by Michael Elleman, Senior Fellow for Missile Defence
North Korea’s missile programme has made astounding strides over the past two years. An arsenal that had been based on short- and medium-range missiles along with an intermediate-range Musudan that repeatedly failed flight tests, has suddenly been supplemented by two new missiles: the intermediate-range Hwasong-12 and the intercontinental ballistic missile (ICBM), Hwasong-14. No other country has transitioned from a medium-range capability to an ICBM in such a short time. What explains this rapid progression? The answer is simple. North Korea has acquired a high-performance liquid-propellant engine (LPE) from a foreign source.
Available evidence clearly indicates that the LPE is based on the Soviet RD-250 family of engines, and has been modified to operate as the boosting force for the Hwasong-12 and -14. An unknown number of these engines were probably acquired though illicit channels operating in Russia and/or Ukraine. North Korea’s need for an alternative to the failing Musudan and the recent appearance of the RD-250 engine along with other evidence, suggests the transfers occurred within the past two years.
Tests reveal recent technical gains
North Korea ground tested a large LPE in September 2016, which it claimed could generate 80 tonnes’ thrust. The same LPE was again ground tested in March 2017. This test included four smaller, steering engines. On 14 May 2017, with Kim Jong-un overseeing test preparations, North Korea launched a new intermediate-range ballistic missile, the Hwasong-12. The single-stage missile flew on a very steep trajectory, reaching a peak altitude of over 2,000km. If the Hwasong-12 had used a normal flight path, it would have travelled between 4,000 and 4,500km, placing Guam, just 3,400km away, within range.
The success of the Hwasong-12 flight in May gave North Korean engineers the confidence needed to pursue a more ambitious goal: the initial flight testing of a two-stage missile capable of reaching the continental United States. Less than two months after the Hwasong-12 test, the two-stage Hwasong-14 was launched on 4 July. A second Hwasong-14 was tested on 28 July. The Hwasong-14 launches flew on very steep flight paths, with the first shot reaching an apogee of 2,700km. The second test peaked at about 3,800km.
North Korea’s announced results were independently confirmed by the Republic of Korea, Japan and US. In both tests, the mock warheads plummeted towards the East Sea, 900–1,000km from the launch point. If flown on a trajectory that maximises range instead of peak altitude, the two missiles would have reached about 7,000km and 9,000km respectively, well exceeding the 5,500km minimum distance for a system to be categorised as an ICBM.
The dimensions and visible features of the Hwasong-12 indicate an overall mass of between 24,000 and 25,000kg. The Hwasong-12’s acceleration at lift-off, as determined by the launch video aired by KCNA, is about 8.5 to 9.0m/s2. Assuming North Korea did not manipulate the launch video, the thrust generated by the Hwasong-12’s complete engine assembly is between 45 and 47 tonnes’ thrust; the main engine contributes between 39 to 41 tonnes’ force, and the auxiliary engines about 6 tonnes’ force. The Hwasong-14 has an estimated mass of 33,000–34,000kg, and an initial acceleration rate of about 4–4.5m/s2, resulting in a total thrust of 46–48 tonnes’ force.
Identifying the new LPE and its origins
The origins of the new engine are difficult to determine with certainty. However, a process of elimination sharply narrows the possibilities.
There is no evidence to suggest that North Korea successfully designed and developed the LPE indigenously. Even if, after importing Scud and Nodong engines, North Korea had mastered the production of clones, which remains debateable, this does not mean that it could design, develop and manufacture a large LPE from scratch, especially one that uses higher-performance propellants and generates 40 tonnes’ thrust.
Claims that the LPE is a North Korean product would be more believable if the country’s experts had in the recent past developed and tested a series of smaller, less powerful engines, but there are no reports of such activities. Indeed, prior to the Hwasong-12 and -14 flights, every liquid-fuelled missile launched by North Korea – all of the Scuds and Nodongs, even the Musudan – was powered by an engine developed and originally produced by the Russian enterprise named for A.M. Isayev; the Scud, Nodong and R-27 (from which the Musudan is derived) missiles were designed and originally produced by the Russian concern named after V.P. Makeyev. It is, therefore, far more likely that the Hwasong-12 and -14 are powered by an LPE imported from an established missile power.
If this engine was imported, most potential sources can be eliminated because the external features, propellant combination and performance profile of the LPE in question are unique. The engine tested by North Korea does not physically resemble any LPE manufactured by the US, France, China, Japan, India or Iran. Nor do any of these countries produce an engine that uses storable propellants and generates the thrust delivered by the Hwasong-12 and -14 LPE. This leaves the former Soviet Union as the most likely source.
http://www.iiss.org/en/iiss%20voices/blogsections/iiss-voices-2017-adeb/august-2b48/north-korea-icbm-success-3abb
