The following one-shot was the second "chapter" in the Silhouette Formula project back in the 90s. While this was intended to serve as a bridge from F91 to Victory Gundam, nothing else came of it. We'll likely see more in the future, though. With that, here's some data I translated on the Cluster Gundam courtesy of the 1/100 model kit and additional information:
Model Number: F90IIIY
Code Name: Cluster Gundam
Head Height: 15.0m
Base Weight: 9.7t
Full Weight: 26.5t
Armor Material: Gundarium alloy ceramic composite
Generator Output: 4,550 kW
Thruster Propulsion: 16,010 kg x 4, 7,400 kg x 2, 10,480 kg x 4
Apogee Motors: 46
Hardpoints: 10
Weapons Rack: 1
Armaments: vulcan gun x 2, beam vulcan x 2, beam saber x 2, beam shield, beam rifle, mega beam bazooka x 2
The F90Y Cluster Gundam is a testament to the culmination of SNRI's F Project, with its most striking feature being the incorporation of the C.B.S (Core Block System). This groundbreaking development has streamlined the process of equipping the F90 series' optional armaments, including the interchangeable backpack units, and has also enabled energy supply from the hardpoints. (As this unit is the third prototype of the F90, it is also referred to as the F90 Third.)
The driving force behind the development of this machine was to use the ultra-high-performance mobile suit, which had reached a certain milestone in the development of the F91 as a test bed on par with the F90. Moreover, there was intel that a rival company was misappropriating data from the F Project. To mitigate data leakage, the machine itself was designed to centralize data management and official control within the Core Fighter. (Essentially, the C.B.S was deemed effective in maintaining data confidentiality and improving pilot survival rates.)
Conversely, it can be argued that SNRI, recognizing the potential of the C.B.S that had been abandoned for over three decades, concentrated on this system as a crucial component for the development of high-performance mobile suits and as a valuable function for the development of the next-generation mainstay mobile suit, making it the focus of comprehensive research. (Incidentally, as a lesson from past machine thefts, the Core Fighter itself serves as the key to operating the machine. Also, the Y in the model number indicates that it is the second machine out of the unknown XYZ.)
Furthermore, the Core Fighter can detach its dedicated booster, which also functions as a backpack in mobile suit form. In essence, this machine was being researched and developed to evaluate its capabilities as a pure mobile suit, even with the backpack removed. This is characterized by evaluating the machine's mobility under gravity without the assistance of thruster propulsion, and it seems that it was also envisioned to be operated as a "mobile suit that has been stripped down to the bare essentials as a humanoid general-purpose weapon."
New technology has also been introduced into the beam shield, similar to the one equipped on the F91, enabling it to operate to a certain extent even when detached from the main body, with an energy supply circuitry on par with that of the beam rifle. There is speculation that they were attempting to integrate functions beyond the shield, but it remains uncertain. As the beam shield is an optional equipment like a standard mobile suit, the base of the unit has a shape reminiscent of the physical shield for the F90.
Notes from subsequent publications:
The core block docks horizontally from the back and the canopy section switches to a monitor. (Comic Bombom V Gundam Special Issue, June 1993)
Some sources claim a bio-computer is installed and that the Metal Peel-off Effect (MEPE) is also possible. (Gundam Perfect File 123 and Gundam Weapons Gundam F91 & Crossbone Gundam Special Edition)
According to the winter special digest issue (No. 5) of the Universal Century military magazine "Monthly MS Journal," SNRI's Development Department announced that they would unveil the F90III to the media at their lunar headquarters on November 20, U.C. 0122. However, what was actually revealed was the first prototype of the F91, a machine whose development was not even known. It's worth noting that the rollout of this machine took place in February U.C. 0123, the same time as AE's Neo Gundam, which also adopted the Core Block System for a high-performance compact mobile suit. However, the Neo Gundam was unveiled first, and SNRI, lagging behind, put all their efforts into completing their machine. (B-CLUB No.74, December 1991 and Hobby Japan, March 1993)