Something I gave to Dan awhile ago to put on his site...*wink wink* *nudge nudge* 
Introduction
The following is an introductory text on starship engineering. It is designed for freshman who have not been exposed to Subspace Mechanics, Hyperdynamics, or Fractal Calculus yet.
Chapter I
Federation ships, as opposed to ships of other species, are built for speed. Since the Phoenix, every Earth starship and subsequently every Starfleet starship has been built with the primary purpose of traveling as fast as possible. Other technologies in the Federation arsenal have been developed around the concept of speed and that subsequent design philosophy.
Warp drive operates by creating a forward and aft warp field, expanding and contracting space respectively. Simply, the larger the difference between these two warp fields determines the performance of that ship.
The overall shape of a starship, known as the profile, can profoundly affect the disparity, and thus the performance, of the warp fields. In the year before the founding of the Federation, researchers theorized that a ship with a double hull � a forward penetrating hull and an aft trailing hull � would facilitate the penetration of subspace. Both hulls served as foundations upon which their respective warp fields formed around, the larger the primary hull, the larger the forward warp field formed around it and so on. Imagine a starship with an impossibly large primary hull and an extremely small secondary hull and one can easily visualize that this design taken to the extreme serves very little purpose. Thus, it is the job of starship engineers to find the best balance based on these principals and the design goals of the specific class (i.e. hardware requirement, etc.)
Each warp field is �pulling� the ship in its direction through space. Although, in actuality, the aft field�s polarization is the inverse, which effectively produces the same result as the forward field�s �pushing� motion. Thus, in order to keep the fields balanced and a stable, the fore and aft fields need to be centered as much as possible around the center of mass. The closer the field is centered, the more inherently symmetrical it is, or simply, the sturdier it is.
The center of mass should rest in the �neck�, or the connecting structure between the primary and secondary hulls. Parenthetically, the lower the mass of the connection between the primary and secondary hulls, the larger the amount of disparity between the penetrating and trailing warp fields and thus the higher efficiency. This is because the disparity strength is the coefficient of the mass of the respective hull. �Neck� hull mass diminishes the coefficients of both hulls, and also if not centered well, could upset the stability of the warp field as a whole.
The interactions of the horizontal and vertical warp fields � both fore and aft � are also contingent upon the overall ratio of ship length versus ship height. For better warp performance, disparity between the fore and aft warp fields needs to be significant. However, this compromises the balance. The Constitution-class had a ratio of approximately 1.5:1, although it was not a consideration when being designed. The Excelsior-class had a ratio of almost 3:1, and further research into the overall astounding performance of the class revealed the first data on the importance of ratio in warp performance. Though the research did not yield constructive data in time to be of use for the Ambassador and her sister designs, it would become a major influence in designs such as the Sovereign (5:1) and Intrepid (5.5:1). On the other hand, though it was available, Galaxy engineers held volume as a higher priority, though it is not to say that it didn�t play a role.
Though the best way to maintain a warp field is to use two hulls - one dedicated for each lobe, it is not essential. There are multiple advantages to having a single hulled starship. Smaller ships use less power, are more maneuverable, and if well designed, can be faster than larger cruisers. The viability of single-hulled ships has led to two distinct forms in Starfleet, the saucer/drum cruisers and the saucer only escorts.
Whereas cruisers generally have uninterrupted circles or ellipsoids for primary hulls, single hull ships usually have extensions or additional hull forms on the aft (Miranda, Constellation) to partially make up for the lack of projection area inherent in the design. More recent designs have supplanted this concept with vestigial secondary hulls that serve specialized purposes (Akira, Steamrunner) which project an aft field more efficiently in a sort of blend between cruisers and traditional escorts.
Specific components in a starship�s design affect performance. Resistance in the subspace continuum acts in much the same way as any fluidic medium acts on atmospheric craft. The less the amount of surface that is presented in the forward profile, the less resistance that the ship encounters at warp speed. Also, the more streamlined the overall characteristic, the easier the subspace medium is displaced by the ship.
Warp Coils (and nacelles), the primary hull, and engineering hull are the three major structural components that compose a starship.
Primary Hull
When the first ships were divided into two hulls, they were given a spherical design for efficiency - both of internal volume and field projection. But research revealed subspace drag, a force that operates much as fluidic drag. It thus became undesirable to have a high front profile structure like a sphere. Ships of the Valley Forge era had a discoid primary hull. This was a compromise between the spherical genesis and the eventual flat disc shape, mainly because the ships were still on a scale that was too small to allow flat discs that would be large enough to be effective.
Though a notable exception is the Asia class, it is an exception and a primary hull comparable to the Asia would not be seen again until the Constitution. It was not until the Constitution era that a flat disc hull became the standard feature of every new Starfleet design. From this, the primary hull has taken on its most recognizable form as the basic disc shape has evolved but remained essentially the same.
Since Comet and Fireball, the radius of the sphere/disc had always been constant. The Galaxy Project, however, wanted a way to make the massive ship more maneuverable laterally. Though RCS thrusters control orientation during delicate maneuvers, a warp field is used to control the ship at impulse as well as warp in standard and combat maneuvers. By making the saucer elliptical, greater projection in the y-axis warp field was achieved and thus greater precision in altering the warp field could also be accomplished.
In more recent designs, the ellipse design has been kept, but turned ninety degrees so that the longest points face along the z-axis (Sovereign, Intrepid). The result is a greater maximum speed and greater precision in speed control. Though the lateral precision is lost, these ships are generally smaller and have more advanced nacelles anyway, making their lateral maneuverability equal or superior to the Galaxy family.
Triangular saucers incorporate the best combination of both concepts. The forward point of a triangular saucer can offer as much forward projection and precision as a z-axis ellipse of the same size and the port/starboard points can provide nearly as much control as a y-axis ellipse. Triangular designs have been floated several times, though only recently with the above knowledge in mind. Each time, they have been quite successful, though the maneuverability inherent in the design was somewhat limited by other technology. The Norway class is the most recent triangular design, and every aspect of the ship is designed around this principle, to take the most advantage of it.
Two hundred years of starship design has turned a sphere into a triangle.
Engineering Hull
Like the other major components, the engineering hull started off as a simple geometric shape. Starships of Earth were essentially monstrously scaled up versions of Cochrane�s missile derived Phoenix, bulbous and tubular. With the Comet and Fireball pathfinders, the entire concept of starship design was changed. Though the pathfinders themselves bore additional elements for test-bed purposes, the first production two hulled design, the Daedalus, was a simple cylinder. Like the primary hull, this was the most efficient design for the two lobe design.
Warp Coil Shape
Phoenix-Constitution
Beginning with the Phoenix, warp coils were circular. This was for the very simple fact of fitting them with the most ease into the fuselage of the rocket. However, the mathematical formulas governing the projection of warp fields was assumed to have been the most efficient with circular coils. For the next hundred years, engineers refined and improved upon components, materials processing, configurations, power sources, and the overall design of the warp system. It was not until over a hundred years after Cochrane�s flight that somebody experimented with the shape of the coils themselves.
Constitution-Excelsior
The result was the development of rectangular warp coils, the Mark XVIII Megadyne nacelles. These were applied to first, among other technologies, the Soyuz class and incorporated into a keel-up design first in the Miranda class. All the designs were relatively small primary hull only designs. Unfortunately, Mark XVIII Megadyne nacelles were effective only over relatively small areas. When stretched away from the ship, their coefficient of strength dropped rapidly as the area from the hulls increased. Thus, while extremely effective for small, primary hull only ships, they were inadequate for larger ships of the line. This would be partially overcome by square nacelle coils, such as those employed on the Excelsior family, though for a number of reasons, the Constitution-refit family was incompatible with these designs.
Ambassador-Galaxy
The rectangular and subsequently square warp coils proved a significant leap in warp speed technology. Further experimentation was conducted on the optimal shape for warp coils. It was found that oval coils bridged the gap between the efficiency of rectangular with the uniform strength of circulars. The oval concept was first test-bedded in several different prototype ships for the Ambassador family and became the design of choice for the Ambassador and Galaxy families.
Intrepid-Akira
Further advances in warp systems engineering allowed engineers to use rectangular coils for their power while using other technology to increase the area over which the warp field is projected. While this new technology presently only partly compensates for the lack of projection area, it is becoming more refined with each design.
Sovereign-Equinox
A novel idea was floated during the final days of shakedown cruise of the USS Galaxy. Creating warp nacelles and coils that were relatively large in the front and tapered off farther aft. Experimentation with differing warp coil sizes quickly revealed that in order to keep the warp field stable, small differences were required. Early simulations with visibly large differences revealed horribly unstable ships. The result was warp coils whose difference between the first and last pair is so small that it is unnoticeable on a Masters Systems Display. However, even this small difference provides starships with sustained speeds unachievable before. The coils themselves took on a novel shape as well, combining the angular efficiency of the Constitution/Excelsior with the oval Ambassador/Galaxy coils. Essentially, each coil is composed of two pieces attached at a hundred twenty degree angle.
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If God didn't want us to fly, he wouldn't have given us Bernoulli's Principle.
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