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A Partial Success for the Musudan

By
23 June 2016


Summary

North Korea’s latest Musudan (Hwasong-10) missile test finally demonstrated the full performance of the missile’s propulsion system, and at least a minimally functional guidance system. The trajectory was not representative of an operational launch, and so leaves open questions about the performance of the reentry vehicle. Perhaps more importantly, two launches only a few hours apart and with one missile breaking up in flight, gives the North Koreans little chance of understanding what went wrong. The Musudan is not a reliable weapon, and Pyongyang does not seem to be trying to make it a reliable weapon. But even if this is just a propaganda stunt and the Musudan is to be quietly abandoned, this partial success increases the likelihood that North Korea’s KN-08 and KN-14 road-mobile inter-continental ballistic missiles (ICBMs) will reach operational status early in the next decade.

(Photo: Rodong Sinmun)

(Photo: Rodong Sinmun)

The Persistent Pursuit of the Musudan

After four consecutive failures in rapid succession, we figured we might have seen the last of North Korea’s Musudan missile. Given the pace of testing earlier this year, faster than any technical results could be interpreted and incorporated into a revised design, there was little chance of North Korea obtaining a useful weapon. At best, and only by luck, it might have scored a propaganda victory with a marginally successful flight. And with every failure, the odds of that seemed increasingly remote.

But if the North Koreans are in too much of a hurry to do the job right, they are at least persistent in doing something. And now it appears that they have at least a partial success to show for it. We have confirmed reports that two missiles were fired from mobile launchers near Wonsan on June 21, with one missile disintegrating in flight perhaps 150 km downrange and the second impacting at a range of 400 km. That is little more than a tenth of the Musudan’s expected range of roughly 3,500 km, but it is more than we had ever seen before.

This may be due to a modification in the missile’s aerodynamics. North Korea has released pictures of what appears to be a Musudan in flight with a set of eight grid fins around the base, which weren’t present in previous satellite or parade photos or in the old Soviet R-27 missile on which the Musudan is based. Presumably the North Korean engineers guessed that their modifications to the Musudan had compromised its stability in early flight, and that some extra aerodynamic controls would fix that problem. With no more than two months to work, this cannot have been much more than a jury-rigged fix based on an educated guess, but it was apparently a good one. Now they have to guess what went wrong to cause a missile to break up at 150 km, which will be rather more difficult.

schilling0623

(Photos: Rodong Sinmun)

Reports from Japan indicate that the second missile had reached an altitude of over 1,000 km, with North Korea claiming a very precise 1,413.6 km. This is far higher than would be normal for a missile of that size. A bit of analysis indicates that achieving this altitude would require roughly the full performance of the Musudan missile’s propulsion system, devoted to an almost perfectly vertical ascent. That’s not very useful from a military perspective, but it is still an impressive feat for a missile that last month was blowing up on the launch pad.

As a test, this isn’t as useful as launching the missile on its more usual ballistic arc. It gives the engines a full workout, but makes it harder to verify the performance of the guidance system. It also provides a different reentry environment, and testing the reentry vehicle is going to be critical to North Korea. Their older missiles entered the atmosphere at no more than half the Musudan’s speed. The North Koreans probably now know, for the first time, what happens when one of their warheads enters the atmosphere at roughly 10,000 miles per hour, but at an abnormally steep angle which will give a shorter but more intense heating load and do most of its deceleration lower in the atmosphere than it would in an operational launch. They might still not know whether the warhead would survive in an operational flight.

Why would they have tested a missile in such a manner? Examining a map of the region shows that there is really no way to launch a missile from Wonsan to a range of more than 1,000 km without overflying some foreign country, most likely Japan. The Japanese take a dim view of North Korean missiles flying over their country, and they have Aegis-equipped warships capable of shooting down missiles. Pyongyang apparently didn’t want to take that provocative risk.

They could have launched the missile from their Sohae Satellite Launching Station, which has clear range to the south as far as the Philippines. North Korea’s orbital launches have used this site and this trajectory, and it would have made for a more realistic test of the Musudan. Given that the Musudan is a mobile missile, they could have launched from any paved road along the southeast coast for the same effect. But North Korea’s engineers almost certainly would have wanted the support of powerful tracking radars and other infrastructure associated with a permanent launch site, and the Sohae site has only been used for North Korea’s nominally civilian satellite launches. There may have been some internal politics involved in the decision to loft the missile high over the East Sea and bring it down at such a short range.

The bigger limitation of this test is the decision to launch two missiles only a few hours apart. That decision greatly limits what can actually be learned from the test. There is no possibility, in that timeframe, of figuring out what went wrong with the first missile and fixing it. As with the earlier Musudan tests, this isn’t so much an engineering program so much as an exercise in tossing a coin or rolling a die until it comes up with the result they like. If North Korea’s sixth and latest Musudan launch counts as a success in their minds—and it well might—the one before it was still clearly a failure. Do they now have a reliable missile that had a spot of bad luck, or a dud that got lucky and worked once? We don’t know. Neither do they. And they knew from the start that they wouldn’t know if they had a reliable missile in the end.

So we should probably assume they don’t really care, that this was about propaganda and image rather than engineering and weapons development. They have achieved something that is as close to a win as possible without overflying Japan, and if they try again there’s a good chance that Musudan #7 will be an embarrassing failure just like Musudan #5.

Best case, they declare victory and go home, and make a quiet note to never actually trust the Musudan in wartime. Worst case, they tell their engineers to go back to their ground test facilities and turn this one-shot stunt into a useful weapon. The engineers in question would probably be quite happy to know they still have jobs, and turning the results from this spurt of unreasonably fast testing into a reliable weapon, would occupy them for a year or two at least. If they come back a year from now, testing Musudan missiles one at a time and with three to six months between tests, then we can start worrying about an operational Musudan.

But we should also consider worrying about an operational KN-08 or KN-14. These missiles use the same ex-Soviet engine as the Musudan, but in a clustered and multi-stage configuration capable of reaching much of the US mainland. We have seen them test this engine on the ground, but until now they had never successfully flown one. Even if North Korea retires the Musudan as too unreliable for anything but propaganda stunts, they will presumably ship any test data to the engineers building the ICBMs. And those engineers don’t seem to be under any pressure to rush into premature flight testing.

Regardless of the ultimate fate of the Musudan, the credibility of the KN-08 and KN-14 road-mobile ICBMs has increased a few notches. The North Koreans have the engines they need, and they can at least sometimes make them work in flight. There is still a great deal of work for them to do. The clustered twin-engine installation in particular will likely give them a few surprises on its first flight, and it will likely take them several tries to get the complete system right. We still don’t expect them to have those missiles operational before 2020, but early flight testing by that date is increasingly likely.

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Addendum: Since the publication of this analysis, North Korea released an image of Kim Jong Un in front of a Musudan missile with the reentry vehicle removed. The author offers additional observations here.

Reader Feedback

13 Responses to “A Partial Success for the Musudan”

  1. Clay Ramsey says:

    I don’t know who hacked my phone, from here or from there, but whoever did it all I can say is, good job! I was actually on my phone as it happened, I got the data usage warning and saw how much was lost and pretty much figured out what was taken. Well, at least the phone still works and nothing was damaged.

  2. Clay Ramsey says:

    Frank Plantan:

    For the first part, yeah, that’s pretty much been the de-facto situation ever since Clinton shot off her big mouth about 7 years ago trying to act tough. She doesn’t know there is a difference between being tough and just being an asshole. For the second part, no. That may have been somewhat true 30 or 40 years ago, but for the last 20 years or so, not really. This is 2016, that artillery can be targeted and hit faster than it can shoot. If they shoot, their location is known, if they don’t pack up and leave immediately, they’re hit. If they do move, they can’t shoot and are still exposed and vulnerable. It’s hopeless. RoK and US literally spend more each year protecting against it than the cost would be to endure the attack. They may inflict maybe $100 million in damage on Seoul, or if they get really lucky up to a Billion, but that’s chicken feed compared to what they already are spending. Hostage? Maybe a little, but just a little.

  3. It is always refreshing to read an article about North Korean testing (nukes or missiles) that have substantive technical content–kudos to Schilling. I am more concerned about J.Fiery’s calls to shot down these missiles–which may happen the minute they begin to cross over into Japanese airspace or on trajectory to do so, but prior to that this will be considered an aggression or act of war by the North Koreans (keep in mind that they don’t subscribe to the global norm on any of this). The reason we haven’t shot them down yet, or made a preemptive strike on Yongbang or other nuclear sites is that Seoul remains a hostage. It will be one thing if NK starts a war, but another if we provoke action that will harm one of the US’s closest allies on the planet and endanger millions.

  4. Clay Ramsey says:

    J. Fiery:

    They *could* do all those those things, I guess the decisions have been made not to. I’d say that if any projectile were fired along a trajectory that was a threat, it would be targeted.

  5. Clay Ramsey says:

    Rats. Below I said ‘left vernier’, I meant ‘right’.

  6. Steven Hayden says:

    If the Apogee was 1,413 kilometers then at Terminal velocity in falling the rocket had at least 5,200 plus meters second by my rapid rough calculations .This calculation ignored air resistance in atmosphere since it affects only last 50 km in fall. The calculations used gravity as a constant not a variable. The calculations did not include forward movement 400 kilometers over about 600 seconds……..What is calculated max velocity for this rocket when hitting reentering atmosphere?

  7. J Fiery says:

    Thank you Mr Ramsay for your reply.
    I dont think its been a mee development regarding nations wanting to blame the other side. The Nazis false flag operation in an attack on a radio station inside their borders dressed as Poles comes to mind. Same with the Gulf of Tonkin incident that gave Johnson the Congressional approval to start the Vietnam War. Hell even the Romans did this routinelu. Aside from the US invasion of Iraq in 03 I think that what you describe has been the norm. Especially since the dawn of the 20th century. I mean the USS Maine explosion, now widely believed to have been caused by an accidental boiler explosion gave the US the incentive to go to war with Spain in 1898.
    I guess I should have worded my question better. Why cant we treat NK missile launches the way we did the no fly zones in Iraq in the 12 years between wars there? We had a UN mandate and if the Iraqis violated it by sending up planes we shot them down. Hell we even would blow up their surface to air radars if they even turned them on to track US ans coalition planes. So to me it seems logical given we have a UN mandatw forbidding NK from launching ballistic missiles we could use either land based THAAD type anti missile weapons or keep a few Aegis destroyers on station when our satellites show they are preparing to launch a missile.
    To me it seems we could make things much more difficult for them, maybe even to the point of forcing them to just stop launching them because theyll know they are going to fail every time. Now I dont advocate attacking the missile at initial launch but the second it leaves NK airspace its toast. With the sanctions and the UN resolutions what really could they do about it? Especially given China has “assisted” in getting increasingly tougher sanctions in place. The last thing China wants is a renewal of hostilities that would likely lead to the fall of the Kim dynasty and its much less likely to happen if they never have the chance to develop operational ballistic missiles.
    Still. Thank you sincerely for your answer.
    One last think. I noticed you put my last name in ” not sure why but that actually is my last name.
    Thanks again.

  8. Clay Ramsey says:

    J. Fiery:

    Hi ‘Fiery’, yeah, I can actually think of two reasons why not. The first one is that in this modern age, it seems that countries really want to blame any war on the other side. They don’t want to be accused to starting it for media view purposes. They wait until everything breaks their way then say ‘they started it!, they started it!, now we attack.’ The other is that I doubt the three main DPRK opponents actually believe that there is any true long range missile threat, so why start something over nothing. Of course, it’s very much more complex, especially since both sides seem to delight in confusing the situation so much that everything is a guess.

  9. Clay Ramsey says:

    Dr. Schilling:

    I hadn’t heard the 1000 km altitude figure, it sure doesn’t jive with the stated flight range though. The lack of smoke is a good catch for sure, not sure what to make of that, but the plume in the ‘in flight’ photo definitely shows a dark streak which I thought could be impingement with cold turbopump exhaust. As far as the two images go, the ‘lift off’ shot shows a rational installation as you would expect, but the ‘in flight’ image shows a much smaller (by half) installation with the ‘verniers’ very far inboard. The two images are not of the same thing The ratio between the bright spots (vertically) and the width of the rocket body is 3.65. The Verniers in the ‘submerged’ engine test photos have a separation of 46” if you assume a 23” nozzles (referencing an imagined 6′ door in the shed to the left). If you multiply the ratio in the rocket image with the much more known 46 inches, you get a body width for that missile of 14 feet. If someone has data on a scud (I don’t), they can see if the 3.65 ratio is more consistent with the separation of the steering vanes on that missile, just as a sanity check. My guess is that the clear lift off photo may be one of those engines used in the ‘submerged’ test images revealed earlier. In fact, the left vernier shows a weak, less defined, exhaust jet just like it did in the test photos. If that’s what they did (and that’s what I suspect) this particular missile sure didn’t get far. Ten seconds flight time max. Do like I said and compare the two, you’ll see they could not be the same missile. I think I’ll keep my place in the ‘no’ line, I still not at all convinced.

  10. John Schilling says:

    Clay, the last Musudan reached an apogee of over 1,000 kilometers. No variant of the Scud could reach even half that altitude under the most favorable conditions. The engine plume in even the low-resolution pictures is sufficiently soot-free to rule out the use of a Scud engine, and I’ve since obtained a high-resolution version of this photo,

    http://www.janes.com/images/assets/729/61729/1682041_-_main.jpg

    clearly showing the engine configuration of one main nozzle, two verniers, no turbopump exhaust, and no jet vanes. That’s the Isayev 4D10 engine from an R-27 Zyb, or SS-N-6 Serb if you prefer, and not a Scud.

  11. J Fiery says:

    It may sound Naive but since there are an over abundance of UN, US, and other nations who have comitted to sanctions against NK from developing, let alone usinf ballistic missiles. Why do we ans our regional allies simply state any NK ballistic missile launch will be intercepted and ahot down immediately in accordance with UN resolutions? At the very least it would prevent them from ever truly knowing if they have ANY missile that would work if they wanted to use them for real. The sanctions are in place why not act on them and stop them from incrementally making progress until they get a missile that is a serious threat?

  12. Xu Tianran says:

    Unlike the KN11, the Musudan is indeed liquid and the two are totally different. NK never ceases to surprise…If KN08/14 are too difficult for them but they can make a single set of Musudan engine reliable, maybe they can build a rocket using Unha-3 first stage (120/108 ton thrust–with/without verniers) and a single Musudan as second stage. This rocket will be significantly shorter than Unha3, good for tunnel storage and out-of-tunnel launch preparation, and much easier and more reliable than the KN08/14.

  13. Clay Ramsey says:

    Take a look at the bottom left image of the launch in that collage of images below (search on ‘Rodong Sinmum Musudan photos’ to get a better, but still not good, image of that portion of the flight). Download the image, enlarge to 800% then run the gamma down to around 0.25 (or run the contrast up and brightness down if you don’t have gamma correction). You will notice 4 symmetrically spaced bright spots around the perimeter of the exhaust nozzle. Those look a lot like what could be graphite steering vanes to me. Could simply be a Scud in a Musudan shell. This launch is the one that broke up (as you would expect is surely would) and the second one was simply a scud (it did match it’s performance rather well).

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Credit for photo of young North Korean girl: T.M. All rights reserved, used with permission.