Propulsion, FTL

Overview
Space is big. Mind numbingly huge, as a matter of fact. A lot of it a mostly empty void between the interesting places. Distances are intimidating enough within solar systems, measured in Astronomical Units, but at least it's still possible to travel between planets in a reasonable amount of time, just a matter of days or weeks at the most since the advent of the sublight pulse drive (also known as the Gravitic Mass Reductor drive, or GMR) in the 22nd century. But the distance between the stars is even more mind-boggling. Even with the best GMR drive a starship would require decades to travel from one star to another. Early in the history of interstellar travel many civilizations designed ships designed for just that kind of journey, putting the crew in cold sleep while the years passed. People realized that interstellar travel would be much easier if there was a way to cover such an immense distance in a shorter time, but physicists were adamant that it was impossible to ever reach the speed of light, let alone exceed it.

And then some clever people discovered a few interesting things about hyperspace, and how it could be exploited to provide just such a shortcut.

The existence of hyperspace was known, as early as the 20th century on Earth, and earlier on on Arua and Talesia. Terrans had learned that it was possible to shunt part of the mass of a moving starship into hyperspace, effectively reducing the mass of the ship in exchange for gaining momentum...this was the basis for the GMR drive. But the GMR drive was limited to sublight speeds...a starship using it was still present in realspace and was still subject to special relativity....no amount of energy could accelerate the ship to the speed of light, let alone beyond it. Experiments with piercing the membrane of realspace revealed that hyperspace could be entered under very specific circumstances, but that this extradimensional space was extremely hostile to any matter that entered it; in hyperspace the rules of physics that allow matter as we understand it to exist break down, causing matter to dissolve into a haze of strange quanta, lost forever. Any means of using this strange dimension as a means of supralight travel was a mystery...but not for long.

After the first contact between humanity and the Selvens in 2155, humans are introduced to the Hyper-Light Warp Drive, a technology that allows rapid travel across interstellar distances. Humanity mastered the technology in a short time, greatly expanding their influence beyond their native solar system, finally joining the Selvens and the Talesians as a true intersellar civilzation.

Warp Drive
The successor to the GMR drive, the Warp Drive (alternately known as a hyperdrive) is the form of FTL travel used by virtually all known interstellar civilizations. The Warp Drive allows a ship to travel through hyperspace by first warping a bubble of realspace around the ship in order to protect it from the hostile conditions of hyperspace. The encapsulated ship then oscillates its realspace membrane in order to move it through hyperspace, effectively skimming over the membrane of realspace like a little bubble of air skimming over the membrane of a much larger bubble. Because the ship is moving through hyperspace it's not really traveling faster than light, and so special relativity is not violated. As far as anyone on the ship is concerned, the ship does not feel like it is moving....there is no acceleration or deceleration....at one moment it's in realspace, and at the next moment it's in warp. Conservation of momentum still applies to a ship moving through warp...it is moving at exactly the same velocity when it reaches its destination as it was when it departed from its starting point.

While moving through warp, a ship cannot interact directly with realspace. No radiation passes between the ship and realspace, nothing in realspace is visible to the ship (or vice versa) and it is not possible for the ship to collide with anything in realspace while moving through warp. The interior of hyperspace is visible as a tunnel of distorted blue-white light, seeming to rush past the ship. The sole exception to this rule of hyperspace/realspace interaction is gravitational force: a ship at warp can detect the gravitational "topography" of the membrane of realspace, and use that topography to navigate, even seeing ahead far enough to be aware of potential obstacles.

Since the ship is not moving faster than light while in warp it cannot gain any momentum (or lose any) while in warp, so it is not possible to gain free energy to use when it arrives at its destination. Any objects (incliding weapons fire) launched from the ship while in warp will drop out of warp as soon as it passes through the ship's membrane; at that point the object will either drift off in hyperspace and dissolve, or it will reenter realspace as a cloud of scattered atoms and radiation, or, in very rare circumstances, arrive intact but moving at the same velocity as the ship before it entered warp.

Changing hyperspacial velocity is a tricky matter. It is possible to increase the oscillation of the ship's membrane by pouring more power into it, which will allow it to go faster, but there is a limit to how fast the ship can go due to a degree of resistance between the ship's membrane and the membrane of realspace, known as phase resistance. Phase resistance can be reduced by increasing the "distance" between the ship's membrane and the membrane of realspace, that "distance" being known as phase displacement. The greater the phase displacement, the faster the ship moves through hyperspace....but with this greater speed comes the increased risk of the ship losing contact between membranes and effectively "skipping" along the membrane, resulting in uncontrolled jumps in across space and time. Worse still if the ship "skips" off of realspace and into deep hyperspace, lost forever. Thus most ships using warp drive are hardwired to limit how much phase displacement is allowed, giving the ship an upper speed limit.

Of the three major factions, the Selvens developed the Warp Drive first, in 2010 C.E., and the Talesians invented theirs in 2065 C.E. Terrans did not develop their first Warp Drive until 2155 C.E., after having learned the technology from the Selvens. Consequently the Terrans lag behind the other factions in this technology, their drives ranging around Class D to C. In recent decades the Talesians have exceeded even the Selvens in this technology, their ambitious studies placing a number of their latest ships squarely in the Class A range.

Warp Drives have two general configurations when incorporated into a starship. Either they are fully placed inside of the fuselage of a ship, or they are built into outboard units called nacelles. Nacelles have an advantage in alllowing more energy to be channeled through the drives, while maximizing heat dispersion and improving the duration and accuracy of the Warp Drive. The drawback to nacelles is that they are vulnerable to attack, and that they are massive devices, requiring a ship to be designed especially to accomadate them. Internalized Warp Drives are better protected, but they produce more heat and radiation that poses a threat to the crew of the ship, requiring such ships to have more heavily shielded engineering sections. Internalized drives do not perform as well as nacelles overall, but they are more versitile, allowing nearly any starship design to be able to accomadate them.

Talesian ships most commonly make use of nacelles, while Terran ships most commonly use internalized drives. Selvens ships make use of either design, based upon design trends at the time, as well as the intended function of the ship.

Displacement Factor Ratings & Warp Drive Grading
The effective velocity of a Warp Drive is measured by a spectrum of energy states known formally as "Phase Displacement Oscillation Factors" or "DFs" for short. A Displacement Factor is an approximate meansure of the tenuous balance of a drive's phase displacement and the oscillation of the ship's membrane. There is room for variation of velocity within each Displacement Factor, depending on additional power being added to the field and a slight increase to the phase displacement, but there is a limit to how much of an increase of velocity is possible within a given DF before it is necessary to shift into a higher DF. The maximum DF rating of a given Warp Drive depends upon the Grade of the Warp Drive.

A DF rating is usually desginated by the initials "DF" followed by a number from 1 - 12. While it is theoretically possible to achielve a higher speed than DF 12, it has not yet been accomplished.

Warp Drives are broken down into grades based upon the quality of their design. The DF rating of a warp drive is affected by its grade; while there is room within a given grade for a drive to be adjusted to be faster or slower, the changes in phase displacement put a lot of stress upon a drive. It is possible for a higher-grade warp drive to adjust to a lower DF, though no lower than DF 1: the speed of light. Too much alteration of the phase displacement within a given grade to gain more speed will cause serious danger of a warp field's membrane becoming disrupted or detached from the realspace membrane. The grading is desgnated by the numerals I to  V , with I being the worst quality and  V  being the best.

A rough breakdown of DF speeds is given below, in multiples of the speed of light (c), and grouped under the Grades required to reach those speeds:

Class I:

DF 1 = 1 c = 1 LY in 1 year = 1 AU in 8 minutes.

DF 2 = 5 c = 1 LY in 73.05 days = 1 AU in 1.67 minutes.

DF 3 = 45 c = 1 LY in 8.12 days = 1 AU in 11.11 seconds

DF 4 = 365 c = 1 LY in 24 hours = 1 AU in 1.37 seconds

Class II:

DF 5 = 1,500 c = 1 LY in 5.84 hours = 3 AU/second = 4 LY/day

DF 6 = 3,000 c = 1 LY in 2.92 hours = 6 AU/second = 8 LY/day

Class III:

DF 7 = 21,000 c = 1 LY in 25.03 min = 42 AU/second = 57.53 LY/day

DF 8 = 43,000 c = 5 LY/hour = 88 AU/second = 120 LY/day

Class IV:

DF 9 = 182,000 c = 20 LY/hour = 365 AU/second = 480 LY/day

DF 10 = 365,000 c = 40 LY/hour = 730 AU/second = 960 LY/day

Class V:

DF 11 = 1,500,000 c = 1 LY in 21.02 seconds = 171.233 LY/hour = 3000 AU/second = 4109.589 LY/day

DF 12 = 3,000,000 c = 1 LY in 10.51 seconds = 342.466 LY/hour = 6000 AU/second = 8,219.178 LY/day

Warp Gates
An invention of the Saurians, this method of FTL travel involves a series of massive ring-shaped gates which serve as anchor points for stable wormholes that thread through hyperspace. The gates are always located in space, usually orbiting a star at a distance of at least 10 AU. Each gate is fixed to another specific gate, and so a journey across the galaxy would involve planning a course around which gates link to which. Any specific information about how the gates work is a secret that the Saurians guard jealously. They do allow other species to use their gate networks, for a reasonable toll.

Warp Portal Networks
An invention of the Imaja, this technology opens temporary wormholes from a central location to virutally anywhere in the known universe. The immense machinery that generates these portals is buried deep inside the Imaja homeworld of Tarlec, and can be controlled remotely by the comm devices that the Imaja carry when they are away from home. They can request portals directly between Tarlec and another location, or a portal linking one external location to another. The portals are limited in size, not allowing anything larger than a small shuttlecraft to pass through, and they typically only can remain open for several seconds at a time. Considering that the modern era Imaja generally shun space travel, they don't see this limitation as being a problem. During the Galactic Empire Era the Imaja had spacecraft capable of generating warp portals to other locations, allowing personnel to rapidly move between ships and planetary locations.

Inter-Phase Stasis Cloaking
A technology derived from the Warp Drive, the Inter-Phase Stasis Cloaking System (also known as an IPS Cloak) involves a ship warping itself into hyperspace yet synching its membrane so that it remains attached to the membrane associated with a fixed location in realspace, allowing the ship to effectively hide in hypespace without having to be constantly in motion. Instead of the standard tunnel of light effect, people within inter-phase stasis see a shifting field of blue-white clouds, occasionally flashing with bursts of random energy. It is possible for a ship with highly refined sensor suites to spy upon activity within the corresponding area of realspace without being seen. The ship can phase back into realspace at a moment's notice, ambushing a target. This kind of cloaking is quite dangerous, the interaction between membranes resulting in a very thin membrane that is susceptible to spillover of corrosive energies from hyperspace. It is rumored that the Terrans have been using this technology since the early 22nd century to create hidden extra-dimensional rooms where especially valuable items can be stored without any possibility of detection. In recent years the Terrans have aggressively sought to adapt this technology to allow the cloaking of entire starships.