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H-II

Dwarfing its predecessor, the H-II consists of a 2-stage core vehicle, burning liquid oxygen and liquid hydrogen in both stages, with two large solid-propellant strap-on boosters. Nissan produces the 4-segmented strap-on boosters which are considerably larger than the main stages of ISAS' M-3 and M-5 series vehicles. The LE-7 first-stage main engine overcame numerous developmental difficulties, while the LE-5A engine used by the second stage merely represents an upgraded version of the proven LE-5 flown on the second stage of the H-I (References 125-133).

The H-II launch vehicle, the central rocket in Japan's space program, with the capability to launch a two-ton class satellite into geostationary orbit, is a two-stage rocket that was developed with Japanese independent technology in all stages. In addition to geostationary satellite, it can also be used to launch payloads into low and medium-altitude orbits. For greater economy, it is possible to launch simultaneously two geostationary satellites weighing about one ton each.

The 1st stage had a large, high-performance liquid oxygen/liquid hydrogen engine known as the LE-7. Newly developed for the H-II launch vehicle, it offers propulsion of approximately 110 tons in a vacuum. The 2nd stage uses the LE-5A engine. This reignitable engine offers higher performance and reliability than the LE-5 engine developed for the H-I launch vehicle. The guidance system employs an inertial guidance method, a further improvement on H-I development results.

The H-II launch vehicle, since the first successful launch in 1994, was utilized in a total of 7 launches. Due to launch failure of the vehicle No.8 in 1999 came next to unsuccessful injection of the satellite by the No.5 in 1998, scheduled launch of the No.7 was cancelled, but the technology used in developing the H-II was exploited for developing H-IIA.

The first stage of the H-II launch vehicle consists of the first stage core vehicle equipped with the LE-7 engine and two solid rocket boosters(SRBs) . The LE-7 engine is a liquid hydrogen/liquid oxygen engine with 86 tons of thrust(at sea level) . The SRBs are polybutadiene composite solid propellant boosters with 158 tons of thrust each(at sea level) . The guidance and control of the first stage is performed by the hydraulically steerable nozzles of the LE-7 engine and of the SRBs controlled by the Inertial Guidance Computer(IGC). Two auxiliary engines are also provided to control attitude.

The second stage of the H-II launch vehicle was equipped with the LE-5A Iiquid hydrogen/liquid oxygen engine. The LE-5A engine is an improved LE-5 engine(developed for the second stage of the H - I launch vehicle) and provides 12 tons of thrust (in vaccum). The guidance and control of the second stage is performed by the hydraulically steerable nozzle of the LE-5A engine and the reaction control system controlled by the IGC.

The H-II launch vehicle employed a strapped-down inertial guidance and control system. The system consists of the Inertial Measurement Unit(lMU) which uses three ring laser gyros and the IGC. The inertial guidance and control system enables the H-Il launch vehicle to correct errors automatically and to maintain the planned orbit without commands from the ground station. The payload fairing protects the payload from the severe launch environment and from contamination on the ground.

H-II (Japan)

Background Information First Launch: February 1994 Flight Rate: 1-2 per year Launch Site: Yoshinobu Launch Complex (Tanegashima, Japan) Capability: 23,000 lb to 100 NM circular, 30° orbit;14,000 lb to 100 NM circular, 90° orbit; 8,800 lb to GTO; 4,800 lb to GEO History H-II development began in April 1985 First launch February 1994 Eight missions scheduled through 1999 Description Two-stage vehicle with two strap-on solid boosters Stage 1 burns LH2/LO2 in one Mitsubishi LE-7 engine, generating 189,596 lb of thrust at sea level Stage 2 burns LH2/LO2 in one Mitsubishi LE-5A engine, generating 27,313 lb of thrust (vacuum) Two Nissan solid strap-ons burn HTPB/AP/AI, generating 350,688 lb of thrust each Profile Length: 164.1 ft Launch Weight: 573,040 lb Diameter: 13.13 ft Liftoff Thrust: 890,972 lb Payload Fairing: 39.4 ft x 13.5 ft (16.4 ft diameter fairing available)

References

• 125. NASDA. National Space Agency of Japan, NASDA, 1994.
• 126. H-II Launch Vehicle, NASDA, 1994.
• 127. R. Nagao, "Development Status of the LE-7 Engine", Paper IAF-93-470, 44th Congress of the International Astronautical Federation, 16-22 October 1993.
• 128. T.S. Sienko, "Lift-off at Dawn", Space, March-April 1994, pp. 6-8.
• 129. N.W. Davis, "Japan's Space Hopes Ride on H-II", Aerospace America, March 1994, pp. 36-40.
• 130. E. Sekigawa, "Kawasaki Completes Design of New H-2 Payload Pairings", Aviation Week and Space Technology, 18 April 1994, p. 56.
• 131. E. Sekigawa, "High H-2 Cost Worries NASDA", Aviation Week and Space Technology, 19 July 1993, p. 66.
• 132. M. Mecham, "Japan Space Programs Keyed to H-2 Success", Aviation Week and Space Technology. 31 January 1994, pp. 50-51.
• 133. "H-2 Commercial Use Limited by High Costs", Aviation Week and Space Technology, 31 January 1994, p. 52.
• Adapted from: Europe and Asia in Space 1993-1994, Nicholas Johnson and David Rodvold [Kaman Sciences / Air Force Phillips Laboratory]