Cheng Kung-class frigate
The "Cheng Kung"-class frigates are guided-missile frigates (PFG) currently in service of the Republic of China (Taiwan) Navy (ROCN). They are based upon the U.S. and built by China Shipbuilding Corporation in Kaohsiung, Taiwan under license throughout the 1990s as parts of the "Kuang Hua One" patrol frigate, guided project. These frigates served as the mainstay of the ROCN's theater air defense prior to the ROCN's acquisition of "Keelung" ("Kidd")-class destroyers in 2005. Design. In order to control the new weapon systems on the frigates, which the Mk 92 Fire Control System could  not integrate at the time, a second Combat Direction System (CDS), the H930 Modular Combat System (MCS) was installed in order to control the 8 HF-2 (or four HF-2 and four HF-3 on certain ships) Anti-ship missile and the two Bofors 40mm/L70 guns. However, the Mk 92's Harpoon mode was deleted due to the US government refusal to sell the Harpoon missile system to Taiwan at the time. Also deleted were some of Mk 92's ASW modes, along with the refusal to sell SQR-19 Towed Array sonar system. Originally only two lead ships were going to  be built to this standard, with the remaining six ships in the class built under the ACS (Advance Combat System) project with a lighter AEGIS (that later became SPY-1F), 48-64 cell Mark 41 Vertical Launch System and other systems, and a plug-in section. Delay in the design and budget changed the project to four ships in PFG-1101 configuration and the last four ships in ACS configuration, then more delays changed to 6+2, then 7+1. By the mid 1990s, the ROCN decided the ACS project was too risky, too long and too over budget, finally  canceling it after the seventh ship was built to the PFG-1101 standard. However, enough of the long lead items were already purchased so that in late 2000, the ROCN decided to go ahead with the eighth ship's construction with PFG-1101 configuration—minus the two Bofors 40mm/L70 guns, after getting necessary funding. Upgrades. The "Cheng Kung" class was initially fitted with 8 × Hsiung Feng II ship-to-ship missiles, instead of the Harpoon missiles that the "Oliver Hazard Perry" class used. In 2001, ROCS "Cheng Kung" (成功, PFG-1101) was refitted with four Hsiung Feng III missiles, replacing four  of the Hsiung Feng II missiles. In 2009 ROCS "Chi Kuang" (繼光, PFG-1105) was seen with same configuration. All the other ships in the class received the new missile upon their major overhaul. Originally, all HF-2 missiles were to be removed, while 4-8 Harpoon were to be carried in the Mk 13 launcher's magazine (with the necessary upgrade to the ship's Mk 92 CDS which had a Harpoon control mode and functionality deleted when ship was built), and 8 HF-3 supersonic AShM to put in place of 8 HF-2 AShM, giving these ships a total of 12 -16 anti-ship missiles. But the Legislative Yuan refused to release funding for the CDS upgrade, and the ROCN had to settle for just 4 HF-2 and 4 HF-3 configuration. All ships had the Link 16 datalink installed. Seven out of eight ships added Bofors 40 mm/L70 guns for both surface and anti-air use. In 2014, the Republic of China Navy revealed plan to develop a naval air defense missile system derived from the land-based Sky Bow system. The "Cheng Kung"-class frigates are speculated to be one of the potential platforms to carry the system. On November  5, 2012 Taiwan announced the U.S. government would sell Taiwan two additional Perry-class frigates that are about to be retired from the U.S. Navy for a cost of US$240 million to be retrofitted and delivered in 2015. The Naval Vessel Transfer Act of 2013 was signed by President Obama in 2014, allowing up to four of the frigates to be sold to Taiwan. Two ships were eventually selected and were reactivated by VSE Corporation and transferred to Taiwan on 9 March 2017. These ships would replace aging Chiyang class (US ex-Knox-class frigate) vessels that joined the  ROC Navy more than 20 years ago. After the US stopped supporting the SM-1 and their associated launch system support was taken up by NCSIST which also implemented an upgrade program for the missiles. Upgrades to the SM-1 include a better rocket motor and an active seeker. The class's Mk 75 main guns have been upgraded and have an improved firing rate of 100 rounds a minute. Ships. The "Cheng Kung"-class frigates are named after historical Chinese generals who were famous for defeating foreign threats.