Sky Bow

The Sky Bow series of surface-to-air missiles were developed by the Republic of China (Taiwan) and are currently in used for air defense purposes.

Development
The development of the Sky Bow 1 (Tien Kung 1) missile system was started in 1981 by the Chungshan Institute of Science and Technology (CSIST). Firing trials started in 1986, using a semi-active radar seeker. A passive IR terminal seeker was also developed as a secondary seeker for the TK-1, this was successfully tested against a HAWK missile target but never put in the production missile. CSIST also developed a large multifunction, phased-array radar known as Chang Bai (long white) for use with the Tien Kung (Sky Bow) series surface-to-air missile systems with 120 degree coverage and a maximum range of 450 km. Two versions of the phased array radar exist, a towed trailer radar and fixed "hardened" radar sites.

The Chang Bai radar system is reported to be based on the Lockheed Martin's ADAR-HP (Air Defense Array Radar-High Power) design and operates in the 2–4 GHz range (S-band). At least seven systems are said to be currently in service. The system performance specifications remain classified, but its reported effective detection range against 1m2 target to be around 400 km.

There was also a mobile version of the phased array radar developed in the late 1990s which could provide all-round radar cover with four separate faces but with a much decreased detection range. This version only appeared in public once but was never put into service. The development of Sky Bow 2 started around 1986, this added a tandem boost motor and an active radar terminal seeker. Proposals were reported to develop Sky Bow 2 into a surface-to-surface missile; unconfirmed reports suggest that this missile is known as Tien Chi. Modifications have been developed for Sky Bow 2, changing it into a single stage rocket and to provide it with a limited capability against shorter-range ballistic missiles; the first test firing against a ballistic missile target was reported in September 2008. Seven batteries of TK-1/2 SAMs are in service and deployed throughout Taiwan, on the Pescadores, and Dong Ying island.

Sky Bow I
The Sky Bow I (TK-1) (天弓一, Tien Kung I) is a surface-to-air missile (SAM) system developed by the Chungshan Institute of Science and Technology (CSIST) in Taiwan, ROC. Originally based on the aerodynamics of the MIM-72 HAWK missile, the original missile design resembled a scaled-up Raytheon AIM-54 Phoenix. The TK-1 missile was subsequently redesigned and eventually became very similar in appearance to the US Patriot missile after the US government allowed Raytheon to transfer 85 percent of the MIM-104 Patriot missile technology. There is no track-via-missile (TVM) homing capability as this technology was not included in the technology package licensed to Taiwan; the TK-1 system operates in a similar manner to the US Standard SM2 missile, requiring an illuminating radar during the terminal phase.

The TK-1 is designed primarily to target low and medium altitude attacks. Each TK-1 battery has one Change Bai S-Band phased-array radar for search and target tracking and two CS/MPG-25 target illuminator radars that operates in the X-Band (18–32 GHz) range for the terminal phase, servicing three or four 4-round missile launchers. The combination of inertial/autopilot and mid-course command guidance with a terminal semi-active radar seeker allows the TK-1 missile to fly an energy-efficient flight path to the vicinity of the target where the seeker's semi-active radar would then receive target illumination for the final seconds of the engagement, giving the target minimum amount of time either to evade or commence electronic countermeasure (ECM). The CS/MPG-25 is a continuous wave disk antenna illuminator radar with a 200 km range that is solely developed by CSIST, and was derived from the I-HAWK AN/MPQ-46 High-Power Illuminator (HPI) radar but is estimated to be 60 percent more powerful in output with improved EW, ECM, and IFF capabilities. It is tied into the main phased-array radar on a time-share basis similar to that employ by the US Navy's AEGIS air defence system, allowing the TK-1 surface-to-air missile system multiple target engagement capability.

Two versions of the missile launcher exist, one is housed in underground shelters designed to survive an intensive attack. The other is a towed mobile version, and is an integral part of Taiwan's dense air defense network. In addition to bases on Taiwan proper, the TK-1 has also been deployed by the ROC Army on the outlying islands of Penghu and Dong Ying, bringing all of the Taiwan Strait and parts of the PRC's Fujian, Zhejiang and Guangdong Provinces within range.

It was reported in Jane's Missiles and Rockets, August 2006's issue, that the Tien Kung 1 surface-to-air missile (SAM) system would be retired. The TK-1 missiles would be replaced with TK-2 missile rounds and the existing TK-1 system would be upgraded with radar and training simulator to the Tien Kung II standard.

General characteristics

 * Primary Function: Surface-to-air missile
 * Power Plant: Single stage dual thrust solid fuel rocket motor
 * Launch platform: Towed quad launchers and underground silos
 * Length: 5.3 m
 * Diameter: 0.41 m
 * Weight: 915 kg
 * Top Speed: Mach 4.0
 * Range: 100 km
 * Guidance: Inertial with mid-course guidance update from ground based phased array radar, Semi-active radar homing (SARH) for terminal guidance
 * Date Deployed: 1993

Sky Bow II
The Sky Bow II (TK-2) (天弓二, Tien Kung II) is a SAM system also developed by the Chungshan Institute of Science and Technology. Originally a TK-1 with a first-stage booster, the system became a slightly-enlarged modified version of the Sky Bow I (TK-1) missile using an X-Band active-radar seeker, with a longer range and limited anti-missile capability. The TK-2 active radar seeker operates in the 28–32 GHz frequency range and provides reasonably good performance against air-breathing targets of typical aircraft size. The X-Band active radar seeker used on the TK-2 SAM system was developed from licensed radar technology that CSIST purchased from the U.S. in the 1980s.

The TK-2 also have the added benefit of being able to use the same box launcher as the TK-1. Internal components were replaced with miniaturized parts to take advantage of modern electronics technologies, yielding extra room within the missile for more fuel and a more powerful main rocket motor. It is speculated that the earlier TK-2 design has been developed into a surface-to-surface missile. The TK-2 has also been modified for use as a sounding rocket to perform upper atmospheric research for the civilian space program. The sounding rocket test vehicle launched on December 24, 2003, measures 7.7m in overall length and 1,680 kg in launch weight. It reached a maximum altitude of almost 270 km and splashed 142 km down range around 8 minutes after launch into the Pacific. The science mission payload was in the 220 lb weight class and the rocket reached a burnout velocity of 2,000 m/s. According to the report from Taiwan Defense Review, depending on its payload and launch parameters, the rocket can be converted to attain a horizontal maximum range of up to 500 km.

General characteristics

 * Primary Function: Surface-to-air missile
 * Power Plant: Single stage dual thrust solid fuel rocket motor
 * Launch platform: Underground silos
 * Length: 5.673 m
 * Diameter: 0.42 m
 * Weight: 1,135 kg
 * Top Speed: Mach 4.5
 * Warhead: 90 kg
 * Range: 200 km
 * Guidance: Inertial with mid-course guidance update from ground-based phased array radar, Active radar homing (ARH) for terminal guidance
 * Date Deployed: 1998

Sky Bow III
The Sky Bow III (TK-3) (天弓三, Tien Kung III) is the third generation version of the Tien Kung family of surface-to-Air missile (SAM) systems developed by the Chungshan Institute of Science and Technology (CSIST) in Taiwan.

It was reported that Taiwan had initially sought and even proposed a joint development effort to co-produced a missile defense interceptor with the U.S., Taiwan officials asked for U.S. technical support for Taiwan's indigenous anti-tactical ballistic missile (ATBM) effort, including the transfer of Hit-to-Kill (HTK) technologies, specifically those related to an active radar Ka-band seeker and precision attitude control. CSIST was reported to had sought the release of the associated traveling-wave tube (TWT) transmitter of the Ka-band active radar seeker technology. However, U.S. refusal of the export release of a complete Ka-band active radar seeker without tamper protection or to provide the TWT on a stand-alone basis, forced CSIST to use a different (see below for related discussion) active radar seeker technology with significant European content.

The TK-3 (formerly known as TK-2 ATBM) is a lower-tier missile defense system based on the TK-2 missile that uses an imported Ku-Band (12–18 GHz) active radar seeker, a directed fragmentation warhead, and improved precision controls for engaging high-speed, low radar cross-section (RCS) targets such as tactical ballistic missiles. It is designed with greater mobility in mind than the original TK-1/2 systems, with an integrated battle management system, and uses an upgraded Chang Bai phased array radar or with the new mobile phased-array radar that is reportedly called the Mobile 3-Dimensional (3D) Air Defense Fire Control Phased Array Radar (Mobile 3D ADFCPAR).

The upgraded Chang Bai phased array radar is reportedly called the Chang Shan ("Long Mountain") radar system,  it will reportedly increase the radar's radiated power over the Change Bai system by 170%, employs four times the number of phase shifter elements vis-a-vis the Chang Bai radar system, with substantial improvement in tracking ability to include tactical ballistic missile warhead sized targets, and with a reported range of 1,000 km.

The new mobile radar bears a striking physical resemblance to the Patriot's Raytheon AN/MPQ-53 radar system. It is reported to operate on the C-Band (4–8 GHz) frequency range, and like the AN/MPQ-53 system, it is trailer-mounted with a rectangular planar array radar of approximately similar size. However, it does not appear to have any identifiable missile guidance sub-array like those found below the main array on the AN/MPQ-53 system and it is therefore not clear if this new radar can provide target guidance illumination function in support of TK-1 SARH missiles. However, this should not present any problem for the new radar to be utilized on both TK-2 missile (X-Band) and TK-3 missile (Ku-Band) active radar seekers, as these missile systems does not require target illumination. The new radar enhances the survivability and operational flexibility of the TK2/3 missile systems by allowing a TK surface-air-missile battery to be deployed rapidly to a previously unprepared site. Unlike the TK-1/2 systems, TK-3 missile system uses vertical launch cells drawn by a transporter-erector-launcher and the TK-3 is reported to have a maximum range of better than 200 km. It was officially revealed on the October 10, 2007, military parade. By summer in 2013, it enters mass production and becomes a part of Taiwan's Anti-Tactical Ballistic Missile (ATBM) project, Taiwan's planned missile shield. The R.O.C.(Taiwan) develops the Sky Bow III missiles to engage stealth aircrafts such as J-20/31 with the AN/MPQ-53 system of PESA radar.