From Q to N to H, from Technological Dependence to. Independence
While ISAS was working on the K, L, and M series of solid booster rockets in the early 1960s, NSDC, the precursor of NASDA, worked on solid – and liquid – fuel rockets designated as the JCR (Jet Controlled Rocket) and the LS-C series. Both the JCR and LS-C rockets were two-stage rockets, the first using solid fuels only, the second a combination of solid and liquid fuels. Both were later built into a three-stage Q rocket, which was in turn overtaken by the more powerful N (Nippon) launcher built with American help. Work on Q was not entirely wasted, however. Flight-testing of the JCR helped develop the control system of N-1, while a liquid stage from the LSC was later adopted as the second stage of N-1, which made its maiden flight in 1975.
The successful N-1 launch vehicle built after the 1969 agreement comprised three stages. The liquid first stage was adopted from the Thor-Delta Vehicle produced by McDonnell Douglas. The liquid fuel used was LOX and RJ-1 propellants. The engine for this first stage was produced in Japan under license with technological assistance from Rocketdyne. To give added thrust it had three strap-on boosters, Thiokol’s Castor II-TX354-5, which were also produced under license in Japan. The second-stage engine was adopted from the Q rocket, as mentioned a moment ago, with some American assistance. It used nitrogen tetroxide and Aerozine 50. NASDA wanted to build this stage in Japan indigenously so as to retain some Japanese component and as a platform for building its own stages in future. Mitsubishi Heavy Industries (MHI) constructed the rocket engines for the second stage. The third-stage motor was imported from the United States.
During the 1970s N-1 launched six satellites into orbit including Kiku 2 (1977), Japan’s first geostationary satellite that was built indigenously based on American technology. It was upgraded for launching heavier satellites up to 350 kilograms and was designated N-2. Following the N series the logical step toward launching heavier application satellites led to the development of the H series of rockets. Preliminary studies on the H began in the mid-1970s and two test flights were conducted in August 1986 and August 1987. The first stage, strap-on boosters, and fairing were manufactured under license and the rest—cryogenic second-stage, inertial guidance system and the third-stage solid motor—were developed indigenously. Thereafter a fully indigenous more advanced rocket called H-II was developed in the mid-1980s with the first test flight on February 4, 1994. Though this was a technological triumph for Japan it was not a commercial success. The launch cost was around $190 million, which was twice the cost of a launch with the European Ariane or American Atlas.42
To overcome the cost problem Japan initiated the H-IIA development program, with the primary goal of cutting launch costs in half by increasing the launch rate. While Japanese technological independence was a primary purpose of the original H-II program, the overriding commitment to low cost in the H-IIA program led to contracts with ATK Thiokol in Utah, who supplied solid rocket booster technology. Boeing and Man technologies of Germany were also selected to produce core stage tank domes.43 Table 10.2 gives one some idea of the extensive presence of American firms in Japanese launcher development, and the gradual reliance on national industries to provide key components such as guidance and control.