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Aviation History
1988
1988 - 1611.PDF
can place 550kg into geostationary orbit, with the aid of a satellite-mounted apogee kick motor making the final firing from transfer orbit. Six further launches are planned: CS3b in the summer, MOSlb and GMS4 in 1989, BS3b in 1990, and ERS1 and BS3b in 1991. Then it will be the turn of the HII, launching ETS VI into GTO, after one test flight. Development of the HII will be managed by the National Space Development Agency, Nasda, which has designed the launcher to reduce costs through the use of off-the-shelf technology. The HII will thus use cryogenic propulsion technology, the inertial guidance system, and the second-stage engine from the HI. Solid-rocket technology, used in Japan's breed of eight science satellite launchers since 1970, will be incorporated into the boosters. The Yen 200 billion ($1-6 billion) HII programme is being funded jointly by industry, government, and univer sities, and is unique in this regard. Mitsubishi Heavy Industries is responsible for HII integration and support. Cost-effectiveness is reflected in the basic specifications of the vehicle. The 48m-high booster incorporates first- and second-stage cryogenic engines and two solid booster strap-ons with thrust-vector control systems. The liquid oxygen tank is situated forward of the first stage, placing the vehicle's centre of gravity as far forward as possible (close to the centre of aerodynamic drag) for better atti tude control. The aluminium propellant tanks are thermally controlled with poly- isocyanate foam. Propellant delivery will be accomplished by pressurising the tanks, bleeding off gaseous hydrogen and oxygen from the main engine. Auxiliary engines, close to the main engine, are used for roll control after solid-rocket booster separation, and for attitude control during stage sepa ration. Each 200kg-thrust engine uses gaseous hydrogen from the running main engine and cold nitrogen gas after engine Key 1 Payload fairing 2 Spacecraft 3 Fairing separation joint 4 Payload attachment fitting 5 Guidance equipment bay 6 Second-stage LH2 tank 7 Hydrogen gas vent port 8 Umbilical connector 9 Cryogenic helium bottle 10 LH2 fill port 11 LOX fill port 12 Second-stage LOX tank 13 Reaction control subsystems 14 Ambient helium bottle cut-off. The second stage carries one, restartable, LE5 engine from the HI second stage, with increased propellant load. The policy of autonomy is reflected in plans for domestic procurement of parts and materials, including electronics for the guid ance and propulsion systems, such as diodes and sensors. However, since domestic pro duction of all parts would be uneconomical, components such as connectors, printed circuit boards, and terminals, will be procured from Europe. The HII first stage is 28m. long, 4m in diameter, and weighs 97 tonnes, of which 85 tonnes is propellants. Its single Mitsubishi LE7 cryogenic engine, weighing 1,560kg, generates a thrust of 93 tonnes at sea level and 120 tonnes in vacuum. The nozzle expansion ratio is 60:1 and burn time is 316sec. High specific impulse of 449sec in vacuum is achieved by a two-stage com bustion cycle. Like the US Space Shuttle's main engines, the LE7 propellants are partially burned in a preburner; the gas produced drives the high-pressure propellant feed pumps, then combines with oxygen to be completely burned in the main com bustion chamber. This ensures higher performance by burning the propellants at greater temperatures and pressures. The bad news is that this requires an increase in pump exit pressure, necessitating develop ment of advanced technologies. A chamber pressure of 150 kg/cm2 has been selected. The LE7 will be the third first-stage engine to use liquid hydrogen, after the SSMEs and the core-stage engines of the Soviet Union's Energia heavylifter. Europe's HM60 cryogenic engine for the more power ful Ariane 5 will be next. Nonetheless, this will be less efficient, and its performance will be reduced by the incorporation of an inde pendent gas generator for driving the turbopumps, with gas exhausted afterwards —technology that will be 30 years old by the time it flies. 15 Second-stage engine (LE-5) 16 Interstage 1-2 17 Oxygen gas vent port 18 First-stage LOX tank 19 Centre body section 20 Electronic equipment bay 21 Hydrogen gas vent port 22 First-stage LH2 tank 23 First-stage engine section 24 Auxiliary engine 25 Umbilical connector and LH2/LOX fill port 26 First-stage engine (LE-7) 27 Solid-fuel rocket booster (SRB) FLIGHT INTERNATIONAL, 18 June 1988
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