The third currently operational series in the CZ family is the CZ-4 (also referred to as the CZ-4A) which to date has been employed only twice for inserting payloads into sun-synchronous orbits. Both flights in September of 1988 and 1990, respectively, lofted the PRC's first domestic meteorological satellite Feng Yun-1. The CZ-4 is a 3-stage launch vehicle carrying UDMH and nitrogen tetroxide for all stages. The CZ-4 first stage uses the same power plant as the CZ-3A but is nearly two meters taller. Likewise, the CZ-4 second stage is similar to that of the CZ-3A. The CZ-4 third stage is a specially designed unit powered by the YF-40 main engine. The payload capacity of the CZ-4 into a sun-synchronous orbit is cited as 2.5 metric tons (References 159, 189-190).
159. Zhao Bing, "A System Analysis of the Launch Vehicle Technology in China", Paper 92-824, 43rd Congress of the International Astronautical Federation, August-September 1992.
189. LM-4 Launch Vehicle, specification sheet distributed by China Great Wall Industry Corp., 1992.
190. Long March-4, specification sheet distributed by China Great Wall Industry Corp., 1991.