GT: Far Trader: Jump Masking

[RainOfSteel]

Originally posted by far-trader:
Make jump entry smooth and safe (no DM) at 0.001 m/s2 [...]

The trouble with reducing to .001 m/s^2, is that a 1 Solar Mass star then has a a much higher Jump Limit.

The whole and entire point of altering the Jump Limit from 100D to anything else at all is removing the existence of so many mainworlds that sit inside the 100D Jump Limit of their primary (never mind the extra and more extensive problems caused by Jump Masking). (Oh, and that it makes scientific and mathematical sense doesn't hurt, either.) Chosing a lower gravity acceleration than Malenfant has already selected removes the major benefit of switching to the new system.

The reduction in travel time to any particular world's Jump Limit by a switch to Gravity Jump Limits is small, usually a few hours at most. This is a small, small change.

The reduction in travel time from a mainworld swamped by its primary's 100D Jump Limit via a switch to some other Jump Limit is huge; and resets it to the travel time to the origin world's Jump Limit. Yes, the origins world's is now lower, too. But it's consistent, accurate, founded in science, and doesn't ruin the adventuring starship economic system (by reducing the number of Jumps to fewer than 2/month).

 

[Malenfant]

Originally posted by RainOfSteel:
The whole and entire point of altering the Jump Limit from 100D to anything else at all is removing the existence of so many mainworlds that sit inside the 100D Jump Limit of their primary (never mind the extra and more extensive problems caused by Jump Masking). (Oh, and that it makes scientific and mathematical sense doesn't hurt, either.)

Well, speaking as the guy who is proposing this method the whole and entire point TO ME of altering the way jump limit is defined is to have it done in a way that makes some kind of scientific sense. Any in game effects of changing that limit are entirely secondary.

I don't really care how big or small the limit is, just as long as it's defined using gravity or tidal force and not 100D.

 

[TheEngineer]

Ok. There seems to rise an agreement, that the gravity based way make some sense

Anybody willing to generate a new table for that ?

Should the "tidal overlay" effect be ignored ?
If a planet is near to the "jump limit" of the primary, the gravity/tidal fields add up, thus extending the effective jump limit of the mainworld. I did not check the amount of this effect. Perhaps its just neglegtable....

 

[Malenfant]

Originally posted by TheEngineer:
[QB] Ok. There seems to rise an agreement, that the gravity based way make some sense

Anybody willing to generate a new table for that ?

Here's a table for different jump limits. The 0.001, 0.005, 0.01, 0.05, and 0.1 at the top are the jump limits used for each column in m/s2 - the distances in the columns are in km from the centre of the object, the AU next to them is the distance in AU. The Ms section gives masses in solar masses, the Mj section gives masses in jupiter masses, and the Me section gives masses in earth masses.

So take your pick

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">m m/kg 0.001 AU 0.005 AU 0.01 AU 0.05 AU 0.1 AU

Ms
15 2.98E+31 1410977699 9.407 631008409.8 4.207 446190325.5 2.975 199542379.8 1.330 141097769.9 0.941
7 1.39E+31 963881267.3 6.426 431060807.2 2.874 304806019.9 2.032 136313396.1 0.909 96388126.73 0.643
6 1.19E+31 892380651.1 5.949 399084759.5 2.661 282195539.7 1.881 126201682 0.841 89238065.11 0.595
5 9.95E+30 814628354.1 5.431 364312875.2 2.429 257608104.6 1.717 115205846.7 0.768 81462835.41 0.543
4 7.96E+30 728625750.5 4.858 325851341.7 2.172 230411693.3 1.536 103043241.8 0.687 72862575.05 0.486
3 5.97E+30 631008409.8 4.207 282195539.7 1.881 199542379.8 1.330 89238065.11 0.595 63100840.98 0.421
2 3.98E+30 515216209.1 3.435 230411693.3 1.536 162925670.8 1.086 72862575.05 0.486 51521620.91 0.343
1.75 3.48E+30 481940633.7 3.213 215530403.6 1.437 152403009.9 1.016 68156698.04 0.454 48194063.37 0.321
1.5 2.98E+30 446190325.5 2.975 199542379.8 1.330 141097769.9 0.941 63100840.98 0.421 44619032.55 0.297
1.25 2.49E+30 407314177.1 2.715 182156437.6 1.214 128804052.3 0.859 57602923.33 0.384 40731417.71 0.272
1.1 2.19E+30 382094567.1 2.547 170877885.2 1.139 120828911.3 0.806 54036331.88 0.360 38209456.71 0.255
1 1.99E+30 364312875.2 2.429 162925670.8 1.086 115205846.7 0.768 51521620.91 0.343 36431287.52 0.243
0.9 1.79E+30 345617540 2.304 154564862.7 1.030 109293862.6 0.729 48877701.25 0.326 34561754 0.230
0.8 1.59E+30 325851341.7 2.172 145725150.1 0.972 103043241.8 0.687 46082338.67 0.307 32585134.17 0.217
0.7 1.39E+30 304806019.9 2.032 136313396.1 0.909 96388126.73 0.643 43106080.72 0.287 30480601.99 0.203
0.6 1.19E+30 282195539.7 1.881 126201682 0.841 89238065.11 0.595 39908475.95 0.266 28219553.97 0.188
0.5 9.95E+29 257608104.6 1.717 115205846.7 0.768 81462835.41 0.543 36431287.52 0.243 25760810.46 0.172
0.4 7.96E+29 230411693.3 1.536 103043241.8 0.687 72862575.05 0.486 32585134.17 0.217 23041169.33 0.154
0.3 5.97E+29 199542379.8 1.330 89238065.11 0.595 63100840.98 0.421 28219553.97 0.188 19954237.98 0.133
0.2 3.98E+29 162925670.8 1.086 72862575.05 0.486 51521620.91 0.343 23041169.33 0.154 16292567.08 0.109
0.1 1.99E+29 115205846.7 0.768 51521620.91 0.343 36431287.52 0.243 16292567.08 0.109 11520584.67 0.077
0.08 1.59E+29 103043241.8 0.687 46082338.67 0.307 32585134.17 0.217 14572515.01 0.097 10304324.18 0.069

Mj
70 1.33E+29 94169869.72 0.628 42114046.02 0.281 29779127.53 0.199 13317630.69 0.089 9416986.972 0.063
60 1.14E+29 87184358.18 0.581 38990030.29 0.260 27570114.82 0.184 12329730.18 0.082 8718435.818 0.058
50 9.49E+28 79588066.06 0.531 35592865.18 0.237 25167956.33 0.168 11255452.24 0.075 7958806.606 0.053
40 7.59E+28 71185730.36 0.475 31835226.42 0.212 22510904.48 0.150 10067182.53 0.067 7118573.036 0.047
30 5.70E+28 61648650.88 0.411 27570114.82 0.184 19495015.15 0.130 8718435.818 0.058 6164865.088 0.041
20 3.80E+28 50335912.66 0.336 22510904.48 0.150 15917613.21 0.106 7118573.036 0.047 5033591.266 0.034
10 1.90E+28 35592865.18 0.237 15917613.21 0.106 11255452.24 0.075 5033591.266 0.034 3559286.518 0.024
5 9.49E+27 25167956.33 0.168 11255452.24 0.075 7958806.606 0.053 3559286.518 0.024 2516795.633 0.017
2 3.80E+27 15917613.21 0.106 7118573.036 0.047 5033591.266 0.034 2251090.448 0.015 1591761.321 0.011
1 1.90E+27 11255452.24 0.075 5033591.266 0.034 3559286.518 0.024 1591761.321 0.011 1125545.224 0.008

Me
100 5.97E+26 6313731.225 0.0421 2823586.442 0.0188 1996577.12 0.0133 892896.4327 0.0060 631373.1225 0.0042
50 2.99E+26 4464482.164 0.0298 1996577.12 0.0133 1411793.221 0.0094 631373.1225 0.0042 446448.2164 0.0030
25 1.49E+26 3156865.612 0.0210 1411793.221 0.0094 998288.5602 0.0067 446448.2164 0.0030 315686.5612 0.0021
15 8.96E+25 2445297.589 0.0163 1093570.327 0.0073 773270.9937 0.0052 345817.3014 0.0023 244529.7589 0.0016
10 5.97E+25 1996577.12 0.0133 892896.4327 0.0060 631373.1225 0.0042 282358.6442 0.0019 199657.712 0.0013
9 5.38E+25 1894119.367 0.0126 847075.9326 0.0056 598973.1361 0.0040 267868.9298 0.0018 189411.9367 0.0013
8 4.78E+25 1785792.865 0.0119 798630.8482 0.0053 564717.2884 0.0038 252549.249 0.0017 178579.2865 0.0012
7 4.18E+25 1670456.267 0.0111 747050.7531 0.0050 528244.6534 0.0035 236238.1908 0.0016 167045.6267 0.0011
6 3.58E+25 1546541.987 0.0103 691634.6028 0.0046 489059.5177 0.0033 218714.0653 0.0015 154654.1987 0.0010
5 2.99E+25 1411793.221 0.0094 631373.1225 0.0042 446448.2164 0.0030 199657.712 0.0013 141179.3221 0.0009
4 2.39E+25 1262746.245 0.0084 564717.2884 0.0038 399315.4241 0.0027 178579.2865 0.0012 126274.6245 0.0008
3 1.79E+25 1093570.327 0.0073 489059.5177 0.0033 345817.3014 0.0023 154654.1987 0.0010 109357.0327 0.0007
2 1.19E+25 892896.4327 0.0060 399315.4241 0.0027 282358.6442 0.0019 126274.6245 0.0008 89289.64327 0.0006
1 5.97E+24 631373.1225 0.0042 282358.6442 0.0019 199657.712 0.0013 89289.64327 0.0006 63137.31225 0.0004

0.8 4.78E+24 564717.2884 0.0038 252549.249 0.0017 178579.2865 0.0012 79863.08482 0.00053 56471.72884 0.00038
0.5 2.99E+24 446448.2164 0.0030 199657.712 0.0013 141179.3221 0.0009 63137.31225 0.00042 44644.82164 0.00030
0.4 2.39E+24 399315.4241 0.0027 178579.2865 0.0012 126274.6245 0.0008 56471.72884 0.00038 39931.54241 0.00027
0.3 1.79E+24 345817.3014 0.0023 154654.1987 0.0010 109357.0327 0.0007 48905.95177 0.00033 34581.73014 0.00023
0.2 1.19E+24 282358.6442 0.0019 126274.6245 0.0008 89289.64327 0.0006 39931.54241 0.00027 28235.86442 0.00019
0.1 5.97E+23 199657.712 0.0013 89289.64327 0.0006 63137.31225 0.0004 28235.86442 0.00019 19965.7712 0.00013
0.05 2.99E+23 141179.3221 0.0009 63137.31225 0.0004 44644.82164 0.0003 19965.7712 0.00013 14117.93221 0.00009
0.01 5.97E+22 63137.31225 0.0004 28235.86442 0.0002 19965.7712 0.0001 8928.964327 0.00006 6313.731225 0.00004</pre>[/QUOTE]Note that if you make the gravity jump limit in m/s2 100 times larger than a given value, the Jump Limit distance becomes 10 times smaller than for that value. In other words, there's an inverse square relationship, as you'd expect.

Should the "tidal overlay" effect be ignored ?
If a planet is near to the "jump limit" of the primary, the gravity/tidal fields add up, thus extending the effective jump limit of the mainworld. I did not check the amount of this effect. Perhaps its just neglegtable....

I'd say ignore it, it adds too much complication.

I still have no clue what a decent limit would be for the Tidal Force approach though.

 

[RainOfSteel]

Beware extra-wide code tables.

 

[robject]

Originally posted by Malenfant:
What are the 1G-6G numbers? Travel time from where to where? And is the jump limit determined by the radius at which gravity is at 0.01m/s2?

And why did you use diameter for the planets instead of mass? What is the purpose of using two different systems to figure out the limit at the same time - you're right, that's an abomination, the worst of both worlds. Either use mass for everything, or use diameter for everything - don't mix them.

Travel time from 'surface' to jump point, zero v to zero v, relative to the planet/star. My calculations might be wrong, by the way. They serve as examples.

I used 100D for worlds because that still seems like a good distance to have to travel for jump, and it's a nice heuristic concept.

I was pleasantly surprised how well the two systems mesh distances so nicely at the GG/BD break.

I don't give a flying flip about nearly all other solar systems, but I figure the G2 V jump limit ought to be just under 1 AU, and the jump limit for the Earth ought to be around 1 million kilometers.

It doesn't look like that can happen without using two different systems, one which dominates when mass is large, and one which dominates when mass is small.

 

[Malenfant]

It doesn't look like that can happen without using two different systems, one which dominates when mass is large, and one which dominates when mass is small.

This approach defeats the whole point of the exercise though, which is to come up with a consistent, realistic way to determine a jump limit. What happens if you have a mass that's right on the border between the two methods? There is no logical reason at all for why planets should use one method and stars should use another.

 

[RainOfSteel]

Originally posted by dzibilrobjectaplaketl:
I was pleasantly surprised how well the two systems mesh distances so nicely at the GG/BD break.

Except that a dual system snaps the old suspenders back in my face, hard.

Originally posted by dzibilrobjectaplaketl:
I don't give a flying flip about nearly all other solar systems

Could you please provide further details of what you mean?

 

[TheEngineer]

Hi !

Just another table a la Malenfant, just filled with the tidal limit data.
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">a 100D (earth) 0,000241820 GM/r^2
da 100D (earth) -3,77844E-13 -2GM/r^3

Object m (kg) 100D (tkm) a 100D (tkm) a 100D(AU) da 100D(tkm) da 100D(AU)
Ms
15 2,98E+31 352445 2866981 19,11 219122 1,46
7 1,39E+31 273332 1958052 13,05 169936 1,13
6 1,19E+31 259538 1811716 12,08 161360 1,08
5 9,95E+30 244508 1656641 11,04 152016 1,01
4 7,96E+30 226981 1481744 9,88 141119 0,94
3 5,97E+30 206226 1283228 8,55 128215 0,85
2 3,98E+30 180155 1047751 6,99 112006 0,75
1,75 3,48E+30 172271 979730 6,53 107104 0,71
1,5 2,98E+30 163591 906619 6,04 101708 0,68
1,25 2,49E+30 154082 828736 5,52 95796 0,64
1,1 2,19E+30 147628 777211 5,18 91783 0,61
1 1,99E+30 142989 740872 4,94 88899 0,59
0,9 1,79E+30 138029 702657 4,68 85815 0,57
0,8 1,59E+30 132684 662240 4,41 82492 0,55
0,7 1,39E+30 126870 619190 4,13 78877 0,53
0,6 1,19E+30 120467 572915 3,82 74897 0,50
0,5 9,95E+29 113491 523876 3,49 70560 0,47
0,4 7,96E+29 105355 468569 3,12 65502 0,44
0,3 5,97E+29 95722 405792 2,71 59512 0,40
0,2 3,98E+29 83621 331328 2,21 51989 0,35
0,1 1,99E+29 66370 234284 1,56 41263 0,28
0,08 1,59E+29 61586 209419 1,40 38290 0,26
Mj
70 1,33E+29 58028 191533 1,28 36077 0,24
60 1,14E+29 55121 177325 1,18 34270 0,23
50 9,49E+28 51853 161789 1,08 32238 0,21
40 7,59E+28 48132 144690 0,96 29925 0,20
30 5,70E+28 43750 125387 0,84 27200 0,18
20 3,80E+28 38219 102378 0,68 23762 0,16
10 1,90E+28 30335 72392 0,48 18860 0,13
5 9,49E+27 24068 51162 0,34 14964 0,10
2 3,80E+27 17740 32375 0,22 11029 0,07
1 1,90E+27 14080 22893 0,15 8754 0,06
Me
100 5,97E+26 5918 12832 0,09 5951 0,04
50 2,99E+26 4700 9081 0,06 4726 0,03
25 1,49E+26 3726 6411 0,04 3747 0,02
15 8,96E+25 3145 4971 0,03 3163 0,02
10 5,97E+25 2747 4058 0,03 2762 0,02
9 5,38E+25 2653 3852 0,03 2668 0,02
8 4,78E+25 2551 3631 0,02 2565 0,02
7 4,18E+25 2439 3396 0,02 2453 0,02
6 3,58E+25 2317 3142 0,02 2329 0,02
5 2,99E+25 2182 2872 0,02 2194 0,01
4 2,39E+25 2025 2568 0,02 2036 0,01
3 1,79E+25 1839 2222 0,01 1849 0,01
2 1,19E+25 1605 1812 0,01 1614 0,01
1 5,97E+24 1275 1283 0,01 1282 0,01
0,8 4,78E+24 1184 1148 0,01 1191 0,01
0,5 2,99E+24 1013 908 0,01 1018 0,01
0,4 2,39E+24 940 812 0,01 945 0,01
0,3 1,79E+24 853 703 0,00 858 0,01
0,2 1,19E+24 745 573 0,00 749 0,00
0,1 5,97E+23 592 406 0,00 595 0,00
0,05 2,99E+23 470 287 0,00 473 0,00
0,01 5,97E+22 275 128 0,00 276 0,00 </pre>[/QUOTE]As you might see its just like people already noted. For planetary bodies the tidal limit nearly fits perfect and for star like objects the limit shrinks a bit, decreasing primary masking/shadowing effect and leaving a more space to operate.

Regarding binary/close companion systems I think the r^3 effect keeps influence of larger central masses in limit.

Regards,

Mert

 

[Anthony]

The tidal limit basically boils down to XD, where X depends on density. Assuming 100D is correct for earth, which might not be my first choice, since most planets will be less dense than earth, we get:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Density 0.7 1.0 1.5 2.0 3.0 4.0 5.0 6.0
Diameters 50 57 65 71 82 90 97 103</pre>[/QUOTE]Typical densities in the solar system: Sun 1.4, Mercury 5.4, Venus 5.2, Earth 5.5, Moon 3.3, Mars 3.9, Jupiter 1.3, Saturn 0.7, Uranus 1.3, Neptune 1.6, Pluto 1.8.

Note that star densities vary widely, and since you'll pretty much need a table anyway as finding the diameter of a star isn't always easy, 0.59 AU * (M/Msol)^3 is probably easier.

This will tend to put stars orbiting M-class and smaller K-class dwarfs within the jump limit of the star (which the 100D rule also does). It will not, however, generally result in huge distances, since the jump limit for such a star is still pretty small.

 

[Jamus]

Or do you mean something like the Battletech approach? IIRC in Battletech you could only jump into/out of a system through two points, one above the star's north pole and one above the star's south pole. The distance depended on the star type.

yes, with the addition of there maybe being other points that a captain could use to try and slip past the patrolled j-points.

 

[Malenfant]

Are we using (GM/R^3) or (2GM/R^3) for the tidal limit?

 

[Anthony]

Originally posted by Malenfant:
Are we using (GM/R^3) or (2GM/R^3) for the tidal limit?

Does the constant really matter?

 

[TheEngineer]

As long as we use the same formula to calc the value at 100D (reference system e.g. earth) for the "base" tidal limit and for the jump limit of the actual system it just dosent matter, meaning the results are the same

Technically the expression (-)2GM/R^3 is perhaps more correct, as its simply the derivation of GM/R^2.

 

[Malenfant]

Originally posted by Anthony:
</font><blockquote>quote:</font><hr />Originally posted by Malenfant:
Are we using (GM/R^3) or (2GM/R^3) for the tidal limit?

Does the constant really matter? </font>[/QUOTE]Well, it makes the tidal limit that little bit bigger (by a factor of (cuberoot 2)) if we keep the constant.

 

[Anthony]

Technically, the formula is 2GM/r^3 <= K.

Combining constants, we get M/R^3 <= K/2G.

We can then call K/2G a constant 'C', and just say that M/R^3 <= C.