Nacelle Design and Field Design

Nacelle Design and Field Design by Pope Torak

Starship design is always a compromise between competing design goals. In warp propulsion the characteristics in the balance range from cruise endurance, energy efficiency, field density, and coil life. Modern warp nacelle designs generally have a balanced combination of the requisite properties, but ship design also plays a significant part in determining the capabilities of a warp nacelle.

For example, the Nebula and Galaxy class starships share a common warp nacelle in the GN-41, but have substantial differences in their hull, mass, volume configurations and as a consequence significantly different field geometry. Variable field geometry has been a goal of starship designers for the last twenty years as subspace physics are better understood, but a practical in-flight configurable geometry with greater than 10-20% variability in field configuration remains in the realm of speculative fiction and holonovels. The most flexible field dynamics currently exist on ships with variable pylon geometry like the Intrepid class, but even their highly efficient warp systems are incapable of reconfiguring field geometry by more than 25% without substantial replacement of nacelle elements like coils.

Perhaps the greatest trade-off required of modern warp nacelle designers is between integer and decminal warp factor power consumption. Raising the energy efficiency of a nacelle at integer velocities increases its power consumption near peak transition thresholds, while engines optimized for lower power transitions require greater power to sustain an integer speed. The GN-41 series features greater integer efficiency while the LF-42 in the Sovereign is focused upon peak transition efficiency. The ability for a coil to generate a high cochrane field is not as important in modern engine design as its power consumption at a given field strength.

The GN-41H Mod.3 (Galaxy-class 2380 spec) and LF-42B (Vesta-class and Sovereign 2382 spec) each have similar top end performance, theoretically capable of sustaining a field of up to 10,000 cochranes without substantial coil stress. However, the GN-41H's power consumption past Warp 9 increases at a substantially higher rate meaning a ship with that engine can only sustain a maximum speed of Warp 9.9 (3,053 cochranes) for 12 hours compared to a LF-42B equipped ship's Warp 9.99 (7,912 cochranes) for 12 hours with a standard tanker fuel load of 6,000 m³ and identical output Class XII warp core. At integer velocities, the gap in endurance is reversed, with the GN-41H capable of sustaining Warp 9 (1,512 cochranes) for 3 months compared to the LF-42B's 1 month with the same fuel capacity and warp core configuration.

As a consequence nacelle choice and warp geometry calibration are highly dependent on the needs of a given starship. Long range starships of explorer configuration are equipped with high integer efficient engines, while ships with a greater requirement for rapid deployment have peak transition efficiency boosted engines. A typical Sovereign class starship equipped with a LF-42 series nacelle pair requires nearly three times the fuel stowage compared to a Galaxy to attain similar mission endurance of three years at cruise velocity (warp 8 as of 2381). However, in a crisis situation, the Sovereign is capable of sustaining Warp 9.99 for 36 hours compared to the Galaxy sustaining Warp 9.9 for 12 hours.

In general greater Z-axis compression increases integer warp factor efficiency while peak transition thresholds are easier to cross with a smaller x-y axis profile, helping visual cues identify a starship's emphasis. Some ships like the Intrepid class attempt to combine properties, using high density warp coils and variable pylon geometry to switch from z-axis compressed fields to a narrower warp field to sustain speeds in the Warp 9+ range. In practice this leads to a substantial decrease in coil life, requiring regular refurbishment every 400,000 cochrane-hours due to inconsistent field stress on the coil structures and the greater density of the coil resulting in greater material stress. By contrast the typical coil life of a GN-41 series warp nacelle exceeds 1.2 million cochrane-hours between refurbishment and nearly double that between replacement.

Finally mention must be made of coleoptric warp "nacelle" configurations. Typically used by native Vulcan craft, a small number of Starfleet ship designs utilize this design of nacelle configuration. Coleoptric drives have excellent acceleration and peak transition crossing capabilities at lower warp velocities and have extensive coil lifespans in the order of 2-3 million cochrane-hours. The drives are inefficient at higher warp factors and do not sustain decimal warp velocities well. As a consequence they are most useful for ships that require long endurance at moderate warp factors, low-end acceleration with large mass burdens, or long deployments without coil refurbishment. They are usually found in workhorse civilian designs with a rated output of 350 - 650 cochranes. Currently Starfleet does not operate any mainline starships with coleoptric warp drive configurations.

Juggling Act: Modernization and Mobilization

Starfleet from 2340 - 2350.

President Hikaru Sulu's announcement that he would not seek a fourth term of office in the 2340 election signalled an end to a period of stability for Starfleet. Despite encouragement from Starfleet's veteran associations and several members of the Federation Council, Starfleet Chief of Staff Admiral T'Pragh declined to run for the office. T'Pragh's refusal meant that for the first time since 2312, none of the major candidates for the Presidency had served in any capacity in Starfleet.

The presidential contest focused on matters of domestic concern, ranging from expansion of Federation membership to matters of environmental stewardship on colony worlds. With the Federation at peace and the economy fully recovered from the impacts of the Replicator Revolution the political emphasis remained prosaic. Starfleet received scant attention both in the media and in the voting booth while political observers and think tank analysts alike noted high levels of public trust and satisfaction with Starfleet.

Fleet analysts were shocked when in 2341, newly elected President Kav jav Gek absorbed the post of Commander in Chief Federation Starfleet into the presidency and appointed former Admiral Les Landau as Starfleet Chief of Staff. Kav jav Gek was committed to a program of retrenchment and reform, safe-guarding the gains made in the previous decade. The President's speeches emphasized the need to reduce public waste and inefficiency starting with his famous inaugural address stressing that "no sacred icons will be spared".

Landau, who had previously served as fleet commander on the Cardassian border, had a reputation as a strict disciplinarian who disliked the extravagance of modern Starfleet designs. He was seconded in his efforts by Admiral Arlen McAteer as Starfleet Liaison to the Office of the President and Vice Admiral Bradley Yacobian as the head of Fleet Administration. All three men were opponents of the "Nogura Clan" that had held sway from the 2310s and were well known for their dislike of the procurement practices of the previous administrations. McAteer in particular became famous in early 2342 when he appeared on Illuminating the City of Light and declared that "civilian contractors are more likely to be working for the Tal Shiar than the interests of the Federation!"

Under Landau's leadership Starfleet Command undertook a substantial effort to curtail the independence of dockyards and contractors. All existing orders for new Miranda-class hulls at all civilian yards were cancelled, while new drydock facility deliveries to Yoyodyne and Federation Space Systems were suspended. The end result severely constrained Starfleet's ship building capacity at a time when the first generation of post-Khitomer starships due for their half-century rebuild.

Unlike the regular decennial refits, the 50-year rebuilds included a thorough hull stress survey. SIF-integrated trusses and structural frames withstood the rigors of hard service better than the original engineers had anticipated. Only about a third of Miranda and a fifth of Excelsior hulls subjected to the most extreme use were deemed beyond economical repair.

From both public statements and private sentiment it was clear the Landau Admiralty disliked the emphasis on newer, larger hulls outlined in the 2335 Decennial Plan. Instead of ramping up Ambassador-class production and spinning off large derivative designs, Ambassador production was restricted to two dockyards in San Francisco. Taking advantage of the glowing review of existing frames, the Landau Admiralty instead chose a wide-scale modernization of existing designs with an emphasis on Excelsior derived designs.

The Theseus Project (named for the Ship of Theseus) included a thorough refurbishment of the basic hull trusses, updating the hull frames with modern SIF and power transfer conduits. Advances pioneered in the Ambassador-class found their way into the older hulls, albeit at reduced scale. Isolinear based computer networks replaced old duotronics, verterium cortenide warp coils were installed, and phase-transition welding used for outer hull plating.

With relations between Starfleet Command and civilian dockyards at an all time nadir, Starfleet shipbuilding projects were brought to a complete standstill as fleet dockyards struggled to process the volume of rebuilding. Deactivated starships piled up in orbit around fleet yards in Sol, Proxima, and Andor waiting for slips to open up. This shortage of dockyard space was exacerbated by the order for 20 new Excelsior class frames per year, a number which even the great Utopia Planitia Shipyards struggled to fulfill.

Escalating tensions with the Klingon Empire and deteriorating relations with the Tzenkethi and Cardassians required a large number of ships to be deployed to the border regions, ships that Starfleet no longer had. By November of 2343 approximately a third of Starfleet's total fleet strength was either in the process of being refurbished or deactivated awaiting refit. Several ships were cannibalized to provide a ready stock of spare parts, while others were reactivated for rapid deployment along the border regions. Large numbers of ships previously slated for refit and modernization instead were assigned to border assignments now with the intention of sending them to the breaker's yard after their last deployment.

Border skirmishes against all three potential belligerents soon confirmed the dire predictions of media pundits. A raiding squadron of three Klingon K'Vort-class battlecruisers destroyed the Excelsior-class Belleisle (NCC-11819) during a survey mission at FGC-907. Cardassian raids in the Argolis Cluster resulted in the loss of the USS Malabar (NCC-11818) and suspected loss of Myrtle (NCC-18830) along with heavy damage to a dozen other vessels including the Excelsior-class Gelykheid, San Josef, Aboukir and Hibernia. The ships worst hit by these incidents were those pulled off from their refit schedules. The enlisted security staff often assigned to these vessels had started referring to them unironically as "coffin ships".

The 2344 election season promised to be a nasty one, with accusations flying on all sides on Starfleet readiness. War between the Klingon Empire and the Federation seemed inevitable by May of 2344. Only the rapid detente following the Enterprise-C's sacrifice at Narendra III and the replacement of the bellicose Chancellor Kravokh with the more level-headed K'mpec salvaged peace between the two Great Powers. Kav jav Gek won a narrow reelection on the back of the renewed Khitomer Accords and subsequently sacked Landau, McAteer and Yacobian.

Landau's successor, Admiral Mehdi, quickly reshuffled Starfleet Command's administration with newly promoted officers such as Denton Greenbriar and McGeorge Finnegan. Although the Klingon crisis had passed with the signing of the Second Khitomer Accords in 2345, the situation along the Federation's Alpha Quadrant frontier remained tense. Under Mehdi Starfleet Command worked to rebuild its relationship with civilian contractors such as Yoyodyne Shipyards and worked to undo the backlog established during the Landau Admiralty.

Hard experience had shown civilian dockyards to be unsuited for dealing with complications that often emerged during repair and refits. As a consequence, the Mehdi Admiralty chose to decommission a large number of existing starships and restore Starfleet's numbers with new builds using hulls in Ordinary. Yoyodyne, Salazaar, and Federation Space Systems were contracted to fit out ships using existing hulls of Excelsior and Miranda-class vintage, while Starfleet operated dockyards focused on modernizing ships of Excelsior class and larger. The large number of partially completed frames in Starfleet's drydocks were moved for finishing in civilian dockyards.

Although most of the major civilian shipyards in Federation space were now capable of handling some ships of Excelsior size or greater, Yoyodyne and Salazaar continued to have a large number of drydocks capable of only handling ships up half a million cubic meters in volume. Both companies convinced the Mehdi Admiralty to experiment with new variations of the Miranda-class hull frame, including an expanded medical transport, a hospital ship, and an enhanced sensor pod equipped picket ship configuration.

By the end of Kav jav Gek's second term in office, Starfleet had managed to recover its shipbuilding capacity. In an era where the Federation's responsibilities and threats grew in number, the rebuilt capacity would soon be employed by Starfleet Command.

Starfleet Fleet Strength 2350

Excelsior-class Starships

In Service: 347

Ordinary Reserve (Hull only): 118

Undergoing Refit/Repair: 48

Lost/Missing: 1

Decommissioned: 6

Miranda-class Starships (Note Includes only post-2293 builds)

In Service: 1,528

Ordinary Reserve (Hull only): 625

Undergoing Refit/Repair: 0

Lost/Missing: 11

Decommissioned: 50

Constellation-class Starships

In Service: 17

Ordinary Reserve (Hull only): 0

Undergoing Refit/Repair: 0

Lost/Missing: 1

Centaur-class Starships

In Service: 208

Ordinary Reserve (Hull only)*: 0

Undergoing Refit/Repair: 10

Lost/Missing: 4

Apollo-class Starships

In Service: 6

Ordinary Reserve (Hull only): 0

Undergoing Refit/Repair: 3

Lost/Missing: 0

Hokule'a-class Starships

In Service: 4

Ordinary Reserve (Hull only): 0

Undergoing Refit/Repair: 3

Lost/Missing: 1

Wambandu-class Starships

In Service: 9

Ordinary Reserve (Hull only): 0

Undergoing Refit/Repair: 5

Lost/Missing: 1

Merced-class Starships

In Service: 36

Ordinary Reserve (Hull only): 25

Undergoing Refit/Repair: 15

Lost/Missing: 0

Renaissance-class Starships

In Service: 9

Ordinary Reserve (Hull only): 15

Undergoing Refit/Repair: 0

Lost/Missing: 3

Ambassador-class Starships

In Service: 27

Ordinary Reserve (Hull only): 11

Undergoing Refit/Repair: 0

Lost/Missing: 1

All Other Ship Classes (Note: This category refers to auxiliaries such as the Istanbul, Sydney, Mediterranean and Shelly-class ships)

In Service: 516

Undergoing Refit/Repair or in Reserve: 153

Lost/Missing: 32

Total Fleet

In Service: 2,710

Ordinary (Hull Only): 809

Undergoing Refit/Repair or in Reserve: 249

Lost/Missing/Decommissioned: 113

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