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N-I, N-II, and H-I: The Nippon Delta
The National Space Development Agency of Japan (NASDA) was established in 1969 “to act as the nucleus for the development of space and promote the peaceful use of space.” To achieve these ends, NASDA was charged with the mission of developing satellites and launch vehicles along with the methods, facilities, and equipment required to launch and track the craft. Though Japan had the necessary heavy manufacturing and electronics industries, not to mention significant sounding rocket experience, it was felt that a purely domestic launch vehicle development program would take too long to get off the drawing board. Thus, in October 1970, an agreement was struck between NASDA and the United States for development of the N-I vehicle, a plan that jump-started Japan’s space launch capability.
N-I was essentially a Delta M, built for the most part in Japan with a number of subsequent minor differences from its American counterpart. The first stage was a Long-Tank Thor, built by Mitsubishi Heavy Industries (MHI) under McDonnell-Douglas license. The main engine was a Rocketdyne-licensed MB-3 Block III design built by Ishikawajima-Harima Heavy Industries (IHI), generating about 172,000 pounds of thrust. Three Castor-2 solid booster motors, built by Nissan under Thiokol license, provided liftoff augmentation.
The second stage was powered by the Japanese-designed LE-3 engine. Similar in size to the Aerojet AJ10-118F, which used the same propellants of nitrogen tetroxide and Aerozine-50, LE-3 provided 12,000 pounds of thrust in vacuum, with a specific impulse of 285 seconds, during a burn time of 250 seconds. This was about 2,300 pounds more powerful than the AJ10, but slightly less efficient and with significantly less burn time. LE-3 was built by MHI with a TRW license for its vernier steering engines.
For the third stage, N-I used the Thiokol TEM-364-14 (Star-37N) solid fuel motor, built by Nissan. A radio-inertial guidance system, built by Nippon Electric Co. Ltd. and most likely a licensed version of the Bell Labs BTL-600, was installed atop the second stage for flight control. The payload fairing was a U.S.-built import.
The first N-I launch took place on 9 September 1975 from Launch Complex Osaki at Tanegashima Space Center, south of Kyushu island. It carried Kiku (ETS-1), an 85-kg engineering test satellite that was used for technical experiments regarding satellite tracking, launching and control technologies, and basic measurements of the satellite environment. On 23 February 1977, the third N-I rocket launched Kiku 2 (ETS-2), Japan’s first geostationary satellite, making Japan the third country in the world to place a satellite in geostationary orbit. Between 1975 and 1982, seven N-I vehicles were launched. Of these, two flights were failures due to problems with their spacecrafts’ apogee kick motors.
Documentation for N-I lists its capacity at around 100-130 kg (220-285 lb) to GTO. Considering the similarity with the Delta M (with a capacity of 785 pounds), this figure likely omits the often-considerable weight of an apogee kick motor. (Encyclopaedia Astronautica, on the other hand, lists the GTO capacity at 360 kg [790 lb], which would seem more reasonable if not for other discrepancies in that site’s listing.) Tanegashima’s somewhat more northerly location versus that of Cape Canaveral, and/or vehicle flight path requirements, may be other factors. At any rate, N-I was quite underpowered for the next generation of applications satellites Japan was building. An upgrade was needed.
Rather than wait for a more powerful vehicle to be ready, NASDA chose to manifest two of its larger payloads aboard Delta 2914 rockets. In 1977, Delta 132 launched Himawari 1, a geostationary meteorological satellite that was Japan’s contribution to the international Global Atmospheric Research Program. The following year Delta 140 launched Yuri, a three-axis-stabilized experimental communications satellite that spent 3 years on station near 100 E longitude.
The N-II vehicle, flown eight times from 1981 to 1987, continuedand expandedJapanese dependence on U.S. launch vehicle technology. It was essentially an early version of the “Straight-Eight” Delta. First stage was an MHI-built Extended Long Tank Thor, likely powered by the IHI MB-3. Boosters remained Nissan Castor-2 motors, but were increased in quantity from three to nine. The second stage used the restartable Aerojet AJ10-118FJ (J for Japan) engine, built by IHI under license. The all-inertial Delta Inertial Guidance System (DIGS) was installed at the top of the second stage, but whether this was imported hardware or built by Nippon Electric is unknown to this author. The third stage was the TEM-364-4 (Star-37E) solid motor, built by Nissan under Thiokol license. An imported, 8-foot-diameter fairing protected the payload. All told, N-II was equivalent to a Delta 1904, a configuration that was conceivable in the numbering scheme but never in fact flown in the U.S. Capacity is listed at 350 kg (about 770 lbs) to GTO, though may have been as much as 1,200 pounds. All eight flights of N-II were successful.
Despite their reliability, the utilityand pride of ownershipof N-I and N-II were hampered by technology export restrictions that required many of the vehicle subassemblies and components to be imported, pre-assembled, from the United States. NASDA, heeding the call of the Japanese public and government, strove to gain its independence in the launch vehicle industry. The H-I rocket was the first step along that path.
H-I was very similar in appearance to N-II, and its first stage, boosters, and fairing remained identical to that predecessor. However, H-I stood 4.6 meters (about 15 feet) taller. This was primarily due to its all-new second stage, which was developed in Japan (without U.S. assistance) by ISAS and the National Aerospace Laboratory (NAL). It used the LE-5, a cryogenic LOX/LH2 engine built by MHI, IHI, and NAL with a specific impulse of 448 seconds. Its 8-foot diameter tanks had a common bulkhead and accounted for the increased length of the total vehicle. External insulation for the tanks gave a distinctive bulge to the second stage portion of the stack. Meanwhile Nissan, drawing on its experience in building Thiokol motors, designed a third stage with an average thrust of over 20,000 pounds during a 62-second burn.
H-I could deliver 1,100 kg to GTO. It flew nine times between 1986 and 1992, all to success, and delivered a total of 13 satellites to orbit. Among these were 4 telecommunications satellites and several others with applications in geodesy, ham radio, meteorology, ocean observation, and remote sensing.
H-I was followed by H-II, the first heavy lift launch vehicle to use exclusively Japan-developed technology. Development of H-II began in 1986, with its first flight in February 1994.
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