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In a reflection of global economic and technological changes since the Second World War, some nations have given up the ability to produce conventional submarines and new players are emerging. Countries that are no longer in the game are the United States and Britain – concentrating exclusively on nuclear boats – as well as Italy and the Netherlands. These latter two still operate diesel-electric submarines, but seem to have given up the desire to construct them. Sweden continues to produce submarines, but is the first country to give up national ownership of the company undertaking the work following the sale of Kockums to Germany’s ThyssenKrupp Marine Systems.

At the end of the Second World War the only nation in Asia with a history of building major conventional submarines was Japan. To this can now be added: India; Australia; China; and South Korea. The first two have the ability to manufacture submarines under license – though India is moving towards indigenous capabilities for nuclear boats – while Japan and China have the know-how to design and produce their own craft. South Korea is in an intermediate position with manufacturing ability beyond question and the country is now also taking the first tentative steps towards an export design – leaning heavily on German technology – with three submarines being built by Daewoo for Indonesia. North Korea produces mini subs up to 300 tonnes displacement – one of which sank the South Korean corvette Cheonan in 2010.

Three nations have the ability to design and build both conventional and nuclear submarines: France, Russia and now China. It is only the latter two that operate combined fleets, with the French Navy – like the US and UK – opting for all-nuclear fleets. India also now operates a mixed fleet, and is hoping to introduce the indigenous nuclear powered Arihant class into service soon. Curiously, the next generation of Indian conventional submarines will still be an imported design in the form of the French ‘Scorpene’. The first Indian nuclear submarine to enter service is the imported INS Chakra – an Akulla II leased from Russia in 2004.

The reasons for this substantial geographical change in submarine production capabilities are complex. Both the Netherlands and Italy were producers and operators of high quality conventional designs, but both found the cost of staying in the business too high. The UK and France moved to all nuclear fleets (though France produces conventional submarines for export) partially for cost reasons – when possessing an undersea nuclear deterrent force was their highest priority – and they no longer possessed the military budgets to simultaneously operate mixed fleets. This decision was made easier by the allocation within NATO of various submarine responsibilities, where missions better suited to conventional submarines – such as SSK operations – fell on countries astride the Baltic Sea, especially West Germany. This partially explains the continuing strong position of German submarine design on the export front, which started with the Type 209 series and now with the addition of Type 214s.

While the US had the economic size to maintain both a conventional and nuclear fleet, the hugely influential Admiral Hyman Rickover decided in the early 1950s to go down the all-nuclear path. As a consequence the United States does not sell submarines, though it does release some technology to countries such as Britain and Australia. Russia – and previously the USSR – persevered with both conventional and nuclear submarines that are continuing to enjoy design advances and export success after the economic hiatus of the early 1990s.

So why are Asian nations becoming increasingly heavily involved in submarine production – especially conventionally powered ones? Because they can. China has been investing heavily because their naval doctrine is to be able to push the USN back out to the second island chain and beyond. Submarines are an excellent sea denial asset and China is believed to be examining several design possibilities for future classes. More on this later.

Japan has a long and distinguished history of submarine production and as an island nation wishes to be able to safeguard sea lines of communication. Japan has built the world’s largest conventional submarine – the I400 Class. These were two 6,000 tonne beasts constructed during the Second World War to attack the Panama Canal with embarked seaplanes – from the Atlantic Ocean side. Japan is prevented by its pacifist constitution from exporting military products, including submarines, but there are signs that this situation might change. Australia has had some preliminary discussions with Japan about gaining access to that country’s diesel-electric propulsion technology as a possible alternative to the trouble plagued Hedemora diesels of the Collins Class.

South Korea, India and Australia have all been acquiring the skills not only to manufacture submarines under license, but also to develop indigenous designs. The former two countries have arguably had more success to date, though with Australia looking to eventually introduce a new class of 12 conventional submarines, that country, too, will be ramping up its skill base. Another Asian nation that might also enter the submarine production field is Taiwan, which is believed to be considering building its own submarines.

It is too early to predict that Asia will one day overtake Europe in producing leading edge conventional submarines, but the possibility is not farfetched due to the large number of technology transfer programs that have been put in place. However, for the moment design expertise for diesel-electric submarines remains substantially in the hands of existing producers.

Developments in China are especially interesting. That country certainly added a new dimension to IDEX’2013 and LIMA’2013 by participating in those shows with stands. The wares on display included a scaled model of the S20 diesel-electric submarine, the first-ever submersible vessel from China specially developed for export. With this, the People Republic of China has filed an application (figuratively speaking) to join the very narrow club of nations exporting conventional submarines. China comes in after two other recent applicants, South Korea and Spain. The latter country has split from France and is now returned to the field of submarine design and production in its own right, while South Korea is benefiting from German technology transfer.
LIMA’2013 was the first air and maritime show on the Malaysian holiday island of Langkawi to have a Chinese exhibitor with a stand. During conferences and press briefings at LIMA’2013, the Malaysian defense minister Ahmad Zahid Hamidi touched on China several times. Answering a question whether Malaysian government and the military are concerned with growing Chinese naval might, and expanding presence, he answered: “They have been here for ever! We have lived with them by our side for centuries. We do not have issues with China”.

This explains the fact that China Shipbuilding & Offshore Co. Ltd. (CSOC, actually received an invitation from the Malaysian side to take part in LIMA’2013. In other words, Chinese industry is now a welcomed partner for Malaysia, so that collaboration programs between the two countries shall be considered a future possibility. CSOC is a subsidiary of China Shipbuilding Industry Corporation (CSIC), one of the two largest shipbuilding conglomerates in PRC with nearly a thousand enterprises and a workforce of 300,000.

A CSOC spokesman told media members that “LIMA is very impressive and interesting” and that his company “enjoys the opportunity to exchange information”. CSOC will certainly take part on the next show on Langkawi in 2015, he added. A number of countries in the region already operate ships built by CSOC. The spokesman said that the company is offering to its traditional overseas customers and potential clients landing platform docks (LPDs), frigates, fast craft and submarines, adding that exportable versions are similar to the baseline designs already in service with the People’s Liberation Army’s Navy (PLAN).

Information available on the S20 remains scarce: the Chinese manning their stands briefed spoke only to invited guests. Graphics indicated that the S20 can attack surface targets using “anti-ship missile”, lay “mines”, launch “torpedoes” (with no indication of intended targets) and release “frogman”. Nothing indicated the ability to launch the long-range CH-SS-NX-13 ASCM or any other sort of land-strike missiles (which might be of interest to some potential customers, knowing that PLAN’s diesel-electric boats are land-strike capable). The scaled model itself was relatively schematic, with no cutaways. It indicated presence of six torpedo tubes in the nose section and seven-blade propeller in the tail with highly curved blades.

In appearance, the S20 bears resemblance to the Yuan class or Type 041. The latter is believed to have an air-independent propulsion (AIP) system, most likely employing Stirling type of engines (which, again, might be of interest to potential customers). By US estimates, the Yuan class possesses a lower relative detectability than the Song. By noise characteristics, the Yang is placed in between the Project 636 and the Type 039, according to Office of Naval Intelligence (ONI).

Making an exportable version of the series produced Yang does make sense, as this promises reduced costs, parts commonality and interoperability with PLAN assets. Currently, China is known to have in series production only one diesel-electric boat, with 11 Type 041 vessels completed in 2009-2012 timeframe.

The potential of the local industry has allowed PLAN to keep a steady-state force of conventional submarine force at roughly 50 units throughout this century. Construction rate has been about 2.2 per year in 1995-2012 timeframe, with PLAN intake rising to 2.8 with Russian-built Kilo class included. Ever-growing potential of the local industry leaves little doubt about PRC’s ability to deliver obligations before foreign customers if there will be some making decision in favor of Chinese submarines.

Today, China is one of the established submarines operators, along with India, Pakistan, Iran, Japan, Taiwan, Australia and both Koreas. All of them continue building up their submarine fleets. Countries that recently added submarines to their assets or have placed orders include Malaysia, Vietnam and Indonesia. Naturally, this fact motivates other countries in the region to consider submersible assets for the navies of their own. “These facts give a clear indication of ongoing arms race in the region. We see a number of new nations coming to possess underwater capabilities and many more considering such a move”, says Andrei Baranov who leads the exportable diesel electric submarine operations at Russia’s Rubin submarine designer. There are quite a few of disputed islands in the Asia-Pacific waters. Submarines are seen as the right argument in defending a smaller nation’s claims to these islands in the case when these are disputed by a larger nation with far bigger naval forces. “Submarines are the sort of weapons that can be successfully employed in the region”, Baranov insists. “There are indications that many nations of the region are going to buy submarines… and buy them in worthwhile quantities”, he continues. For example, Bangladesh indicated its intent to follow the trend as well as Thailand. The Philippines may also join in – though all these countries face budget constraints and competing demands on expenditure.

South East Asia is becoming a very lucrative market for shipbuilding companies. Traditional suppliers of such equipment in Germany, Russia and France hope for a big portion of orders. But they are to meet growing competition from within the region, notably from the Korean and Chinese manufacturers. Viewed from this perspective, the presence of those at IDEX and LIMA with their wares on display makes no surprise.

The sensitivity of the situation is that, while offering the S20 for export, China continues to import Russian submarines. In addition to 12 Kilos – the last batch of which was accepted in 2006 – PRC has recently ordered from Russia four submarines of the Amur 1650 design – which is similar to the S20. This fact might give a third country seeking to procure submarines a base to believe that the Russian design is somewhat more advanced. This, however, will hardly produce a worthwhile affect on the S20 target market. Its core is likely to be made of traditional clients for Chinese military equipment, the countries that receive help from China or in other ways dependant on PRC and motivated/inclined to buy “made in China” products.


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X 51A Waverider 617x416 X 51A Wave Rider Hypersonic Aircraft

X-51A WaveRider

The experimental X-51A Waverider is an unmanned, autonomous supersonic combustion ramjet-powered hypersonic flight test demonstrator for the U.S. Air Force.

The X-51A is designed to be launched from an airborne B-52 Stratofortress bomber. The flight test vehicle stack is approximately 25 feet long and includes a modified solid rocket booster from an Army Tactical Missile, a connecting interstage, and the X-51A cruiser. The nearly wingless cruiser is designed to ride its own shockwave, thus the nickname, Waverider. The distinctive, shark-nosed cruiser has small controllable fins and houses the heart of the system, an SJY61 supersonic combustion ramjet or scramjet engine built by Pratt & Whitney Rocketdyne designed to burn JP-7 jet fuel. Boeing’s Phantom Works performed overall air vehicle design, assembly and testing for the X-51′s various component systems.

The X-51 was made primarily using standard aerospace materials such as aluminum, steel, inconel, and titanium. Some carbon/carbon composites of the leading edges of fins and cowls are used. For thermal protection, the vehicle utilizes a Boeing designed silica-based thermal protection system as well as Boeing Reusable Insulation tiles, similar to those on board the NASA Space Shuttle Orbiters.

Four X-51As were built for the Air Force. The X-51A program is a technology demonstrator and was not designed to be a prototype for weapon system. It was designed to pave the way to future hypersonic weapons, hypersonic intelligence, surveillance and reconnaissance, and future access to space. Since scramjets are able to burn atmospheric oxygen, they don’t need to carry large fuel tanks containing oxidizer like conventional rockets, and are being explored as a way to more efficiently launch payloads into orbit.

In addition to scalable scramjet propulsion, other key technologies that will be demonstrated by the X-51A include thermal protection systems materials, airframe and engine integration, and high-speed stability and control.

The X-51A represents one of the service’s most significant reinvestments in hypersonic flight since the rocket-powered X-15 program which flew 50 years earlier.

Air Force officials anticipate the X-51A program will provide a foundation of knowledge required to develop the game changing technologies needed for future access to space and hypersonic weapon applications. For example, hypersonic speeds on the order of flying 600 nautical miles in 10 minutes may provide the ability to accurately engage a long-distance target very rapidly.

The X-51A program is a collaborative effort of the Air Force Research Laboratory and the Defense Advanced Research Projects Agency, with industry partners The Boeing Company and Pratt & Whitney Rocketdyne. Program management is accomplished by the Air Force Research Laboratory Propulsion Directorate at Wright-Patterson Air Force Base, Ohio.

Hypersonic flight, normally defined as beginning at Mach 5, five times the speed of sound, presents unique technical challenges with heat and pressure, which make conventional turbine engines impractical. Program officials said producing thrust with a scramjet has been compared to lighting a match in a hurricane and keeping it burning.

The Air Force currently plans to fly each X-51A on identical flight profiles. Like the X-15, the X-51A is designed to be carried aloft by a B-52 mother ship launched from the Air Force Flight Test Center at Edwards Air Force Base, Calif. It is released at approximately 50,000 feet over the Pacific Ocean Point Mugu Naval Air Warfare Center Sea Range. The solid rocket booster accelerates the X-51A for 30 seconds to approximately Mach 4.5, before being jettisoned. Then the cruiser’s scramjet engine, remarkable because it has virtually no moving parts, ignites. The ignition sequence begins burning ethylene, transitioning over approximately 10 seconds to the same JP-7 jet fuel once used by the SR-71 Blackbird.

Powered by its scramjet engine, the X-51A will accelerate to approximately Mach 6 as it climbs to nearly 70,000 feet. Hypersonic combustion generates intense heat so routing of the engine’s own JP-7 fuel will serve to both cool the engine and heat the fuel to optimum operating temperature for combustion. The fuel load and flight profile provides for a 240-second engine burn, transmitting vast amounts of telemetry data on its systems to orbiting aircraft and ground stations, before the vehicle exhausts its fuel supply, splashes down into the Pacific and is destroyed, as planned. Flight test vehicles are not recovered.

The X-51A development team elected from the outset not to build recovery systems in the flight test vehicles, in an effort to control costs and focus funding on the vehicle’s fuel-cooled scramjet engine. A U.S. Navy P-3 Orion aids in transmitting telemetry data to engineers at both Naval Air Station Point Mugu and Vandenberg AFB, Calif., before it arrives at its final destination, the Ridley Mission Control Center at Edwards AFB.

Conceived in 2004, the X-51A made its first “captive carry” flight Dec. 9, 2009. The flight test verified the B-52′s high-altitude performance and handling qualities with the X-51 attached and tested communications and telemetry systems, but the vehicle remained attached to the B-52s wing.

The X-51A made history during its first supersonic combustion ramjet-powered hypersonic flight May 26, 2010, off the southern California Pacific coast. Officials said the flight test vehicle flew as anticipated for nearly 200 seconds, with the scramjet accelerating the vehicle to approximately Mach 5, nearly 3,400 miles per hour. The fuel-cooled scramjet performed as planned transmitting normal telemetry for more than 140 seconds, then observing a decrease in thrust and acceleration for another 30 seconds. An anomaly then resulted in a loss of telemetry, and the test was terminated and vehicle was destroyed by flight controllers on command.

Despite the anomaly, the May 26 flight is considered the first use of a practical hydrocarbon fueled scramjet in flight. The longest previous hypersonic scramjet flight test performed by a NASA X-43 in 2004 was faster, but lasted only about 12 seconds and used less logistically supportable hydrogen fuel.

Following an extensive analysis of flight data from the X-51A’s first hypersonic flight test, slight modifications are planned to strengthen the rear seal area near the engine exhaust nozzles for the three remaining X-51As.

The next two X-51A flights ended prematurely. The second vehicle was boosted by the rocket to just over Mach 5, separated and lit the scramjet on ethylene. When the vehicle attempted to transition to JP7 fuel operation, it experienced an inlet un-start. The hypersonic vehicle attempted to restart and oriented itself to optimize engine start conditions, but was unsuccessful. The vehicle continued in a controlled flight orientation until it flew into the ocean within the test range.

The third X-51A safely separated from the B-52, however after 16 seconds under the rocket booster, a fault was identified with one of the cruiser control fins. Once the X-51 separated from the rocket booster, approximately 15 seconds later, the cruiser was not able to maintain control due to the faulty control fin and was lost.


The final flight of the X-51A occurred May 1, 2013 and was the most successful in terms of meeting all the experiment objectives. The cruiser traveled more than 230 nautical miles in just over six minutes reaching a peak speed of Mach 5.1.

Overall the more than 9 minutes of data collected from the X-51A program was an unprecedented achievement proving the viability of air-breathing, high-speed scramjet propulsion using hydrocarbon fuel.

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General Characteristics
Primary Function:
 Hypersonic scramjet-powered flight test demonstrator
Contractors: Boeing, Pratt & Whitney Rocketdyne
Power Plant: JP-7 fueled/cooled SJY61 supersonic combustion ramjet
Thrust: 500 – 1,000 pound class
Length: Full stack 25 feet; Cruiser 14 feet; Interstage 5 feet; Solid rocket booster 6 feet
Weight: Approx. 4,000 pounds
Fuel Capacity: Approx. 270 pounds JP-7
Speed: 3,600+ miles per hour (at Mach 6)
Range: 400+ nautical miles
Ceiling: 70,000 + feet
Crew:  ground station monitored
Unit Cost: Unavailable
Initial Flight Test: May 26, 2010
Inventory: Four purpose-built for flight test, not designed for recovery (one vehicle expended as of Feb. 1, 2011)

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US Sea Radar Tracking N. Korean Threat


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Blue Marlin carrying sea-based x-band radar. T...

Blue Marlin carrying sea-based x-band radar. The heavy lift vessel MV Blue Marlin with its deck cargo of the Sea-Based X-Band Radar enters Pearl Harbor, Hawaii, after completing a 15,000-mile journey from Corpus Christi, Texas, on January 9, 2006. (Photo credit: Wikipedia)


With North Korea’s launch of a mid-range Musudan missile believed to be imminent, a U.S. official confirms that the SBX radar has been deployed to the Pacific to assist with tracking the missile if it is launched.  That tracking could help bring a missile down if needed.

The Sea-Based X-Band Radar looks like a giant golf ball placed atop a platform that resembles a floating oil rig.

It contains a precise long-range radar that is part of the integrated missile-defense system and helps track launched missiles so they can be brought down by missile interceptors.

With North Korea threatening to launch missiles against the United States, the Pentagon reportedly sent the radar system out to sea April 1 from its home port of Pearl Harbor to assist with tracking a potential missile launch.

The next day, Pentagon spokesman George Little denied that was the case, underscoring that the radar had gone to sea as part of previously scheduled sea trials.  ”They’re undergoing semiannual system checks,” Little said. “Decisions about further deployments have not been made to this point.”

A U.S. official now says the SBX is no longer undergoing sea trials and “has been deployed to the Pacific for an operational missile-defense mission.”

“It’s up and running and active,” the official said.

U.S. officials believe that at least one Musudan missile transported to North Korea’s eastern coast last week is ready for launch and has been fueled.

Defense Secretary Chuck Hagel told reporters Wednesday that the United States “is fully prepared to deal with any contingency, any action that North Korea may take or any provocation that they may instigate.”

He said the international community has been very clear that North Korea “with its bellicose rhetoric, with its actions, have been skating very close to a dangerous line.”  He said their actions and words “have not helped defuse a combustible situation.”

He urged North Korea to turn down the rhetoric.

U.S. Pacific Command Adm. Sam Locklear told a Senate panel Tuesday that the United States has the capability to intercept a Musudan missile, but that he would not recommend shooting it down if its trajectory did not pose a threat to the United States or its allies in the region.

With a range of more than 2,000 miles, the Musudan cannot reach Hawaii or the U.S. mainland, although it could reach U.S. bases in Okinawa and Guam.

The U.S. Navy has deployed two Aegis destroyers to the region that are equipped with SM-3 missile interceptors that could bring down a North Korean missile.  Both South Korea and Japan have each deployed two similar Aegis destroyers to the waters off the Korean peninsula to provide missile defense.

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Musudan (“New Insights on the North Korean SS-N-6 Technology “)

The so-called Musudan missile is commonly seen as an operational North Korean Intermediate Range Ballistic Missile (IRBM) with a range of more than 3,000 km. There seems to be a consensus in the open source literature that this missile is based on the Soviet SS-N-6 submarine missile, and that the second stage of the North Korean Unha2/-3 satellite launcher is related to the Musudan, or that it actually is an original SS-N-6. New photos of the Unha-3 second stage indicate a different situation.

Scud Transporter Erector Launcher (TEL) with m...

Scud Transporter Erector Launcher (TEL) with missile in upright position (Photo credit: Wikipedia)

Common View of the Musudan Missile

The Musudan missile, also sometimes designated the BM-25 or the Nodong-B, is commonly seen as another example for the North Korean capability to design and produce missiles based on available technology from other countries.

According to the common view, earlier North Korean missiles, for example the so-called Scud C or the Nodong, were based on the Soviet Scud B technology from the late 1950s that North Korea had acquired by reverse engineering the Soviet Scud B missile in the 1980s.

Somewhat later, North Korea is said to have gained access to the more advanced Soviet R-27/SS-N-6 missile that features technologies that – even though developed in the early 1960s – can still be seen as high-end even today. Open source literature usually states that the North Koreans managed to adapt this technology, just as they did with the comparatively rugged Scud technology, and with that knowledge they designed and produced the Musudan missile. Some assessments claim the use of old Soviet SS-N-6 parts in these missiles, others assume completely indigenous production.

When photos of the North Korean satellite launcher Unha-2 were published in 2009, analysts noted that the rocket’s second stage closely resembled an SS-N-6 in appearance and dimensions. One year earlier, elements of the SS-N-6 had been identified in the upper stage of the Iranian Safir satellite launcher, and a certain level of cooperation between Iran and North Korea is widely assumed. Therefore, it seemed consequent to identify the Unha-2 second stage as a modified SS-N-6, which also underscored the rumors at that time of a road-mobile SS-N-6-based North Korean IRBM – the Musudan.

In October 2010, North Korea finally seemed to confirm these rumors by displaying the Musudan at a parade in Pyongyang.

What Is Special About SS-N-6 Technology?

Two BM25 Musudan missiles on the 65 KWP annive...

Two BM25 Musudan missiles on the 65 KWP anniversary parade, 10 October 2010 (Photo credit: Wikipedia)

Before the Unha-2 and the Musudan, North Korea was believed to only have access to Scud technology. Even though the Scud B still is a formidable weapon system with combat-proven and reliable technology, this technology has certain limits. Due to the cold equations of rocketry, missiles with Scud technology quickly grow in size once a certain range threshold is crossed: An ICBM with Scud technology (and aluminum structures!) would easily weigh about 80 t, while a satellite launcher for very small payloads would weigh almost 50 t.

The Iranian Safir satellite launcher illustrates how the use of SS-N-6 technology can reduce a rocket’s size: With a launch mass of less than 25 t (according to reconstruction done at Schmucker Technologie), the Safir can orbit microsatellites of up to 50 kg, and perhaps even more, even though the Safir only seems to use some SS-N-6 propulsion system elements in its upper stage: The vernier engines (with the according propellants) and the turbo pump.

However, the SS-N-6 offers many more advances over the Scud technology:

  • Extreme lightweight aluminum isogrid structures
  • Engine submerged in the fuel tank
  • Efficient main engine with staged combustion cycle instead of gas generator cycle
  • Propellants that are more energetic (NTO/UDMH instead of IRFNA/kerosene)

Another comparison may illustrate the potential of this technology. Weighing little more than 14 t, the SS-N-6 offers a range of 2,400 km, perhaps even more. With the same warhead mass and a comparable launch mass of around 15 t, the Nodong or Shahab 3 – based on Scud technology – only offers half that range.

The Unha-3 Second Stage

English: Military personnel examine a Scud mis...

English: Military personnel examine a Scud missile shot down in the desert by an MIM-104 Patriot tactical air defense missile during Operation Desert Storm. (Photo credit: Wikipedia)

As portrayed, the second stage of the Unha-2 satellite launcher had played a key role in the claim that North Korea has mastered SS-N-6 technology. In April 2012, North Korea launched a rocket designated Unha-3, with the first and second stage apparently the same as Unha-2. High resolution photos of the second stage now allow a detailed analysis, with an unexpected result.

To save weight and space, the SS-N-6 has a common bulkhead between the oxidizer tank on top and the fuel tank below. The oxidizer tank is divided, and the lower compartment is emptied first to keep the center of gravity at the front.

The Unha-3 second stage, however, clearly shows an area with several rivet joints in the lower half of the stage (see Figure 3). This is a clear sign for an empty space between the oxidizer tank and the fuel tank, meaning that there is no common bulkhead. The rivets indicate the use of internal stringers to stiffen this part of the structure. This is further underlined by a retro rocket that is mounted at this position (see also Figure 3). The different sizes of the tanks and the color scheme of the filling or draining valves (typical Soviet color code: red for oxidizer, yellow for fuel), as well as the Korean markings/abbreviations at these valves all indicate that the upper tank is the oxidizer tank, and the lower tank is the fuel tank.

Figure 3: The Unha-3 Second Stage

The tank dimensions are clearly visible. Assuming standard domes for these tanks that extend beyond the visible cylindrical parts (in Figure 3, only the cylindrical sections are marked!), the propellant volumes are easily calculated with close to 6.2 m³ for the upper tank and around 3.8 m³ for the lower tank. Taking the required ullage (empty space when filled) and the feedline from the upper tank through the lower tank into account (which is usually also filled with the respective propellant), the effective propellant volumes are estimated with around 6 m³ and 3.5 m³. The resulting effective volume ratio is 1.7 – a number that is far from the typical value of around 1.4 for the NTO/UDMH propellant combination that a SS-N-6 engine would require. However, values around 1.7 are typical for the IRFNA/kerosene combination that is used by the Scud and the Nodong.

SS-1c Scud B ballistic missile

SS-1c Scud B ballistic missile (Photo credit: Wikipedia)

Assuming that the rocket stage uses these Scud/Nodong propellants, the analysis yielded a propellant mass of 9.5 t IRFNA and 3 t kerosene. These numbers are a perfect match for the Nodong’s estimated oxidizer mass, and deviate from the Nodong’s estimated fuel mass by only a few percent.

The upper end of the Unha-3 second stage’s engine compartment is easy to locate (see Figure 3). A submerged engine would further reduce the fuel mass, further increasing the effective volume ratio of oxidizer and fuel toward a value of 2. This alone is a showstopper that rules out the option of a submerged engine for the Unha-3 second stage.

Therefore, the engine has to be located below the fuel tank, and not submerged in it. With that, there only is enough room for an engine below the fuel tank if it is situated in the conical structure. At this configuration, a complete engine compartment might have a length of up to 2.5 m. With a length of about 2.4 m, the Nodong’s engine compartment would fit in nicely.

It is also noteworthy that the thrust level of the Nodong engine is fully sufficient to be used as the Unha-3 second stage engine.

With the mentioned indications of

  • propellant type (same as Nodong),
  • propellant mass (same as Nodong),
  • engine compartment length (same as Nodong),
  • engine thrust level (compatible with Nodong)

and, of course, the known availability of the Nodong in North Korea (opposed to the assumed(!) availability of SS-N-6 technology), it seems reasonable to assume that the Unha-3 second stage is not related to the SS-N-6. It also seems reasonable to assume that this stage is based on the well known original Nodong missile.

In this case, adding Tonka to the kerosene would be a logical step to create a hypergolic oxidizer/fuel combination and guarantee second stage ignition. This would not be very hard to do. However, this is speculation.

English: Laucher vechicle 8U218, missile R-11,...

English: Laucher vechicle 8U218, missile R-11, Scud-A Polski: Wyrzutnia 8U218, zestawu R-11, Scud-A. Muzeum Wojska Polskiego w Warszawie. (Photo credit: Wikipedia)

The choice of a 1.5 m diameter for this rocket stage seems logical. The 1.25 m diameter of the original Nodong would invite structural problems: A 1.25 m second stage mounted on a 2.4 m first stage, perhaps with a third stage on top, would not only look very strange, it would also be very sensitive to loads induced by crosswinds and other effects. Since there are no photos available of the first Taepodong II launch in 2006, it cannot be ruled out that this rocket was equipped with a 1.25 m Nodong second stage, and the North Koreans had to learn their lesson about structural loads the hard way.

A diameter of 2.4 m would have been too large for the stage’s small fuel tank. The tank shape would resemble that of a lentil and would have been hard to manufacture. The new stage diameter therefore had to be somewhere between 1.3 m and perhaps 2 m. Therefore, the choice of 1.5 m seems reasonable. It might be coincidence that this is the same diameter as that of the SS-N-6. However, it cannot be ruled out that the diameter was selected with the intent of creating the impression of a relation to the SS-N-6.

Anyway, it is clear now that the Unha second stage is in no way related to the SS-N-6.

The BM-25 Transfer to Iran

MRBM (Medium range ballistic missiles) and IRB...

MRBM (Medium range ballistic missiles) and IRBM (Intermediate range ballistic missiles) Comparison. (Photo credit: Wikipedia)

There are rumors about the transfer of BM-25 missiles to Iran around 2005. It is not known if these missiles were based on the SS-N-6, but it is generally assumed in open source literature. It is hard to tell how substantiated these rumors are, and the Musudan does not necessarily have to be the same missile as the so-called BM-25. Anyway, there are four possibilities:

  • Iran received BM-25 missiles that were based on the SS-N-6.
  • Iran received BM-25 missiles that were not based on the SS-N-6.
  • Iran received original SS-N-6 missiles that were only transferred via North Korea.
  • There never was a BM-25 transfer.

Without further information, none of the four options can be dismissed with total certainty. However, it is important to note that there is no convincing evidence available in open source literature that the BM-25 missiles were related to a SS-N-6 based Musudan missile – they could as well have been decommissioned original SS-N-6 missiles, or Musudan missiles that have no relation to SS-N-6 technology.

The Musudan Warhead

The Musudan missiles displayed in October 2010, and again in April 2012, featured a warhead that resembled the original warhead of the Soviet SS-N-6 (see Figure 4).

Figure 2: Warheads: SS-N-6 (real), SS-N-6, Musudan, Nodong (all mock-ups)

There are three reasons why the Musudan cannot have the original SS-N-6 warhead. First, the missile and warhead were always stored separately in the Soviet Union (except when they were mated for silo or submarine deployment), they were developed by different teams and design bureaus, and the warheads were not produced at the missile factory, or even by the missile company. Second, the SS-N-6 only had a nuclear warhead, and it is highly unlikely that any Soviet nuclear warheads found their way out of Russia. Third, the SS-N-6 warhead only resembles the Musudan warhead at a first look – overall shape and details are different (as is, by the way, also true for the missile bodies).

Therefore, North Korea has to use an indigenous warhead on its Musudan. The displayed Musudan warhead looks different than the displayed Nodong warhead. This raises the question why North Korean engineers would take the effort to design a new warhead for the Musudan, and not use the available warhead of the Nodong – it should be much easier to mount an existing warhead on a missile than to design a new one.

Displaying a Musudan with a Nodong warhead would have been plausible. But displaying a Musudan with a SS-N-6-like warhead leaves the impression that the North Koreans wanted to force observers into believing that the Musudan is based on the SS-N-6.

Consequences for the Musudan Missile

As stated in the previous paragraphs, the SS-N-6 technology is highly demanding. There only are three pieces of open source “evidence” known to the author that North Korea actually mastered this technology and is using it for its rocket programs: The claimed use of SS-N-6 technology in the Unha second stage, the claimed transfer of BM-25 missiles to Iran, and the displayed Musudan mock-ups that somehow resemble the SS-N-6.

The closer look on these three pieces of “evidence” revealed that

  • the Unha second stage cannot be based on SS-N-6 technology,
  • the alleged BM-25 transfer could have involved SS-N-6 technology just as well as not, or might not have occurred at all,
  • it seems that the displayed Musudan mock-ups were intentionally designed to resemble the SS-N-6 missile.

With that state of knowledge, it seems more plausible to assume that North Korea is still limited to Scud technology at best, then to assume that North Korea has mastered the SS-N-6 technology.

This has consequences for the Musudan missile, assuming that it really exists.

According to photo analysis, the total length of the Unha-3 second stage is between 8.5 and 9 m. Adding a warhead with a length of around 2.5 m, and using a cylindrical structure for the propulsion section instead of the conical structure for the Unha second stage application, this stage would match the reported dimensions of the Musudan and would look like the Musudan mock-ups that were displayed in Pyongyang.

Therefore, assuming that there really is a functional Musudan missile in North Korea, it seems more reasonable to assume that this Musudan is in fact a modified Nodong than to assume that the Musudan is an elongated SS-N-6.

The performance of this Musudan would be much lower than that of a SS-N-6 based missile. It seems that the airframe of the Unha-3 was made of aluminum, and not of steel, so the same can be assumed for the Musudan. As a rough guide value, such a Musudan missile could achieve a range of around 1,500 km with a 0.7 t warhead. If available, this would reduce the North Korean threat radius from the commonly cited range of 3,000 km for the SS-N-6 based Musudan down to half that range.

By Sanindu Fonseka


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Terminal High-Altitude Area Defense (THAAD)

executive summary

  • The Terminal High-Altitude Area Defense (THAAD) system intercepted two short-range targets nearly simultaneously in October 2011.  The program completed this multiple simultaneous intercept as part of an IOT&E, which included a full battle sequence from planning through intercept under operationally realistic conditions.  DOT&E concluded that the IOT&E demonstrated THAAD is operationally effective, operationally suitable, and survivable against the threats and in the environments tested.
  • The THAAD system successfully intercepted a medium-range ballistic missile target for the first time in October 2012.
  • All planned THAAD Build 1.0 capabilities have not yet been demonstrated.  The most significant example is that the performance of the system using the radar advanced algorithm against a complex target has not been scheduled for test until FY14.  The algorithm has been implemented in the operational software, but THAAD flight test profiles prior to FY14 are not expected to trigger demonstration of it.
  • Redesign and retesting of a number of components are required to address all of the Army materiel release conditions imposed before full materiel release can be granted.  In particular, many reliability improvements are required to meet Army requirements with confidence. system
  • The THAAD ballistic missile defense system consists of five major components:

THAAD_2011_2920 (Photo credit: U.S. Missile Defense Agency)

–       Missiles

–       Launchers

–       Radars (designated AN/TPY-2 (TM) for Terminal Mode)

–       THAAD Fire Control and Communications (TFCC)

–       Unique THAAD support equipment

  • THAAD can accept target cues for acquisition from the Aegis Ballistic Missile Defense (BMD), satellites, and other external theater sensors and command and control systems.
  • THAAD is intended to complement the lower-tier Patriot system and the upper-tier Aegis BMD system.


U.S. Strategic Command intends to deploy and employ THAAD, a rapid response weapon system, to protect critical assets worldwide.  Commanders will use the THAAD kill vehicle to intercept an incoming threat ballistic missile in the endo-atmosphere or exo-atmosphere, limiting the effects of weapons of mass destruction on battlefield troops and civilian populations. major contractors

  • Lockheed Martin Missile and Fire Control – Dallas, Texas
  • Lockheed Martin Space Systems Company – Sunnyvale, California
  • Raytheon Integrated Defense Systems – Tewksbury,


US Army THAAD launcher

US Army THAAD launcher (Photo credit: Wikipedia)


  • Flight Test THAAD Interceptor-12 (FTT-12) IOT&E occurred in October 2011.  The test was a multiple simultaneous engagement of two short-range targets.  This test supported materiel release of the first two THAAD batteries and future Beyond Low-Rate Initial Production decisions.  The THAAD battery performed battle planning, overseas deployment, emplacement, and mission operations under operationally realistic conditions within the constraints of test range safety.

The THAAD battery also conducted additional simulated intercept events against a raid, defeating threats generated by the Simulation Over Live Driver (SOLD).

  • The combined developmental/operational Flight Test Integrated-01 (FTI-01) in October 2012 included a THAAD engagement against a medium-range target for the first time.  The test evaluated interoperability between THAAD; Aegis

BMD; Patriot; Command, Control, Battle Management, and

Communications (C2BMC); and AN/TPY-2 Forward-Based Mode (FBM) elements with multiple live targets.

  • Ground Test Integrated-04 Israel (GTI-04 ISR) in

November 2011, Ground Test Other-04e (GTX-04e) in


THAAD_2010_June_a (Photo credit: U.S. Missile Defense Agency)

April 2012, Fast Eagle Increment 1 Hardware-In-The-Loop (HWIL) in June 2012, and GTI-04e in November 2012 included laboratory HWIL representations of THAAD.  Interoperability, engagement coordination between the theater elements, and engagement capabilities against short- and medium-range ballistic missiles were tested using BMDS configurations that are deployed or nearing deployment.

  • The MDA conducted testing during FY12 in accordance with the DOT&E-approved Integrated Master Test Plan.
  • The THAAD and AN/TPY-2 Radar systems performed a successful engagement of two targets during the FTT-12 test.  The classified DOT&E February 2012 THAAD and AN/TPY-2 Radar Operational and Live Fire Test and Evaluation Report concluded the following:


–      THAAD is operationally effective against short-range ballistic missile threats of the types tested to date.  It has not been demonstrated against medium-range threats.  However, empirical data from short-range flight testing, ground testing, and analyses indicate THAAD likely has capability against medium-range threat missiles.

–      THAAD is operationally suitable.  Nevertheless, examination of reliability data, ground test results, challenges encountered during testing, and Soldier feedback indicate that THAAD has suitability-related limitations.  Adequate availability and maintainability were demonstrated, but testing identified maintenance shortfalls.  Different failure modes were seen in two tests creating uncertainty in the Mean Time Between System Abort.  Improvements are also needed in deployability, manpower and training, human factors engineering, and interoperability.

–      THAAD is survivable in chemical, biological, radiological, and external electromagnetic environments.  It has not been tested in electronic warfare environments.

  • Conditional Materiel Release of the first two THAAD batteries in February 2012 included 39 conditions that need to be resolved before a full materiel release could be granted.  The THAAD Project Office and the Army have begun to address these conditions including verification testing of the thermally initiated venting system on the interceptor, electrical stress testing of the optical block in the interceptor flight sequencing assembly, and validation and verification demonstrations of changes and updates to the technical manuals.  Four

conditions (equipment grounding, air load certification, spares transport shelter, and the Surface Deployment and Distribution Command-Transportation Engineering Agency transportability certification) have been closed.  Analyses of data collected during the FTI-01 test are ongoing, which potentially will close eight additional conditions.  Fixes and testing of remaining conditions are scheduled through 2017.

  • Initial assessment from the FTI-01 test mission data indicated that the THAAD system successfully intercepted a medium-range ballistic missile target.  The interoperability assessment between THAAD and other elements based on FTI-01 test data is ongoing.
  • Ground tests utilizing HWIL representations of THAAD demonstrated interoperability and engagement coordination between THAAD and other theater elements revealing problems that need to be addressed for multi-element coordination.
  • Status of Previous Recommendations.  The MDA has satisfactorily addressed all previous THAAD recommendations.
  • FY12 Recommendations.  The MDA and the Army have begun to address the 22 THAAD recommendations contained in the classified DOT&E February 2012 THAAD and AN / TPY-2 Radar Operational and Live Fire Test and Evaluation Report.  Fifteen of the recommendations align directly with the Army materiel release conditions, which are being addressed through a corrective action plan agreed to by the THAAD Project Office and the Army.  Of the remaining seven recommendations, three are classified (Effectiveness #2, Effectiveness #5, and Survivability #4).  The four remaining unclassified recommendations are:


  1. The MDA and the Army should reassess the required spares and tools (including their quantities) that should be on site with the battery based on all available reliability and maintainability data (Suitability #5).
  2. The MDA and the Army should define duties related to THAAD at the brigade level.  Until a battalion is established for THAAD, it should also define duties and training for THAAD battery personnel on any required battalion-level duties (Suitability #10).
  3. The MDA and the Army should implement equipment redesigns and modifications identified during natural environment testing to prevent problems seen in testing (Suitability #11).
  4. The MDA and the Army should conduct electronic warfare testing and analysis (Survivability #3).



By : Sanindu Fonseka