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In My Traveller Universe Detail what parts of Traveller you do (or don't) use in your campaign.

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Old December 8th, 2005, 08:53 PM
Ptah Ptah is offline
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I'm wondering what changes, modifications or elaborations others have made on how jump drives function and jump space.

Below is a long post on the approach I've taken IMTU. I'd be interested in hearing constructive comments on these ideas and especially on any naval strategy, pirate strategy, and trade consequences you might see resulting from my 16 axioms on jump space.

J-Drives & Jump Space IMTU

Design Goal:
Speed of communication is equal to the speed of travel. Interstellar space travel is analogous to ocean voyages of the 18th century. This requires jump travel by larger ships to be slower IMTU. Scout ships cover interstellar distances faster than other ships.

Axioms:
1. Jump Duration Jump duration is quantitized in weeks, e.g., 1 week, 2 weeks, 4 weeks, 6 weeks etc. Jump transit can be made safer by taking more time (+ modifier to jump success roll).
2. Ship Size There is a delta function in the jump duration equations that results in ships at almost exactly 100T having the shortest jump duration 1 week/jump. For ships up to and including 400T, the shortest jump duration is 2 weeks/jump without penalty. For ships greater than 400T, the shortest duration is 2 weeks/jump but this is at a -2 penalty.
3. Decreasing Jump Duration There is a first order “ringing” in the jump equations in that jump duration may be ±1 day from the central value. There is higher order ringing (e.g., ±2 days etc.) but the probability of successfully making these jumps is miniscule and the lower end of the duration is strongly attenuated. In game terms a navigator can attempt to shorten the jump duration by 1 day, failure results in a minor misjump.
4. Minor Misjumps A minor misjump causes minor power plant damage which can spill over into all systems connected to the power plant (e.g., weapons, G drives, etc.), as these power surges are intentionally shunted away from the power plant, jump engines, computers, etc. Life support by convention operates off an independent system. Power plants that are in poor condition may fail even with power surge shunting. Failure of the power plant or failure to maintain sufficient energy for the jump field can result in jump field collapse and loss of the ship.
A common misconception IMTU is that jump-dimming arise from the need to shunt all power to the jump drives. The power, however, required for ship’s lights, ventilation, and all other systems is miniscule compared to the enormous energies required for jump, i.e. the conversion of matter on the multi-ton scale into energy. The actual cause of dimming is the switching of life support, ventilation and lighting systems to secondary power circuits to prevent their overload in case of jump-field fluctuations. The actual reason was found to greatly unnerve passenger’s so the myth of the “temporary” shunt of extra power was invented and the lights were kept dim until jump space was entered. The transfer circuits have been improved and the lights no longer dim as in the old days.

The Navigation
5. Jump Success The probability of a successful jump in LBB2 is for a well mapped jump route. Accurate mapping of a jump route requires accurate prediction of the properties of the destination stellar system at the time of arrival and the nature of jump space in between. The prediction of the required system parameters requires decades of careful observation per parsec of distance of the observer. The best data for the prediction of system parameters is that obtained by a jump ship. The more recent the data the better; thus, one primary role of the scout service is to constantly jump ships between worlds along trade routs to ensure the needed data is up to date.
6. Blind Jumps Observations made for only 3.26 years per parsec can be used to initiate a jump, but such jumps are highly dangerous. These are called “blind” jumps. Assuming a navigator skill of 4, only 1 in 36 ships are expected to survive. No ship with a navigator skill of less than 4 has ever successfully made a “blind.” Jumps can be made with less or no data, but it is only rumored that navigators with skills ranked 6 or above have survived such attempts.
7. Jump Routes Some jump routes are inherently safer than others allowing for safer jumps. These safer routes are often between main-sequence stars. Some are more dangerous. These more dangerous routes are often between stars off the main sequence, trinary systems, or trace a jump path through a dense interstellar cloud or nebula. Some of the most dangerous routes involve variable stars (e.g., Wolf-Rayet stars), brown dwarf, neutron stars, or ones that trace a route within J parsecs of a rotating singularity. However, harvestable neutronium (at TL14+) and trans-actinide elements (at TL12+) are often found in variable star, brown dwarf, and neutron star systems.
8. Navigating Navigation of a starship requires the near constant attention of a navigator. Well know routes require only that a navigator be present to occasionally address dangerous fluctuations in the jump-field. More dangerous routes can require the navigator to be constantly monitoring the navigation equipment and adjusting the jump field. Accordingly, the Scout service has developed stimulants (aka Nav-drug) that allow navigators to stay awake, alert and focused for a week or more. Civilian ships typically employ at least three navigators, working in shifts, and use only established jump routes.
9. AI and Computer Navigators Computers and AI systems have not demonstrated a Navigation skill rating above 2. It is believed that this is due to some psionic-like component to navigation. However, navigational talent does not appear to correlate with an individual sophont’s psionic ability or that of his species. The ability to predict who will be a good, or merely average navigator, is a highly active area of Imperial research.
For calculation purposes, AI and computer navigation systems are calculated at x2 the desired rating with a maximum obtainable rating of 2 for such systems.
10. Jump Points Jump points are not points, rather they are a spherical volume roughly 10 light seconds (edited from 1 to 10 ls) in radius. Jump points occur at or near the gravitational focus of an object (edit: and at resonance points in a system). (edit: The gravitational focus is about 500AU for a typical main sequence star, with resonances at about 22AU and about 5 AU, however exceptions are known. Travel from jump point to jump point is the safest jump route (+ to jump success). One primary task of stellar surveys is to find the jump points around a star. In the simplest case, the best jump point from star A to star B, is at the gravitation focus point of the light from star B. However, it is also possible to travel from any point on the gravitational focus sphere, or resonance focus sphere(e.g., 22AU, 5AU), of one star to that of another. Such a sphere is called the jump sphere. It is impossible to “block” a jump point. The concentration of sufficient mass (e.g., complete mining) can cause the point to shift away from the mass. There are usually a limited number of jump points in a system 2D6 on average. Some jump points only lead to one other jump point, these are called “closed points.” Generally, jump points are “open” in that you can travel to any other jump point within range of your drives.
11. Virtual Jump Points Jump points that are not near any stellar object. Theory has it they are resonances in jump space that appear and disappear from time to time. Prediction of these points is an area of active research. There are many myths about vast fleets of ghost ships stranded at such points.
12. Jumping in Formation A primary goal of The Navigation is the refinement of techniques for the emergence from jump space in formation. Currently, it is believed that emergence in formation is only possible when jumping from jump point to jump point, and even then a difficult navigational task, minimum of Nav-3 on all ships. Jumping from or to the jump sphere generally results in a somewhat random distribution (vector is preserved etc.) of the ships in space, time or both across the jump sphere. It is generally known that emergence on the jump sphere at the same place or the same time is possible to a degree, but that simultaneous emergence in roughly the same space at roughly the same time is impossible. Private research on the emergence from jump space in formation is forbidden by Imperial edict. All such research must be conducted under the control and oversight of the Imperial Navy. Open discussion of navigational methods and techniques for emerging in formation on a jump sphere is considered high treason.


The Jump Field
13. Field Volume The volume of a jump field is not variable. Jump drives can only be designed to produce a given field volume which can not be substantially increased or decreased. Therefore, for example, a 400T variable tonnage ship cannot double its jump performance for configurations where it is only 200T. Early jump drives could not vary the overall shape of the jump field, this led to the standardization of ship dimensions in the early days of jump drive to facilitate standardized jump drives.
14. Iridium Grids Early jump drives required an iridium grid in the hull to help maintain and shape the jump field and better constrain the field near the hull. Modern jump drives (TL12+) are able to project the jump field minimizing or eliminating the need for an iridium grid. However, and iridium grid does provide an added safety margin for control of the jump field and many scout, military and passenger ships still employ these grids.
15. Jump Sickness The fields formed by early jump drives were not properly calibrated to protect sophonts from the effects of hyperspace. Early fields allowed some jump space to “leak” in. This made early jump travel unpleasant for many causing nausea and headaches. In extreme cases a condition known as “hyperspace madness” could develop, characterized by paranoid-schizophrenic behavior. Modern (TL11+) jump fields are properly calibrated and the days of jump sickness are generally gone, although some species remain sensitive to jump space. However, straining jump fields to decrease jump duration can destroy this calibration.
16. Jump Wake A skilled sensor officer and skilled navigator working in unison can determine the jump destination of a starship if they can get a read on the jump wake within a certain period of time after the ship has jumped.

Some of the Consequences IMTU:
1. Axioms 1-3 100T ships due to their jump performance, among other things, are the ship of choice for jump exploration given that they have an extra duration step to employ in making a jump safer. In addition, 100T hulls are the predominant scout as the can get to a system and back faster than any other sized ship. Such military scouting missions often are along less than optimal jump routes, thus the superior navigational skills of the Scout service are often called upon. 100T ships are of course the ship of choice for couriers. 100T ships are also favored as raiders, gun ships, and pirate sloops. Their speed and improved navigation allow these ships to go into the “shallow water” of jump space, so to speak.
2. Axioms 1-2 Ships at 400T and under are favored because of their extra margin of safety particularly in situations where ships do not travel from jump point to jump point. Accordingly, patrol ships are made the largest size possible to still retain these benefits. Commercial ships are often in the 200 to 400T range to take advantage of these benefits as well. However, along well mapped and established jump routes these benefits are often outweighed by the economics of scale which favor large ships.
3. Axiom 10 The importance of jump points means they are heavily defended in populated systems. In addition, large repulsar/tractor beams are positioned to move ships quickly out of the jump point if needed. Given the long distances between jump points and worlds, starport facilities are often built nearer the jump point for the shipment of cargo in-system. All these facilities and defenses cost money, so “emergence fees” and “entry fees” for using a jump point can be pricey. Some merchantmen, especially with the safer 200T and 400T vessels, eschew the use of jump points and jump from jump sphere to jump sphere. Slightly more dangerous navigationally, but far more dangerous in regions where piracy occurs. In important systems there may be sufficient patrol ships to rescue any ship beset by pirates on the vast jump sphere. However, in most systems, there are insufficient ships to guarantee that a patrol ship will arrive in time to rescue a beleaguered merchant from pirates.
4. Axioms 10 & 12 System defense and invasion are dictated by the nature of jump space emergence. Invasion through a jump point is analogous to landing on a fortified beach head. Invasion through the jump sphere is an exercise in stealth as ships often appear over a period of 1-2 days and more analogous to a parachute drop. Detection of an invasion fleet before it can assemble means that defenders can often destroy at least a portion of the force. System patrols are key to effective defense against jump sphere invasion.
5. Axiom 11 Virtual jump points are of immense strategic value. The Imperial Navy and Scout service deny their existence but carefully monitor such research.
6. Axiom 15 Patrol ships carry extensive sensors, and both skilled sensor operators and navigators. If a destination fix can be obtained, 100T “raiders” designed to beat a target to its destination are usually employed. Therefore some pirates prefer the 100T sloop to a large but slower ship.
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