Axial Tilts

[tseitsei89]

On 1/1/2017 at 1:30 AM, MaxL_1023 said:

A change like this would be almost as significant as switching to numerical N-body simulation, if not more so. Implementing this would be worthy of a new game release - a true sequel. I would expect to see it eventually, as KSP seems to be selling enough to justify a sequal or at least a bunch of copycats. 

Nope. It would be pretty much the same. You are just plain (maybe pun intended :P) wrong here. Interplanetary burns would be just the same but you would need a few hunderds of more dv since the plant rotates in a different direction but that's about it.

N-body simulation would allow LaGrange points and other nice stuff. Unlike axial tilt. Also Jool system is HIGHLY unstable in N-body simulation. I modeled that by myself with a simple bruteforce code and 1 moon ejects instantly and the second one after a while... Other than that the Kerbol system seems quite stable to me. Some vibrations with Eeloos and Mohos orbits but nothing significant...

On 1/1/2017 at 1:30 AM, MaxL_1023 said:

Axial tilt would also make the game quite incredibly annoying for newer players, with every interplanetary ejection orbit putting you onto a different solar inclination and also messing up gravity assists and all transfer burns. Mechjeb's porkchop plot could probably handle it, but it would turn into a near-necessity for interplanetary travel. 

Plus this, So it will never be worth the effort. Ever.

Since it will be harder for new players that dont know what they are doing and it will just be a minor change (just add few 100 m/s to your landers) for "older" and more capable players...

Edited January 2, 2017 by tseitsei89

[MaxL_1023]

13 minutes ago, tseitsei89 said:

Nope. It would be pretty much the same. You are just plain (maybe pun intended :P) wrong here. Interplanetary burns would be just the same but you would need a few hunderds of more dv since the plant rotates in a different direction but that's about it.

N-body simulation would allow LaGrange points and other nice stuff. Unlike axial tilt. Also Jool system is HIGHLY unstable in N-body simulation. I modeled that by myself with a simple bruteforce code and 1 moon ejects instantly and the second one after a while... Other than that the Kerbol system seems quite stable to me. Some vibrations with Eeloos and Mohos orbits but nothing significant...

Plus this, So it will never be worth the effort. Ever.

Since it will be harder for new players that dont know what they are doing and it will just be a minor change (just add few 100 m/s to your landers) for "older" and more capable players...

Interplanetary burns would be different in the sense that they will have significant normal components in order to get the proper ejection inclination. Launch windows will also be narrower as they are essentially expanded to 3 dimensions. In stock you can get to Eve and Duna by ejecting from an equatorial orbit - this will not work with axial tilt.

RSS is bad enough for this - you either need to launch into a perfect plane match (which means you get 2 windows per day to launch if you are close enough to pass under the tilted ecliptic) or add a plane change to every transfer burn. 

[tseitsei89]

4 minutes ago, MaxL_1023 said:

Interplanetary burns would be different in the sense that they will have significant normal components in order to get the proper ejection inclination. Launch windows will also be narrower as they are essentially expanded to 3 dimensions. In stock you can get to Eve and Duna by ejecting from an equatorial orbit - this will not work with axial tilt.

It will definitely work. You'll just arrive at non-equatorial orbit but that should be fine. Landing though (as I said) will take (somewhat) more dv than before since the planet is not turning the way you want it to

But I think you are confusing axial tilt and inclination here since I am quite sure that interplanetary transfer burns are not effected by axial tilt at all...  

[MaxL_1023]

Axial tilt effects the inclination you launch into from any specific point on the surface. With Earth tilted 23 degrees to the Ecliptic, you need to launch into an inclined orbit to match the plane of the solar system, allowing an ejection to another planet. You usually only get two launch opportunities per day, and even then only from within 23 degrees of the equator. It may only take 300m/s of delta'v to change your ejection angle to compensate, but figuring out what you need is much more difficult than two-dimensional intercept plotting. 

[tseitsei89]

10 minutes ago, MaxL_1023 said:

Axial tilt effects the inclination you launch into from any specific point on the surface. With Earth tilted 23 degrees to the Ecliptic, you need to launch into an inclined orbit to match the plane of the solar system, allowing an ejection to another planet. You usually only get two launch opportunities per day, and even then only from within 23 degrees of the equator. It may only take 300m/s of delta'v to change your ejection angle to compensate, but figuring out what you need is much more difficult than two-dimensional intercept plotting. 

1. Interplanetary burns are exactly the same. Period. They are only affected by how far the planet(s) orbit and what inclination they have. This is a fact

2. Yes you have to launch at a specific time of the day if you want zero inclination (or whatever inclination compared to the orbiting plane) orbit and and yes you get 2 of these launch windows a day. 

3. No you don't want to change your ejection angle because of axial tilt since ejection angle is related to the target orbital SMA and inclination (Just check your thinking again and you'll get it  

4. Figuring out how much more you need (about) is quite trivial with trigonometric functions (cosine and sine...) and that is enough for any design purposes at least. I would like to draw a picture but I cant just now...

[MaxL_1023]

I am measuring ejection angle relative to your starting orbit, not the planet's orbit. The problem with figuring out the angles is even knowing what your inclination is - I don't think the stock game tells you much about your orbit, or at least I do not remember it doing so.  

[tseitsei89]

14 minutes ago, MaxL_1023 said:

I am measuring ejection angle relative to your starting orbit, not the planet's orbit. The problem with figuring out the angles is even knowing what your inclination is - I don't think the stock game tells you much about your orbit, or at least I do not remember it doing so.  

Define starting orbit. 

You can choose that by launching at a specific time of the day and to a certain direction. And you get 2 launch windows per day for any given "starting orbit". If I understand your meaning of startimg orbit correctly  

If I don't please elaborate.

 

Because obviously you choose your "starting orbit" so that the ejection burn puts you in the same plane as the target planet. And that is defined by inclination rather than by axial tilt. 

For example if I want to go to Moho (without any of this 'gravityassistfromeve -stuff because gravity assists are hard) I'll launch my craft to an inclined orbit (i.e. away from 90 degrees on the nav ball) and the inclination is such that when I do ejection burn when Kerbin is on the ascending/descending node I will be at the same plane as Moho.

This however has NOTHING to do with axial tilt and DEPENDS ON THE inclination of the planets orbit...

 

Do you now understand the difference between axial tilt and inclination of planets orbit?

The former has very little (no effect) on interplanetary burn and the latter is VERY significant when planning an interplanetary burn...

[MaxL_1023]

I assume that axial tilt determines where on the planet you can launch from to get those orbits, and how inclined they are relative to the equator. If you can't get the orbit you want because you are too far from the equator than your transfer burn needs to include the plane change.

Also, can you really get to Moho that way? The plane matching works, but would Moho be in the right place for a transfer orbit or would you need to lower your AP for a resonant capture months later? Seems like a big coincidence for both windows to line up.

[Red Iron Crown]

9 hours ago, MaxL_1023 said:

RSS is bad enough for this - you either need to launch into a perfect plane match <...>. 

It's neither necessary nor ideally efficient to do this, that advice really needs to die. Though I suppose it is better than just launching into equatorial and hoping for the best.

[MaxL_1023]

It would usually cost less delta-v to put the plane change on the ejection burn I admit - I just can't figure out how to do it without using Mechjeb.