From the Hwasong-14 Limited Range ICBM to a Long Range ICBM: Booster Engine Speculation

When you get excited you tend to shoot first and ask questions later, and I think I might be getting a bit too excited, and shooting a bit too much from the hip, regarding North Korea’s limited range ICBM test. These things have long been a concern of mine, since I was kid mucking around about this stuff with my fellow nerds, so at least I kinda have an excuse. That said, I’ve attempted a rocket test myself and I still have the remains of my failed flight test.

Given that the excitement hasn’t abated I figured I might continue to scribble away, this time a little bit about the engine.

The Hwasong-14 engine is most likely the March 18 revolution engine, which uses UDMH (unsymmetrical dimethyalhydrazine) for the propellant, according to imagery, and has 80 tonnes of thrust, according to North Korean statements.

North Korea seems to be following China’s early missile development programme, and it is useful to refer to China’s experience as a guide to North Korean developments.

Recent North Korean advances have a lot to do with that March 18 revolution engine. One of China’s earliest missiles, the medium range DF-3, generated 64 tonnes but that from a cluster of 4 engines.

The DF-4, no too dissimilar in range to the Hwasong-12, used four YF-1 engines for the first stage. The DF-4 formed the basis of the Long March 1 space launch vehicle, and astronautix gives a thrust of about 28 tonnes for the Y1. That provides us with about 112 tonnes of thrust for the DF-4 four engine cluster.

Again, that put’s the March 18 revolution engine into some perspective. It really does represent a very significant advance in North Korea’s capabilities.

What interests me here is the possible configuration of a long range North Korean ICBM, that is about a 10,000km range ICBM, able to strike the contiguous United States. The DF-5 is the closest Chinese analogue, indeed that was the first Chinese ICBM to possess this capability. The DF-5 first stage formed the basis of the Long March 2 space launch vehicle, and that stage is designated by astronautix as the FB-1-1.

The total thrust of the FB-1-1 was 305902 kilograms, that is 305 tonnes, which gives a thrust for each engine of 76 tonnes.

That’s just about the thrust of the March 18 revolution engine.

So, if the DF-5 serves as any guide, and assuming the March 18 revolution as its basis, a North Korean long range ICBM able to strike the contagious United States would need a first stage consisting of a cluster of four main, March 18 revolution, engines.

The Hwasong-14, as noted, employs the single March 18 revolution engine.