Starship Propulsion Systems

Warp Propulsion System
The Warp Propulsion System (WPS) is comprised of four major components: the Matter/Antimatter Reactor Assembly (M/ARA); the Plasma Transfer Conduits (PTCs) and Electro-Plasma System (EPS); the warp nacelles; and the associated computer control systems. The M/ARA and PTCs provide plasma at the required energy levels and pulse frequencies to the warp nacelles, where the warp coils transform the energy in the plasma into a warp field. The strength and frequency of the individual pulses is determined by energy level and the frequency of the plasma that is used to produce the pulse. Impulse plasma cannot be used for warp propulsion because it lacks the critical pulse frequency imparted to the M/ARA plasma by the dilithium crystal assembly.

The warp coils are generally fired in sequential order from fore to aft (for forward motion). Alterations in firing order and in individual pulse strength are used to maneuver the ship while under warp drive. Each pulse from a warp coil generates a subspace field of a particular strength. As this field propagates, a number of things happen:

(1) Field strength decreases in inverse proportion to the square of the propagation distance of the field from the coil;

(2) Field propagation rate relative to the ship is proportional to the input energy level (the higher the level of energy input to the coil from the PTCs, the higher the propagation speed);

(3) Each individual pulsed field interacts with the field from the preceding pulse, creating a pattern of mutual interference and reinforcement. The reinforcement increases the local subspace stress values, while interference decreases it. The ship moves towards the area of lower subspace stress ("downhill") at a rate dictated by the differential between the two (the higher the differential, the higher the velocity);

(4) Subspace stress differential values would have to be the same for all ships traveling at a stated warp factor (given identical local subspace conditions);

(5) Pulse timing would be dictated by the desired subspace stress values. These values are determined in turn by the pulsed field interaction (desired stress differential), the amplitude and cycle point of the plasma flowing to the warp coil from the PTC, and the critical distance from the ship's hull for the field interactions (which is fixed for the various modes of flight and desired maneuvers for each particular class of ships). More fields interacting would increase/decrease the localized stresses, increasing the stress differential and the velocity of the ship;

(6) The ENERGY requirement per pulse remains constant (ignoring efficiency losses) as a function of coil mass and critical distance for a given subspace domain. POWER requirement increases as a function of pulse rate.

The subspace pulse is (in simple terms) an expanding bubble. This bubble interacts with the bubbles from previous and following pulses to form a combined field whose geometry is shaped so as to provide a subspace field gradient. Again, note that there is not one, singular field. Rather, each pulse creates a separate field that, in interaction with previously propagated fields (from previous pulses) and post-propagated fields (from following pulses), creates the combined subspace field gradient (in essence, a field that is the summation of the constituent fields from the various pulses).

Using a "rubber sheet" analogy akin to that used to explain gravitation effects,the field creates a slope that the ship runs down by building a "hill" behind the ship and a "valley" in front of it (if the coils fire fore to aft in the standard sequence). The relative "heights" of these high and low spots are also affected by local subspace background stress values–if an area of high stress is in front of the ship, this will reduce the effective combined subspace field gradient, requiring a higher gradient than expected to achieve the desired warp factor. The orientation of the slope is dependent upon combined subspace field geometry. The "steepness" of the slope is due to the value of the gradient.

A dimensionally smaller ship has a lower critical field distance and the warp coils of a smaller ship are usually less massive. This indicates that a smaller ship usually has lower energy(and hence power) requirements for a stated warp factor than a larger ship. This is a consequence of ship dimensions rather than ship mass (except for the warp coil mass effects). This can be seen when we compare the power requirements for warp propulsion for the Galaxy and Defiant class ships (See Chart 1). A smaller ship is generally more energy efficient. One drawback of the smaller size, however, is that (in the instance of Defiant, for example) the use of fewer and smaller warp coils lowers the theoretical limit on subspace field stress values due to the requirement of higher pulse rates per individual coil and the subsequent more rapid approach to coil saturation and efficiency drop-off. Thus, a smaller ship has a lower theoretical top velocity. This is balanced somewhat by the lower energy requirements for pulse activation (slowing approach to saturation)-the balance between these two variables is dependent upon the specifics of the coil set mass and physical composition/geometry. In a general sense, having a larger number of coils is better, this equating to higher warp maneuverability (greater or more precise ability to manipulate field geometry) and a higher theoretical top speed. Theoretically, a four nacelle ship would be more maneuverable than a 2 nacelle ship (though the control system and software would be more complex) and would also have a higher theoretical top speed.

Plasma from the M/ARA is used to energize the warp coils in a specific firing sequence and timing, running from fore to aft. The plasma is moved to the warp coils from the M/ARA via the PTCs. Plasma from the M/ARA during warp operations differs from impulse (fusion) plasma in that it possesses what is referred to as the Critical Warp Pulse Frequency (CWPF). The CWPF is a result of the partial suspension of the M/A reaction in the Dilithium matrix during warp power operations. The CWPF is determined by the warp factor desired. Higher warp factors require a higher CWPF. Each pulse travels via the PTCto the warp coils, where magnetic gates are sequenced to admit the plasma to each coil in succession. Each coil fires at a slightly different energy level (with each resultant pulsed field propagating at a speed proportional to the pulse energy level at the moment of plasma injection).

In normal forward motion, the pulse energy level rises as the coils fire from fore to aft, the after fields propagating at a slightly higher speed than the immediately previous field. In reverse motion, the coils fire in reverse order, the pulse energy rising as the coils fire from aft to fore. The speed differential between the pulsed fields allows for field interaction (and the formation of the subspace differential nodes necessary for FTL flight). The pulsed nature of the combined fields (and node formation) means that the ship is moved via a method akin to peristalsis. Each combined field forms and collapses (and the subspace nodes and subspace field gradient with it) and the ship moves with each pulse.

The cyclic nature of the pulsed fields means that the ship does not fully enter subspace. Instead, the ship is partially phased into one of a number of subspace domains (the particular domain being a function of field strength-the particular domain determining the local value of c and, hence, the pseudo FTL velocity that the ship attains (otherwise known as warp factor)). This partial phasing of the ship allows continued interaction of the ship with the normal space environment on a number of levels that would not be available if the ship were to fully enter the subspace domain. Alterations in course are effected by altering the location of the field differential nodes-thus altering the vector of the combined field gradient. This alteration is achieved by subtle differences in coil pulse timing/energy. Ship pitch, yaw and bank can be altered in this manner.

Torpedo Warp Propulsion: Torpedo propulsion at warp velocities differs somewhat from normal ship propulsion in that the torpedo drive uses sustainer coils to maintain a parasitic warp field that is handed off from the ship to the torpedo during the launch process. Torpedo velocity can be up to 110% of ship velocity upon launch. The torpedo warp sustainer field is a static rather than pulsed field (due to torpedo power and control system limitations). This means that the field differential node loci and field stress gradient are fixed and that maneuverability is a function of differential constriction of the M/A reaction cell exhaust. Torpedoes will normally sustain the parasitic field until ½ of the onboard antimatter reactant load is exhausted (although this parameter may be changed via input from the tactical system by the ship's Tactical Officer). Torpedo field strength and combined field differential can also be adjusted by the Tactical Officer in order to maximize the torpedo's ability to penetrate into the outer layers of target defensive shields. It is theoretically possible (with correct selection of torpedo drive parameters) to match target shield parameters, allowing the torpedo to pass through the target's shields.

High Warp Corridors: Highways or high speed warp corridors are a phenomenon of the local and area subspace field stress levels. The combined differential stress is a function of the differential stress created by the WPS and of the background subspace field stress. What this means is that in areas of higher stress, a higher differential must be created by the WPS to maintain the same speed that existed in an area of lower field stress. In essence, the extremely low background stress levels allow you to create a much higher combined stress field differential than you would be able to do normally, for the same power input. It is the direction of the combined stress differential that overrides here, rather than any particular gradient in the background stress–because the input of the background stress is essentially zero.

The best way to look at this is to consider it from the perspective of friction or drag (though this is somewhat misleading). High background stress levels are the equivalent of high drag or high friction–it requires substantially more power to travel at Warp 6 in a high stress area than it does in a low stress area–the actual power/stress differential in the high stress area might actually be equivalent to those required for travel at warp 9 in an area of normal background stress. A high speed corridor has an extremely low background stress–it might be so low as to make the normal power/stress differential for warp 1 sufficient to enable you to travel at warp 9–so that theoretically you could hit the high multiple 9's in such a corridor.

High speed corridors would tend to be found in volumes with little or no mass or concentration of energy (it is the presence of large masses/energy concentrations, among other things, that distorts subspace). Using a topographical analogy, a planetary system would represent a hill or a mountain (in regards to subspace stress) whereas intergalactic or interstellar space (where no significant dust/gas mass or energy concentrations exist) would be a valley. This would imply that corridors do not generally lead directly from star system to star system, but might lead by or close to (relatively speaking) systems of interest.

Impulse Propulsion
The Impulse Propulsion System is the primary drive for STL travel. The IPS is a combined action/reaction-subspace drive system capable of accelerations in excess of 1000 gravities (g's). A generic IPS consists of one or more impulse engines, each of which is comprised of one or more Impulse Reaction Chambers (IRCs), an Accelerator/Generator (A/G), a Driver Coil Assembly (DCA), and a Vectored Exhaust Director (VED).

An IRC is essentially a proton-proton fusion reactor, with a output that can be throttled from 10e11 to 10e8 MW. The high energy plasma from the IRC is exhausted from the IRC through the A/G, which can operate in one of three modes: (1) propulsion–in this mode the A/G raises the velocity of the plasma for more effective propulsion and the plasma is directed to the DCA; (2) power generation–the A/G is shut down and the plasma is diverted to the Electro-Plasma System for power generation or; (3) combined–the A/G generates power from the IRC via MHD while allowing the plasma to proceed to the DCA. The DCA uses energy from the plasma to create a low level (less than 1 Cochrane) subspace field that: (1) reduces the effective mass of the ship by a significant magnitude (from 4.5e6 metric tons to less than 1 metric ton for a Galaxy class, for example); and (2) acts as a streamlining field to allow the ship to pass more easily through the continuum. The plasma is then directed outboard via the VED for propulsive effect. The VED allows the thrust to be vectored and, in combination with the Reaction Control System (RCS) provides maneuverability for the ship during STL operations.

The continuum slippage effect operates in a similar manner to the pulsed warp fields during FTL operations. The primary differences being that the subspace field generated has insufficient strength to transition the ship into subspace (thus the c barrier is not exceeded) and the field is continuous rather than pulsed (the field pulsing requirement is unnecessary since the ship never leaves normal space). The DCA field creates a subspace field gradient that does provide some propulsive effect to the ship on the 000.0 vector (directly forward). This velocity vector is fixed, since field geometry is fixed.

Note: The operation of the IPS is not particularly well explained in the literature or the episodes/movies, leaving the question of exactly how it manages to produce the stated accelerations open. An examination of the data in the TNG TM shows that there is insufficient fuel carried onboard a Galaxy class to accelerate it to a significant fraction of c even once without running out of fuel if the drive is a pure action/reaction drive. Reducing the apparent mass of the ship via the subspace field does not solve this problem since the mass of the fuel carried is also reduced in proportion (thus maintaining a constant propulsive impulse for a given volume of fuel). The only way the stated acceleration can be obtained (and a reasonable fuel mass be retained) is via the conservation of energy during the ship's change of mass. Using the Galaxy class as an example:

Initial (actual) mass is 4.5e9 kg with the ship at an initial velocity of 10 m/s at 000.0. When the mass reduction effect is applied (reducing the effective mass to 4500 kg for this example) the ship will jump to a velocity of 1e4 m/s at 000.0. This would be an instantaneous acceleration of about 1000 g's. Deceleration would work in reverse–raise the mass of the ship to decelerate. Failure of the drive or loss of power to the DCA would cause an immediate deceleration of the ship. It would seem likely, on this basis, that the ship's mass can be selectively altered to achieve a desired velocity (in combination with minimal output from the IPS in the form of plasma). Actual, applied accelerations to the ship via thrust would be minimal. It also seems likely that the field can be ramped up or down–that is, the timing of the mass change can be altered, from nearly instantaneous to being stretched over several seconds.

My comments regarding the continuum slippage effect are supposition, but they go some way towards explaining several observed phenomena–the ability of the ship to accelerate given the insufficiency of fuel mass and the fact that we never observe any ships in the ST universe use decoupled maneuvering (pointing the ship in one direction while continuing to travel along the original velocity vector) during combat, implying that the ships are continually under some form of acceleration and that changing the axes of orientation will change the base velocity vector.

Reaction Control System
The Reaction Control System (RCS) provides low speed thrust and maneuverability during evolutions such as docking or station-keeping and provides for directional and attitude control during STL maneuvers (in combination with the IPS). Reaction Control Modules (RCMs) are located along the periphery of the ship in order to provide thrust and directional/attitude control. Each RCM consists of a gas fusion reaction chamber, a magnethydrodynamic (MND) energy field trap, and a set of vectored-thrust exhaust nozzles. Local fuel supplies (deuterium) exist as part of the RCM and fuel may also be transferred from the main deuterium storage tanks to the local fuel storage as the local stores are depleted.