"1995-06-01Z"^^ . "Retired" . . . "2002-01-03Z"^^ . "28.22"^^ . "1"^^ . . "8.165e+07"^^ . "During the 1990's CALT developed an improved version of the DF-4 to test the reentry vehicle warheads of the DF-31. They took advantage of this development and offered it as the Long March 1D for commercial application. The modification included: An DF-4 improved first stage, which used the new version of the YF-2B, and switched propellants to UDMH/N2O4 for improved performance. The use switch of the second stage YF-3A, for the Long March 4 third stage engine, the YF-40."@en . . "2.25"^^ . "2"^^ . "3"^^ . "3"^^ . "Long March 1D"@en . .