Originally Posted by Pomphis (Post 843034)

Ger a copy of Space 2e. It had nice and simple rules to roll up systems. Of course, they were probably considerably less realistic.

Originally Posted by Brett (Post 843047)

Space 4e is fine once you have computerised it.

But if you insist on a sequence you can turn manually, I think that the one in GURPS Traveller: First In has an excellent balance between realism and tractability.

Originally Posted by Noven (Post 843051)

I have manually done 33 systems.

Originally Posted by Brett (Post 843052)

... the spreadsheet with which I now design a thousand systems in thirty seconds.

Originally Posted by Figleaf23 (Post 843055)

[wheedling]Any chance of sharey-sharey?[/wheedling]

Originally Posted by Brett (Post 843059)

It isn't a perfectly straight implementation, since I used a formula for tides with my corrections, used my own variant rules of generating rotation periods, added a few minor features such as calculating aphelion and perihelion temperature, visual illuminance, etc., and couldn't implement the spacing of moon's orbits correctly. It would not be legal or proper for me to distribute garbled copies of SJ Games' copyright material.

Originally Posted by Trachmyr (Post 847265)

I have a question...

If a planet & sattelite form a binary system (barycenter not below the surface of the planet), and are "tide-locked" to each other, but still rotate in regards to the star... would these planets have "Tides"? Would they only be affected by the star, or would they affect each other as normal?

Originally Posted by dataweaver (Post 345903)

For the record, the means of determining how long it would take to get from one rotational period to another is:

A = 62.5 * [(P2 - P1)] / [P1 * P2 * M/D^5 * (S1 - S2)]
A: time needed in billions of years
P1: initial rotational period in hours
P2: final rotational period in hours
M: mass of planet in Earth masses
D: diameter of planet in Earth diameters
S1: sum of squares of tides from sun and satellites with orbital periods greater than P1
S2: sum of squares of tides from remaining satellites.

For multiple satellites:

First Step:
P1 is randomly determined
P2 is the longest satellite orbital period in hours (multiply days by 24)

Subsequent Steps (skip to end if S2 >= S1):
P1 is the previous step's P2
P2 is the next longest satellite orbital period in hours (multiply days by 24)

repeat until you run out of satellites

Last Step (skip if S2 >= S1):
P1 is the previous step's P2
P2 is the planet's orbital period in hours (multiply years by 8766)

For one satellite:

First Step:
P1 is randomly determined
P2 is the satellite orbital period in hours (multiply days by 24)

Last Step (skip if S2 >= S1):
P1 is the previous step's P2
P2 is the planet's orbital period in hours (multiply years by 8766)

For no satellites:

P1 is randomly determined
P2 is the planet's orbital period in hours (multiply years by 8766)

Again, keep a running total of the A's; stop and interpolate the current rotational period if the running total equals or exceeds the system's age.

(Oddly enough, the only equation I'm having trouble with is the interpolation of the current rotational period; and that's simple Algebra. Need sleep...)