franchise-star-trek-tng-technical-manual1

6.0 IMPULSE PROPULSION SYSTEMSG.1 IMPULSE DRIVEThe principal sublight propulsion of the ship and certainauxiliary power generating operations are handled by theimpulse propulsion system (IPS). The total IPS consists oftwo sets of fusion-powered engines: the main impulse engine,and the Saucer Module impulse engines. During normaldocked operations the main impulse engine is the activedevice, providing the necessary thrust for interplanetary andsublight interstellar flight. High impulse operations, specificallyvelocities above 0.75c, may require added power fromthe Saucer Module engines. These operations, while acceptableoptions during some missions, are often avoided due torelativistic considerations and their inherent time-based difficulties(See: 6.2).During the early definition phase of the Ambassadorclass, it was determined that the combined vehicle mass ofthe prototype NX-10521 could reach at least 3.71 millionmetric tons. The propulsive force available from the highestspecific-impulse (/ s ) fusion engines available or projected fellfar short of being able to achieve the 10 km/sec 2 accelerationrequired. This necessitated the inclusion of a compact spacetimedriver coil, similar to those standard in warp enginenacelles, that would perform a low-level continuum distortionwithout driving the vehicle across the warp threshold. Thedriver coil was already into computer simulation trials duringthe Ambassador class engineering phase and it was determinedthat a fusion-driven engine could move a larger massthan would normally be possible by reaction thrust alone,even with exhaust products accelerated to near lightspeed.cousin, the warp engine. Magnetohydrodynamic (MHD) andelectro plasma system (EPS) taps provide energy for all shipsystems in a shared load arrangement with the warp reactioncore.IPS FUEL SUPPLYThe fuel supplies for the IPS are contained within theprimary deuterium tank (PDT) in the Battle Section and a setof thirty-two auxiliary cryo tanks in the Saucer Module. Redundantcross-feeds within both spacecraft and fuel managementroutines in the main computers perform all fuel handlingoperations during flight and starbase resupply stopovers.While the PDT, which also feeds the WPS, is normally loadedwith slush deuterium at a temperature of 13.8K, the cryoreactants stored within the Saucer Module tanks are in liquidform. In the event that slush deuterium must be transferredfrom the main tank, it is passed through a set of heaters toraise the temperature sufficiently to allow proper fuel flow withminimal turbulence and vibration.As with the PDT, the auxiliary tanks are constructed offorced-matrix cortanium 2378 and stainless steel, laid down inalternating parallel/biased layers and gamma-welded. Penetrationsfor supply vessels, vent lines, and sensors are madeby standard precision phaser cutters. They are installed byFleet Yard transporters and may be transporter-removed forservicing at Starfleet maintenance docks. The internal volumeof each auxiliary tank is 113 cubic meters and each isExperimental results with exhaust products temporarilyaccelerated beyond lightspeed yielded disappointing results,due to the lack of return force coupling to the engine frame.The work in this area is continuing, however, in an effort toincrease powerplant performance for future starship classes.In the time between the Ambassador and the Galaxyclasses, improvements in the internal arrangement and constructionof impulse engines proceeded, while continuing thepractice of using a single impulse engine to perform bothpropulsion and power generation functions like its larger6.1.1 Impulse drive systems