Outsize

“Finally, let us turn to the biggest megaships of them all, the fleet carriers. Including them in this work is a choice which I expect to be somewhat controversial – many would argue that a fleet carrier is a formation, not a vessel – but with respect to those readers who may hold that position, since the Imperial Navy treats fleet carriers as a single vessel for asset accounting and command designation purposes, so in turn shall I.

“Let us begin with a look at the history of the type. Fleet carriers were not known before the Exterminomachy (5782-5901). While before that time lighthuggers had met with occasional hostility, they had proven more than capable of defending themselves against local system defense forces, in particular with the Perreinar Wheel¹ – and in those cases where they were not, it was because they had encountered a Power not readily opposed by pure military force. This changed with the arrival of the skrandar berserker probes, whose numbers and willingness to embrace suicide tactics made them a serious threat to even well-defended vessels, and eliminating breeding site for which required the transport of full task forces to their host systems.

“The first fleet carriers, then, were improvisations; lighthuggers pressed into service under the right of angary. Stripped down by removing all cargo capacity, much crew space, and all other less-than-essential facilities, and enhancing their fuel capacity with multiple drop tanks, it became possible to clamp a small number of light units – overstocked with fuel and supplies – to the spine of such a vessel, and have it haul them slowly and painfully to a target system.

“Such crude improvisations were fraught with problems, from wear and tear on ships and crew during the slow transit, to the risk of interception before the transported units could free themselves from the carrier – both due to the inefficiency of the mechanical clamps, and the need to cut clamps frozen in transit or actual hard welds used where clamps would not suffice, to even entire vessels lost from the carrier in transit. (The last of these to be recovered, CS Bloodwashed³, was salvaged with all hands in 6722.)

“Fortunately, by the third year of the Exterminomachy, new designs were emerging from the cageworks at Ashen Planitia and Armory. The second-generation fleet carriers were custom-built starships, or rather, the specialized elements (the “propulsion head” and “collier module”) were, since the second generation eschewed the rigid designs of the first in exchange for dispersed tensegrity structures.

“In effect, the starships transported by the fleet carrier, along with the specialized elements, formed the floating compression struts of the overall structure, while being linked by braided cables (derived from orbital elevator technology) into a unified structure. The majority of the propulsive thrust is provided by the dedicated propulsion heads, while specialized fleet mediator software enables the use of the drives of the various carried ships to balance the structure and correct attitude. Meanwhile, supplies carried in the collier modules, distributed by rigged flexpipe and by cable-crawling logistics robots, eliminated the need to overload any individual ship with supplies, and indeed enabled the transportation of greater volumes of fuel and replenishment. Moreover, such fleet carriers could separate instantly if intercepted by simply blowing the explosive cable-couplers and engaging their drives independently, the dispersed tensegrity structure providing adequate safety separation for this.

“Such dispersed-design fleet carriers served with distinction throughout the remainder of the Exterminomachy, and have remained a key element of IN subluminal doctrine since. While there exist a third generation of fleet carrier designs, these merely reflect the evolution in technological reliability that allows the physical cables of the second generation to be replaced with vector-control tractor-pressor beams, and does not reflect any change in fundamental design or doctrine.

“As ad hoc structures, of course, it would be incorrect to say that fleet carriers have classes, in the strictest sense. However, the individual propulsion heads and collier modules, the former full starships in themselves, do. Thus, we shall begin our examination of fleet carriers with a look at the most common propulsion head in Imperial service, the Legends-class…”

– Megaships of the Imperium, Lorvis Maric, pub. 7290

1. Perreinar² Wheel: a fight-and-flight maneuver in which a lighthugger puts its stern towards the battle and engages its interstellar drive, thus retreating from the engagement while simultaneously treating the enemy to the close-range efflux of a pion drive – a situation which is very rarely survivable for anything larger than a baryon.
2. From the eponymous horse archers who had perfected the “Perreinar shot” centuries before.
3. Lost in the wreck of CS Cúlíän Daphnotarthius, which suffered a structural collapse of the spine while outward bound to IGS 31238 in the second year of the war.