[Tutorial] Interactive Illustrated Interplanetary Guide and Calculator

[adammada]

Phase Angle Show Plugin: http://kerbalspaceprogram.com/forum/showthread.php/21111-PLUGIN-0-17-AdamKSP-Show-Phase-Angle-v0-1

[DakotaSpace]

Will that show the ejection angle too? I've been trying to avoid using any addons..

[adammada]

I'm trying to add that.

[bsalis]

It's a shame you can't see the planets from orbit, which I think you should be able to.

Since if you could do that, you could work out if the phase angle is correct from the nav ball.

[adammada]

Ok, added ejection angle.

[olex]

Btw, are there any chances that we will get planet -> moon calculations soon?

Yes, this will part of an update I'm currently working on.

[billyzero]

This mod is so fantastic! Once again thanks for the hard work. Bye bye protractor.

[Jaysuhn368]

This is a great guide and is very helpful, but I cant seem to use it right.

I use mechjeb to get into an 80km orbit around Kerbin, and set my heading to 270 because I was going to go to Eve. I also waited beforehand so the phase angle was almost at the right place, so I got up into orbit and warped until i was at the ejection angle and went full throttle prograde to my orbit. All that happens after i get to ejection velocity is a trajectory to escape Kerbin orbit and make Kerbol's orbit bigger. What am I doing wrong? Am I really stupid?

[togfox]

So how does this work when going to Moho or Eve? I get the higher orbits but when going to a lower planet, you need to prograde to leave the Kerbin SOI then retrograde to enter Moho/Eve. Not sure how this tool manages that. thx.

[Xeo]

When you want to go to moho or Eve, simply take-off heading 270 instead of 90, so you will be able to leave Kerbin's SOI parallel to the planet retrograde.

[Kosmo-not]

So how does this work when going to Moho or Eve? I get the higher orbits but when going to a lower planet, you need to prograde to leave the Kerbin SOI then retrograde to enter Moho/Eve. Not sure how this tool manages that. thx.

You can exit Kerbin's SOI in different directions. Exit it in the planetary retrograde direction to lower your orbit about the sun.

[togfox]

Aye, but the exit velocity mentioned on the web site puts my sun AP ABOVE kerbin and therefore above Eve.

Step 1 exit kerbin SOI

Step 2 REDUCE velocity so that PE is lowered to intercept Eve.

Maybe im missing something very obvious and basic. Leaving kerbin retro will give the PE required?

[Kosmo-not]

Aye, but the exit velocity mentioned on the web site puts my sun AP ABOVE kerbin and therefore above Eve.

Step 1 exit kerbin SOI

Step 2 REDUCE velocity so that PE is lowered to intercept Eve.

Maybe im missing something very obvious and basic. Leaving kerbin retro will give the PE required?

There is only one step, which is to do the ejection burn from Kerbin orbit.

[Jaysuhn368]

whenever I do the ejection burn I end up with an orbit above kerbin even when i was trying to get to Eve, I dont know what i'm doing wrong but I hope someone knows.

[Supernovy]

Burning during the day in an easterly orbit gives you a lower sun orbit.

[adammada]

I'm trying to get back from Dune to Kerbin. (I'm using mine plugin to determine angles) - and i'm having troubles - always missing Kerbin. Kerbin goes behind me. I'm trying to change angle, i tried -75.19, -75.09, and 74.99 - still nothing.

Also, i noticed that going to Dune requires more early burn (i missed with 44.36, 44.40 is much better).

Hmm, i see that Dune has circular orbit like Kerbin, but they have differen centers. Is it even posibble?

Edited September 23, 2012 by adammada

[olex]

Hmm, i see that Dune has circular orbit like Kerbin, but they have differen centers. Is it even posibble?

Duna's orbit is eccentric, not circular - which is also why the calculator results for it are imperfect. I described the steps to fix early/late transfers a few pages ago, just follow that advice and you'll arrive, as long as your transfer angles were at least in the ballpark.

[adammada]

Duna's orbit is eccentric, not circular

I measured it (printscreen + draw rectangle around it), and its shape is perfect circle, just Sun is not in center.

[BigD145]

This is awesome. Thank you.

[Brenok]

I measured it (printscreen + draw rectangle around it), and its shape is perfect circle, just Sun is not in center.

Kepler's first law:

"The orbit of every planet is an ellipse with the Sun at one of the two foci."

Maybe the measurement isn't precise enough. The orbit is either a perfect circle with Kerbol in the center or a ellipse with one focus on the sun. Other situations would be physically impossible.

[adammada]

Other situations would be physically impossible.

Yes, but they programmed it like that anyway. You can see measurement here:

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

[gosnold]

You have to keep in mind that if the line between kerbol and the camera is not normal to the planet's orbital plane, the orbit will appear distorted. Maybe it is the case.

[Stoup]

Hmph. I'm utilizing a few plugins and various assistants to give myself precise values for planetary phase angles and ejection angles, yet I still seldom ever encounter the planets I put myself on a trajectory to. I think this is due to the low thrust of the nuclear engines I use when doing my transfer from parking orbit. I start burning at the correct ejection angle, yet by the time I reach ejection velocity I'm off by as many as 40 degrees. Should I compensate for this by burning 20 degrees ahead of where I should burn?

[Carthaginian]

Question: the program won't give me an answer for any moon?

Is it something I'm doing wrong?

[Enture]

Hmph. I'm utilizing a few plugins and various assistants to give myself precise values for planetary phase angles and ejection angles, yet I still seldom ever encounter the planets I put myself on a trajectory to. I think this is due to the low thrust of the nuclear engines I use when doing my transfer from parking orbit. I start burning at the correct ejection angle, yet by the time I reach ejection velocity I'm off by as many as 40 degrees. Should I compensate for this by burning 20 degrees ahead of where I should burn?

I basically have the same problem (I guess all of us who started to play around with the NERVA have it...), although I hadn't measured the angle covered during the burn... 40°, you say?

Well, since the ship's mass changes during the burn, the burn itself is actually more and more efficient, meaning the change of velocity gets exponentially quicker. So to do things right, you'd have to burn more than 20° before the theoretic burn point; exactly where could be told us by a bit of messing around with expoenential/logarithmic equations, but yeah, I guess burning 20° before the theoretic burn point should be a good correction already.