tidal locked?

[twobit]

So i\'m new here, play the demo for a bit before getting the game. the demo got me used to Kerbal being tidal locked making it easier calculate moon landings.

now with the full version, each launch the moon moves farther counter clockwise, is the mun no longer tidal locked in the full version 0.14? or am i just glitching?

[Kosmo-not]

Mun is still tidally locked. It\'s orbiting around Kerbin. I don\'t see any problem here.

[HarvesteR]

I think he meant that with a non-persistent game, the Mun is always at the same position in relation to Kerbin when you start a new flight, making it pretty easy to create a works-every-time flight plan to the Mun.

On the persistent game though, time is passing, and the Mun will be somewhere else when you launch.

Although, nothing stops you from sitting on the pad, and time-warping until the Mun is 'in position' again.

And just to correct the terminology here, \'tidal lock\' is what we call a celestial body that always presents the same face to the central body, there is no real term for a moon that always begins at the same spot, because that sort of thing really doesn\'t happen too much in real life

Cheers

[sneakeypete]

there is no real term for a moon that always begins at the same spot, because that sort of thing really doesn\'t happen too much in real life

Sure there is, a Geosynchronous orbit.

Although yes, it doesn\'t happen at all anywhere that i know of.

[r4m0n]

Sure there is, a Geosynchronous orbit.

Although yes, it doesn\'t happen at all anywhere that i know of.

Actually, Pluto and Charon are mutually tidally locked, so it does happen

[twobit]

so my question was answered that the moon is not always in the same location on the persistent world game. and i did not quite under stand completely what tidal locked meant. thanks!

I guess i just like to time warp to get the mun aligned to where i want before launching, easier for me to get aligned that way.

[togfox]

I guess i just like to time warp to get the mun aligned to where i want before launching, easier for me to get aligned that way.

That\'s what they do in r/l.

[Cykyrios]

and i did not quite under stand completely what tidal locked meant

Tidal lock is basically the reason you can only see one side of the moon: as it revolves around the Earth, it rotates around its own axis in such a manner that 1 orbit = 1 revolution about its axis.

[lars]

Getting to the moon tip:

I am assuming that you are orbiting in an eastward direction. Perform your TLI as soon as the Mun comes over the horizion, and put your apogee at around the Mun\'s orbit.

[samstarman5]

It doesn\'t matter where the Mun is in the big picture, as the same strategy of performing your TMI still works. Get into orbit and then perform the burn as the Mun just gets over the horizon. However, where the Mun lies in its orbit determines how long you have before your first opportunity at performing a TMI burn. This gives you a feel for what NASA lovingly calls launch windows. Even though sitting in orbit doesn\'t use fuel, time can be just as much a valuable resource as fuel for any number of reasons, life support being one of them. Hence the reason for wanting to launch at an ideal time in order to achieve the ideal position for a TLI(talking real world stuff here, now) as soon as possible without leaving the astronauts up there to have to perform one more orbit than they should have to.

It does raise the question, is the default position of the Mun an ideal launch window? Or perhaps there is another that might be more economical in both time and fuel? I would say that is a question we can easily answer, with time, and kerbals.

[Awaras]

It does raise the question, is the default position of the Mun an ideal launch window? Or perhaps there is another that might be more economical in both time and fuel? I would say that is a question we can easily answer, with time, and kerbals.

I guess the ideal position of the Mun would be one in which the Mun begins to rise over the horizon at the moment you circularize your orbit after launch, so that you never turn off your engines and just keep thrusting for a TMI burn...

[samstarman5]

But not the most efficient. Though it may seem I discount it in my post, where you do begin a TMI burn in orbit can make a difference(it just isn\'t an absolute necessity if you aren\'t going for efficiency). Consider how much speed you gain on the way to Periapsis. If you can perform your TMI burn right at Periapsis, you would actually use less fuel to achieve transition, considering how much speed you already have at your disposal. So the idea would be to achieve orbit, and then have your periapsis right at the point where a typical TMI burn would be made, right when you begin to see the Mun come over the horizon.

So all that is needed to be done then, is make a typical launch with a rocket able to reach the Mun and do whatever you want there, and then when you achieve your ideal orbit, make note where periapsis lies. Draw a line from your periapsis across Kerbin\'s surface to the munar orbit. That spot on the orbit is the ideal position of the Mun you want to have for when you launch. (Maybe a wee bit before it to allow for how long it takes you to achieve orbit)

[Awaras]

But not the most efficient. Though it may seem I discount it in my post, where you do begin a TMI burn in orbit can make a difference(it just isn\'t an absolute necessity if you aren\'t going for efficiency). Consider how much speed you gain on the way to Periapsis. If you can perform your TMI burn right at Periapsis, you would actually use less fuel to achieve transition, considering how much speed you already have at your disposal. So the idea would be to achieve orbit, and then have your periapsis right at the point where a typical TMI burn would be made, right when you begin to see the Mun come over the horizon.

So all that is needed to be done then, is make a typical launch with a rocket able to reach the Mun and do whatever you want there, and then when you achieve your ideal orbit, make note where periapsis lies. Draw a line from your periapsis across Kerbin\'s surface to the munar orbit. That spot on the orbit is the ideal position of the Mun you want to have for when you launch. (Maybe a wee bit before it to allow for how long it takes you to achieve orbit)

But you only gain speed \'on the way to Periapsis\' if your orbit is elliptical and your Apoapsis is considerably higher than the Periapsis, and the speed you \'gain\' that way is the same speed you lost while climbing to Apoapsis (that is, speed you didn\'t need in the first place).

[samstarman5]

Consider though that Periapsis isn\'t where your ship is initially at when establishing orbit.

[Kosmo-not]

Consider though that Periapsis isn\'t where your ship is initially at when establishing orbit.

I think you\'re nitpicking. If you start your TMI from a circular orbit, your position basically becomes the periapsis in a second. The velocity difference between AP and PE is so small, it\'s not worth worrying about. Do you really need to increase your efficiency by 1% (and that\'s being conservative)?

[Millitron]

But you only gain speed \'on the way to Periapsis\' if your orbit is elliptical and your Apoapsis is considerably higher than the Periapsis, and the speed you \'gain\' that way is the same speed you lost while climbing to Apoapsis (that is, speed you didn\'t need in the first place).

This is true if you aren\'t planning any additional burns, but we\'re discussing moon missions, so we are planning additional burns.

Due to the Oberth Effect, (http://en.wikipedia.org/wiki/Oberth_effect) making your burn at periapsis is more efficient, since burns at high speeds are more effective than a similar burn at low speeds. Because of this, lining up your TMI with your periapsis is beneficial.

Admittedly, we\'re dealing with relatively low speeds and low masses, so the effect isn\'t as powerful as it is IRL, but its still there.