IHI Corporation

IHI Corporation is a major Japanese industrial and aerospace conglomerate founded in 1853 as the Ishikawajima Shipyard in Tokyo, evolving over 170 years into one of Japan's largest manufacturers of aircraft engines, rocket propulsion systems, industrial machinery, and energy infrastructure — serving as a critical supplier to Japan's national space program.

In the space domain, IHI (through subsidiary IHI Aerospace) is the primary manufacturer of Japan's liquid rocket engines. The LE-5B engine — a restartable liquid hydrogen and liquid oxygen expander cycle engine producing approximately 137 kN of thrust — powered the second stages of the H-IIA and H-IIB rockets, Japan's primary heavy-lift vehicles.

For the successor H3 rocket (developed by JAXA and Mitsubishi Heavy Industries as prime contractor), IHI developed the new LE-9 first stage engine: a 150 kN thrust expander bleed cycle LH2/LOX engine designed for improved manufacturing cost-effectiveness through simplified turbomachinery compared to the LE-7A it supplements. IHI Aerospace also manufactures solid rocket boosters (SRB-A and SRB-3 series) used as H-II and H3 strap-on boosters, and the solid motors for JAXA's smaller Epsilon orbital rocket.

Beyond space propulsion, IHI manufactures high-bypass turbofan aircraft engines through GE Aviation partnerships (CF34 and CFM LEAP programs), industrial gas turbines and compressors for power generation, aerostructure components for Boeing commercial aircraft, industrial pressure vessels and heat exchangers for petrochemical plants, and shipbuilding equipment. IHI's industrial diversification across capital equipment sectors reflects the company's origins as a shipbuilding and heavy manufacturing enterprise that continuously diversified into new industrial domains through the twentieth century.