H-II

H-II

The launch of H-II Flight 4, carrying ADEOS I
Function	Launch vehicle
Manufacturer	Mitsubishi Heavy Industries
Country of origin	Japan
Size
Height	49 m (161 ft)
Diameter	4 m (13 ft)
Mass	260,000 kg (570,000 lb)
Stages	2
Capacity
Payload to LEO	10,060 kg (22,180 lb)
Payload to GTO	3,930 kg (8,660 lb)
Associated rockets
Family	H-II
Derivatives	H-IIA, H-IIB
Comparable	Ariane 4
Launch history
Status	Retired
Launch sites	LC-Y, Tanegashima
Total launches	7
Successes	5
Failures	1
Partial failures	1
First flight	3 February 1994
Last flight	15 November 1999
Boosters
No. boosters	2
Engines	1 Solid
Thrust	1540 kN
Specific impulse	273 s (2.68 km/s)
Burn time	94 seconds
Fuel	Solid
First stage
Engines	1 LE-7
Thrust	1,078 kN (242,000 lbf)
Specific impulse	446 s (4.37 km/s)
Burn time	346 seconds
Fuel	LOX / LH2
Second stage
Engines	1 LE-5A
Thrust	121.5 kN (27,300 lbf)
Specific impulse	452 seconds
Burn time	600 seconds
Fuel	LOX / LH2

The H-II (H2) rocket was a Japanese satellite launch system, which flew seven times between 1994 and 1999, with five successes. It was developed by NASDA in order to give Japan a capability to launch larger satellites in the 1990s.^[1] It was the first two-stage liquid-fuelled rocket Japan made using only technologies developed domestically.^[2] It was superseded by the H-IIA rocket following reliability and cost issues.

Background

Prior to H-II, NASDA had to use components licensed by the United States in its rockets. In particular, crucial technologies of the H-I and its predecessors were from the Delta rockets. The H-I did have domestically produced components, such as the LE-5 engine on the second stage and the inertial guidance system. H-II added to this by domestically developing the LE-7 liquid-fuel engine of the first stage and the solid booster rockets.

The H-II was developed under the following policies, according to a NASDA press release:^[1]

1. Develop the launch vehicle with Japanese space technology.
2. Reduce both development period and costs by utilizing developed technologies as much as possible.
3. Develop a vehicle which can be launched from the existing Tanegashima Space Center.
4. Use design criteria which allows sufficient performance for both the main systems and subsystems. Ensure that development will be carried out properly, and safety is taken into account.

History

Development of the LE-7 engine which started in 1984 was not without hardships, and a worker died in an accidental explosion. The first engine was completed in 1994, two years behind the original schedule. In 1990, Rocket System Corporation was established to operate the launch missions after the rockets' completion.

In 1994, NASDA succeeded in launching the first H-II rocket, and succeeded in five launches by 1997. However, each launch cost 19 billion yen (190 million USD), too expensive compared to international competitors like Ariane. (This is in part due to the changes in exchange rates, which was 240 yen to a dollar when the project planning started in 1982, but had changed to 100 yen a dollar by 1994.) Development of the next-generation H-IIA rockets started in order to minimize launch costs.

The successive failure of flight 5 in 1998 and flight 8 in the following year brought an end to the H-II series. To investigate the cause of the failure and to direct resources into the H-IIA, NASDA cancelled flight 7 (which was to be launched after F8 due to changes in schedule), and terminated the H-II series.^[2]

H-II flights

note 1. ^ Faulty brazing in second-stage engine cooling system caused engine burn through and cable damage resulting in shutdown midway through the upper stage's second burn, leaving spacecraft in elliptical LEO instead of GTO. Spacecraft thrusters raised orbit enough to complete some communications experiments.

note 2. ^ Cavitation in the first stage hydrogen turbopump impeller caused an impeller blade to fracture, resulting in loss of fuel and rapid shutdown of the engine at T+239 s. The vehicle impacted the ocean 380 km NW of Chichi-jima.

Gallery

• 
  The Ground Test Vehicle of H-II, now installed at Tsukuba Space Center.
• 
  The first and second stages of the canceled Flight 7, at a hangar in Tanegashima Space Center.

See also

• H-II Orbiting Plane (HOPE)
• H-II Transfer Vehicle (HTV)
• H-II (rocket family)
  • H-IIA
  • H-IIB
• Comparison of orbital launchers families
• Comparison of orbital launch systems

References

Wikimedia Commons has media related to H-II launch vehicles.

External links

• H-II Launch Vehicle, JAXA.

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