Space Transportation Systems H-IIB Launch Vehicle

In Operation

Project Topics

Feb. 6, 2017 Updated

KOUNOTORI6 completed its mission with re-entry!

KOUNOTORI6 completed its mission with re-entry!

The KOUNOTORI6 (HTV6, a cargo transporter to the International Space Station) left the ISS on Jan. 28 and re-entered the atmosphere at around 0:06 a.m. on Feb. 6 (Japan Standard Time.) Reentry of KOUNOTORI6 was confirmed ...

About H-IIB Launch Vehicle

Opening the Door to Future Space Mission

Japan has been developing its own launch vehicles, based upon various researches and experiments. Among launch vehicles, the H-IIA launch vehicle has been supporting satellite launch missions as a major large-scale launch vehicle with high reliability.
It is the H-IIB launch vehicle that is an upgraded version of the current H-IIA launch capacity and will be expected to open the door to a new possibility for future missions, including cargo transport to the International Space Station (ISS) and to the Moon.
The H-IIB launch vehicle has two major purposes. One is to launch the H-II Transfer Vehicle "KOUNOTORI" (HTV) to the ISS. HTV will carry not only necessary daily commodities for the crew astronauts, but also experimental devices, samples, spare parts and other necessary research items for the ISS. The other is to respond to broader launch needs by making combined use of both H-IIA and H-IIB launch vehicles. In addition, H-IIB's larger launch capacity will make it possible to perform a simultaneous launch of more than one satellite, and will reduce the cost. This will contribute to ensuring vitalization of the Japanese space industry.

Characteristics of H-IIB Launch Vehicle

1.Key Capacity Improvement: Clustering

The H-IIB launch vehicle is a two-stage rocket using liquid oxygen and liquid hydrogen as propellant and has four strap-on solid rocket boosters (SRB-A) powered by polibutadiene.
The H-IIB has two liquid rocket engines (LE-7A) in the first-stage, instead of one for the H-IIA. It has four SRB-As attached to the body, while the standard version of H-IIA had two SRB-As. In addition, the H-IIB's first-stage body has expanded to 5.2m in diameter from 4m of H-IIA's one. It has also extended the total length of the first stage by 1m from that of H-IIA. At the result of such enhancement, the H-IIB needs propellant 1.7 times more than the former.
Clustering several engines, whose performance is already fixed, has the advantage in shortening the period and reducing the cost for its development.

2.For Effective Development

At the time of launching HTV, the H-IIB will use a special fairing for HTV. However, in other parts, it will take over most of the specifications and structures of on-board equipments and ground systems already used for the H-IIA. These efforts are designed to reduce development risk and cost. Moreover, it will share the launch facility with the H-IIA and be launched from Yoshinobu Launch Pad of the Tanegashima Space Center.

Major Characteristics

Major Characteristics (H-IIB Test Flight)

Length (m) 56.6
Mass (t) 531 (without payload mass)
Guidance Method Inertial Guidance Method
First Stage Solid Rocket
Second Stage Payload Fairing(5S-H)
Height (m) 38 15 11 15
Outside diameter (m) 5.2 2.5 4.0 5.1
Mass (t) 202 306 (for four SRB-As in total) 20 3.2
Propellant mass (t) 177.8 263.8 (for four SRB-As in total) 16.6 -
Thrust (kN)*1 2,196 9,220 137 -
Combustion time (s) 352 114 499 -
Propellant type Liquid oxygen/hydrogen Polybutadiene composite solid propellant Liquid oxygen/hydrogen -
Propellant supply system Turbo pump - Turbo pump -
Impulse to weight ratio (s)*1 440 283.6 448 -
Attitude control method Gimbal Movable nozzle Gimbal gas jet system -
Major onboard avionics Guidance control equipment
Telemetry transmitter
- Guidance control equipment
Radar transponder
Telemetry transmitter
Command destruct system
*1 In vacuum. Solid rocket booster's thrust is set to the maximum value.

H-IIB Launch Vehicle Launch Capacity

Orbit Altitude Payloads
Orbit for HTV
(Inclination:51.6 degrees)
350km-460km 16.5t

Launch Records