ISO/IEC 17025: History and introduction of concepts

H-I rocket
Function	Medium-lift launch vehicle
Manufacturer	Mitsubishi Heavy Industries (production) McDonnell Douglas (design)
Country of origin	Japan (production) United States (design)
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
[edit on Wikidata]

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.

When the H–1 was announced in 1986, company representative Tsuguo Tatakawe clarified that it would only be used to launch indigenous (i.e. Japanese) payloads, that only two launches per year could be mounted, and that the launch window consisted of a four-month period in which Japanese fishing fleets were not active (the falling launch boosters may damage fishing nets in the ocean waters).^[1]

• Delta rocket
• H-II
• H-IIA
• PGM-17 Thor
• Comparison of orbital launchers families
• Comparison of orbital launch systems

• Wade, Mark. "Delta". Encyclopedia Astronautica. Archived from the original on 17 August 2013. Retrieved 31 August 2008.
• McDowell, Jonathan. "Thor". Orbital and Suborbital Launch Database. Jonathan's Space Report. Archived from the original on 1 August 2020. Retrieved 31 August 2008.
• Krebs, Gunter. "H-1". Gunter's Space Page. Retrieved 31 August 2008.