38 North:
Summary
On September 20, KCNA reported that Kim Jong Un had overseen the testing of a large new rocket engine at the Sohae Satellite Launching Station. They claimed this new engine had a thrust of 80 tons and would be use for a new space launch vehicle. Rocket engine thrust isn’t normally measured in “tons,” and there is some ambiguity in how to interpret that figure. It is also possible that the North Koreans are exaggerating; we can’t directly verify thrust from the images they released. Regardless, we can tell that the engine is substantially larger and more powerful than anything North Korea has tested before, even than the new ICBM engine tested in April, and the thrust may well be in the range of 160,000 pounds or 80,000 kilograms force.
And, while this particular engine may not be slated for an ICBM, we have now seen that North Korea can build large rockets using both solid and high-energy liquid propellants, to their own requirements. Whatever missiles North Korea may roll out in coming years, we can no longer expect to be limited to what can be cobbled together from old Russian cold-war leftovers.
The Engine
The plume coloration indicates that this engine probably uses the high-energy UDMH (unsymmetrical dimethylhydrazine) and NTO (nitrogen tetroxide) propellants used by the Musudan intermediate-range ballistic missile and the April 9 engine test—both derived from the old Russian R-27 submarine-launched ballistic missile whose technology North Korea illicitly acquired in the 1990s. However, a side view clearly shows the exhaust of a gas generator turbo-pump, rather than the more advanced staged-combustion cycle of the R-27. North Korea has previously used the gas-generator design on its (mostly) home-grown Nodong engine. The new engine does not have either vernier nozzles or jet vanes, suggesting the entire engine may be gimballed for steering purposes. This does not appear to be a copy of any Russian engine, but represents a mix of technologies well suited to a North Korean large engine development program.
