Hwasong-14 ICBM Maximised Range Through Four Second Stage Vernier Engines?

How did North Korea increase the performance parameters of the Hwasong-14 on July 28, that is to maximise its range capabilities to a true ICBM distance of 11,7000km (if fired directly East toward the US West Coast)?

This line from the KCNA press statement had me intrigued

The test also reconfirmed the specific features of the rocket system such as the rocket’s separation from its launching pad, stage-separation, structural system, etc. which were confirmed at the first test-fire, and confirmed the performing features of motors whose number has increased to guarantee the maximum range in the active-flight stage as well as the accuracy and reliability of the improved guidance and stability system

It was the “performing features of motors whose number has increased” that had me going.

One thing that was possible, and broached in my earlier posts, was a different engine configuration for the second stage. It looks as if that is the key difference between the July 4 and July 28 Hwasong-14 ICBM.

That is the July 28 Hwasong-14 employed 4 vernier engines for the second stage, at least that’s what I get from this Reuters report

Two separate U.S. officials who discussed the latest test, which lasted about 45 minutes, said it showed greater range than the July 4 ICBM launch, which North Korea said lasted 39 minutes.

One of the officials said it had greater height, range and power than the previous test because it used force stabilizing engines, which counter the effects of winds and other forces that can knock an ascending rocket off course

The image below (I’m on the fly) is of the second stage of Iran’s Simorgh SLV, which I provide for illustrative purposes. Featured image, according to Norbert Brugge, could be of Hwasong-14 second stage static engine test (recently conducted). July 4 used two, July 28 used four (like Simorgh SLV below)

We must stress that we don’t know how compact North Korea’s nuclear warhead is, which would affect its combat range if the warhead is of greater mass than the dummy RV used in the testing programme.

Throw-weight is an important feature of strategic nuclear missiles. The Chinese DF-5 ICBM uses a first stage engine with similar thrust to that of the March 18 Revolution engine North Korea uses for the Hwasong-14 1st stage. The DF-5 has similar range to the Hwasong-14 ICBM.

However, the DF-5 uses a four engine cluster for the 1st stage. The DF-5 has the range of the Hwasong-14, but it has a ~3,000kg throw-weight. That’s what enables it to deliver a multi-megaton hydrogen bomb to ICBM distances.

One infers that the Hwasong-14 ICBM can’t do that. We did see North Korea parade two ICBM TELs with canisters on the Day of the Sun parade this year.

It could well be the case that North Korea is banking on two ICBMs, one to deliver the compact fission based warhead (boosted with thermonuclear reactions) and the second to deliver a two-stage thermonuclear or hydrogen bomb warhead to intercontinental distances. The second could have greater throw-weight than the first.

North Korea has not shown us what’s the deal with the second ICBM (kinda) paraded, and hasn’t tested a hydrogen bomb. First things first. But both probably are on the horizon.

Image below is of the TEL paraded this year, and that’s the TEL used to transport the Hwasong-14 to the mobile erector launcher for firing.

This image is the other ICBM paraded.