N-I (rocket)
The N-I rocket | |
| Function | Small-lift launch vehicle |
|---|---|
| Manufacturer | McDonnell Douglas (design) Mitsubishi Heavy Industries (production) |
| Country of origin | United States (design) Japan (production) |
| Size | |
| Height | 34 m (112 ft) |
| Diameter | 2.44 m (8.0 ft) |
| Mass | 131,330 kg (289,530 lb) |
| Stages | 2 or 3 |
| Capacity | |
| Payload to LEO | |
| Mass | 1,200 kg (2,600 lb) |
| Payload to GTO | |
| Mass | 360 kg (790 lb) |
| Associated rockets | |
| Family | Delta |
| Derivative work | N-II |
| Launch history | |
| Status | Retired |
| Launch sites | Tanegashima, Osaki |
| Total launches | 7 |
| Success(es) | 6 |
| Partial failure | 1 |
| First flight | 9 September 1975 |
| Last flight | 3 September 1982 |
| Boosters – Castor 2 | |
| No. boosters | 3 |
| Maximum thrust | 258.9 kN (58,200 lbf) each |
| Total thrust | 776.7 kN (174,600 lbf) |
| Specific impulse | 262 s (2.57 km/s) |
| Burn time | 37 seconds |
| Propellant | Solid |
| 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-3 |
| Maximum thrust | 52.9 kN (11,900 lbf) |
| Specific impulse | 290 s (2.8 km/s) |
| Burn time | 246 seconds |
| Propellant | N2O4 / A-50 |
| Third stage (optional) – Star-37N | |
| Maximum thrust | 45 kN (10,000 lbf) |
| Specific impulse | 290 s (2.8 km/s) |
| Burn time | 42 seconds |
| Propellant | Solid |
The N-I or N-1 was a derivative of the American Thor-Delta rocket, produced under license in Japan. The N stood for "Nippon" (Japan). It used a Long Tank Thor first stage, a Mitsubishi Heavy Industries-designed LE-3 engine on the second stage, and three Castor SRMs. Seven were launched between 1975 and 1982, before it was replaced by the N-II. Six of the seven launches were successful, however on the fifth flight, there was recontact between the satellite and the third stage, which caused the satellite to fail.
On 29 February 1976, the second N-I conducted the only orbital launch, as of February 2024, to occur on a leap day.