Yu-6

Yu-6 (鱼-6) torpedo is the Chinese counterpart of the US Mark 48 torpedo, and it is the first domestic Chinese torpedo designed to counter both surface ships and submarines from the very start. Guidance can be by wire, active and passive homing, or wake homing. Domestic Chinese sources have claimed that the Yu-6 torpedo is in the same class as the Mk 48 Mod. 4 torpedo, but official information on the Yu-6 torpedo is limited.

At least one Mark 48 torpedo was reportedly recovered by Chinese fishermen in the late 1970s or early 1980s, and the government of China might have begun reverse engineering in the 1980s. However, due to the inexperience of the Chinese technological base at the time and the concentration on economic development, most of the reverse engineering project was put on hold after research had been completed on Otto fuel II, wire guidance and some other subsystems; some research continued on a much smaller scale. The Yu-6 torpedo development program was revived when the Chinese military realized that despite developing several torpedoes including the Yu-1, Yu-2, Yu-3, Yu-4, and Yu-5, the obsolete doctrine of having separate ASuW and ASW torpedoes was unsuited for modern naval warfare, and the Chinese navy needed a torpedo for both ASuW and ASW. As a result, the Yu-6 program was fully resumed in 1995 and 705th Institute was named as the primary contractor, with Dong Chunpeng (董春鹏) as the general designer.

Development of Yu-6 begun in 1995, which took an entire decade to complete when the torpedo was finally ready in 2005. One of the difficulties encountered was that the Yu-6 torpedo had greater operating depth than all previous Chinese torpedoes. A brand new alloy was required to cast the outer casing of the Yu-6 torpedo; under the leadership of Ding Wenjiang (丁文江), professor of material science at Shanghai Jiao Tong University, the problem was solved when ZLJD-1S alloy was successfully developed and used to cast the casing for Yu-6 torpedo. He Yuyao (贺昱曜) was in charge of developing the power module for the newly developed computer of the Yu-6 torpedo, which took three years, from 1999 to 2001.