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 Japan's H-IIA launcher has good capabilities
By Rudolf Hofstätter
On the island of Tanegashima in the southern Pacific Ocean, Japan began building a space launch facility of the same name at latitude 30 degrees north in 1966. Palm trees, white sandy beaches and the turquoise-coloured sea make it one of the most beautiful launch sites in the world. After the National Space Development Agency (NASDA) was founded in Tokyo in 1969, it started building the American Thor-Delta launcher rocket under licence. Initially designated the N-I and later the N-II, it soon came to constitute the backbone of the Japanese transport capability in space and eventually progressed into the H-1. A 40-metre long, Japanese-American hybrid, the H-1 was capable of carrying a 550kg payload into geostationary orbit (GEO). The second stage with its liquid hydrogen/liquid oxygen (LH2/LOX)-powered Liquid Engine (LE-5), the third stage with powdered polybutadiene composite fuel and the guidance system were designed and built by Japan.
In 1983 ten years of indigenous development work on the larger and more powerful, two-stage H-II commenced. With a payload fairing 50 metres long, equivalent to the height of an 18-storey building, a diameter of 4 metres and a take-off weight of 264 tonnes, the H-II was capable of transporting four tonnes of payload to geostationary transfer orbit (GTO) or two tonnes to GEO. The contractors were the Rocket System Corporation (RSC), Mitsubishi-Kawasaki and the Nissan Motor Co, which was responsible for the boosters. The H-I produced valuable experience for the H-IIA programme, launched in 1996, up to 1992 and the H-II up to 1999.
Although the main stage with its solid rocket boosters (SRB) strapped on to the sides and the second stages of the H-II and H-IIA look similar, the foremost objective of the designers was to halve the costs of the new rocket compared with the “old” one. To this end, the boosters (monolithic instead of the four segments used up to now), tank and fairing production, propulsion units and launch preparations were all simplified.
Stages, boosters and satellites are transported by ship to the island harbour of Shimama, where they are tested in the tall assembly building and vertically integrated. A ramp with service tower is situated directly on the coast for refuelling of the 53-metre long H-IIA on its mobile platform with LH2/LOX by Air Liquide Japan, whereas the booster fuel comes from the NOF Corporation. The maiden flight of the H-IIA took place in 2001. Due to the exertion of massive influence by the national fishing industry, no H-II or H-IIA launches are allowed between April and the middle of August every year.
The main stage with 100 tonnes of fuel and the LE-7A engine produce 1,100kN of vacuum thrust, almost the same as the LE-7 for the H-II. The first stage burns for six and a half minutes. Each SRB-A booster is 15 metres long, 2.5 metres wide and contains 65 tonnes of solid fuel which, with a vacuum thrust of 2,256kN, produces 10 percent more than each of the two SRBs of the H-II. The cause of the only failed H-IIA launch out of 12 missions to date was the failure of one SRB-A to separate, whereupon the boosters were modified.
With additional, narrow polybutadiene composite small solid boosters (SSB) each weighing 13 tonnes and generating 735 kN of thrust as H-IIA versions 2022 and 2024, the capacity to transport payloads to GTO was deliberately raised to 4.5 and 5 tonnes respectively. The take-off weights are 320 and 350 tonnes respectively. An SSB is 15 metres long and has a diameter of 1 metre. Choosing the type and number of boosters to deploy as a function of the weight of the cargo is a sensible, low-cost approach. Thus, there are four permutations of the H-IIA, each with a different combination of type and number of boosters,. The most powerful version 204 with four SRB-A's and a 445 tonne take-off weight can carry six tonnes to GTO, thus approaching the capacity of the Ariane 5 Generic, which can transport 6.7 tonnes into space from Kourou, close to the equator. The H-IIA204 is currently the 13th most powerful launcher in the GTO category, ahead of the Zenith 3SL and the Chinese CZ-3B.
Commercial offerings in the Launch Service Alliance
The SSBs work for one minute, and the SRBs for two. After seven minutes' flying time, the first and second stages separate at an altitude of 180 kilometres, following which the second stage then burns for five and a half minutes. The boosters, protective mantle and 37-metre long first stage crash into the sea and are not recycled.
The second stage carries 16.7 tonnes of liquid hydrogen/liquid oxygen in its tanks. It is powered by the LE-5B, which generates a vacuum thrust of 137 kN, is a derivative of the LE-5A of the H-II and can be ignited two to three times, allowing multiple satellites to be released on different orbits. The inertial guidance system from NEC Toshiba, consisting of laser gyroscope and guidance control computer, controls the rocket without any radio commands from the ground and automatically corrects any deviations. After 28 to 40 minutes, the satellite is released at an altitude of 300 kilometres. The apogee engine then “pushes” it into GTO or, as will shortly be the case for the Japanese 2.9 tonne lunar satellite Selene, towards the moon. A third ignition has already been tested on one H-IIA flight, with a view to transporting satellites directly into GEO. The nine metre long second stage finally burns out in the atmosphere.
Marketing of the H-IIA for commercial satellite launches has been transferred from the RSC to Mitsubishi. Customers of the Launch Service Alliance of Boeing Sea Launch, Arianespace and Mitsubishi can transfer to a different platform of the three launch services in the event of problems with dates. To further reduce costs, Mitsubishi recently became the prime contractor for the launcher, the SSB and standard version launches.
In 2003 the Japan Aerospace Exploration Agency (JAXA) was formed as an offshoot of NASDA and the Tokyo University Space Institute. It is currently working on an H-IIB with twice the performance of the H-IIA202 and hence almost the same performance as the American Atlas V-541 launch vehicle. Under maximum load, the 55 metre long, 560 tonne two-stage H-IIB will be accelerated by almost twice the quantity of liquid hydrogen/liquid oxygen and four SRB-A boosters. Due to the larger tanks, the first stage is 5.2 metres wide and is powered by two LE-7A engines. The maiden flight is expected to take place in 2008 or 2009.
Apart from the capability to transport several satellites at once, which is intended to reduce the launch costs still further, the H-IIB will also launch the unmanned H-II Transfer Vehicle (HTV) carrying food and equipment to the Space Station from Tanegashima. The bus-sized, Japanese freighter weighs 16.5 tonnes, of which six tonnes are accounted for by supplies. After its maiden flight, planned for the start of 2009, the H-IIB will be one of the top ten most powerful launch vehicles. The technology heavyweight Japan will thus have demonstrated its capability.
From page 60 of FLUG REVUE 6/2007
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