Songrim SR-8

Songrim SR-8
The four domestically built service variants of the SR-8
Role	Multirole combat aircraft
National origin	Menghe
Manufacturer	Songrim Aircraft Corporation
Introduction	2000
Primary user	Menghe
Produced	1999-2025 (planned)
Number built	406
Developed from	Glasic International Aircraft Eagle

The Songrim SR-8 is a twin-engine, all-weather multirole strike fighter based on the Glasic International Aircraft Eagle air superiority fighter. It is produced under license in Menghe by the Songrim Aviation Design Bureau. In a nod to its original designation, it is also known as the Gŭmdoksuri, or "Golden Eagle," making it the first Menghean combat aircraft to bear an official nickname.

Though it originated as a foreign derivative, the original SR-8G incorporated a number of unique changes to suit Menghe's needs, including wingtip missile rails and a refueling probe. During the 2000s and 2010s, Menghe also developed its own domestic improvements to the SR-8 airframe, driving further divergence with other Tripartite models. Over 460 SR-8 airframes were produced between 1999 and 2019, making Menghe the third-largest operator of the Iolar family after Tír Glas. Menghe is set to surpass Dayashina as second-largest operator in 2021.

Licensing and development

Import competition

The Menghean Ministry of National Defense began examining candidates for a twin-engine heavyweight fighter in the early 1990s, seeking a platform that would fit between the DS-5's poor range and the SR-7's poor maneuverability. As sanctions on Menghe had been lifted following its regime change and the nuclear disarmament, foreign imports or license deals were once again on the table, and the MoND viewed them as a practical way to cut development costs and speed up availability.

Four foreign aircraft were selected for evaluation in 1993: the Letnian Or-27, the Glasic Iolar, the Sieuxerrian Super-Mirage Export Model, and the Ostish Greif. The Greif, in competition with fighters well outside its weight class, was quickly ruled out, though not before Daesŭngri's engineers could thoroughly look it over. The Mirage was also eliminated, though Sieuxerrian engineers refused to hand over the airframe after trials, concerned about the risk of reverse-engineering. This left the Or-27 and Iolar, both outstanding in speed and maneuverability, as the finalists.

The decision between the two became a high-stakes one, not only because of the planes' capabilities, but because it could affect Menghe's geopolitical alignment for years to come. For much of 1994 the Or-27 seemed to be the preferred option, but the Letnian government pressured Orlov to export it with downgraded radar systems, angering the Menghean representatives. Tír Glas, hoping to exploit this break, offered to the Iolar-F with its APG-70 radar. As a further guarantee, GAC exported APR-70 kits for use on SR-7 upgrades, and held out the possibility of technology transfers for future domestic Iolar improvements. These promises won Menghe over, and in 1995 the MoD ordered 40 Iolar airframes for training and evaluation, with a production license under negotiation. The OR-27 was still held out as an option if the Iolar did poorly, but the deal nevertheless marked a key milestone in Menghe's transition away from Letnian military equipment.

Iolar-M

The forty airframes delivered to Menghe in 1995 and 1996 were manufactured in Tír Glas under the designation "Iolar-M," with M denoting Menghe. They were based on the Iolar-F, and came with the still-new APG-70 radar system, but incorporated some downgrades to protect sensitive technology. The ECM system and radar warning receivers were both last-generation models, but otherwise the onboard systems were up-to-date. Some custom changes were applied to the hardpoints, allowing compatibility with the YGG-5 missile and Menghean GP-series bombs. The basic airframe was entirely original.

Menghe's Iolar-Ms were assigned to the 56th Operational Testing Squadron, which compared their capabilities against those of the SR-7 and a single Or-27 purchased for testing. Pilots trained on the SR-7 roundly praised the new aircraft's thrust and agility, as well as its impressive radar suite. The Or-27 was found to have better agility, but the difference was deemed minor, and the Iolar's high thrust-to-weight ratio and full multirole capability easily counterbalanced it.

After 18 months of flight testing, the commanders of the 56th Operational Testing Squadron formally approved the Iolar-M, but presented Songrim with a list of desired changes for the licensed version. Songrim engineers, who had broken down one airframe for study, concurred.

Domestic production changes

License production of the Menghean domestic variant began in 1999, with deliveries starting in 2000. In line with previous aircraft of foreign origin - like the DS-1 and SR-3 - it was given a domestic manufacturer designation, Songrim SR-8G.

Based on feedback from flight trials with the Iolar-M, the Songrim design team made a number of changes to the airframe, some of them based on features of the Or-27. To protect the engines from foreign-object ingestion on takeoffs and landings, variable-angle grated screens were added on the intake floors. An IRST scanner was added just forward of the canopy, with both air-search and ground-mapping modes. Some other changes were made to the avionics, navigation lights, and ECM system.

The question of how to change the refueling system stirred greater debate. No other Menghean combat aircraft refueled through flying-boom receptacles like those on the Iolar, so conversion to a probe-and-drogue system was necessary for compatibility. The Ministry of Defense required that the probe be retractable to reduce drag, and that it be part of the core airframe, usable when no drop tanks or conformal fuel tanks are fitted. Disturbance to existing fuel space, complexity, and visibility of the probe from the cockpit were also factored into comparisons. An Orlov-style probe in the nose was deemed ideal for space and visibility, but ruled out due to the lack of nose space, especially with the addition of an IRST system. This left two options: a telescoping probe which retracted into the right wing root, where the original receptacle had been, and a hinge-up probe which would wrap around the right side of the forward fuselage when not in use. The latter option was eventually adopted, as it was lighter and less mechanically complex.

Design

Performance

Due to the combined effect of many small changes, such as the added wingtip hardpoints and sturdier landing gear, the SR-8G is slightly heavier than the Iolar E, and has slightly more drag. Nevertheless, its powerful engines give it excellent acceleration, including the ability to conduct a vertical climb. Its large wing area gives it a low wing loading, allowing it to pull sharp turns without bleeding too much velocity - a persistent problem on the DS-5 and SR-7.

Early-production SR-8s used the Glasic TF-530 turbojet. Under a memorandum of understanding signed in 1997, the first 120 engines were manufactured in Tír Glas by Morris Foley Aero Engines, and the next 120 were shipped in knock-down kits for local assembly. Subsequent engines would be built under license by Donghae Heavy Industries. Locally built engines bore the designation Donghae Type 74-124.

Like the Iolar C and E, the SR-8 can mount conformal fuel tanks (CFTs) on either side of the fuselage beneath the wings, each carrying 2,270 kilograms of fuel. Menghean Army SR-8s generally fly air-superiority missions without CFTs, which cannot be jettisoned mid-air, in a bid to maximize maneuverability on contact with the enemy. CFT use is nearly universal in Navy squadrons, which emphasize range and payload.

Armament

In its "clean" configuration, with no CFTs attached, the SR-8 has 13 hardpoints:

• 1 on each wingtip (YGG-5 only)
• 3 under each wing, in a combined unit (center: 2050 kg; sides, 2 air-to-air missile rails)
• 2 under each lower fuselage corner (YGG-6/7 only)
• 1 centered under the fuselage (2050 kg).

With conformal fuel tanks attached, the four corner under-fuselage hardpoints are obstructed, but six new hardpoints become available. These can be fitted with bombs, bomb racks, or air-to-air missiles, though air-to-air missiles can only be mounted to the front and end hardpoints and obstruct the center one.

Gun armament consists of a six-barreled rotary autocannon in the right wing root, carrying 400 rounds of 23×133mm ammunition. As Menghe already operates 23×115mm ammunition in some fighters - notably the DS-5 and SR-7 - standard Army and Navy practice is to designate the SR-8's gun as 24mm and its ammunition as 24×133mm, in order to avoid errors in supply shipments and the arming of planes.

Sensors and electronics

The SR-8G uses the AN/APG-70 radar, which has both air search and ground search modes. The designers also added a terrain-following mode which, in combination with a radio altimeter on the underside of the fuselage, allows the SR-8 to conduct low-level flight in poor-visibility conditions.

Another sensor change comes in the form of a Sieuxerrian IRST system mounted above the nose, offset slightly to the left. In air-search mode, it can detect aircraft and cue missile launches, allowing the SR-8 to engage enemy aircraft without triggering their radar warning systems. Menghean publications claim that the SR-8's IRST has a range of 50 kilometers against a fighter-size target, though actual detection range depends heavily on humidity, altitude, and whether the target is using afterburner. The IRST sensor also has a ground-search mode, which can either track individual targets for ground-attack missions or project a view of the landscape ahead onto the pilot's HUD for low-visibility flying.

Due to the addition of integral terrain-following capability and IRST imaging, the SR-8G no longer needs the separate features of the AN/AAQ-13 navigation pod. As Menghe had already purchased ATLIS-II and PDL-CT laser targeting pods from Sieuxerr, these were used in place of the AN/AAQ-14. Domestic sensor pods replaced both of these in the 2000s. Owing to these changes, Menghean SR-8s never carried the LANTIRN targeting pods which had been ubiquitous on Glasic and Dayashinese Iolars until the introduction of the Litening system.

Differences with Iolar

A condensed summary of the differences between the SR-8G and Iolar E is reproduced below, in approximate order of prominence:

• Wingtip hardpoints for YGG-5 air-to-air missiles
• IRST sensor ahead of cockpit, offset to the left
• Large, squared-off ECM antennas on top of the vertical stabilizers
• Folding grates on the intake lower surfaces
• Refueling probe on the right side of the nose, folds flush with the airframe when not in use
• Original refueling receptacle is absent
• Slightly reinforced tires and landing gear
• Different datalink and VHF antennas on upper and lower fuselage

Subsequent variants of both aircraft introduced further changes, some of which were functionally similar, but as design work was conducted independently, implementation differs. The Iolar Fíréan CAT.3 features an IRST sensor, but it is smaller and further forward, and it adds two-dimensional thrust vectoring nozzles, but these are squared off rather than gimballed as on the SR-8N.

Variants

Iolar M:

Special variant of the Iolar E downgraded and adapted for export to Menghe. Manufactured in Tír Glas and delivered in 1995 and 1996. Not technically part of the SR-8 family, as it lacked the SR-8G's changes, but closely related.

SR-8G:

Initial production variant. These were exclusively twin-seater multirole aircraft; no single-seat version was produced. Production started in 1999. 95 produced from 1999 to 2006.

SR-8G1:

Software update of the SR-8G to support the YGG-7 Hwasal air-to-air missile. All existing airframes had been converted by 2005. The G1 designation was also applied to SR-8Gs produced after 2003 with built-in YGG-7 compatibility.

SR-8N:

New variant of the SR-8 introduced in 2006. Though externally identical to the SR-8G and G1, it featured greatly improved ECM equipment underneath its antenna fairings, and its radar reportedly had greater resistance to jamming. It also carried new engines with 137 kN wet thrust and an extra pair of under-wing hardpoints, supported by an improved fly-by-wire system to maintain maneuverability. 212 produced from 2006 to 2017.

SR-8G2:

Designation applied to SR-8G1 airframes refitted with the SR-8N's ECM equipment, radar modules, and extra hardpoints.

SR-8D:

This is a dedicated air superiority variant introduced in 2013 to compete with supermaneuverable Or-27 derivatives in Maverican service. It features thrust-vectoring engine nozzles, which pivot around a canted axis to produce roll, pitch, and yaw depending on combination. It also came with a greatly improved phased-array radar, with extended range and improved frequency hopping to improve resistance to jamming and detection. The SR-8D is exclusively single-seat, as its features were deemed less useful on an attack aircraft, and it was produced in tandem with the SR-8D after its introduction. 62 were produced between 2013 and 2018; more orders may have been planned, but production switched to the SR-8R.

SR-8R:

Unveiled in 2017, the SR-8R is a low-observable variant of the SR-8, built with radar-absorbent materials and fitted with the 8D's radar (though not its engines). The vertical stabilizers are canted outward and the wingtips once again lack launch rails. Its improved engines make it supercruise-capable. Though less stealthy than a dedicated fifth-generation fighter like the Huntress or SR-12, it still has a greatly reduced radar cross-section, especially over the frontal aspect.

For maximum stealth, the SR-8R can be flown with its under-wing hardpoints removed, and four air-to-air missiles carried in special enclosed weapons bays on the conformal fuel tank positions. Alternatively, it can be fitted with the baseline CFTs and external hardpoints, giving it the same range and payload options as previous SR-8 models with a still appreciable reduction in radar cross section. Reduced-RCS drop tanks and hardpoint-mounted enclosed missile bays were displayed at a 2019 expo. As of December 2019, 37 have been built.

Operational service

Ummayan Civil War

Menghe deployed two squadrons of SR-8Gs, or 24 aircraft in total, to its intervention in the Ummayan Civil War, where they supported land operations by intervening Menghean forces and the rebel Taleyan People's Front. Menghean commanders mainly used them as bomb trucks, making low-level attacks with unguided munitions while DS-5s provided air cover. A subsequent internal review by the Ministry of National Defense criticized this approach, which put both types at greater risk.

Menghean records show that a total of four SR-8s were lost during the deployment in Ummayah. Menghean sources claim that both combat losses were a result of surface-to-air missiles, while the remaining losses were accidental crashes. Sources in Tyran claim that one of the accidents was in fact a Typhoon pilot's air-to-air kill, and claim another probable kill from air-to-air fire. The latter may have been an SR-6 engaged at long range, also reported in Menghean records as an accident.

Innominadan Crisis

SR-8s saw combat again during the Innominadan Crisis, when Menghe launched a ground invasion of Innominada during its civil war. Employment of SR-8s in this conflict initially focused on delivery of standoff munitions from safe ranges, but after Maverica mobilized forces to prepare its own intervention from the north, the Menghean Army stepped up its tempo of operations in an effort to occupy Innominada's southern provinces before Maverican forces could arrive. This resulted in riskier attacks, often without proper SEAD support or preliminary reconnaissance. Non-combat accidents also became more common, with a mid-air collision between an SR-8 and a BAC 1-11 AWACS plane on February 5th, 2015 killing all aircrew involved. Subsequent reviews of the fighting also indicated that Menghean planners had underestimated the capability of Tyrannian- and Sieuxerrian-designed surface-to-air missile systems exported to Innominada.

Total combat losses from the Innominadan Crisis came out to 14 aircraft, of which eleven were lost to surface-to-air missiles and two were lost to ground fire, one of them nearly returning to base but losing power after its remaining engine shut down. The fourteenth was lost in air-to-air combat with an Innominadan Rafale fighter. As in Ummayah, some sources speculate that Menghean sources attributed one or possibly two further air-to-air kills to surface-to-air missiles in an effort to improve the SR-8's air-to-air kill-to-loss ratio, but the total figures for airframes written off appear to be valid. Five additional airframes were lost in accidents, including one in an air-to-air collision.

SR-8 losses over Innominada led Menghean Army Aviation to re-evaluate some of its strategies, as well as the quality and vulnerability of its equipment. Work on the Keikō HMD was restarted in an effort to improve pilots' situational awareness, and the MoND's procurement board began an investigation into the effectiveness of the SR-8's then-current ECM suite, which is also fitted to the DS-9. Three years after the Menghean intervention, Songrim unveiled the SR-8R, which incorporates additional passive sensors and makes use of radar-absorbent materials. Experience from SR-8 losses may also have pushed the MoND to accelerate work on the Songrim SR-12, though further issues with the latter plane would delay its production approval to 2019.

Total losses

As of December 2019, a total of 42 SR-8 and Iolar-M fighters of all variants have been lost in Menghean service. A loss is defined here as any damage so serious that the plane had to be written off from the national stockpile. Accidents in training and peacetime flights are included, and crashes during military operations which were not plausibly due to enemy action are counted under "non-combat losses" below.

Notably, the Iolar-M, Iolar-M2, and SR-8R have not seen combat, and the SR-8D was only introduced in 2013. Therefore, their low loss figures mainly indicate less active service in and out of combat.

Variant	Non-combat losses	Losses due to enemy action
Iolar M	2	0
Iolar M2	1	0
SR-8G	11	7
SR-8N	10	8
SR-8D	2	1
SR-8R	0	0
Total	26	16

Current status

As of December 2019, Songrim Aircraft Corporation reports that its factory in Insŏng has completed 406 SR-8 airframes of all types, not including Iolar-Ms built in Tír Glas. Subtracting 42 lost airframes and adding 50 surviving Iolar-Ms, this brings the total currently in service to 414, of which 156 (12 squadrons) are in Naval Land-Based Aviation and 258 (21 squadrons) are in Army Aviation, with 6 spares in reserve. These numbers are reported on the website of the Menghean Ministry of National Defense.

Declassified MoND documents state that the Army requires 288 airframes and the Navy 180 in order for all Advanced Multirole squadrons to be fully equipped; with 32 spares, the total procurement goal comes out to 500 aircraft. A central government press release states that mass production of the SR-8R will continue until at least 2025, by which time the production goal will have been met. Production may also be renewed for additional years to replace Iolar-Ms, which the MoND does not consider front-line units, and possibly to replace early-model SR-8Gs.

The appearance of the fifth-generation Songrim SR-12 has also led to speculation about the future of the SR-8 program. Though the Menghean government has not published firm cost figures on either airframe, the SR-12 is believed to be considerably more expensive in both procurement and maintenance, and will not be able to replace the SR-8 on a 1:1 basis. Notably, while both aircraft are reportedly produced at Songrim's Rogang Aircraft Factory, the 2025 deadline suggests that SR-8 production is continuing at 3/4 of its peak level. Some analysts speculate that production of both aircraft will continue into the foreseeable future, with full retirement of the SR-8 occurring as late as 2075.