Transwarp was first put into test in 2285 aboard the USS Excelsior. Equipped with the latest in technology, the Excelsior was not supposed to be tested for some months, however when the USS Enterprise under the command of James T. Kirk broke free from confinement, the Excelsior was ordered to pursue and was about to test its experimental Transwarp Drive for the first time, were it not for the deliberate sabotaging of its engines my Chief Engineer Montgomery Scott prior to her launch. Looking back on the incident, it was only a deliberate act of sabotage by Mr Scott which prevented a catastrophic nacelle implosion on the first flight, which would have resulted in the Excelsior blowing up. Despite years of further work on the engines, the Excelsior was branded a failure - never made a successful test flight, and never having broke the transwarp barrier. Starfleet abandoned the Excelsior transwarp project altogether in 2287 and refitted the ship with a standard warp drive.
This was not the end for Federation transwarp technology, however. Two decades before the United Confederation came into being, the crew of the USS Voyager succeeded in conducting two brief shuttlecraft flights at warp 10 - actually straddling the warp barrier itself, and achieving infinite speed. However, several significant problems remain with this approach; Voyager crew members who conducted the flight experienced severe health problems, including genetic abnormalities. Voyager relayed some details of this flight back to Starfleet in 2373 via an alien subspace communications array; experts analysing the technology have indicated that the difficulties experienced by Voyager are in fact only the tip of the iceberg. As well as the guaranteed genetic damage, the subspace fields associated with this form of transwarp drive results in an 85% chance of fatality per flight. Significant problems also remain with navigating a vessel using this form of drive system, and as a result even unmanned probes have proved to be unusable.
The 'TNG Warp Scale' which was constructed by Professor Terrance and Doctor Neltorr, had calibrated the scale so that the velocity of an object - under ideal conditions - would be given by raising the warp factor it was travelling at to the power of 10/3, up to warp factor nine. Beyond warp nine the exponent increased gradually, then sharply as warp 10 was neared. At warp 10 itself the exponent became infinite - an object reaching warp 10 would thus achieve infinite speed, passing through every point in the universe simultaneously. However, standard warp drives required infinite power to achieve warp 10 - naturally this seemed an impossible task. Scientists of the day where quite confident in proclaiming Warp 10 as the ultimate impassable barrier.
In 2269, scientists working for the Daystrom Institute took the theoretical models of subspace created by Terrance and Neltorr one step further. It was realized that the mathematics allowed for a second subspace region stretching from the warp 10 barrier up to another, similar barrier at warp 20 - a region which a public relations officer in the Daystrom Institute press office dubbed the "transwarp domain", a name which has stuck despite its inaccuracy.
In 2270 it was realized that even this theoretical transwarp domain was only part of the whole structure. The theory allowed for an infinite number of such domains, each separated by a warp barrier. Throughout the early 2270's there was a huge effort to discover whether these transwarp domains where just theoretical constructs, or where actually real. In 2273 the Starfleet science vessel USS Wanderer conducted a subspace particle dissipation experiment which proved conclusively that not only did transwarp domains actually exist, but that under certain circumstances it was possible for matter to circumvent the warp barrier and pass into the transwarp domain.
Theoretical and practical studies quickly established that at a point infinitesimally past Warp 10, the warp factor exponent fell from infinity to zero and then began to gradually rise again. By Warp 11 the exponent reached 12/3, after which it mirrors the behaviour of the normal warp curve. At Warp 19 the exponent begins to climb, again reaching infinity at warp 20 to form the next warp barrier. The whole process is repeated again in the second transwarp domain, and again in the third, and so on. In each domain the 'steady' central value of the exponent increases exponentially - from 10/3 in the warp domain to 12/3 in the first transwarp domain, 16/3 in the third, then 24/3, 40/3, and so on.
The power required to hold a given warp factor is generally given in Megajoules per Cochrane per second. Within the warp domain the power requirements follow a sawtoothed curve, ising towards infinity at warp 10. Once into the first transwarp domain the basic shape of this curve repeats itself, although it is shifted upwards relative to the first by the higher energy requirements involved in transwarp drive. In general, transwarp factors require much higher engine power to maintain than the equivalent warp factor - for example holding Warp 13 requires 50,000 times as much power as holding Warp 3 does. But in terms of the power required to hold a specific speed, transwarp is far more efficient. The power needed to hold Warp 13 with a transwarp drive could maintain Warp 9.82 with standard warp drive, but while Warp 9.82 equates to 2,530 times lightspeed, Warp 13 is 28,561 times lightspeed - an increase in speed of almost 1,130%.
For the following decades, a workable, practical transwarp drive remained beyond the reach of Confederation science and although some efforts to develop this technology were still being made, no progress was achieved until later in 2392. Proffesor Klenmier, taking over from the work of Terrance and Neltorr succesfully refined the Transwarp Drive which used Dilithium as its primary power source. However after testing the drive for another 2 years, further research into the transwarp drive found that by using the Dilithium chamber which powered 'conventional' warp cores created such a drain, that the useful life of the Dilithium was a year at most. Although still a 'experimental' technology, this was found to be vastly inefficient to operate, and so a new source of power had to be found for the transwarp drive.
In 2396, such a fuel source was found accidently during a trial of the conventional warp propulsion sytems in use by current Federation Starships. Cryogenic Deuterium was the proposed new source for current warp engines, replacing the Dilithium which had been in use even before the first Galaxy Class was constructed. However tests revealed that engine performance in conventional warp cores only increased slighlty, but nowhere near enough to warrant overhauling the fleet. Proffesor Klenmier noticed though that were no spikes in the power outage that was associated with the typical warp core element of Dilithium each time a ship increased to a higher warp factor. Putting his theory to the test, the Proffesor replaced the Dilithium Transwarp core with the new Deuterium in its Cryogenic state and began several warp speed models. The signs were encouraging, upon entering the transwarp domains, there appeared no sign of any spiking in the power outage of the Deuterium, and whats more, the Deuterium was actually able to sustain increases in the Transwarp Domain. The discovery of Cryogenic Deuterium marked a huge step warp in warp propulsion technology - while it didnt increase speeds of the conventional warp cores - which was what the research was for - the spin off was that it sustained current top speeds for extended periods, as it did with the Transwarp Speeds. The puzzel to Transwarp had finally been solved, or at least it was thought so.
Not being able to beleive the good fortune of his discovery, the Proffesor ran a multitude of tests on the Transwarp power systems only to discover that over the course of the testing, it was revealed that there was a 8% chance of a spike in Deuterium exceeding that of uncontainable levels - thus resulting in the destruction of the drive. Further tests brought up zero, the Cryogenic Deuterium wasn't stable enough on its own and the United Confederation Labs would never approve the technology for use on Starships until the figure of 8% was decreased. New catalysts and elements were mixed with the Deuterium but only created worse results, until it was discovered that by mixing the Deuterium with Anti-Hydrogens (in their cryogenic state) added stability to the fueling system of the Transwarp Drive and allowed for much safer travel, with the margin of error reduced to 0.0891%.