Hello Folks,
I figured I'd toss out a few random thoughts here and get some people's input on them. Perhaps some kind soul will have figured out an answer to this and tell me where my thinking has gone wrong.
Jump space exit points do NOT rely upon having a planetary or solar mass handy to precipitate them out of jump space.
Given:
1) Jump durations are 168 hours plus or minus 10%. This gives us a temporal displacement of 151.2 hours on through 184.8 hours. This total time displacement is such that there are 33.6 hours (or 120960 seconds) between early or late exits from jump space.
Fact:
Earth travels around the sun at a speed of 1 AU x 2 x Pi / (365.25 days x 24 hours x 3600 seconds/hour) or roughly 18.5 miles per second. Earth's diameter is roughly 7926.397 miles with a 100 planetary diameter range of 792639.7 miles.
Question: how long of a window does a navigator have when plotting for an exit point that REQUIRES earth's physical presense to precipitate him out of Jump space?
Answer: The navigator has to aim his ship such that it coincides with that mystical 100 diameter limit. The Navigator must also plan on his ship exiting where the planet will BE in the future rather than where it is NOW (after all, the trip in Jump space lasts 168 hours +/- 10%). As a consequence, the window of opportunity to "hit" his targeteted destination is equal to the 100 Diameter radius divided by the planet's speed to Move 100 diameters. Dividing 792639.7 by 18.5, we get some 42845.23 seconds worth of time before Earth has moved 100 planetary diameters. This is roughly 11.9 hours of window time. Keep in mind that I have kept this example simple because the sun itself is moving at a rather fast speed which adds to the problem and the earth's orbit is not a perfect circle - which means at times its speed relative to the sun is slower and at other times, relatively faster.
Problem: what happens when a ship targets for the earth's future position, and the ship is either 11.91 hours early or 11.91 hours late? Sure, the ship *might* be "caught" by the sun's 100 diameter radius, but what if it isn't? What if instead of aiming for earth, the pilot had been aiming for Jupiter - whose 100 diameter limit is no where NEAR the sun's 100 diameter limit?
Tentative Answer: if it is required to exit at the 100 diameter limit of a star or a planet or anything else - that "variable" aspect of 10% is more than enough to Miss a planet or star (just based on the star's velocity alone!). This "jump space" model has some flaws in it that make it unsuitable for use with Traveller as we know it. Oddly enough? I've looked through the rule books of the following:
GURPS TRAVELLER: jump dur = 168 hours +/- 10%
TRAVELER TNE: Jump Dur = Roll 1d6, 6,7, or 8 days
Classic Trav: Jump dur = approximately 1 week
Megatraveller: Jump dur = 1 week
I don't know where my copy of T4 Traveller is, so I can't include that in it.
All in all, I almost wish that Traveller had just flat out said:
a) jump duration is based on pilot skill. If Duration is variable - then make it so that good navigators are worth it. Since the limits are +/- 10%, why not make it so that pilots who attempt to shave off time can make the effort to shave off time and if they fail, LOSE time instead.
b) keep jump space duration relatively stable such that instead of missing by up to 16 hours either way - make it so that the miss is by a matter of a few hours at most either way (closing the missed window of opportunity flaw pointed above)
c) make Jump space duration exact and predictable. Duration is precisely 168 hours and any longer duration an obvious sign of misjump. Either that, or make the misjump duration exactly 168 hours as well - making the jump space physics an unchanging one.
I figured I'd toss out a few random thoughts here and get some people's input on them. Perhaps some kind soul will have figured out an answer to this and tell me where my thinking has gone wrong.
Jump space exit points do NOT rely upon having a planetary or solar mass handy to precipitate them out of jump space.
Given:
1) Jump durations are 168 hours plus or minus 10%. This gives us a temporal displacement of 151.2 hours on through 184.8 hours. This total time displacement is such that there are 33.6 hours (or 120960 seconds) between early or late exits from jump space.
Fact:
Earth travels around the sun at a speed of 1 AU x 2 x Pi / (365.25 days x 24 hours x 3600 seconds/hour) or roughly 18.5 miles per second. Earth's diameter is roughly 7926.397 miles with a 100 planetary diameter range of 792639.7 miles.
Question: how long of a window does a navigator have when plotting for an exit point that REQUIRES earth's physical presense to precipitate him out of Jump space?
Answer: The navigator has to aim his ship such that it coincides with that mystical 100 diameter limit. The Navigator must also plan on his ship exiting where the planet will BE in the future rather than where it is NOW (after all, the trip in Jump space lasts 168 hours +/- 10%). As a consequence, the window of opportunity to "hit" his targeteted destination is equal to the 100 Diameter radius divided by the planet's speed to Move 100 diameters. Dividing 792639.7 by 18.5, we get some 42845.23 seconds worth of time before Earth has moved 100 planetary diameters. This is roughly 11.9 hours of window time. Keep in mind that I have kept this example simple because the sun itself is moving at a rather fast speed which adds to the problem and the earth's orbit is not a perfect circle - which means at times its speed relative to the sun is slower and at other times, relatively faster.
Problem: what happens when a ship targets for the earth's future position, and the ship is either 11.91 hours early or 11.91 hours late? Sure, the ship *might* be "caught" by the sun's 100 diameter radius, but what if it isn't? What if instead of aiming for earth, the pilot had been aiming for Jupiter - whose 100 diameter limit is no where NEAR the sun's 100 diameter limit?
Tentative Answer: if it is required to exit at the 100 diameter limit of a star or a planet or anything else - that "variable" aspect of 10% is more than enough to Miss a planet or star (just based on the star's velocity alone!). This "jump space" model has some flaws in it that make it unsuitable for use with Traveller as we know it. Oddly enough? I've looked through the rule books of the following:
GURPS TRAVELLER: jump dur = 168 hours +/- 10%
TRAVELER TNE: Jump Dur = Roll 1d6, 6,7, or 8 days
Classic Trav: Jump dur = approximately 1 week
Megatraveller: Jump dur = 1 week
I don't know where my copy of T4 Traveller is, so I can't include that in it.
All in all, I almost wish that Traveller had just flat out said:
a) jump duration is based on pilot skill. If Duration is variable - then make it so that good navigators are worth it. Since the limits are +/- 10%, why not make it so that pilots who attempt to shave off time can make the effort to shave off time and if they fail, LOSE time instead.
b) keep jump space duration relatively stable such that instead of missing by up to 16 hours either way - make it so that the miss is by a matter of a few hours at most either way (closing the missed window of opportunity flaw pointed above)
c) make Jump space duration exact and predictable. Duration is precisely 168 hours and any longer duration an obvious sign of misjump. Either that, or make the misjump duration exactly 168 hours as well - making the jump space physics an unchanging one.