was completely redesigned for the DS-9MG/MN, and was a major source of delays in navalization. While land-based variants have nose landing gear that swings aft to retract, carrier variants have nose landing gear that swings forward to retract, with the pivot point mounted further aft and a large supporting strut bracing it while deployed. This arrangement allows for better reinforcement when the entire airframe is propelled forward by a steam catapult pulling on the forward landing gear element. The new landing gear system takes up more space lengthwise, requiring the rearrangement of some electronics under the cockpit and a reduction in autocannon ammunition storage.

For easier storage, carrier variants have powered wing fold mechanisms. This required reducing the capacity of hardpoints 3 and 9, which on the MG/MN can only support air-to-air missiles; these hardpoints are on the folding sections. Hardpoints 4 and 8 were moved slightly outboard to allow split-payload adapters, partially compensating for this, and hardpoints 3 and 9 were also moved outboard within the revised outer wing sections. Though the DS-9's wingspan is 9.86 meters when extended, it falls to 6.20 meters when folded, narrower than the DS-5 with wings swept. The narrow inboard elevator on the carrier Haebang can easily fit a single DS-9M with a safe margin around it, and the aft elevator can fit two DS-9Ms side-by-side; deck park spots for the DS-5 also fit the DS-9M, allowing aircraft capacity to remain unchanged.

Less visible changes include modified avionics and new blade antennas on the upper fuselage for the Navy's airborne radio equipment. Internally, navalized variants use corrosion-resistant materials to maintain reliability at sea, even when parked on the flight deck. Collectively, these changes leave the DS-9MG and DS-9MN only slightly heavier than their land-based counterparts, as the removal of the thrust reverser mechanism partially compensated for weight gains elsewhere.

Despite the Navy's many concerns over a joint project and its prolonged effor to find alternatives, the DS-9M has proven to be a highly capable carrier fighter. Some of the Army's requirements, such as a short takeoff distance and good control characteristics at low speeds and high angles of attack, overlapped with the Navy's requirements for STOBAR operations on the Haebang. The DS-9's high reliability and easy maintenance also proved beneficial to the Navy, and dimensionally it was a nearly perfect fit for the Navy's requirements. The fit, however, was not completely perfect: the large Donghae 74/124 turbojet cannot be lowered vertically through the bottom of the airframe for maintenance, and must instead be pulled out the rear on a trolley. This operation requires a great deal of space behind the aircraft, making major maintenance work difficult in the cramped hangar. This problem is not unique to the Menghean Navy, as F-16Ns in the Hallian and Dayashinese navies suffer the same problem, but it nevertheless became the Navy's main complaint about the DS-9 airframe. To compensate, the Navy assigned 24 rather than 28 DS-9s to the Haebang (the extra four DS-5 spaces were found to complicate movement anyway) and expanded the hangar for the planned Sibiwŏl Hyŏgmyŏng class.

DS-9SG/SN Suchul Biho

Unveiled as a small-scale mockup at a defense expo in 2004, this model sports the fixed refueling probe of the carrier-based variants. The upper fuselage spine profile is also based on the carrier variants, to accommodate the removal of the refueling boom receptacle and the addition of custom radio equipment. It was marketed toward smaller air forces which lack tankers, or which already operate tankers without flying booms and are not in a position to replace their tanker fleets. Marketing materials also mention the ability to request a selection of other autocannon models, to maintain ammunition commonality with existing aircraft. There are some other internal changes, mostly associated with piping fuel around the original nose landing gear compartment, but no electronics downgrades and no significant reduction in performance apart from small differences in empty airframe weight. Like other Biho models, it comes in single-seat (SG) and tandem-seat (SN) models.

This redesign proved to be an immediate success, with Idacuan representatives negotiating a 25-airframe sale with an option for 50 more shortly after the expo at which it was revealed. The DS-9SG/SN was also sold to Medacapre and Kolodoria. Most Namhae Front members, however, received DS-9G/N models with the flying boom ports retained, allowing commonality with Menghean tankers.

Because the engine and electronics were not downgraded, the DS-9SG/SN is governed by the same export restrictions that apply to the baseline DS-9 models.

DS-9G1/N1 Biho 1

These designations are applied to existing DS-9G and N airframes which were rebuilt to an enhanced standard in the late 2010s and early 2020s. A numeral "1" is applied after the original designation to indicate that the modifications were applied.

The main change was the installation of a more powerful engine, based on the Glasic F110-GE-129 EFE+ and licensed by Donghae. This engine can generate 151.2 kN (34,000 lbf) of thrust in afterburner, or 84.5 kN (19,000 lbf) of dry thrust, raising the fighter's thrust-to-weight ratio to 1.08 on full internal fuel. Daesŭngri claims that the re-engined Biho Gae has limited supercruise ability, able to reach Mach 1.2 on dry thurst alone when cruising at high altitude with a light air-to-air missile load. Running at these higher loads increases fuel consumption and shortens the interval between major maintenance checks, but when matching the DS-9G/N's standard cruise speeds, fuel consumption is the same and maintenance requirements are reduced.

Because the new engines require higher airflow at maximum power, the intakes on these variants were also rebuilt to a wider pattern. This is the most visible difference between the baseline variants and the re-engined "Biho Gae" variants; the aft portion of the airframe was retained, with bucket-type thrust reversers and no thrust vectoring. The original Biho Gae modification also left the radar, electronics, avionics, and wings in their original state.

Because Daesŭngri's main assembly lines were already at maximum capacity with new orders flooding in, the General-Directorate for Procurement of the Ministry of National Defense authorized the Yŏng'an Aircraft Factory to carry out rebuilding work on DS-9s. This was both a political move and a strategic one; with Y-4HR production terminated and B-1M production taking place overseas, the Yŏng'an Heavy Aircraft Corporation was in danger of going bankrupt. The modification contract, granted in 2015 as Y-4HR production wound down, allowed Yŏng'an to retain its skilled workforce and averted a negative economic shock in central Menghe.

DS-9D/R Shin Biho

This pair of variants entered service in 2018, with the first orders placed the previous year. As with the preceding G/N pair, the DS-9D is the single-seat version, and the DS-9R is the tandem-seat version. To emphasize the scope of the upgrades, these aircraft are designated Shin Biho, or "new Biho." In light of the extensive changes, Daesŭngri markets it as a "4.5++ generation" fighter.

These aircraft use a further upgrade of the F110-GE-129 engine, designated F110-GE-129 EFE++. It generates 160 kN (36,000 lbf) of thrust on afterburner and 89 kN (20,000 lbf) of dry thrust. This engine terminates in a rectangular 2-D thrust vectoring nozzle with thrust reversing capability, based on the nozzles used on later variants of the Songrim SR-8. Because there is only one engine, the DS-9 cannot perform thrust-vectored rolls with opposing nozzle angles, but it does have enhanced pitch performance. The addition of upper and lower thrust reversers also eliminates the need for the heavy bucket-type panels seen on earlier variants, while retaining the DS-9's renowned short-field and rough-field capability. Because of the nozzle's square shape, the rear section of the fuselage has a more rectangular cross-section.

As on the DS-9G1/N1 modifications, the engine intakes were enlarged to increase airflow to the engine, but the use of an all-new airframe allowed more comprehensive changes. The DS-9D/R uses diverterless supersonic intakes, possibly derived from the Songrim SR-12 program, in place of the square intakes and splitter plates seen on previous models. In addition to improving airflow, the new intakes also reduce the plane's radar cross-section, improving stealth.

Compared with previous variants, the DS-9D/R makes much greater use of composite materials in the airframe, particularly the wings, canards, and vertical stabilizer. This results in a significant reduction in empty weight with a modest increase in structural strength, compensating for the mass of the heavier engine and allowing larger payloads of weapons and fuel. The composite materials used on these surfaces also have modest radar-absorbent properties, as on the Sieuxerrian Rafale. The canopy also uses a radar-absorbent composite material, and is similar in color to the canopy seen on SR-12 early production models. While the DS-9D/R is not a "true" stealth aircraft like the SR-12, it does have a moderately reduced radar signature, reducing the range at which enemy radars can consistently detect, lock, and engage it.

The final set of changes concerned the electronics and avionics. In the nose, the DS-9D/R carries the Samsan GJ-16, an active electronically scanned array resembling (but reportedly developed independently of) the AN/APG-79. This system has an extended range and improved multi-target tracking capability, and uses frequency hopping to reduce its probability of intercept by enemy passive antennas. Daesŭngri claims that maintenance on the new radar is also easier and less frequent. The missile approach warning system and radar warning receiver units are also enhanced to increase their effectiveness, and the #3 and #9 hardpoints can now carry pylons with towed radar decoys in addition to other payloads. To process information from the new array of sensors, both the pilot and the WSO have glass cockpit instruments with multifunction LED displays, and both can use the Keikō helmet-mounted display.

DS-9MD/MR Shin Haeho

One year after the first DS-9R entered service, Daesŭngri began deliveries of a navalized version. The DS-9MD (single seat) and DS-9MR (tandem seat) combine the airframe improvements of the DS-9D/R with the landing gear, recovery equipment, and corrosion-resistant materials of the original DS-9M variants. Given the speed of the DS-9MD/R's introduction, it is likely that development work took place in tandem with development work on the DS-9D/R.

The Menghean Navy conducted extensive land-based testing of this variant at Chungsŏk airbase, which in 2009 was modified with arrestor wires and steam catapults to train pilots in CATOBAR operations. DS-9MR fighters of the 110th Carrier Fighter Squadron were delivered to the nuclear aircraft carrier Choe Sŭng-min in early 2021, shortly after its commissioning.

DS-9G2/N2 Biho Gae

After the introduction of the DS-9D/R and DS-9MD/MR, Daesŭngri updated the DS-9G/N modernization program to incorporate parts and features from the new variant. The designation DS-9G2 denotes a DS-9G single-seater with the changes applied, and DS-9N2 denotes a tandem-seat variant with the changes applied. The Gae (개/改) modifier on the name means "changed" or "improved."

The main change is the addition of the Donghae-licensed F110-GE-129 EFE++ engine producing 89 kN of thrust dry and 160 kN wet, bringing further improvements in thrust-to-weight ratio and enabling low-supersonic supercruise capability. The DS-9D/R's thrust vectoring unit was not carried over, as this would have required a full rebuild of the fuselage, but the DS-9D/R's composite wings and canards were carried over to reduce empty weight and radar cross-section. So were the new AESA radar, the enhanced defensive electronic warfare suite, and the Keikō HMD compatibility.

As with the G1/N1 rebuilds, all G2/N2 variants are rebuilt from existing G or N airframes, and all rebuilding work takes place at the Yŏng'an Aircraft Factory. The first deliveries of refitted airframes took place in 2020.

Operational history

Ummayan Civil War

The DS-9 saw limited action in the Ummayan Civil War. A single squadron was transferred to Qusayn before the Menghean intervention, and its fighters performed well during the conflict, suffering no losses across a string of successful sorties. These figures may be misleading, as the Menghean Army used them sparingly and cautiously, sending DS-5Ds and SR-3Rs on high-risk missions.

Though the carrier Sŭngri did deploy to Ummayah after the DS-9HG's introduction, deliveries were still in progress and pilot conversion was not complete. Sŭngri deployed with a full combat wing of DS-5 fighters, while existing DS-9HGs and HNs remained behind with the Haebang to continue pilot conversion and air crew familiarization training.

Menghean invasion of Innominada

DS-9s played a pivotal role in the Innominadan Crisis, conducting round-the-clock airstrikes in support of the 4th and 8th Armies' advance into Innominada. Naval DS-9s from the carriers Sibiwŏl Hyŏgmyŏng and Sŭngri also supported amphibious landings off the country's south coast.

As a result of their aggressive use, Bihoss bore the brunt of Menghean air losses in the Innominada campaign. Menghean Army Aviation lost 27 DS-9s during the course of the conflict, while Carrier-Based Aviation lost eight. Seven of these losses occurred in air-to-air combat, though Biho pilots also claimed a total of 32 air-to-air victories, a 4.57:1 kill:loss ratio. Losses were nevertheless higher than Army planners had anticipated, leading to a postwar investigation into Army Aviation tactics and equipment. Most losses were attributed to inadequate planning ahead of operations, the result of Menghe's rush to occupy Innominada's southern provinces before Maverican forces could arrive, as well as a dangerous reliance on low-level interdiction flights in areas where light AA and MANPADS were the main threats. Pilot training was adapted in light of these results, and existing airframes were adapted to "G2/N2" standard with improved ECM defenses; the D and R variants, with RCS-reducing intakes and materials, were also unveiled in 2016.

Karpatya

Karpatya negotiated a $6.5 billion dollar deal in 2009 for 150 DS-9G1/N1 fighter jets, to be delivered between 2010 and 2015. The price tag included training, familiarization, and a supply of spare parts. The delivery of the last 38 airframes was deferred in 2014 as Menghe moved to expand its air force during and after the Innominadan Crisis, but deliveries finished in 2017.

Export deals

In 2016, when Nukkumaa began looking to replace its aging F-16 airframes, Menghe offered to sell DS-9Ds. Key attractions of the sale included a lower purchase cost and claimed lower operating costs, as well as engine commonality with later F-16 models and good rough-airfield performance. Ostland also marketed its Greif-E/F as a competitor. In the end, Nukkumaa opted to purchase newer F-16 airframes of more recent variants, to maintain training and parts commonality.

As of 2019, Menghe still considers the new DS-9D/R "Shin Biho" too advanced to export on the open market. Instead, Daesŭngri developed a trade-and-upgrade program in which customers can buy used DS-9G/N airframes from the Menghean Army, with revenue from the sales financing the production of additional DS-9D/Rs as replacements. By the end of 2021, the Menghean Army had replaced 150 of its existing DS-9G/N airframes in this manner.

Total losses

According to figures published by the Menghean Ministry of National Defense, 35 Menghean DS-9s were lost in combat over Innominada, and 27 were lost in peacetime accidents and crashes. A total of 286 more were exported to countries outside Menghe; losses among these airframes are not recorded by the MoND. As of December 2019, total production from Daesŭngri totals 925 completed airframes, and thus 577 are left in Menghean service, with 431 in Army Aviation and 146 in carrier-based aviation.

The Ministry of National Defense has stated that it plans to continue DS-9D/R production "well into the foreseeable future," with no clear number for the total procurement target. Several Menghean combat squadrons have already traded out their G/N variant fighters for newer D/R variants, with the used planes exported abroad to Menghean allies, feeding speculation that the Army plans to procure enough D/R variants to replace its entire fleet.

Variant	Non-combat losses	Losses due to enemy action
DS-9G	11	11
DS-9N	7	16
DS-9HG	4	2
DS-9HN	2	6
DS-9D	2	0
DS-9R	1	0
Total	27	35

Operators

The DS-9G base variant in the liveries and camouflage schemes of the Namhae Front's member and observer states.

• Argentstan: Ordered 40 used G/N airframes in 2018, but delivery of the first 12-unit batch was delayed until 2020. Eighteen more were delivered by the start of the One-Month War, bringing the total to 30.
• Template:Country data Azbekistan: 90 new-build DS-9G/N airframes delivered between 2011 and 2015, to replace losses during a 2011 conflict with Khalistan.
• Dzhungestan: 12 used G/N airframes delivered in 2021.
• Idacua: Ordered 25 new-build DS-9SG/SNs with an option for 50 more in 2004. Delivery of these airframes began the following year, and were completed by 2011. Ordered an additional 30 new-build DS-9D/R airframes in 2017, with deliveries completed in 2020.
• Republic of Innominada: 50 used G/N airframes delivered from 2017 to 2021.
• Template:Country data Kolodoria: 84 new-build G/N airframes delivered from 2008 to 2013.
• Template:Country data Medacapre: 50 new-build G/N airframes delivered from 2007 to 2011.
• Menghe: 1,260 airframes were produced for Menghean service by the end of 2021.
• Polvokia: 52 new-build G/N airframes delivered from 2011 to 2016.
• Qusayn: 44 used G/N airframes delivered from 2018 to 2021.
• Template:Country data Ummayah: 110 new and used G/N airframes delivered from 2009 to 2017.
• Template:Country data Virshahr: Ordered 28 used G/N airframes in 2020 as replacements for its Su-27P fleet. Eight were delivered before the start of the One-Month War; of these, three were lost.

Specifications (DS-9G)

General characteristics

• Crew: 1
• Length: 16.31 m (53 ft 6 in)
• Wingspan: 9.86 m (32 ft 4 in)
• Height: 5.17 m (16 ft 11 in)
• Wing area: 38.67 m² (416.2 ft²)
• Empty weight: 8,970 kg (19,780 lb)
• Loaded weight: 14,080 kg (31,040 lb)
• Max. takeoff weight: 19,860 kg (43,780 lb)
• Powerplant: 1 × Donghae 74/124 afterburning turbojet
  • Dry thrust: 73.8 kN (16,590 lbf)
  • Thrust with afterburner: 124.5 kN (27,990 lbf)

Performance

• Maximum speed:
  
  • At altitude: Mach 2.1 (2,230 km/h; 1,386 mph)
  • At sea level: Mach 1.28 (1,565 km/h; 975 mph)
• Combat radius: 940 km (584 miles) full internal fuel, air-to-air loadout, 4.4 minutes combat
• Ferry range: 4,100 km (2,500 miles) with three external tanks
• Service ceiling: 15,140 m (49,670 ft)
• Wing loading: 364.1 kg/m² (74.58 lb/ft²)
• Thrust/weight: 0.90 (clean, full internal fuel)

Armament

• Guns: 1× GP-24/3 revolver cannon, 220 rounds
• Hardpoints: 11 hardpoints with a capacity of 6,000 kg and provisions to carry combinations of:
  • Missiles:
    
    • Air-to-air missiles:
      • YGG-5 Dando
      • YGG-6
      • YGG-7 Hwasal
    • Air-to-surface missiles:
      • YDJ-48 Salmusa
  • Bombs: Bombs up to 500kg (1,100 lbs)
  • Other:
    
    • Drop tanks:
      • Drop tank with 750 kg fuel (centerline)
      • Drop tank with 1200 kg fuel (under wing)