SST-722 torpedo
| SST-722 Torpedo | |
|---|---|
 | |
| Type | Supercavitating torpedo |
| Place of origin |  Carthage |
| Service history | |
| In service | 2008–present |
| Used by | Carthage Gensokyo Republic |
| Production history | |
| Designer | Hayami Marine Technologies Naval Armaments Research Center |
| Designed | 2000-2008 |
| Manufacturer | Hayami Marine Technologies RMA Corporation |
| Unit cost | NSD$4.4 million (FY2014) |
| Produced | 2008-present |
| No. built | 2,400 |
| Variants | Mark 1 Rev. 4 |
| Specifications (Mark 1 Rev. 4) | |
| Weight | 3,250 kg (7,170 lb) |
| Length | 8.21 m (26.9 ft) |
| Diameter | 660 mm (26 in) |
| Effective firing range | 5 km (3.1 mi) in snapshot mode |
| Maximum firing range | 25 km (16 mi) |
| Warhead | Aluminised PBX explosive |
| Warhead weight | 375 kg (827 lb) |
Detonation mechanism | Proximity or contact |
| Engine | LQ34A liquid-fuel rocket |
| Maximum depth | Greater than 1,000 m (3,300 ft) |
| Speed | 350 knots (650 km/h) |
Guidance system | Active sonar Inertial guidance |
Launch platform | Submarine |
The SST-722 Starlight Typhoon is a heavyweight supercavitating submarine-launched torpedo developed in Carthage and in service with the Punic Navy. The Starlight Typhoon is the first supercavitating torpedo in active Carthaginian service, designed to supplement the SST-720 Double Spark and SST-721 Master Spark heavyweight torpedoes as the primary anti-ship and anti-submarine armament of Punic Navy submarines. Unlike earlier supercavitating torpedoes used in other navies, the SST-722 incorporates active sonar guidance for target acquisition at longer ranges.
History
Despite basic research into the field of supercavitation in the 1960s and 1970s by development agencies, Punic Navy submarine officers resisted proposals to develop a supercavitating torpedo, on the grounds that such programs would draw funding away from other development projects and lead to a mindset with a reduced emphasis on acoustic quieting and submarine performance. Prevailing doctrine held that a focus on submarine quieting, extremely sensitive passive sonar, and sufficiently long-ranged conventional torpedoes and missiles would be sufficient to maintain an advantage over European submarine designs. Under such conditions, there would be no need to develop a high-speed, short-range weapon, especially one as noisy as a supercavitating torpedo.
Throughout the 1980s, European submarine designs began making large advances in acoustic quieting and passive sonar, largely bridging the gap between Carthaginian and European boats in terms of speed, quietness, and detection ability. In March 1989, a European Type 209 submarine was discovered tailing the Punic Navy submarine SN-3067, with SN-3067 having been unaware of its pursuit until intentionally alerted at a range of less than 2 kilometers (1.2 mi) by an active sonar ping. A second incident occurred six months later in which European and Carthaginian submarines collided, with neither having been aware of the other's presence and sudden maneuver beforehand. These incidents demonstrated the considerable advances made in European submarine construction and the narrowed technological lead possessed by Carthaginian submarines.
In response to these incidents, the Punic Navy submarine command initiated a study program, Future Concepts in Undersea Warfare, to analyze new technologies and trends for consideration in future construction. In addition to new designs and technologies for inclusion in future submarine classes, the study investigated new weapons concepts, including the use of supercavitating torpedoes for short-range engagements. In both 1989 encounters, analysts concluded that conventional heavyweight torpedoes would have been unable to engage the threat boat within the expected engagement window. Furthermore, future trends indicated that sufficiently quiet submarines would very likely be capable of approaching within very short range of each other undetected by passive measures, increasing the likelihood of a short-range engagement. Under such conditions, a high-speed, short-range weapon would be desirable as a defensive measure, to offset a potential enemy advantage in the opening salvo.
The report concluded that among other systems for detailed investigation, the development of a high-speed "knife fight" weapon should be considered, recommending the development of a supercavitating torpedo capable of integration with existing torpedo tubes and handling systems. Such a weapon could suffice with a relatively short maximum range, and would be focused on minimizing the engagement cycle to allow an ambushed submarine to counterattack its assailants rather than remain entirely on the defensive.
Advanced High-speed Torpedo program
As a result, in 1996 the Advanced High-speed Torpedo program was funded by the legislature, with the goal of developing a 660 mm (26 in) supercavitating torpedo. By this time, the Russian VA-111 Shkval had entered service and an upgrade program in development, and intelligence reports indicated that European and Asian powers had begun investigating the development of such weapons as well. In 1998, the contract for torpedo development was awarded to Hayami Marine Technologies, with the stipulation that research and testing be conducted with the assistance of the Naval Armaments Research Center, which had developed a number of the baseline technologies for incorporation in the design.
In 2002, the first full-scale test vehicle was launched at the Naval Armaments Test Range in the Canary Islands. The test vehicle reached the expected 200-knot (370 km/h) speed requirement, matching the performance of the initial-production VA-111. Two months later, the submarine command issued a new speed requirement of 400 knots (740 km/h), later revised downward to 350 knots (650 km/h), requiring an additional three years of development time and testing to meet the new requirements. The first full-scale test of the improved torpedo body was conducted in 2005, and met the uprated speed requirements.
The first fully-functional test, including onboard sensors and guidance, occurred in 2006, with onboard tests from active fleet submarines continuing throughout 2006 and 2007. In 2008, the completed SST-722 Starlight Typhoon design was certified for service and low-rate initial production commenced. First deliveries to fleet submarines occurred in May 2009 with submarines of the Southern Fleet. An estimated 20,000 torpedoes will be procured throughout the lifetime of the program.
Operational features summary
The SST-722 Starlight Typhoon is designed as a complement to the SST-720 Double Spark and SST-721 Master Spark, intended for use as a defensive weapon at comparatively shorter ranges than the quieter, longer-ranged but slower Spark series. With an extremely high transit speed, the SST-722 is designed to give targets little time to react and to force them on the defensive to avoid impact. At its maximum speed of 350 knots (650 km/h), the Starlight Typhoon can reach its maximum range in slightly more than two minutes, compared to the over ten minutes required of the SST-721 to reach the same distance.
Despite its tremendous speed advantages, the enormous noise caused by the torpedo's rocket motor and gas generator prevent stealthy use, and the high rate of propellant consumption limits range compared to the slower SST-721. As such, the SST-722 is generally reserved for short-range combat against other submarines or urgent surface threats that pose an imminent danger to the launch platform. The Starlight Typhoon is designed to be fired in two distinct modes depending on the target's range and immediate threat level:
- Snapshot mode: The torpedo is fired at a target within 5 kilometers (3.1 mi) of the submarine, using inertial guidance to home in on a preselected location derived from the launching submarine's onboard sonar. In this mode, the torpedo remains at supercavitating speed throughout its engagement. With a maximum speed of 350 knots (650 km/h), the Starlight Typhoon can close this distance in approximately 30 seconds, giving little time for evasion or other defensive measures.
- Homing mode: The SST-722 is fired at a more distant target up to 25 kilometers (16 mi) away, transiting at its supercavitating speed before slowing to 70 knots (130 km/h) for terminal engagement and activating its onboard sonar. The use of onboard sonar compensates for a greater uncertainty volume at range while allowing the torpedo to close to terminal range in less than three minutes.
In both modes, the torpedo is initially launched at a swim-out speed of 50 knots (93 km/h) before activating its gas generator and main rocket motor and accelerating to its transit speed. With its high flow noise and the noise created by the rocket motor, sonar guidance is impossible at transit speed, necessitating the reduction in speed for terminal guidance in homing mode.
Characteristics
Guidance
The SST-722 incorporates both inertial and active sonar guidance modes for use at short and longer ranges against a variety of targets. When launched the torpedo proceeds under inertial guidance at transit speed, which creates too much noise for the use of onboard sonar. For short-range engagements, the torpedo's entire flight may be conducted under INS, with the torpedo detonating under the influence of its magnetic detonator or at a preset location.
For terminal engagement at longer ranges with a greater uncertainty volume, the torpedo slows to a speed of 70 knots (130 km/h) to search for and acquire the target. In this mode the seeker may be tasked to look for specific signatures and ignore others to prevent friendly fire incidents.
Warhead
Although shorter and much heavier than the SST-721 which uses the same 450 kg (990 lb) warhead as the previous Type-27 Mark 2, the greater space allocation to the propulsion systems required the installation of a slightly smaller warhead of 375 kg (827 lb). The smaller warhead uses the same aluminised PBX shaped charge construction as the larger, allowing it to penetrate thick submarine pressure hulls and surface ship torpedo protection systems.
The warhead may be triggered via magnetic sensor, active sonar, or impact fuzing, depending on the engagement mode selected. This allows the torpedo to effectively engage even titanium-hulled submarines which may be resistant to magnetic fuzes. Alternatively, the torpedo may be set to detonate at a certain distance in the event it fails to lock on or is unable to activate its active sonar.
Like the Master Spark, the Starlight Typhoon is also capable of accepting the 10 kiloton R-47 nuclear warhead, although none are believed to have been manufactured in this configuration.
Propulsion
The SST-722 is propelled by a thrust-vectoring LQ34A liquid-fuel rocket motor in conjunction with a steerable cavitator including a gas generator to sustain the friction-reducing gas sheath. When accelerating to transit speed, the cavitator is designed to induce a cavitation bubble, into which additional gases from the gas generator are injected to expand the bubble and ensconce the entire torpedo. The rocket motor is throttleable, allowing the torpedo to accelerate and decelerate during different phases of attack.
Steering is provided by the nose cavitator as well as the motor's thrust-vectoring mechanism as the gas sheath and high speeds make conventional control surfaces ineffective. Four cavity contact sensors are arranged toward the rear of the torpedo body to stabilize the torpedo during travel and provide feedback to the cavitator.