KerikBalm

Orbital period changes in 1.2

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So according to the changelog, there were slight changes to the gravity constants... this has caused slight changes in mass, and apparently slightly changed the height of Keostationary orbit

 

I am wondering if any orbits or rotation periods have changed as a result.

If Duna is slightly less massive now, then either:

1) Ike orbits closer, or

2) Duna rotates slower, or

3) Duna is not tidally locked to Ike anymore

What has it done to the length of kerbin's year? Is it slightly longer? what of the other orbital periods?

I also wonder about some resonances.. because of the V^2 relationship to centripetal acceleration, a change to gravity (and hence A) shouldn't proportionally affect the orbital periods of everything (some will change by a different % than others), breaking resonances...

Just how much has changed due to this little constant change?

I just played with one version of my planet "Rald" and the tidal locks are broken, at maximum mtimewarp, there is drift evident that wasn't there before...

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I could be wrong, but my understanding was that the planets/moons are on rails. Their paths are predetermined, and not actually dependent on gravity. Kerbol could be removed and nothing would change about the planet themselves. You could even fly around normally within the sphere of influence of each planet/moon, but things would break when you entered Kerbol's SOI.

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9 minutes ago, Enorats said:

I could be wrong, but my understanding was that the planets/moons are on rails. Their paths are predetermined, and not actually dependent on gravity. Kerbol could be removed and nothing would change about the planet themselves. You could even fly around normally within the sphere of influence of each planet/moon, but things would break when you entered Kerbol's SOI.

from minor tinkering with planetfactory/kopernicus the orbital speeds are calculated, as there was no option for orbital speed, but at different heights planets/moons would orbit at different speeds by themselves.

and removing Kerbol would DEFINITELY break everything.

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I don't pay attention to the numbers until I need them, and then forget them. Therefore I have no knowledge of past values or if they changed. However, I can tell you for pretty darn sure that Ike and Duna are still tidally locked. At least, they were in one of the last pre-releases. I fast forwarded for MONTHS watching Duna wiggle on the horizon, just for the novelty of it :D

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well, I watched Duna wiggle in the sky of Rald in my mod (Duna becomes a moon of the larger "mars-with-water" Rald), as there was some inclination and eccentricity, it went back and forth...but after many cycles, it seemed to be moving... starting with it low on the horizon, soon enough it disappeared completely below it... I need to find my old spreadsheet and update some numbers...

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Don't spend too much an effort in redoing spreadsheets or calculator thingies, you might end up having to doit all over again shortly:

On 10/21/2016 at 11:42 PM, SQUAD said:

An example of these bugs people have found is the standardisation in gravity values to 9.80665, making the planet orbits shift ever so slightly and the geosync heights change - they’ll be back in their right positions,

 

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uh oh... I wonder what that means... are they going to tweak surface gradvities?

Revert the constants?

I don't see why orbits would shift. The orbital period might change, but there's no reason for Ap and Pe/sma etc to change, as that is what is stored when on rails.

Velocity when loaded should change... I don't know why orbits would

In the case of my modded planet, the orbital period went from 65517.47 seconds to 65529.05... an 11.58 second change... so for now I just slowed the planet rotation by that much, and it seems fine now. I don't know what squad will be doing though...

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2 hours ago, Enorats said:

I could be wrong, but my understanding was that the planets/moons are on rails. Their paths are predetermined, and not actually dependent on gravity. Kerbol could be removed and nothing would change about the planet themselves.

Sort of. The planets have predefined orbital parameters, and from those parameters their positions and velocities can be calculated at any time. The gravitational constant G is fairly important in those calculations; changing it affects all the derived values, of which orbital period is one.

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