The KN-11 / Pukguksong-1, SLBM Prototype Flight Test Program of the DPRK

©By C. P. Vick, 2015/2016

Senior Technical & Space Policy Analyst

5-2-13/5-12-15/11-2/12-8-15/1-6-/4-23/9-28-2016

Introduction

Prepackaged Liquid Propulsion Single Stage SLBM Development Suggested Events?

** Possible Program Demise? , *** Submerged ocean platform ejection /start up testing

****No successful high ballistic vertical probe flight test

Note:It would appear that the so called “KN-11” designation utilized by the South Korean Ministries of Defense of the DPRK, SLBM testing applies to both the liquid propellant and solid propellant versions. That is exceptionally confusing coming from the Ministry of Defense and Intelligence agency. It would appear that the liquid propellant SLBM program is in fact terminated with the success in the accelerated solid propellant SLBM program development based on foreign missile technology transfer.

Some of the problems the DPRK has experienced in recent missile firings are not easily explained in the face of the same similar systems success in the post flights known. The land based similar system has been successfully flown but when the system of origin has failed in flight in its submarine launch test suggest that they have missed some key technologies procedures required in recent test. This is the recent derivative Soviet era Serb, Zyb, R-25, RSM-27, SS-N-6 SLBM called NK-11 versus the longer No-Dong-B/ HS-10 possibly known as the KN-07 land based system. At least two suffered from a launch hard start of the main engine with the catastrophic results clearly displayed. Yet static test firings have shown it works correctly.

NOTE: It would appear that the prepackaged liquid propulsion single stage SLBM derived design development similar to the Soviet era SS-N-6, KN-X-? SLBM has been terminated because of multiple failures like those experienced in the No-dong-B / Hwasong-10 / Mirim / Musudan flight test program. The SS-N-6, KN-X-? SLBM derived design is believed to not be 1.5 meters in diameter but only 1.4 meters in diameter making it longer than the Soviet era SS-N-6 design but still having its 2,500 kilometer range intend yet to be successfully flight demonstrated. Those liquid propellant KN-X-?,SLBM flight test attempts became an exercise in defining what the failure technical issues were benefiting the No-dong-B / Hwasong-10 / Mirim / Musudan flight test program leading to its success Hwasong-10 development conclusion. That program must now repeat the flights and demonstrate two full range flights to make it operational also.

This DPRK SLBM prototype KN-X-?, is believed now to only be about 1.4 meters in diameter and close to 9.375 (9.4) - 9.5 - 9.67 meters in height making it somewhat different from the Soviet Era Serb, Zyb, R-25, RSM-27, SS-N-6 SLBM of 1.5 meters in diameter and 8.75 meters long.

The Soviet RD-4D10 closed cycle rocket engine schematic diagram. The KN-11 SLBM as well as the KN-07/No-dong-B/HS-10 shares the same common Soviet era rocket engine design variant seen in this diagram above of the RD-4D10 engine configuration.

Recent launches of the shorter KN-11 SLBM / Soviet era SS-N-6, SLBM of some 8.75 meters with a body diameter of 1.5 meters has suffered launch tub/missile ejection launch issues and inflight RD-4D10 engine hard start failures. The KN-11 SLBM has a range of 2,500 kilometers with a 650 kilogram warhead with a 4,400 m/sec velocity max attained.  The KN-14 Limited Range ICBM prototype uses the same engine in a cluster of two in its first stage directly impacting it development because of these launches failures.

The KN-11 / SLBM launch vehicle general internal details are very similar to this Soviet era illustration of the Soviet era Serb, Zyb, R-25, RSM-27, SS-N-6 SLBM. This illustration is incomplete in its internal systems details especially the lack of vertical anti-Slosh baffle’s. The forward instrumentation and warhead details are not accurate to the actual systems designs.

The KN-11 SLBM has a range of 2,500 kilometers with a 650 kilogram warhead with a 4,400 m/sec velocity max attained.

This is the Soviet era classic SS-N-6 also the present KN-11 flight range performance profile

The DPRK Recent KN-11 Launch Flight Experimental Attempts

5. Successfully December 21, 2015 Experimental launch Ejection Test

The KN-11 / No-dong-B the Zyb/SS-N-6 SLBM pop-up experimental launch ejection test operations resumed successfully on December 21, 2015 after its failed launch ejection attempt test on November 28, 2015 according to the Bill Gertz, Washington Free Beacon 01-05-2016 information. No prior warning or further information was provided by the reports source or the official DPRK organizations. The KN-11/No-Dong-B is obvious a non-full systems up experimental ejection test vehicle not a full up flight test vehicle. It is only a demonstration ejection and flight start up test vehicle that apparently had a hard start requiring post flight test study for corrections to be demonstrated later. It was previously successfully tested on May 8, 2015. This test like the previous ones was conducted off its East Sea (Sea of Japan) coastal waters near Wonsan, Sinpo, South Hamygong Province from the same two launch tube on the same the Gulf-II class remade single Sinpo-class 2,000 ton, 67 meter long submarine names “Gorae” (Whale) by the DPRK.

DPRK engineering technical personnel along with it Russian Federation Makeyev OKB acquired personnel clearly have defined the expected launch problems with the known snubber solutions applied to the external missile skin to assist with a clean launch from it launch tube via its solid motor burn hot gas pressure release and ejection to get the rocket above the ocean surface for rocket engine startup.

Subsequent to the initial information noted above on late January 8, 2016 the DPRK state-run KCBS, Korean Central Broadcasting Station released a video of the SLMB test launch observed by the Kim Jung-un. It displayed the missile rising above the sea to about 40 meters at which point the solid propellant charge starts the rocket engine followed with the engine ignition and steering refinements from guidance commands before disappearing into the clouds at the end of the test. The DPRK video was then followed by a Scud firing above the clouds from a previous test earlier in the year. It was not the SLBM firing after start up indicating another hard start failure in the flight test attempt.

4. November 28, 2015 Experimental Flight Test Launch Ejection Failure

The KN-11 / No-dong-B the Zyb/SS-N-6, 2,400 kilometer range SLBM copy of about 9.4-9.67 meter length, that misfire in a mishap on November 28, between 2:20 - 2:40 PM South Korean Time was an experimental failure to launch properly. It is indicated to be obvious non full systems up ejection failure on the East Sea (Sea of Japan) then off limits shipping and air zone test range area. The failure suggest a fundamental quality control failure of the launch ejection process and missile start-up operation that has previously flown successfully from land bases semi mobile systems from Iran and the DPRK with in its territory though not reported openly. The KN-07 is the No-dong-B, some 12 meter long an evolved stretch SS-N-6 previously deployed in the DPRK land bases semi-mobile Strategic Rocket Force as an operational system.

The DPRK had cordoned off from maritime shipping a part of its East Sea coast off the Wonsan, Sinpo range area for artillery fire but this also offered a possibility of a public flight of the No-dong-B=KN-07 or KN-11 for a more complete test from the May 2015 experimental launch ejection operation. This was yet another pop-up ejection launch experimental test among several others already conducted previously. The South Koreans military and intelligence went on alert for a missile test around November 11, 2015 when the DPRK announced the no maritime sail zone and no fly zone on its East Sea (Sea of Japan) coastal waters near Wonsan, Sinpo, South Hamygong Province through December 7, 2015. On November 16, 2015 according to AFP reports and other subsequently suggested it was an artillery training drill by the DPRK with no long range international Maritime or Air Traffic warnings zones issued such as seen in previous satellite launch attempts.

The KN-11 launch required a successful solid motor burn hot gas pressure release and ejection to get the rocket above the ocean surface for rocket engine startup. That hot gas pressure ejection will only allow it to go less than 50-75 meters ballistic ally above the sea surface unless the engines starts properly. In this case it apparently did not start causing no missile to be identified by intelligence sources and methods as having taken flight. A solid propellant charge starts the rocket engine followed with the engine ignition and steering refinements from guidance commands. If the missile was fueled partially or fully it may have exploded on impact with the sea unless it blew up prematurely at or during ejection from one of the launch tubes. Was the missile an intentional full mass model dud for submarine launch demonstration like the US did with Polaris remains unknown? Much of the debris may be the missile or more probably the plastic breakable sea water cap above the missile nose cone and base launch systems seal to eject the missile from it cylinder via solid motor hot gas release. If the missile fired in the silo canister on the Sinpo-class submarine would have created a real catastrophic explosion because it is not designed to operate that way. This leaves the question of submarine damage and or fatalities issues. There is no evidence of causalities to date from the sources available per South Korean Official on the remade Sinpo-class submarine which could have been damaged. However subsequent intelligence sources and methods analysis has identified that it was indeed an attempted launch from the submerged submarine and not the submerged platform like last May 2015 following the Soviet procedure to early field deploy of weapons systems to ring out the operational full systems issues. That assessment has defined the Gulf-II class remade Sinpo-class sail mounted two silo tube ballistic missile submarine failed as the missile did not eject properly ultimately heavily damaging the sail structure of the submarine without causalities indicated.

It is believed the dear leader Kim Jong-un attended the ejection test monitoring operation along with the State Military Commission members, pushing the State Planning System industry beyond its capability since the space booster was not ready when he desired it leaving few options on the table for his geopolitical acts. In all probability the DPRK tried to accelerate the R&D process to follow with an attempt to of the full systems up experimental demonstration shooting the works for upcoming diplomatic bluff reasons and it did not even sputter and made a mess with the obvious left over debris on the Ocean surface.

Not much more information is expected anytime soon due to the fact of intelligence gathering and analysis and newer policies controlling data released on intelligence matters. I will point out that public statements take great pains to imply things that the general populace will reach conclusions about and accept without question…those statements are not untrue, but they are misleading on purpose because of National State Policy.

3. 5-8-2015, DPRK Naval SLBM, KN-11 flight test from the submerged 2,000 ton SINPO-class submarine. This is the only submarine that is in this class of the DPRK submarines. It was an in- flight main engine and four steering Vernier’s ( not two) engine start up test firing of the highly toxic storable propellant single stage KN-11, SLBM. This was after the initial ejection hot gas launch solid motor firing from one of two launch tubes on the SINPO-class submarine a modified rebuilt Golf-II class Soviet-era submarine. It carried a dummy warhead payload. The missile is not believed to have carried a full propellant load for this test launch. The R&D variant on the No-Dong-B, KN-11 was about one quarter shorter than the standard Mirim, Musudan, No-Dong-B missile possibly designated KN-07?, length of 12 meters. That placed the KN-11 at about 1.4 - 1.5 meter diameter launch tubes and 9.67 meters long but there is still room for the full No-Dong-B in the two SINPO-class submarine silos. That in turn reduces the KN-11 performance down to the Soviet-era SS-N-6 to 2,400-2,500 kilometers range. Thus we now have two variants on this R&D missile. This is according to South Korean sources. One can see the solid propellant smoke from the ejection motor as well as the subsequent solid propellant charge exhaust start of the engines before their main ignition followed by the pale yellow liquid propellant flame jets from the thrust chambers. The angle of attack was very close to 60 degrees from the horizontal sea surface that later lowered itself close to around 50 degrees. Equally interesting for unexplained reasons there was an observation support naval surface vessel very close to the launch as the KN-11 breached the East Sea surface. Later pictures show the boat deleted or covered with "Photo shopped" steam. Whether the DPRK was pulling a psychological warfare trick by faking and utilizing the submerged platform rather than its only submarine of that type for the public test remains an open question that US officials suggest was the reality. Thus the presence of the servicing surface vessel may be explained or that the DPRK was backing up its efforts? The polemics on the launch event methodology and the reality that only one submarine is potentially capable of launch this class missile means the SLBM threat is some years from becoming a reality. They must first test the system from the submarine to full range and then produce a larger much more sophisticated modern series of submarines capable of carrying more missiles. The fact that the KN-11 requires propellant loading prior to launch from the submarines storable propellant sources definitely limits the systems effectiveness strategically. The fact that no Video of the launch has been released leaving only a hand full of doctored images with different lensing by KCNA News Agency released images of the event as it unfolded over a series of mere seconds suggest that deception was the name of this game by the DPRK. The NK-11, labeled "Pukkuksong-1" or Bukkeunkseong-1 (Polar Star). The next flight test is expected on or before October 2015. It came on November 28, 2015 a failure.

Range and altitude not defined. It was not a full range flight test but only a launch vehicle engine start up demonstration. Estimated ballistic range was suggested to be 150-200 meters altitude before collapsing in the East Sea along the DPRK eastern coastal range. The No-Dong-B was flown from off the coast of the naval port city of Sinpo, South Hamgyong Province possibly achieving a range of less than one kilometer according to South Korean sources.

2. 4-22-2015, DPRK Naval, KN-11, SLBM flight test from submerged ocean launch platform, Range and altitude not defined

1. 1-23-2015 DPRK Naval KN-11, SLBM flight test from above ocean surface launch platform Range and altitude not defined.

DPRK, KN-11= R-25, R-27 / SS-N-6 (NATO)SERB, Soviet ZYB, Russian RSM-25

Notes:
* Data from Russian intelligence sources
** Based on rocket equations derived results.

KN-11 & HS-10 Launch Failures Reasons Focus on Several Issues That Directly Impacts their programs:

Some of the problems the DPRK has experienced in recent missile firings are not easily explained in the face of the same similar systems success in the post flights known. The design bureau may be under such pressure for a full range strategic rocket demonstration as to literally launch for broke as many missiles as possible hoping both to succeed close enough but also get at the vehicles systemic problems defined through accelerated flight testing operational environment observed… All three missiles KN-11, HS-10 & KN-14 are using the same first stage closed cycle RD-4D10 engine variants.

1. It literally blew up on its launch pad destroying the TEL vehicle:

Answer B: The “hard start” is an improper mixing of the propellants at the wrong time or place which is a flow control issue of the propellant manifold issue. That has apparently been resolved by precise presetting programming of the flow control valve system. Typically Soviet era engines are started run and shut off as the only programming required but this has required more homework for the setting parameters.

2. It suggests its single stage main engine fueling apparatus plumbing closed cycle turbo-machinery suffered a catastrophic failure causing the repeated explosions.

Answer D-E: Its single stage main engine fueling apparatus plumbing closed cycle turbo-machinery suffered a catastrophic failure causing the repeated explosions. This kind of failure could occur anywhere in flight but they are systemic of a common issue and failure in design specification requirement. The near max-Q failures seem to relate to the maximum dynamic loading failure of the internal plumbing its single stage main engine fueling apparatus closed cycle turbo-machinery suffered a catastrophic failure causing the repeated explosions.

If the propellant lines whether the main flow line or those associated with the closed cycle turbo-machinery are breached rupture anywhere along the separated flow controlled process the mixing of the propellants cause an instantaneous internal explosion of the hypergolic propellants and launch failure.

This is indicative of a propellant line seal failure possible precipitated by propellant/tankage control stabilization short coming or outright seal/weld stress failures. The propellant slosh baffling or stronger welds of the plumbing are typically required to resolve these hard to identify and resolve issues that require repeated flight testing to resolve.

Alternatively the use of simulated ground static testing of the full systems based on the flight test loading inputs. Additionally the static test firings that do not immerse the full engine turbomachinery in the propellant tanks for the test that if it is breached as suspected will severely damage the test stand from the explosive failure. Careful internal TV imaging during static test firings would be required to identify the failure areas. The DPRK has clearly walked away from this finality test stressing another more tedious approach.

DPRK welding quality does not impress at all from what has been observed.

3 ….. veered off course suggesting steering issues… The flight is stated to have veered deviated from its normal flight trajectory 5-6 seconds after launch liftoff exploding at about 300 feet breaking up in a fiery catastrophic failure collapsing back on the TEL as it disappearing from the radar systems of the South Korean Defense Ministry

Answer C: The veering off course is directly due to the two steering Vernier’s somehow not doing their job properly or outright failure in some element of the proven system.

4. ….the second launched around 7:26 PM seems to have failed midair after flying up several kilometers for about a minute before exploding. This seems to have repeated the April 15 failure mode in the Max-Q region.

Answer D-E. See item”2” answer

5. At least one suffered from a launch hard start of the main engine with the catastrophic results clearly displayed and this may have repeated itself in the land based version this time. Yet static test firings have shown it works correctly in a cluster of two engines seen successfully demonstrated for the KN-14 first stage recently. At least two now have suffered from a launch hard start of the main engine with the catastrophic results clearly displayed.

Answer B: See item “1” answer

6. That hard start if survived through initial launch may leave the lingering turbo machinery damage that soon catches up causing the explosive failures observed.

Answer B: See item “1” answer

7. It suggests its single stage engine fueling apparatus closed cycle turbo-machinery suffered a catastrophic failure causing the inflight explosion. 

Answer D-E: See item”2”

8. ….experimental launch ejection test operations resumed successfully on December 21, 2015 after its failed launch ejection attempt test on November 28, 2015 according to the Bill Gertz, Washington Free Beacon 01-05-2016 information. DPRK engineering technical personnel along with it Russian Federation Makeyev OKB acquired personnel clearly have defined the expected launch problems with the known snubber solutions applied to the external missile skin to assist with a clean launch from it launch tube via its solid motor burn hot gas pressure release and ejection to get the rocket above the ocean surface for rocket engine startup.

A. The first problem was the SLBM “ejection snubbers’ issue” easily resolved already