SAR-775 Nagisa
| SAR-775 Nagisa | |
|---|---|
 Diagram view of the SAR-775 Nagisa BVRAAM. | |
| Type | Long-range air-to-air and air to ground missile |
| Place of origin |  Carthage |
| Service history | |
| In service | 2012-present |
| Used by | Carthage Gensokyo Republic Japan |
| Production history | |
| Designer | Acheron Technologies Mitsubishi Heavy Industries |
| Designed | 1999-2012 |
| Manufacturer | Acheron Technologies Mitsubishi Heavy Industries |
| Unit cost | $1.8 million (FY2012) |
| Produced | 2012-present |
| No. built | 4,000+ |
| Specifications | |
| Weight | 200 kg (440 lb) |
| Length | 3.7 m (12 ft) |
| Diameter | 300 mm (12 in) |
| Warhead | 25 kg (55 lb) blast-fragmentation warhead |
Detonation mechanism | Integrated MMW fuze Backup impact fuse |
| Wingspan | 520 mm (20 in) |
| Propellant | Throttleable ducted rocket |
Operational range | 250+ km (160+ mi) (air-to-air) 300+ km (180 mi) (air-to-ground) |
| Flight ceiling | 27,000 m (89,000 ft) |
| Speed | 4,900 km/h (3,000 mph) |
Guidance system | Dual-band active radar homing Home-on-jam capability Inertial/GPS w/datalink |
Launch platform | Multi-platform |
The SAR-775 Nagisa is a Carthaginian an all-weather long-range air-to-air and anti-radiation missile manufactured by Acheron Technologies and Mitsubishi Heavy Industries. It is designed to be a low-observable long-range missile for use with fifth generation fighters and includes a highly-maneuverable lifting body design and fire-and-forget capability. After a protracted development period beset by numerous delays in developing the ramjet propulsion system, the SAR-775 finally entered service in 2012 with the Carthage Defense Forces, replacing the SAR-778 Sakura in air-to-air roles.
History
The technological basis for the SAR-775 Nagisa comes from several programs developed and tested by the Air Forces and Navy throughout the late 1980s and early 1990s, as potential replacements were considered for the Type-89 MRAAM. The Navy's Ardent Diamond missile body demonstrators were designed to test the use of lifting body airframes for missile applications, ranging from large anti-ship missiles to smaller air-to-air missiles. Tests using the three demonstration vehicles indicated improved energy retention at range and good maneuverability using bank-to-turn control laws. The program was terminated in 1992 following the successful collection of relevant test data.
Separately, the Air Forces tested the use of newer, more advanced and more ECM-resistant radar seekers, notionally as a means of further upgrading the Type-89 MRAAM. Several new seekers using alternative bands were tested for accuracy and decoy resistance, as well as the potential for multi-band and multi-mode seekers. The Future Missile Propulsion program also investigated alternatives ranging from improved rocket propellants, multi-stage designs, and more complex ramjet designs, looking to extend missile engagement range and kill probability.
Next Generation Air-to-Air Missile program
In 1996, with the Advanced Multirole Program underway, the Air Forces initiated the Next Generation Air-to-Air Missile program with the objective of developing a new missile to arm the future fighter, with better integration and new capabilities. Aside from an increased range requirement of at least 150 kilometres (93 mi), an expanded no-escape zone, better discrimination against decoys and countermeasures, and a higher-bandwidth datalink, the NGAAM program introduced internal carriage requirements for the first time, requiring careful consideration of the arrangement and size by any potential contenders. Six bids were received for the initial NGAAM program, including two joint bids from Acheron Technologies partnered with Mitsubishi and from the RMA Corporation partnered with Cordoba Aerospace.
With the AMP fly-offs proceeding in 1997, additional concepts were considered by the Air Forces leadership in light of the projected capabilities of the two competitors. The Type-57 anti-radiation missile was too large to be carried internally by either aircraft, requiring either unstealthy external carriage, reliance on legacy platforms to perform SEAD/DEAD missions, or reliance on pure stealth and ECM for penetration of enemy air defenses. With the NGAAM competition requirements already supporting the development of a relatively large missile body still capable of internal carriage, the ARM requirements were folded into the program and a new request for proposals issued for the re-named Compact Dual-Role Missile (CDRM) program.
Compact Dual-Role Missile program
New requirements were issued for the CDRM program in September 1997, adding ground-attack anti-radiation missile requirements to the original NGAAM proposal. The new requirements emphasized loiter time, greater accuracy against ground targets to compensate for the smaller warhead compared to the Type-57, and reduced susceptibility to jamming and ground countermeasures compared to legacy platforms. Range in the air-to-air role was also extended to over 200 km (120 mi) as performance benchmarks from future radar suites were assessed. After a redesign period to incorporate these features, new bids were submitted with the joint Acheron/Mitsubishi and RMA/Cordoba bids being considered the frontrunners.
The Acheron/Mitsubishi design was a technologically ambitious proposal, integrating a solid-fuel ramjet in a new lifting body airframe. It used bank-to-turn rather than skid-to-turn control laws and composite construction to reduce RCS. The RMA/Cordoba bid took a more technologically conservative but still innovative approach, using a two-stage cylindrical missile composed of a traditional solid rocket booster combined with a multiple pulse rocket in the final stage, allowing the missile to coast during the midcourse and reignite the rocket motor in the terminal phase for increased maneuverability. As the RMA/Cordoba design relied on more proven technology than the Acheron/Mitsubishi design, it was considered the more likely selection by August 1998, but became the focus of an ongoing political battle due to the size of the contract, with the Punic Navy also committed to buying the winning design upon its entry to service.
To great surprise, in September the Air Forces announced the Acheron/Mitsubishi design as the winner, to be classified as the SAR-775 Nagisa. The expected in-service date was 2007. The only significant change to the design was the incorporation of the RMA/Cordoba seeker into the Acheron/Mitsubishi body. Despite protests by RMA and Cordoba, the contract was approved by the contracting office and program development started in earnest.
Delays
As development continued, the program encountered a number of delays, many stemming from the development of the design's ramjet engine. Other areas of difficulty included revising the more complex control laws and solving issues with body rate coupling. By 2004, three years from the expected in-service date, the program had fallen 14 months behind schedule and was likely to fall even further. By this time, the Navy had already invested in the RMA/Cordoba design as a surface-to-air missile and delays in the Nagisa program prompted the Navy to purchase variants of the SAR-778 for air use in order to arm the new RFM-202 Shaheen.
Facing the threat of an external government audit to the program, the Air Forces began a major internal review to reorganize the program. A new in-service date was set for 2012 and additional expertise brought onboard to help solve the problems with the ramjet. The additional time was also expected to allow production difficulties with the composite paneling and frame to be worked out. In the interim, the Air Forces would follow the Navy in also ordering several batches of SAR-778s until SAR-775 was ready for service.
Entry to service
Flight testing was conducted throughout 2009-2010 alongside concurrent captive carry tests. The first production-ready missiles were delivered to the Air Forces in late 2010 for full systems testing, and the design was approved for production in 2011. The first production lot entered service in March 2012, with the Air Forces halting procurement of the SAR-778 Sakura in May following production rate increases for the SAR-775 Nagisa. The first lot was delivered to the Navy in June 2013, at which time it also halted procurement of air-to-air SAR-778s.
An estimated 70,000-80,000 missiles are expected to be procured over the next two decades, replacing the Type-89 and remaining SAR-778s in the air-to-air role. In 2008, the SAR-775 missile body was selected to be the basis of the SPM-782 Hakurei Multi-Purpose Medium Missile, using a turbojet rather than a ramjet for propulsion.
Operational features summary
Featuring ramjet propulsion and a highly efficient lifting body design, the SAR-775 is designed to engage targets at significantly greater ranges than legacy weapons and to be much more effective in the face of electronic countermeasures and decoys. The combination of ramjet motor and lifting body design provides Nagisa with a no-escape zone four times greater than the newest Type-89 variants and over twice as large as that of the SAR-778. The greater propulsive efficiency allows the missile to remain powered through the terminal phase, increasing the chances of a successful engagement and kill probability. Increases in kill probability and engagement range are also due to improvements in seeker power, accuracy, and resistance to jamming.
The Bodastart IntelliMach 2MD40-ME dual-band radar sensor and supporting computing system is responsible for the missile's guidance. It is composed of an X-band radar seeker for primary guidance and a millimeter wave sensor for shorter-range homing and use against surface targets. The seeker was intended to be the first AESA seeker in Carthaginian service when the program was initiated, but schedule slips resulted in the Acheron RS-340A in the SAR-778 Sakura entering service first. Due to the use of a more complex dual-band seeker, the onboard computing system provides an order of magnitude more processing power than legacy weapons, increasing resistance to many jamming and spoofing techniques. The missile is designed to provide an increased acquisition basket in air-to-air use and to be more lethal against stealth aircraft while providing greater accuracy against ground targets in the anti-radiation missile role.
Nagisa is the first missile in Carthaginian service that incorporates additive manufacturing in its construction. During the prolonged development program for the ramjet and control laws, tests using additive manufacturing to build components of the missile body, frame, and maneuvering fins were conducted, demonstrating positive results including reduced costs and improved strength in complex pieces. While the initial production lot was fabricated using conventional methods, all subsequent lots have been produced using additive manufacturing for certain components, and the percentage of components manufactured in this way has increased with each lot. Acheron and Mitsubishi have touted the reduced costs and superior durability as the primary benefits of the program. Composites are also heavily utilized throughout the missile, contributing to its lower radar cross section than conventional missiles of similar size.
Depending on the desired engagement parameters and tactical situation, the SAR-775 can be launched in one of several different modes for air-to-air engagement:
- Active launch: This mode activates the onboard seeker immediately in search of targets designated by the launch aircraft either immediately before or immediately after launch. Active launch is designed for short-range engagements where the mid-course cruise phase is eliminated and the missile is already within terminal range of its target. Although the missile can continue to receive data link updates during this period (including assignment to a different target), it is designed for fire-and-forget use, allowing the launching aircraft to retreat while the target is forced on the defensive.
- Inertial active: This mode launches the missile on a course to a predetermined location outside the range of the missile's seeker at launch. Upon launch, the missile is directed toward this location via satellite and/or inertial navigation and activates its seeker, searching for targets in the vicinity. This mode allows the launching aircraft to engage targets outside the missile's terminal range without the use of the data link, which may reveal the launch aircraft. It also allows the aircraft to immediately retreat as the missile needs no further input. Because the missile receives no updates in flight, the effective range against maneuvering targets is reduced as the missile must manually search out its targets, which may be farther from the target location than predicted.
- Command inertial: This mode uses the data link to provide continuous updates to the missile's trajectory, allowing it to fly the most efficient course toward its target while conserving seeker power for the terminal phase. This is the longest-ranged mode of operation but requires the launching fighter to provide continuous updates to the missile's course, potentially revealing the presence of the launching aircraft. It also requires the launch aircraft to continuously track the target until the missile enters the terminal phase and its onboard seeker takes over. Due to the common nature of the data link, other aircraft may be used to guide the missile on target aside from the launch aircraft, allowing for full cooperative engagement capability.
- Home-on-jam: In a noise jamming environment the missile may be launched with a directive to home in on the source of the jamming signal. In this mode the missile seeker is entirely passive, relying on signals received from the jamming source for guidance. Range is dependent on the strength of the jamming signal.
- Defensive mode: In this mode the missile is immediately launched without a selected target and is programmed to lock on to the first thing the seeker can detect. This is considered a mode of last resort, but allows the launch aircraft to immediately present a threat to a potential target, forcing potential attackers on the defensive to avoid being acquired by the active missile.
The missile can be programmed to fall back to one or another mode if circumstances change, such as if a data link connection is lost during the mid-course phase. In this case, the missile may be pre-programmed to fall back on a designated fixed location or continue along its current trajectory to a determined range before going active. It may also revert to active seeking from home-on-jam mode if the jamming signal is lost and can continue along the same trajectory until a target is locked.
In addition, Nagisa has several ground modes for SEAD use. These modes generally do not use the onboard X-band seeker and instead focus on passive homing with inertial and satellite supplementary guidance. Terminal guidance is provided by the millimeter wave sensor.
- Targeted strike: In this mode the missile is launched against a pre-selected target located either through separate reconnaissance or via the aircraft's onboard sensors. The missile flies toward this selected target and activates its millimeter wave seeker in the terminal stage. Because this enables the missile to be used against targets outside of the seeker's own detection range, it is the longest possible range at which Nagisa can be employed and can even be used as a stand-off general strike weapon.
- Self-protection: This mode allows the missile to be launched immediately against a threatening target, such as a radar emitter within proximity to the carrying aircraft. In this mode the threat is within the seeker's detection range and the missile is self-guided through impact. This allows the missile to be quickly launched against a pop-up threat.
- Captive sensor: This mode allows the onboard seeker to be used as an additional sensor. This mode is only usable when the missile is carried externally and as a result is rarely used by fifth generation fighters, which instead rely on their advanced onboard passive detection suites. The captive sensor mode allows the missile to be used in an anti-radiation capacity even by fighters not designed for the role, although the range of the onboard sensor is inferior to that of dedicated targeting pods.
Description
Seeker
Nagisa is the first Carthaginian air-to-air missile to implement the Common Seeker Architecture, a set of software and hardware standards designed to streamline the replacement and upgrade process for installed seekers. The architecture allows different components, such as the RF sensor and AESA elements or the processing components, to be easily replaced in the event of upgrades without the need to replace the entire seeker section. This allows future sensors to be integrated into the existing processing and flight control system or more powerful signal processors to be added for increased resistance to jamming.
The initial low-rate production run was built using the Acheron Technologies RS-340A seeker due to production difficulties with the Bodastart 2MD40-ME seeker. The RS-340A provides detection capabilities in the L- and X-bands but lacks the millimeter wave sensor integrated into the 2MD40-ME seeker for improved terminal resolution. Approximately 400 missiles were produced in this configuration, but beginning with Lot 2A all missiles have been equipped with the Bodastart seeker. Beginning in 2014, all missiles equipped with the RS-340A underwent a refit and have now been re-equipped with the 2MD40-ME seeker.
The Bodastart IntelliMach 2MD40-ME dual-band seeker incorporates X- and K-band functions, relying on the X-band for long-range search and acquisition and the K-band for shorter-ranged terminal engagement. The combination of two radar bands makes the seeker much more difficult to defeat by conventional electronic countermeasures and provides significantly improved accuracy in the terminal phase. Combined with the expanded onboard memory and processing systems, the missile is capable of distinguishing via a separate MMW sensor specific features of the target, allowing the missile to engage specific vehicles in a formation or specific features of a larger unitary target. Due to this improved resolution, the seeker also integrates fuzing functions.
Fuze
The SAR-775 is equipped with an integrated fuzing system, with the millimeter wave sensor fulfilling the role of the standard RF proximity fuze. This is the preferred mode of operation and is designed to detonate the missile at the optimum stand-off distance from the target for maximum damage. The impact fuze is used in the event the RF fuze fails to trigger and automatically detonates the warhead upon collision. The self-destruct fuze is automatically activated if the onboard control system detects a dangerous malfunction, the missile expends its useful energy without acquiring a target, or upon remote command by the launching (or other friendly) aircraft.
Warhead
Nagisa is equipped with the AW/LWM-2342 25 kg (55 lb) multi-mode blast fragmentation warhead. Upon reaching the optimum standoff distance, the warhead is triggered to fire by one or both of two initiators. Firing the rear initiator creates a forward-focused blast effective against head-on targets, while firing both initiators creates an annular blast most effective against targets surrounding the missile. In both cases fragmentation of the warhead casing and missile body is designed to produce significant amounts of shrapnel in addition to the blast effects. Based on its intended use, the warhead is designed to be effective against both light ground targets such as radar installations and unarmored vehicles as well as a wide range of aerial targets from strategic bomber aircraft to cruise missiles. The estimated lethal radius of the warhead against aerial targets is 20 metres (66 ft).
Propulsion and control
The SAR-775 is propelled by a throttleable ducted rocket rather than a conventional solid rocket motor as in the SAR-778. The ducted rocket is a solid-fuel ramjet design using a solid rocket motor to boost the missile from its launch velocity to a velocity sufficient for the ramjet to take over propulsion for the remainder of the flight. The ramjet is fed by intakes on either side of the missile body which remain sealed during the boost phase. Speed is controlled by varying the throat area of the gas generator, which alters the compression and burn rate of the solid fuel. The variable thrust system allows the missile to throttle down in the cruise phase while retaining sufficient propellant in the terminal phase to maintain pursuit much longer than missiles powered by solid rocket motors. As a result, the SAR-775 has a much larger no-escape zone than the solid rocket-propelled SAR-778.
Maneuverability is provided by four fins at the rear of the missile along with a paddle thrust vectoring system for the ramjet exhaust. Unlike previous missiles using skid-to-turn control laws, the SAR-775 uses more advanced bank-to-turn logic, taking advantage of its lifting body design to reduce energy loss during turns. The air-breathing ramjet also necessitates bank-to-turn logic to minimize sideslip and maintain a steady flow of air into the gas generator. The SAR-775 is designed to engage targets maneuvering at up to 12 g, allowing it to engage nearly all manned aircraft, unmanned aerial vehicles, and most cruise missiles.
Data link
Nagisa uses a standard RF data link to receive mid-course updates on target positioning or even potential new targets in the event the original target is lost or destroyed. This information can be supplied by the launch aircraft as well as other data link-enabled aircraft in the vicinity, allowing the missile to be "handed off" to another aircraft (such as an AEW&C craft) while the launching aircraft retreats or switches to another task. The data link provides two-way communication capabilities, receiving targeting information and returning data on kinematic performance, system status, seeker view, and confirmation of target acquisition.
Maintenance and support
SAR-775 units are delivered from the factory as sealed rounds in rectangular containers. Each container contains basic diagnostic equipment and connections to be plugged into an automated inventory management system in either a land-based munitions depot or an aircraft carrier's armory. In more space-limited environments, the missile may be removed from its travel case for storage. The automated diagnostic and monitoring system is designed to significantly reduce maintenance manpower requirements, allowing faults to automatically be detected and the missile removed from storage for servicing without the need for manual inspections. The system also allows new software updates to be rapidly installed across the current inventory.
Launch platform
The SAR-775 is designed for launch from a variety of aerial platforms and incorporates a folding-fin mechanism to allow storage in the internal payload bays of modern stealth fighters such as the RFM-202 Shaheen. When used in an anti-radiation capacity it may also be carried by tactical bombers and interdictors for deep strikes against enemy air defense networks. Current-generation RFM-200DM1 and RFM-201DM1 aircraft can also carry the missiles conformally on their fuselage hardpoints, reducing penalties to radar cross section and detection range.
Although proposed for ground-based use, no such tests have taken place. The unusual geometry of the missile precludes it from being quad-packed into surface launchers like the Mark 18 VLS, which has limited interest in adopting the missile for surface use over the existing SAR-778 Sakura. The SPM-782 Hakurei MPMM, which uses the same body as the SAR-775 but a different engine and payload, has been successfully adapted for vertical launch via rocket booster.
Operational history
First combat use for the SAR-775 occurred in July 2014, two years after entering service when four Air Forces RFM-201DM1 Gyrfalcon Evos engaged six South Kilovosk MiG-29s during the Second Kilovosk Civil War. All six MiG-29s were shot down with no losses to the Carthaginian fighters, with four MiG-29s downed by Nagisas and two at short range by SAI-774 Sayakas. Throughout the conflict, an additional 63 fighter aircraft plus 124 aircraft of other types would be shot down using the SAR-775 as compared to 16 fighters and 31 other aircraft shot down using SRAAMs.
With a total of 207 Nagisas fired, the resulting Pk of the SAR-775 during the war was over 90%, although none of the aircraft engaged possessed fully modern ECM or self-protection suites.
Since the conclusion of the Second Kilovosk Civil War, no further uses in anger have been recorded. Missile procurement remains underway and Acheron Technologies and Mitsubishi have been contracted to provide another 2,000 missile lot as of the 2015 procurement budget. Although the missile has not yet been formally exported beyond its development partners, a deal with United Kilovosk to equip its new RFM-201DM1 Gyrfalcon Evos is considered likely.
Operators
- Carthage
- Carthage Air Forces
- Punic Navy
Japan
- Imperial Army
- Imperial Navy
Gensokyo Republic
- Republic Aerospace Corps
- Republic Navy