The H -I was a Japanese carrier rocket. It was based on the Japanese N-II, which was a built in license American Delta rocket. As the N-II, was the HI from a Thor - lower level with 6 or 9 Castor II boosters, but in comparison to the N-II significantly larger upper. This stage was powered by a completely developed in Japan LE -5 engine. All take-offs of the 139 -ton missile were successful, but a commercial payload was due to the high price never promoted. For GTO missions, the HI could be started with a third solid stage. Your first launch took place on March 13, 1986 ( local time), the last on 11 February 1992.
The first stage engine using RP -1, and liquid oxygen (LOX ), as a fuel, the use of the upper level of liquid oxygen and hydrogen. The booster and the optional third stage solid propellant worked. The satellites were placed in a mass payload fairing of nearly 8 m in length, 2.44 m in diameter and 600 kg.