syncronous orbit

[Tuareg]

i was always wondering why the objects on orbit in KSP doesnt follow the tidal forces and laughing into the face of basic gravitational laws. its a bit easier to understand if i say lets think we have 3 fueltanks, one at the center, one at the right side connected with a string and one on the left side connected with an other string and we put all three on the same orbit they will naturally always rotate with the same speed as they orbit the planet. if it wouldnt be the case (like it happens in ksp, it would mean that the 2 tanks on the sides would fly on a decentralised circular orbit which is impossible).

you could ask why is that still normal in real life if its naturally impossible? its because the irl launched crafts never reach the state of complete rest as per there are other forces (initial rotation), solar activity, effects of other planets gravitational forces etc.

in most old satellites they use gyros to stabilise them, modern ones are already using the gravitational laws to set the satellites into sync orbit and leave them like that forever.

ksp is however completely theoretically and as such, if we once stop the rotation of a craft on orbit, they should follow the laws of gravity as per the gravitational forces apply to every point of the craft and face always the center of the orbit. and maybe here is where the kraken is hiding. if ksp calculate the forces independently for every parts, with the current orbital mechanism the parts are continuously forcing each other to change orbit in every moment.

in case 1 the fueltank is pushing the engine and pulling the commander module while in case 2 the fueltank is pulling the engine and pushing the commander module causing a continuous wobbling...

more about sync orbit, tidal lock and gravity-gradient stabilisations

what do u think?

Edited October 26, 2014 by Tuareg

[Technical Ben]

Orbits in real life don't work that way. You do need some existing rotation, or as you said need to impart some with a force (your cables are about the same as a reaction wheel). It's just KSP does not save rotation (currently) when saving (to leave the game or enter/exit timewarp). If you leave the ship rotating and never go into timewarp you will get the correct rotation along with the correct orbit.

Edited October 26, 2014 by Technical Ben

[Tuareg]

Orbits in real life don't work that way.

what doesnt work and which way? there are 2 above

If you leave the ship rotating and never go into timewarp you will get the correct rotation along with the correct orbit.

nope, in ksp i get the orbit seen on my picture. in reality the engine would face the center of orbit all the time. thats the natural way, thats why moons orbit showing the same face towards the planets

[Technical Ben]

No it would not. To become tidally locked takes millions of years. The rotation imparted by a ballistic trajectory could be kept I guess, but as said, if you hit timewarp in KSP you loose any rotation.

[Tuareg]

No it would not. To become tidally locked takes millions of years.

for a planet, but for satellites its already in use

The rotation imparted by a ballistic trajectory could be kept I guess,

irl thats the unperfect basic situation as i've mentioned in the op

but as said, if you hit timewarp in KSP you loose any rotation.

if you are zoomed to an obejct it doesnt matter if you are in timewarp or not the orbiting object will always follow the initial trajectory and not the orbitvectors however in my views as ksp is an ideal world if we completely stop the rotation of an object it should fly on sync orbit. the non-ideal way is the irl where u have an initial spin...

[Master Tao]

The SAS in KSP correctly stops the rotation. You're asking for the craft to continually rotate so it maintains a constant orientation relative to the surface (synchronous rotation). You can do that in KSP if you set up the rotation yourself or use gravity-gradient stabilization.

[Tuareg]

use gravity-gradient stabilization.

exactly this is what im talking about but it should work without "cheating"

[tntristan12]

Gravity gradient stabilization was in the game at one point when different parts on a vessel had gravity acting on them individually. However, I believe it was the time warp update that broke this, because all physics calculations for orbit were moved to the center of mass. This became a case where gameplay and programmability were valued as more important than physical accuracy.

[Tuareg]

Gravity gradient stabilization was in the game at one point when different parts on a vessel had gravity acting on them individually. However, I believe it was the time warp update that broke this, because all physics calculations for orbit were moved to the center of mass. This became a case where gameplay and programmability were valued as more important than physical accuracy.

a lookat(vector) isnt difficult to program to fix it...

[Master Tao]

a lookat(vector) isnt difficult to program to fix it...

Technically true. The difficulty is picking the correct, physics-based orientation along the craft for the lookat so that this physics-cheating hack can work. Let us know when you've solved that problem.

[Tuareg]

Technically true. The difficulty is picking the correct, physics-based orientation along the craft for the lookat so that this physics-cheating hack can work. Let us know when you've solved that problem.

erm... orbitcenter... solved

[Master Tao]

Again, all that gives you is a vector from the craft to the center of the orbit. That's a completely different, nonphysical problem from gravity-gradient stabilization. The difficulty with modeling gravity-gradient stabilization is not finding the lookat vector, but choosing the correct spacecraft orientation that should be aligned with that vector. In other words, to presolve this problem in the way your suggesting, you'd need to solve which end of the craft should be lower in the gravity well. Only then can you orient it along the lookat vector.

[Tuareg]

Again, all that gives you is a vector from the craft to the center of the orbit. That's a completely different, nonphysical problem from gravity-gradient stabilization. The difficulty with modeling gravity-gradient stabilization is not finding the lookat vector, but choosing the correct spacecraft orientation that should be aligned with that vector. In other words, to presolve this problem in the way your suggesting, you'd need to solve which end of the craft should be lower in the gravity well. Only then can you orient it along the lookat vector.

i think you misunderstand physics like many. what do you think how the moon have chosen which side will it show to us poor humans? do you think it does have a heavier side and it turns that side towards the gravity? really? do you think that those things like centerofmass, profile or whatever makes any difference? erm. well, no, it doesnt. both the centripetal force both the gravity affects every tiny point of the object. it doesnt matter how it looks like. ergo if once you put an object into perfect rest on orbit it will stick to that and whatever part of it looks into the center of gravity it will always look that way... irl the problem is that everything you launch has an initial spin and they want to use this gravitational force to stop that spinning because irl you cant ever make an object being in complete rest. anyway. in spherical geometry following orbit around a globe isnt even rotation. its moving in straight line (in any chosen point of the object)

Edited October 27, 2014 by Tuareg

[arkie87]

i was always wondering why the objects on orbit in KSP doesnt follow the tidal forces and laughing into the face of basic gravitational laws. its a bit easier to understand if i say lets think we have 3 fueltanks, one at the center, one at the right side connected with a string and one on the left side connected with an other string and we put all three on the same orbit they will naturally always rotate with the same speed as they orbit the planet. if it wouldnt be the case (like it happens in ksp, it would mean that the 2 tanks on the sides would fly on a decentralised circular orbit which is impossible).

you could ask why is that still normal in real life if its naturally impossible? its because the irl launched crafts never reach the state of complete rest as per there are other forces (initial rotation), solar activity, effects of other planets gravitational forces etc.

in most old satellites they use gyros to stabilise them, modern ones are already using the gravitational laws to set the satellites into sync orbit and leave them like that forever.

ksp is however completely theoretically and as such, if we once stop the rotation of a craft on orbit, they should follow the laws of gravity as per the gravitational forces apply to every point of the craft and face always the center of the orbit. and maybe here is where the kraken is hiding. if ksp calculate the forces independently for every parts, with the current orbital mechanism the parts are continuously forcing each other to change orbit in every moment.

http://i.imgur.com/cis0U6A.jpg

in case 1 the fueltank is pushing the engine and pulling the commander module while in case 2 the fueltank is pulling the engine and pushing the commander module causing a continuous wobbling...

more about sync orbit, tidal lock and gravity-gradient stabilisations

what do u think?

Very interesting. I think long strings with counterweights attached are necessary in practice; or so it seems from http://en.wikipedia.org/wiki/Gravity-gradient_stabilization

[Tuareg]

Very interesting. I think long strings with counterweights attached are necessary in practice; or so it seems from http://en.wikipedia.org/wiki/Gravity-gradient_stabilization

only to stop the initial rotation. once its on perfect orbit, that's it. (sure in real life there is no perfect orbit. in a game there could be) anyway, the pointing the same point of the sky isnt a fine solution anyway. that just doesnt exist in any form.