Appropriate references can help observers determine the size of North Korean rockets with modest confidence. Using this method, the author has previously identified the unique North Korean SCUD-ER ballistic missile by establishing its body diameter at almost exact 1 meter instead of the common SCUD’s 0.88m width.
Images from recent parades and test firing of North Korean rockets have offered more opportunities for relatively accurate estimation of the rockets’ dimensions. In this analysis, the author will present findings on the dimension of the missiles/ mock-ups exhibited in the April 15, 2017 parade in North Korea. The findings would in turn shed light on the technological sophistication of these weapon systems.
The “new HS-10”
According to some initial assessments, the new missile is a two-stage HS-13/KN-08. But if assuming warheads on the new missile and the KN-08 are the same, preliminary examination suggests that the new missile is of the same diameter of a 1.5 m-wide HS-10.
Furthermore, as the missile is carried by the MAZ-547 TEL, whose wheel is around 1.5 m wide, the author concluded through image analysis that the new missile is also of 1.5 m width with a small margin of error. The method was to create a virtual plane which the subject being measured and the reference rest on, with minimal distortion caused by perspective relations.
However, by significantly lengthening the missile body by a few meters, the new missile increases its weight a lot, requiring a more powerful engine. The cable raceway and the new rear section on the mock-up hint that the new engine is not submerged, a departure from the complicated HS-10 design. Suffice to say, it is a brand new IRBM design with 1.5 m diameter.
The dimensions of the Pukguksong-1 missile
The Pukguksong-1 ballistic missile’s dimension has remained in obscurity until the recent April 15, 2017 North Korean parade. These missiles were transported on trailers. The prime mover is a HOWO 6×6 truck running on Hualu 306 tires. The trailer tires have ‘HF 313’ markings.
According to information from the producer (Shandong Hengfeng Rubber & Plastic), the trailer’s HF 313 tires (marketed under several brands as well) have a 20-inch rim. But what we can see is the outer diameter of its rim, which is slightly bigger than 20 inches. And according to different tire widths, the HF tire’s outer diameter ranges from 105 cm to 112.5 cm
Using both the estimated rim diameter and the two stated tire diameter and taking perspective relations into consideration, the Pukguksong-1 missile’s width ranges from 144 to 158 cm. With a margin of error of a few centimeters, the author concluded that the North Korean SLBM is 1.5 m wide. The result is further backed by the findings on the dimensions of the Pukguksong-2 missile system.
Pukguksong-1 ‘s current estimated range is about 1300 km.
Establishing references with SCUD
To analyze the Pukguksong-2 system, the author decided to first establish references by measuring the “new” SCUD displayed in the April 15 parade.
The “new” SCUD missile has its fuel port (which is yellow, and oxidizer ports are in red) on the front part of the body, indicating it is an SCUD-B/C type, while 1-meter-wide SCUD-ER has its fuel tank at the bottom and oxidizer tank up front .
Furthermore, the SCUD displayed in April 15, 2017 parade has a long instrument section with typical rectangular-shaped openings, which is another tell-tale sign proving that it is of traditional SCUD design, as the 1-meter-wide SCUD-ER has a compact instrument section. Even if assuming a SCUD-ER has such a bulky instrument section, its appearance would be different from the displayed missile due to its larger diameter.
Being certain that the SCUD with new reentry vehicle has a standard SCUD size of 0.88 m in width, the author established that the TEL wheel has a diameter of 728 mm, with its wheel hub being 228 mm wide. This size is rather close to a 750 mm T-72 wheel.
This finding is in contrast to the common view that the North Korean missile TELs directly utilize T-55/62 tank wheel, which is 810 mm wide with a 235 mm diameter hub. Though basically identical by appearance, the North Koreans seem to have down scaled the wheel by 10% to better fit their engineering enterprise.
The dimensions of the Pukguksong-2 missile
After establishing the reference, author used both test photos of Pukgusong-2 missile system released by North Korea Propaganda organs and photos taken in the parade to measure the missile’s size.
As a result, Pukgusong-2’s canister is between 170 and 176 cm wide. And the missile in the flight test photo is around 1.5 m in width, which is a good fit with the canister and in line with common practice of lengthening (SLBM) missile body to achieve better range.
However, Pukgusong-2’s current estimated range remains in the same class of the Pukusong-1 SLBM. This could be explained by the bulkier warhead carried by the Pukgusong-2, as shown in the official test photo.
The “new ICBMs”
Despite efforts to disguise its origin, image comparison reveals that the mysterious North Korean “DF-31 like” mock up’s prime mover most likely appears to be a HOWO T7H, a commercial tractor truck widely used around the world and available on pre-owned markets. The truck is produced in collaboration with MAN.
HOWO T7H can run on both 12.00R20 and 295/80R22.5 tires, while most T7Hs on the markets use the latter. Close examination by Mr. James Pearson and Mr. Tal Inbar shows the trucks use both Triangle tires and CST 27 tires, and both brands’ 295/80R22.5 tires have a overall diameter of 1.044 m.
Using similar method and considering perspective relations, the author estimated that the diameter of the “DF-31 like missile canister” is around 2 m. If the truck uses 12.00R20 tires, the tube’s diameter is in turn about 2.2 m. And the canister’s total length is about 17m. Due to lack of more appropriate images available, there is a larger margin of error.
However, the 2-meter-wide diameter can somehow be collaborated by another “ICBM” design that looks like a Russian RT-2PM. As its TEL’s wheel diameter and total length are 1.6m and 20.11 m respectively, it is estimated that the “RT-2PM like” canister has a diameter around 2.1 m and is about 24.5 m long.
The reason behind the difference in length of the two new mock-ups remains unknown; it is worth mentioning that since the early days of the Cold War, strategic missiles displayed in military parades are often mock-ups for various reasons, such as to avoid revealing the true status of a program, or to prevent damage to precious strategic assets. If excluding the possibility that the two new mock-ups are merely intended to confuse outside world, the “DF-31-like” missile might be an IRBM variant of the “RT-2PM-like” missile. Or, the two mock-ups are completely different design concepts.
The two “new ICBMs” seem to be of cold-launch design for solid-fuel missiles. While most liquid fuel missiles are hot-launched, the possibility of housing liquid fuel missiles in these tubes cannot be completely ruled out as of yet. For example, Russian R-36M and MR-UR-100 ICBMs are silo-based and cold-launched. While transporting fully loaded liquid ICBMs on off-road condition is not practical, some Russian liquid ICBMs, such as the MR-UR-100, R-27 and R-29, were transported to missile units on railways or good paved roads after being loaded with propellant in factories. There is also likelihood that the canisters have openings so that liquid missiles can be fueled after erection.
Conclusions and hypothesis
- The new liquid IRBM is 1.5 m in width and is considerably longer than HS-10 IRBM, which suggests the possibility that North Korea is pursuing a dual-development path. On one front, it has been developing the sophisticated R-27 style IRBM, while on the other front it might have been continuing its effort to build a domestic engine. As the current failure rate of HS-10 is around 88%, North Koreans might consider replacing HS-10 with this simpler design. And if that is the case, the liquid ICBM/SLV project might also be adjusted accordingly.
- The North Korean SLBM, though bigger in size, has inferior performances compared with its Chinese and US peers, indicating that much is to be desired in increasing specific impulse and reducing weight.
- The approximately 2-meter-wide canisters shown in the parade signal the possibility that North Koreans may be working on larger diameter solid engines.
- With current North Korean solid fuel technology manifested by the SLBM project, it is a far cry from building a solid fuel ICBM. However, there are possibly short cuts to hasten the development, such as incorporating a liquid upper stage.
- North Korea is working on upgrades of their SCUD stocks. As traditional SCUD’s body is made of steel, it can be transported in off-road condition after being loaded with propellant. This helps SCUD shorten its launch preparation time. Thus, upgrading old SCUD with separable RV is a cost-effective solution to modernize Pyongyang’s short range arsenal. However, this development does not deny the possibility of a new solid fuel design, though such a project does not seem to enjoy priority as of now.
This essay has greatly benefited from input and graphics of @ain92ru
 https://twitter.com/stoa1984/status/773528435138318336 measurement of a previously unseen SCUD
 http://www.emotion.hk/catalogos/SUNFULL/SUNFULL%20TBR%20catalog.pdf the technical files only listed 11.00 and 12.00R20’s specifications. However, as the outer diameter of the 11.00 and 12.00R20 tires are identical to that of HUALU 306 11.00 and 12.00R20 tires, it is safe to assume that the 10.00R20 HF 313 tire’s outer diameter is identical to that of a HUALU 10.00R20 tire.
https://www.alibaba.com/product-detail/10-00R20-16PR-306_580726729.html HUALU 306 tire specifications.
 For example, the Soviet RT-20P (SS-X-15 SCROOGE) experimental ICBM has a solid first stage and liquid second stage. Its canister’s size is slightly bigger than that of the DF-31-like missile, and the mass of the missile is 30 tons.