Jumpships are starships found in the writings of science fiction author C.J. Cherryh, amongst other places. I'll describe hers here in this writeup.

A jumpship is a spacecraft that is capable of broaching the 'interface' between normal space and hyperspace. It can only do so at great energy cost, and is incapable (well, those piloted by most folk are) of maneuvering while in hyperspace. 'Jumps' are made by achieving a requisite sub-c velocity, to be 'carried over' into hyperspace, and forming a 'bubble' around the ship which drops into hyperspace (the bubble's contents do not, technically). Time inside the bubble moves in strange ways; although most species cannot experience time in jump and see it as a discontinuity, this is not precisely the case.

Some species (humans, for example) are very disturbed by the otherness of hyperspace travel due to limits of their sensorium. As a result, humans (and stsho) tend to tranquilize themselves during transit. Other species such as hani and mahendo'sat simply dream strangely for a time. Physical aging during a jump is perhaps three to four days; as a result, beings come out of jump extremely hungry, thirsty, aching, etc. as they've essentially been sitting there unmoving for that period of time. As the outside universe calculates it, a jump takes months. And, for a few blessed or cursed oxy-breathers (and the whole knnn, tc'a and kif species) the hyperspace travel period is experienced at a rate which equates to perhaps a few weeks. Oxy-breathers who are 'conscious' in jump are called 'sleepwalkers' and held with reverence, awe, and fear by others of their species. In jump, such beings can 'see' stars and patterns of force, and most new jump lanes or waypoint masses are discovered by such lucid crewmembers during jump.

In Cherryh's universe, jumpships dock only at starstations, which seem to follow a relatively common design across species. A torus is spun for artificial gravity; the outermost (downmost) level is the Docks. Starships mate with docking gear which projects from the side of this level, or from the top/bottom of the torus, so that when in dock they maintain a consistent 'down'. As a result, docking is a relatively complex maneuver of matching spins, timing, etc.

Most jumpships consist of the following relatively consistent components. There is a spaceframe, which usually contains or has attached the cargo holds and the jump vanes, as well as maneuvering thrusters and realspace drives, known as 'the mains' (fusion rockets). This frame contains a cylinder with the inhabitable areas of the ship; this cylinder is spun for gravity when the ship is under way, and locked with the important areas (bridge, crew quarters, etc.) on one alignment so as to create 'down' when docked.

Jumpships are large, expensive beasts. Clans, nations or large companies are the only entities that can afford them. In human space, dynastic families tend to inhabit and operate large merchant vessels, with names that reflect the family heritage: The Reillys of Dublin Again, the Neiharts of Finity's End, the Krejas of Le Cygne. In human history, the jumpships were originally large, sublight colony and long-term cargo vessels that made multi-year runs; as such, they were crewed by families. When jump drive came into being, most were retrofitted, and from then on, most larger merchanters tended towards 'clan' status. When you live in a timestream completely separate from all other humanity, you essentially become a family; spacers (due to their spending a great deal of time in jump and at relativistic velocities) age much more slowly than stationers or planet-bound folk; and ships themselves of different routes share timelines only when in the same system.

Warships do exist, and most of the larger freighters carry arms. In the compact, ships built for combat are called hunter-ships. Humans tend to build carriers, because the investment required to build and outfit a jumpship is immense; in order to project power in a star system, you'd like to be in more than one place at once, hence most human combat starships carry riderships. Large freighters still, however, pack a respectable punch, especially if massed.

Tactics of jumpship combat are dictated by their capabilities. A ship moving at high v (Velocity) will fire energy weapons that are extremely energetic due to Doppler's effect, and missiles that can travel much further much faster due to the launching ship's initial v. However, the only time ships typically travel at such high speeds is on entry to and exit from starsystems, in order to avoid the lethal accident of collision - at such speeds, even small debris can get through a ship's velocity shields and destroy it. Ergo, much of jumpship tactics is in fact strategy; you want to come out of jump in a system at the right time to catch your opponents sitting dead-v at dock, or at relatively low speed, when your energetic fire will rip through them. In addition, the fact that you are travelling near c means that news of your arrival is only a small period of time ahead of your ordnance, especially if beam weapons are used.

Since the jump vanes of a jumpship are vulnerable and large, they are a favorite target; a ship that cannot use its jump engines cannot accelerate or decelerate to/from relativistic speeds. Ships use brief pulses of their jump fields to 'transition' to a higher energy state, bleeding energy back from hyperspace in the form of velocity; a ship that enters a system and loses its jump drive is doomed to fly straight out the other side into the interstellar gulf - a long, slow death.

Of course, system entry is when many species are groggy, tired, and otherwise drained from jump. Some species struggle through this; some of the more helpless after jump (humans, for example) take their ships through Jump on automatics; Human ships are acknowledged to be able to execute preprogrammed maenuvers (including ordnance fires) on automatic immediately following jump exit. This makes things even more interesting.

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