During the 1970s, Ishikawajima-Harima Heavy Industries had built under license the Rocketdyne MB-3 for the N-I rocket, for which it had also developed the second stageattitude control system. In the 1980s it also developed the thrusters for ETS-4, the first to be built in Japan. In 2000 it acquired and merged with the aerospace division of Nissan and became IHI Aerospace. IHI Aerospace started developing the BT-4 for the later cancelled LUNAR-A mission to the moon. While the mission was cancelled, the thruster has seen success as a liquidapogee engine on the Lockheed MartinA2100 and Orbital ATK GEOStar-2 platforms. Two other Orbital ATK products that use the BT-4 due to their leverage of the GEOStar-2 platform are the Cygnus spacecraft and the AntaresBi-propellant Third Stage. The use on the A2100 platform has allowed IHI to export the BT-4 even to American military programs such programs as the MUOS and AEHF. On March 9, 2006, IHI Aerospace announced that the AEHF-2 BT-4 engine had successfully performed its mission, unlike AEHF-1's. On November 29, 2010 IHI Aerospace announced that it had received and order from Lockheed Martin of four BT-4 engines for AEHF-4, MUOS-4, MUOS-5 and Vinasat-2. With this order, it achieved its 100th-unit foreign engine export since it started selling abroad in 1999. For the HTV project, IHI developed a new version, the HBT-5, which enabled them to replace the AmericanR-4D from the third flight onward. On October 3, 2013, with the successful berthing of the Cygnus Orb-D1 mission, IHI announced that the propulsion was based on their 500N Delta-Velocity Engines. In January 2018, a BT-4 kick motor was used on the GovSat-1 geosynchronous commsat flight.
Versions
The BT-4 is a family that has been used as liquid apogee engine, orbital maneuvering engine and as a thruster. Known variations:
BT-4 : Used mainly as thruster, it burns MMH/N2O4 with a thrust of. It weighs and is tall.
BT-4 : Used mainly as LAE, it burns Hydrazine/N2O4 in a 1.69 O/F ratio. It has a thrust of, a specific impulse of and an input pressure of. As of 2014, it had a demonstrated life of 32,850 seconds.
BT-4 : Used mainly as LAE, it burns Hydrazine/N2O4 with a thrust of, a specific impulse of. It weighs and is tall.
490N MON Thruster: Burns MMH/MON-3 with a nominal thrust, a specific impulse of and an inlet pressure of. As of 2014, it had a demonstrated life of 15,000 seconds.
HBT-5: Developed for the HTV to crew-rated standards, it burns MMH/MON-3, and has a thrust of. Used in HTV-3 and since HTV-5 onward.
SELENE OME: Based on the DRTSLiquid apogee engine, the SELENE Orbital Maneuvering Engine burned a Hydrazine/MON-3 mixture. It had a thrust of and a specific impulse of with an input pressure of.
