Jump drive

The Jump Drive is a propulsion system that allows ships to traverse jump points, as well as bring ships along with them.

Overview

Jump drives make ships independent of jump gates, a necessity in exploration craft, as well as to project power outside one's own territory.

A ship equipped with a jump drive can traverse (and potentially tender others ships) between jump points. They essentially work by holding open a wormhole big enough for the ship and any others it is transiting to jump through. Ships using jump drive will suffer the usual jump shock and thus upon entering new system they are vulnerable to attack until they recover.

There are two types of designs military and commercial. The Commercial Jump Drive is larger and less efficient but much cheaper on a per-HS basis. Jump drive efficiency will permit larger ships to jump than lower efficiency engines of the same size. Squadron max jump size and radius are tactical elements. All those characteristics can be improved through research.

Components

Jump Drive Efficiency and Jump Drive Size

Jump Drive Efficiency (a researchable tech line) and Jump Drive Size determine the maximum size of a ship the jump engine can support.

For military jump drives, the max size of ship (in hull spaces; 1 HS = 50 tons) is given by Efficiency * Size For commercial drives, it's a little different. The efficiency of commercial engines is 0.75 x the Efficiency tech, but the size is multiplied by 10 compared to the size listed in the dialogue. The max ship size is thus (0.75 * Efficiency Tech) * (10 * Size), and this is then rounded to the nearest 10 HS.

The Max Ship Size has to be greater than the ship's total hull size; this includes the jump engine itself, so remember when designing a jump engine that you need to account for both the size of the ship + the jump engine's considerable mass. Jump drives below minimum size are only capable of self-jump.

Efficiency	4	5	6	8	10	12	15	18	21	25
RP cost	2,000	4,000	8,000	15,000	30,000	60,000	120,000	250,000	500,000	1,000,000
Size	2	3	4	5	6	8	10	12	...	50
RP cost	600,000	300,000	160,000	80,000	40,000	20,000	10,000	5,000	...	???

Max Jump Squadron Size

The number of ships the ship with the jump drive can bring along with it. For military drives its as shown, but commercial drives reduces the squadron size by one. Increases jump engine size.

Note, that when jumping multiple ships in a fleet, no jump engine can jump a ship larger than the ship it is mounted on, even if the Max Ship Size can accommodate both ships. This means that if you put a jump drive rated at 2250 tons on a 2000 ton ship, the max size ship the jump ship can support is 2000 tons.

Squadron Size	3	4	5	6	7	8	9	10	11	12
RP cost	2,000	4,000	8,000	15,000	30,000	60,000	120,000	250,000	500,000	1,000,000

Max Squadron Jump Radius

Max Squadron Jump Radius is the maximum distance in thousands of kilometres the task group containing the jump ship will appear from the far side of the jump point after a combat transit. It is halved for commercial jump drives. Since jump points are good choke points, increasing this value will allow your combat ships to appear further away from the jump point, which may be useful if an enemy is camping the jump point itself. It slightly increases jump engine size\crew.

Jump Radius (kkm)	50	100	250	500	750	1,000	1,500	2,000	2,500	3,000	4,000
RP cost	1,000	2,000	4,000	8,000	15,000	30,000	60,000	120,000	250,000	500,000	1,000,000

Jump drive type

Military jump engines are smaller in size and suffer no penalty to max jump squadron size, with more efficient use of size. Civilian jump engines make less efficient use of size and significantly larger overall, but can jump larger ships than military version (10x higher Max Ship Size than military). Civilian drives are less costly, but their max jump squadron size is penalized by one.

Additionally a ship whose non-jump engines are flagged as military cannot transit a jump point using a wormhole generated by a commercial jump drive. Military engines create instabilities in the wormhole stabilization field generated by a commercial jump drive and collapse it. On the other hand, commercial-engined ships can transit a wormhole opened by a military jump drive, but this scenario is pretty rare. Military jump drives tend to only support smaller ships, and ships with commercial engines tend to be larger than the capabilities of the military jump drive.

Note that it is not the ship's commercial/military designation that affects this, it is the type of non-jump engines mounted on the ship. Any ship with a military engine is a military ship, but there also exist military ships with commercial engines, and you could feasibly put a commercial jump drive on a military-flagged ship.

Ref

• Commercial Jump Drive v4.3 changes by Steve Walmsley.