Saturday, 29 July 2017

North Korea's July 28 ICBM test

On 28 July 2017 around 14:45 UT, North Korea tested another ICBM. Early reports from US Military sources indicate a night-time launch from a new location (Mupyong-ni), an approximately 45 minute flight time, and launch into a highly lofted trajectory with an apogee as high as 3700 km and a range of about 1000 km, with the launch direction towards Hokaido.

These ballpark figures allow us to estimate a ballpark maximum range for this ICBM. Because this was (again) a lofted test with an almost vertical launch, the true range of the missile is much more than the ~1000 km of the test when it would have been launched on a more normal trajectory.

The results I get are shown in the figure above: using the same delta V impulse as the lofted test but putting the apogee at 1200 km (a typical ICBM apogee) and roughly same launch direction, I get a range of ~8700 km.

That is probably a conservative figure. The true range depends on various factors (including the weight of the warhead, but also whether this test was at maximum missile performance. Reasons why it was perhaps not, is that North Korea might have shown some restraint and  taken precautions in order not to land their missile in or too much near Japan. This is also why they launch in a lofted trajectory).

In the figure above, I have drawn what this cautious reconstruction of the real range entails. It surpasses the distance to Hawaii. It brings San Francisco on the US West Coast in range. Today's test therefore implies that North Korea can strike the US mainland.

Towards the other direction, it brings Moscow in range, and if the true maximum performance of the missile is slightly larger, also Western Europe (*).

By the way, just as with the previous July 4th test, the Russians have come with maverick data for this test again, quoting a much smaller range and lower apogee (732 km and 681 km) based on their own Early Warning Radar observations. There are suspicions that their data only pertain to observations of the ICBM's first stage, explaining the discrepancy.

The analysis in this post is based on the first released ballpark figures for this test. If better data are released, the outcome might slightly change.

UPDATE: North Korea has now published the following figures for their test: apogee  3724.9 km, range 998 km, flight time 47m12s. They say it was a Hwasong-14 tested to simulate maximum range. Photographs published indeed show a missile similar to the one launched on July 4.

photo: Rodong Sinmun

photo: Rodong Sinmun

* the maximum range is (unlike depicted above) not a neat 8700 km circle. The maximum range depends on which direction is launched into, due to Earth rotation effects. Due to this, when launched towards the east the missile will have a somewhat larger range than when launched towards the west. Launched towards the east it gets an extra "push" from the rotating Earth.

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