Just a dumb question about the local charts.

[KZ9999]

While I've been working on the manual, I've stumbled across something that's always bugged me. What does the size of the circles that mark each system in the Local Chart means.

As far as I can work out, the larger the circle the further away the witchspace exit point is from the planet/sun. Any information on this would be gratefully received.

[Disembodied]

I think the bigger the dot, the larger the planet (check the planetary radius on the F7 screen) – which also has an effect on how far away the witchpoint is from the station.

[Eric Walch]

And I always thought it represented the size of the sun. Never checked it. Would be interesting to know.

I think the bigger the dot, the larger the planet (check the planetary radius on the F7 screen) – which also has an effect on how far away the witchpoint is from the station.

Yes, the distance planet- witchpoint is about 12 planetary radii +/- a random distance when I remember right, so those two are always correlated.

[KZ9999]

Well that makes sense.

The larger the Gravitational masses, the deeper and wider the gravity well, and the further way the wormhole will collapse in to real-space. It's also in keeping in with the sequels. Larger the solar mass, the further out you are when you exit hyperspace.

So I will express it in the manual as
The size of the circle represents the distance the craft has to travel real-space to reach the planet relative the planet's size with an allowance of the variance induced by transit through witchspace currents. The average distance is 12 times the planetary radius. i.e. ships will exit hyperspace between 41 - 57 thousand kilometres from Lave.

With a footnote expressing the equation:
Distance in km= (12 x planet radius in km) +/- random range of -2 to 2 planet radius.

[KZ9999]

Hey Eric, are you sure that its 12 planet radii for the witchspace arrival node to the station ageis?

As a test I jumped from Lave to Zaonce (correct spelling this time ). When I transited in I travelled in real time (no hyperspeed) to the station and clocked the time. It took a little over 22 minutes for a coby3 to travel the distance. If the engine speed is 35% light speed or 104927360.3 meters per second. For 22 minutes, that would be a distance of 138504115596 meters or 36612. times the radius of Zaonce! it seems to be the same larger scale distances for other systems.

I could be wrong about the ship speed but since the original manual talks about Light Mach which simply another way of saying light speed. Oolite talks about LS which is light speed one would have assume it the real world 299 Mm per second.

Either the ships arrive at a greater distance than originally suggested or Light Mach is actually slower than the speed of light? Any thoughts anyone?

[tomsk]

You're in the ooniverse where the laws of space, time and physics may be different from the universe.

[Cmdr James]

I think this might be best explained as relativistic effects, leading to Light speed and distance calculations not working out properly

An alternative possibility, is that as we know the ships in oolite use complex thrust control to give the appearance of simple non-newtonian flight, and that therefore the maximum apparent velocity is not the same as the maximum you would expect reading the sales brochure for the cobra.

[DaddyHoggy]

Perhaps it's Discworldian physics - where sometimes the speed of light is less than the speed of sound...

I think it is well established that if LM really stood for Light Mach which really was the equivalent of Light speed then Oolite would be unplayable....

[Sarin]

Or perhaps LM does not mean Ligh Mach in game...perhaps it is some artifical limit for ship speed, like full impulse at Star Trek (for those who do not know, it is 0.25 light speed, set to avoid strong relativistic effects, while impulse engines are capable of higher speed)...possibly GalCop enforced top speed like on roads? (Another DW reference...about Auditors. If someone broke the speed of light, it would be them who would fine him.)

[tomsk]

Or perhaps LM does not mean Ligh Mach in game...perhaps it is some artifical limit for ship speed, like full impulse at Star Trek (for those who do not know, it is 0.25 light speed, set to avoid strong relativistic effects, while impulse engines are capable of higher speed)...possibly GalCop enforced top speed like on roads? (Another DW reference...about Auditors. If someone broke the speed of light, it would be them who would fine him.)

That's all we need. Speed cameras in space.

[KZ9999]

Or perhaps LM does not mean Ligh Mach in game...perhaps it is some artifical limit for ship speed, like full impulse at Star Trek (for those who do not know, it is 0.25 light speed, set to avoid strong relativistic effects)

Actually that would make a lot of sense. Setting a fixed maximum 'light speed' to reduce relativistic effects in real space travel would be logical solution. Then all ships travel at a fraction of the imposed speed limit as trade off of speed vers energy consumption. Not to mention that they would be moving slow enough that a human could actually roll their ship to target them.

Say that the limit was set to 1% light speed or 2990000m per second (thats still 1076400 km/h.) The coby3 would travel at 35% of that or 104650m per second at it's top speed. Going back to my previous post, that would mean that the Zaonce witchpoint is 138138km away from the planet or only 38 planetary radii.

I'll have a think about the maths and see if I can come up with a explanation that would fit the canon.

As for speed cameras in space, I wouldn't put it past a dictatorship to have craft enforcing speed limits "for the traders safety in the crowded space lines."

[Eric Walch]

Hey Eric, are you sure that its 12 planet radii for the witchspace arrival node to the station ageis?

I was 90% sure, so I looked it up in the code:

Code: Select all

double planet_zpos = (12.0 + (Ranrot() & 3) - (Ranrot() & 3) ) * planet_radius;

Indeed 12 times with a variation of 3 radii. Double radius of the planet means double distance to the witchpoint. That is also the reason all planets seems to have the same size when viewed at from the witchpoint. For the larger planets is just takes longer to arrive.

When you see a discrepancy it is because the size given for a planet in the F7 screen is 100 times larger than the size it uses for all its calculations. But in real coordinate distance it is 12 times the radii.

[KZ9999]

Repeating for the sake of clarity...
The witchspace point is: 2 x ((Planetary Data Radius / 100) x (12 + random(-25% to +25))

So Lave with a World Data radius of 4116 km and arriving at the average point....
2 x ((4116 / 100) x 12 )
2 x (41.16 x 12)
2 x 493.92
= 987.84 km away from the planet.

Thanks for the correction, I'll update the work-in-progress that is the manual.

Assuming that I'm correctly reading this, then this raises some interesting questions about the LS rating for ships. If anyone knows what LS 1.00 is in real metres per second, I'd really like to know.

[another_commander]

Repeating for the sake of clarity...
The witchspace point is: 2 x ((Planetary Data Radius / 100) x (12 + random(-25% to +25))

No, the witchspace point is as Eric described:

Code: Select all

	double planet_zpos = (12.0 + (Ranrot() & 3) - (Ranrot() & 3) ) * planet_radius;

which translates to 9 to 15 times the planet radius (or 9 to 15 * planet radius divided by 100, if you are reading the radius from the F7 screen).

[Edit]: Seems like the relevant comment in the code is incorrect. Should be 9 to 15 times instead of 10 to 14.

[Eric Walch]

To get absolute numbers you can also install the console and than type in the console:

1) system.mainPlanet.radius
2) system.mainPlanet.position.z

1 will return the radius as used in all calculations and 2 will return the distance to witchpoint (that has a z-coordinate of zero) that is used in all calculations.

A_C, you also write 10 to 14 times as written in the comment with the code. But does (Ranrot() & 3) not give random integer values from 0 to 3 and thus resulting in 9 to 15 times? But maybe I am thinking wrong as ranrot is a re-implementation of an old elite random generator that could have worked different than I thought.