2024

Supply all bearings for turbo pumps with ultra-high speed rotational performance under cryogenic environment

NTN Corporation (hereafter, NTN) supplies all bearings for turbo pumps of engine in the second H3 Launch Vehicle (H3TF2: Test Flight No.2) launched from Tanegashima Space Center at 9:22:55 (JST) on February 17.

In order for a rocket mounted with satellites or other objects to fly, it is necessary to burn liquid hydrogen and liquid oxygen at high pressure to inject a large amount of gas. Turbo pumps feed fuel of liquid hydrogen and oxidizer of liquid oxygen oxidizer into the combustion chamber of the engine by rotating inner impeller at high speed.

Bearings used in the impeller support ultra-high speed rotation of rocket that is comparable to a jet aircraft with a dmn value*¹ of approx. 2.8 million even in cryogenic environment of liquid hydrogen (-253℃) and liquid oxygen (-183℃). General lubricants including oil and grease got frozen at cryogenic temperatures, so the bearings adopt NTN's proprietary solid lubricant that demonstrates lubricating performance even at cryogenic temperatures. In addition, the bearings also use high-strength retainer made from reinforced fiberglass to meet these harsh environment.

The engine of the “H3 Launch Vehicle” has a higher driving force than one of the preceding model of “H-IIA Launch Vehicle,” in order to launch satellites of various sizes. Thus, each component is required to have high rigidity, and the bearings for “H3 Launch Vehicle” turbo pumps are also designed to have larger diameters so that they can receive greater preload. As bearings become larger in diameter, the centrifugal force of balls used in bearings becomes larger. For this reason, NTN applies rolling elements (balls) made from ceramics for bearings. It is the first time to apply ceramics balls for commercial rockets produced in Japan. The use of ceramics balls, which is more lightweight than balls made from metal, suppresses the centrifugal force of balls during rotating and achieves high speed rotational performance with dmn value 2.88 million.

NTN has been supplying bearings to a number of rockets produced in Japan for many years, including “H-I Launch Vehicle” launched in 1986, “H-II Launch Vehicle” and “H-IIA Launch Vehicle.” As NTN products are highly evaluated in the aviation field as well, NTN has been supplying bearings to major global jet engine manufacturers.

NTN will continue to contribute to the development of the aerospace field by developing and providing high quality and high performance products used in space.

1. An indicator that expresses the rotational performance of bearings and it is multiplied bearing pitch circle diameter (mm) by rotational speed (min^-1)

NTN's history in aerospace field

1986	NTN constructed Japan's first plant exclusively for aerospace bearings (Kuwana Works, in Mie Prefecture) “H-I Launch Vehicle” No.1 was launched (adopting NTN's bearings)
1994	“H-II Launch Vehicle” No.1 was launched (adopting NTN's bearings)
2001	“H-IIA Launch Vehicle” No.1 was launched (adopting NTN's bearings)
2003	NTN acquired aerospace quality management standard JIS Q 9100 for the first time as Japanese bearing manufacturer Asteroid probe “Hayabusa (MUSES-C)” was launched (adopting NTN's bearings)
2006	“H-IIA Launch Vehicle” No.11 mounted with Engineering Test Satellite “Kiku No.8” was launched (both “Kiku No.8” and “H-IIA Launch Vehicle” adopt NTN's bearings)
2009	“H-IIB Launch Vehicle” No.1 was launched (adopting NTN's bearings)
2010	Asteroid probe “Hayabusa (MUSES-C)” returned to the earth, and NTN awarded a certificate of gratitude from the Minister of Education, Culture, Sports, Science and Technology in recognition of project success
2014	“H-IIA Launch Vehicle” No.26 mounted with Asteroid probe “Hayabusa2” was launched (both “Hayabusa2” and “H-IIA Launch Vehicle” adopt NTN's bearings)
2024	The second “H3 Launch Vehicle (H3TF2: Test Flight No.2)” was launched (adopting NTN's bearings)

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