Ultimate Mark

Zeta World: The Approach to U.C.0087
> Back to Data Evolution


Zeta World: The Approach to U.C.0087 was a series of articles published in the anime magazine OUT between August 1985 and January 1986. Written and illustrated by by Kazumi Fujita, the main mecha designer of Mobile Suit Z Gundam, the series provided an in-depth account of the development of the Gundam Mk-II and Zeta Gundam.

Fujita's ideas about the development and technological background of these mobile suits weren't really picked up by later writers. But the second article in the series, published in the September 1985 issue and focusing on the inner structure of the Gundam Mk-II and Hizack, is particularly interesting and accompanied by some great illustrations. I've translated the text of this second installment below.

Special thanks to @combattlerRickV for posting a selection of pages from classic back issues of OUT magazine in this Twitter thread!

The following text is copyright © Minori Shobo


Explanation & Illustration: Kazumi Fujita
Super Advisor: Masatoshi Kondo

In the previous article, we touched on the background behind the development of the Gundam Mk-II. Because postwar mobile suit developers were obsessed with raising various data specs, they had neglected to evolve the fundamental design concepts of the MS system, and by that point the development of new machines had reached a dead end.

The Mk-II project began with the search for a path to true mobile suit evolution, using the design of the famous RX-78 Gundam from the One Year War. In the seventh year after the war, the Mk-II reached the prototype stage. It seemed that the Mk-II might well pioneer the next generation of mobile suits, but there the discussion ended.

  ☆   ☆

The background of weapons development is not just a matter of pure technological theory. In fact, human factors such as cost, feelings of national rivalry, and the pride of development organizations are overwhelmingly more numerous and powerful. As a remake of a famous machine from the One Year War, the Mk-II project showed these aspects very strongly.

Postwar mobile suit development began with the absorption of Zeon engineers by the Federation Forces. In particular, Anaheim Electronics, headquartered on the Moon, recruited a large number of Zeon engineers via the military, and its MS division received the biggest share of orders. Certainly, the engineers from the Earth side were not inferior in their respective fields. But for the Zeon engineers, an environment in which they could pursue development freely without being blamed for the Principality of Zeon's failures had given them the knowhow to develop mobile suits with excellent overall balance, as if they had acquired a kind of "instinct" for mobile suits.

The Earth supremacists within the Federation Forces were unhappy with the strong influence of Zeon engineers on contemporary mobile suits, despite their high performance. In an attempt to develop a mobile suit that would symbolize the superiority of Earthmen, the Federation Forces excluded Zeon engineers from the Mk-II project. But this constraint cannot necessarily be condemned, as it led to a thorough reevaluation of the concepts of the original Gundam and, ultimately, the selection of a new concept for the Mk-II.

Gundam (Mk-I) and Mk-II Leg Structure Diagram
On the right is the Gundam, and on the left the Mk-II. While the Gundam is made up of a monocoque frame with bulkheads in between its armor, and its drive system is directly mounted with shafts and pivots, the Mk-II has a semi-independent cylinder frame using cams and cranks. This prevents stress from being concentrated at the joints, and minimizes interference with the armor. Diagonal shading indicates thrusters and other sub-units.


We will now systematically follow the Mk-II's development process. In fact, even before the Mk-II project, an attempt had been made to add humanoid structural elements to a mobile suit. This was the Hizack. The fluid pulse motors that had been used in the arms and legs were eliminated, and it adopted a drive system based on the cylinder frame. Unfortunately, the reduction in the protruding peripheral systems that supported the drive system was technically incomplete. No noteworthy data was produced, and its drive system was simplified at the mass production stage.

The failings of the Hizack were a cautionary example for the Mk-II. In short, it showed that when introducing a new design concept, basing it on an existing machine meant that the design would be insufficiently thorough. Thus the Gundam and the rest of the RX series were used as nothing more than reference. The resulting invention was the MAS (Movable & Armable inner Skeleton) system, in which the cylinder frame was further developed into a comprehensive MS system. Generally speaking, this system consisted of a cylinder frame that served as an endoskeletal unit, then systems to control it, and finally exterior units to provide protection and added functionality. Its unique characteristic was that these three elements were organically linked together.

The movable inner skeleton (cylinder frame) that formed the foundation of the MAS system was closer in its layout to the human body. This was because, rather than widening the range of motion of the joints, the focus was on increasing the potential movement of the machine itself. In previous mobile suits, the armor served as an monocoque external skeleton, while the joints were driven by pulse motors. Thus the output of the joints and thruster propulsion was limited by the strength of the armor. The flaw with this was that, unless the strength of the armor itself had some extra margin, the output could not be enhanced beyond a set limit.

In the original Gundam, the machine's potential was increased through the use of Gundarium Alpha, which was dramatically stronger than other materials of its time. In the Mk-II's cylinder frame, each part of the machine was organically linked, so the stresses generated by its drive system and by external forces could be dispersed throughout the entire body. Thanks to this system, the Mk-II's machine potential was unaffected by its external armor.

MAS System of the Mk-II
The body structure of the Mk-II can be broadly divided into three levels. On your right, it has been stripped down to the secondary armor, and on your left, to the primary armor. This could be considered the minimum necessary structure for a mobile suit.


This was not the cylinder frame's only role in the MAS system. The frame's joints served as option points for peripheral devices, where external armor, or control and auxiliary devices, could be connected. This approach showed a trend in which armament systems could be extended outside the machine without impairing its flexibility.

At the stage when the Mk-II's core concept was decided, an examination of the armament system was conducted. The mobile suit was treated as a naked human body, which only becomes a soldier when it puts on its powered suit. The basis of the armament system required for a mobile suit is the secondary armor that protects the machine and absorbs stress, but in the Mk-II it also incorporates thruster packs that double as external armor. These were experimentally installed on the Hizack as well, but they were added purely as boosters, and were not present in the design stage. In the Mk-II, on the other hand, they were designed in as part of the armament system.

In order to increase the armament payload, option points were built into the armor, and all internal weapons were eliminated. (Incidentally, there were plans to equip the Hizack with a vulcan pod like that of the Mk-II.) Thus the MAS system was a structure with a latent capacity for extension (advancement) according to the mobile suit's role.

Until now, we have discussed only the advantages of the MAS system, but because it had not yet reached the application stage, there were still some problems in the Mk-II. First, while the cylinder frame drive theoretically had higher flexibility than the pulse motor drive, due to the lack of movement data from actual mobile suits, the minimum necessary strength and output were inflated in its design. In other words, it would not be complete as a weapon until it had been trimmed down based on the accumulation of large amounts of data.

The computer used for control purposes was also a factor here. The prototype machine was equipped with a learning computer for data collection, but to organically link the frame and handle unforeseen accidents, it was also necessary to develop new software and install a high-capacity, high-speed-processing computer. The end product was the GES (Gundam Education System) and its corresponding hardware. This was naturally more expensive than previous models, which was a substantial obstacle to mass production. Reducing its cost by developing a simplified model would be a major issue.

Gundam Mk-II Test Version
A scene of a motion performance test being conducted at Green Noa 1. No vernier thrusters or weapons are installed, and parts of its armor differ from the present version, but its frame is identical. The four long rods are special motion sensors.


The flaws of this prototype are shown by the Rick Dias manufactured by Anaheim at the same time. Developed by Zeon engineers, it was the exemplar of a functional enhancement-type mobile suit. Thus it was highly complete, with excellent performance, firepower, and mobility. It was also a state-of-the-art machine with armor made from Gundarium Gamma. The Mk-II certainly had the potential of an advanced system, but in terms of functional enhancement it it was quite old-fashioned, and thoroughly inferior in performance. The Rick Dias, designed specifically for increased thrust, was particularly superior in terms of thruster acceleration.

No matter how many new concepts a machine incorporates, if it compares unfavorably to other types in terms of actual performance, this can only be seen as complacency on the part of the engineers. The Federation Forces, who had been carrying out the Mk-II project, reached the same conclusion. Deeming the Mk-II a failure, they ordered the suspension of its development when the three prototypes were stolen by the AEUG.

However, this could be considered a hasty decision by the military brass. Though it was merely a plan, the advanced system suggested by the Mk-II had demonstrated the possibility of breaking the deadlock in MS development. Moreover, it appears that a plan had already been submitted for a true Advanced Gundam that would eliminate the Mk-II's flaws and develop it into a functional enhancement type. In every era, this kind of shortsighted decision-making on the part of military authorities has always made engineers weep.

After a thorough examination, the prototypes that had fallen into the AEUG's hands produced tremendous results as combat units on the front lines. This could be considered a result of the Mk-II's GES beginning to draw out its intrinsic capabilities based on combat data. The mobile suit's performance provided a new demonstration of the machine's high potential. Meanwhile, one can only marvel at the ability of the AEUG's engineers. Making numerous improvements to the Mk-II while it was in operation, in order to raise its performance, was no small feat.

According to the latest information, the development of a dedicated booster system for the Mk-II is now in progress. However, this is not the original idea of the advanced system. In fact, developing options that rely too much on the machine's potential could be considered the exact opposite in terms of MS evolution. When a true Advanced MS appears, which addresses the Mk-II's flaws and has options that enable it to handle any aspect of tactics, then its true value can finally be assessed. But when, and in what form...?

(To be continued)

Gundam Mk-III
An artist's impression of the Advanced MS, as inferred from the Mk-II. Its performance is raised to the limit for a mobile suit, and could be compared to that of a human being. The wing-shaped parts on its back are option mount racks.