 H-I rocket | |
| Function | Medium-lift launch vehicle |
|---|---|
| Manufacturer |
|
| Country of origin |
|
| Size | |
| Height | 42 m (138 ft) |
| Diameter | 2.44 m (8 ft 0 in) |
| Mass | 142,260 kg (313,630 lb) |
| Stages | 2 or 3 |
| Capacity | |
| Payload to LEO | |
| Mass | 3,200 kg (7,100 lb) |
| Payload to GTO | |
| Mass | 1,100 kg (2,400 lb) |
| Associated rockets | |
| Family | Thor |
| Based on | N-II |
| Derivative work | H-II |
| Comparable | Delta 3000, PSLV |
| Launch history | |
| Status | Retired |
| Launch sites | Tanegashima, Osaki |
| Total launches | 9 |
| Success(es) | 9 |
| First flight | 12 August 1986 |
| Last flight | 11 February 1992 |
| Boosters – Castor 2 | |
| No. boosters | 6 or 9 |
| Powered by | 1 × TX-354-3 |
| Maximum thrust | 258.9 kN (58,200 lbf) |
| Specific impulse | 262 s (2.57 km/s) |
| Burn time | 37 seconds |
| Propellant | HTPB/Al |
| First stage – Thor-ELT | |
| Powered by | 1 × MB-3-3 |
| Maximum thrust | 866.7 kN (194,800 lbf) |
| Specific impulse | 290 s (2.8 km/s) |
| Burn time | 270 seconds |
| Propellant | RP-1/LOX |
| Second stage | |
| Powered by | 1 × LE-5 |
| Maximum thrust | 102.9 kN (23,100 lbf) |
| Specific impulse | 450 s (4.4 km/s) |
| Burn time | 370 seconds |
| Propellant | LH2/LOX |
| Third stage (optional) | |
| Powered by | 1 × UM-129A |
| Maximum thrust | 77.4 kN (17,400 lbf) |
| Specific impulse | 291 s (2.85 km/s) |
| Burn time | 68 seconds |
| Propellant | Solid |
The H–I (H–1) was a Japanese medium-lift launch vehicle, consisting of a licence-produced American first stage and set of booster rockets, and all-Japanese upper stages. The H in the name represented the use of liquid hydrogen fuel in the second stage. It was launched nine times between 1986 and 1992. It replaced the N-II, and was subsequently replaced by the H-II, which used the same upper stages with a Japanese first stage.
The first stage of the H–I was a licence-built version of the Thor-ELT, which was originally constructed for the US Delta 1000 rocket. The stage had already been produced under licence in Japan for the N-I and N-II rockets. The second stage was entirely Japanese, using an LE-5 engine, the first rocket engine in Japan to use a cryogenic fuel. On launches to Geosynchronous transfer orbits, a Nissan–built UM-69A solid motor was used as a third stage. Depending on the mass of the payload, either six or nine US Castor 2 SRMs were used as booster rockets.
