REACTION CONTROL SYSTEM

	In its normal docked configuration, the USS Enterprise achieves low-
velocity attitude and translational control through the use of six main and six 
auxiliary reaction control engines for fine adjustments. The reaction control 
system (RCS) is designed primarily for sublight operations involving station-
keeping, drift-mode three-axis stabilization, and space dock maneuvering.
	The RCS is divided into two parts corresponding to the two sections 
of the total starship. The Saucer Module RCS consists of four main and four 
auxiliary engines located on the hull edge; the two remaining main engines 
and ten venier thrusters make up the Battle Section RCS and are located 
outboard of the main deflector dish. In the docked configuration, both 
systems are cross-commanded by the main computer propulsion controller 
(MCPC) to provide the required guidance and navigation inputs. In separated 
flight modes, the Saucer Module continues to run modified MCPC routines, 
while the Battle Section switches over to its single computer core guidance 
and navigation (G&N) software.
	Each main RCS engine consists of a gas-fusion reaction chamber, a 
magnetohydrodynamic (MHD) energy field trap, and upper and lower 
vectored-thrust exhaust nozzles. Deuterium fuel for each fusion chamber is 
stored in six immediate-use supply tanks and tied to replenish lines from the 
main deuterium tank group in the Battle Section. Fuel transfer is managed by 
three redundant sets of magnetic-peristaltic pumps, pressure regulators, and 
distribution nodes. Ignition energy for the reaction chamber is provided by a 
step-up plasma compression generator, and supplied through a standard 
capacitance tap by the shipÕs power distribution net. The reaction chamber 
measures 3.1 meters in diameter and is constructed by hafnium carbide 0.2 
meters thick, with a 0.21 cm replaceable inner wall of duranium tritanide. It 
can withstand a total of 400,000 firings and 5,500 hoursÕ operating time before 
requiring inner wall servicing.
	A two-stage MHD field trap lies downstream from the fusion 
chamber. The first stage acts as an energy recovery device and returns 
some of the undifferentiated plasma to the power net. The second stage 
performs partial throttle operations, in concert with fuel flow regulators, to 
control the exhaust products as they enter the thrust nozzle. Both stages are 
manufactured as a single unit 4 x 2 x 2 meters and are constructed of 
tungsten bormanite. The plasma return channels are rated at 6,750 hours 
before the inlets must be replaced.
	The vectored nozzles direct the exhaust products at the proper angle 
for the desired force on the shipÕs spaceframe. Each nozzle assembly 
produces a maximum of 3 million Newtons thrust with one nozzle active, and 
5.5 million Newtons with both nozzles active. Kreigerium plate valves 
regulate the relative proportions of exhaust products flowing through the 
upper and lower nozzle components.
	Each auxiliary engine consists of a microfusion chamber and 
vectored-thrust nozzle, but without the MHD trap. The microfusion chamber 
measures 1.5 meters in diameter and is constructed of hafnium duranide 8.5 
cm thick. Each auxiliary engine channels its exhaust products through the 
main RCS nozzle and can generate a total thrust of 450,000 Newtons. The 
auxiliary engines are rated for 4,500 hoursÕ cumulative firing time before 
servicing.
	Also incorporated into the RCS quads are precision mooring beam 
tractor emitters used for close-quarters and docking maneuvers when 
starbase-equivalent mooring beams are not available.  Æ