help getting to duna

[putnamto]

ok, so last night i sent a probe to duna using this page http://ksp.olex.biz/, and tonight i have a contract to land a probe on duna, so i figured ill reconfigure the probe to become a lander and just do the same thing i did last night............

basically waiting for my window, launching out of kerbin at the right angle and diddling with the node for what seemed like hours to finnally get an encounter.

now ive been playing with the ejection angle and node for awhile and i cant seem to get an encounter, the best i can get is a closest approach, can somebody clue me in, ive been to the moon and minmus enough times i could puke, but with those i never had to worry about things like closest approach i would just be able to immediately get an encounter.

i feel like theirs something fundamental that im not understanding about interplanetary travel.

heres a picture in case i cant explain good enough, my ship is in a 150/170ish orbit around kerbin.

[Hotel26]

It looks like your target indicators are pretty far apart.  Those are the two blue V indicators on Duna's orbit.  They show where you and Duna will be at your closest approach.  If you're ahead of Duna, you need to pull your maneuver node (around Kerbin) back to an earlier angle.  Lagging Duna, then later.  When you get them close together, *pop*, you'll have an encounter.  Unless, of course, you don't.  This is 3D, so you are going to need your inclination, relative to Duna, the target, to match.  At this distance, inclination is going to be V. Important.  So hover over either the AN or DN and see what your inclination is.  If it's not 0 (or as close as you can make it), set a separate Normal or Anti-normal maneuver to first get your inclination aligned.  Then try again with the transit node.

Here's a tip.  (Unless you're using sophisticated aids), when you "grow" your transit maneuver node toward the target orbit, slow the growth right down as you approach.  When you get close, those pale blue co-relative position indicators will appear.    As soon as they do, let go of the prograde or retrograde maneuver handle and take a look at how aligned they are.  Is your indicator approaching the target head on, or before or after?  If it's not head on, grab the maneuver node central ring and drag the node forward or back around your orbit and you'll see how your transit "balloon" will respond with your pale blue indicator at its apoapsis (or periapsis depending on whether you are going to an outer or inner planet).  Once they're aligned, you're more confident you're heading in the right direction for a better encounter, so then continue to "grow" the orbit until you get your encounter.

Edited December 27, 2018 by Hotel26

[Epicdreamer]

Haha I got beaten giving you an answer . But indeed, as depicted your closest aproach is still a long way off. 

At these distances, even an inclination of 0,1° relative to you targets orbital plane can make a huge difference. First place a node on the DN marker and adjust your orbital plane with the normal/antinormal (purple) markers on the node, so that the inclination is 0,0° To fine adjust, use the mousewheel. Then, on your next pass of the right ejection angle make the burn.

It doensn't guarantee an encounter, but can make a huge difference. When the closest encounter marker is really close without an encounter you might need a correctional burn somewhere halfway....

Good luck!

[putnamto]

2 minutes ago, Epicdreamer said:

Haha I got beaten giving you an answer . But indeed, as depicted your closest aproach is still a long way off. 

At these distances, even an inclination of 0,1° relative to you targets orbital plane can make a huge difference. First place a node on the DN marker and adjust your orbital plane with the normal/antinormal (purple) markers on the node, so that the inclination is 0,0° To fine adjust, use the mousewheel. Then, on your next pass of the right ejection angle make the burn.

It doensn't guarantee an encounter, but can make a huge difference. When the closest encounter marker is really close without an encounter you might need a correctional burn somewhere halfway....

Good luck!

strangely enough i just noticed i dont have an An or DN node, only my ap and pe.......weird.

[Hotel26]

3 minutes ago, putnamto said:

i dont have an An or DN node

They are yellow indicators marked AN and DN and I see them in your image.  (There's a yellow dotted line connecting the two orbits to which they measure the inclinatino.)  Hover over them and they will give you the target-relative inclination angle.

Edited December 27, 2018 by Hotel26

[putnamto]

yeah, they are in their in the image, but i quit playing after i made the post, and when i reload the save they are no longer their.

 

[Hotel26]

make sure Duna's orbit appears to be yellow indicating it is still the target.  If not, re-select Duna as your target.

(incidentally, I want to assure you that all this is going to become second nature to you very shortly: you will dream in terms of these diagrams...)

                                                                                                                                                                                                                                                                                                     

I still most vividly recall my very first encounter with Duna!!

I achieved it setting my apoapsis way higher than that of Duna.  As a result, my very heavy ship was speeding past sight of Duna at a totally unstoppable differential.

I was thrilled to catch first sight of another planet but so disappointed to be sailing by.

I loaded as much fuel as I could into a "lifeboat" and cast off, hoping to get closer to Duna with a much lighter ship.

Miraculously, I was able to enter Duna's Sphere of Influence!  Yet, thus undeservingly rewarded by the Gods, I thirsted for more: hoping to capture the Holy Duna and enter orbit!!

Miraculously, this next wish was granted and I took reel after reel of photos from a stable Duna orbit!

Yet, I had enough fuel to enter the atmosphere and crash and burn, so, suicidally, hopelessly in love now with the Fatal Duna, I executed the de-orbit.  I thought I should at least bury myself on sacred ground...  I used the remaining fuel to slow the impending crash.

Then, in the last 30 seconds, I realized two more heaven-sent items:

1. Duna has 20% atmosphere!!
2. and my lifeboat had chutes!!!!

And so, with my last remaining fuel and under chutes, I cushioned the final few meters, extending the landing struts, to land, whole, on Duna!! -- rescuing the mission from the most tantalizing failure in the absolutely most unexpected manner.  If I wasn't already in love with KSP, I became so in that final moment.  [I'll post the shot in the next 24 hours.]

Edited December 27, 2018 by Hotel26

[putnamto]

ok, i got my nodes back.

im confused though, how do i make the two approach markers get closer together? if i move my node forward in my orbit it just shifts the two approach markers one way(their still the same distance apart) and vice versa.

if i pull prograde/retro they either dissapear completely or get farther apart.

 

Edited December 27, 2018 by putnamto

[Hotel26]

20 minutes ago, putnamto said:

just shifts the two approach markers one way

precisely right!

get them aligned with each other.  your target indicator is your apoapsis (approx), the lead point of your trajectory.  if it's not headed toward the Duna indicator, you're not going there.

Drag the maneuver node to get them aligned [Kerbin -- your indicator -- Duna's indicator -- all in a straight line].  THEN drag your maneuever node prograde handle out further to extend your transit out toward Duna and its orbit.  Then...

**POP**

Edited December 27, 2018 by Hotel26

[putnamto]

what do you mean precisely right? they both shift at the same time, never getting closer, and never getting farther apart from eachother relatively. i have no idea how to get them aligned with eachother

anyways, adding a second node to my planned tragectory allowed me to get an encounter.

!!!

one problem though, my encounter will be in 7 years.........am i to early to my window perhaps?

 

[Epicdreamer]

Hmmm. Quick rundown how I get an encounter (for Duna, but it works for any celestial body, thought it might not be the most efficient way):

Select Duna as your target

Launch and circularize into a stable orbit (any orbit will do).

Place a manoeuvre node on the AN or DN node and burn to cancel out any inclination difference.

Delete node an place a new one for the ejection burn. Get the closest approach markers as close as you can. Hopefully an encounter will pop up right away. Burn and smile. Delete the node.

If an encounter doesn't show up, but you are very close, create a correctional burn node somewhere half way out, fiddle around untill the encounter pops up. Burn and smile.

I hope it helps!

 

I've learned reaching Duna the hard way. First try I got an encounter but was 4Dv (!) short for a capture burn. 2nd time I landed (yay!), got Jeb out to plant a flag, slipped of the lander and discovered I forgot ladders! (No way!) Third time went like a charm. I felt great for a day after returning to Kerbin and land safely...

[Hotel26]

30 minutes ago, putnamto said:

what do you mean precisely right

I am very happy you have your encounter!

They shift at the same time and don't get closer because it is Step 1 of 2 Steps.

A Hohmann Transfer moves you from one orbit to another orbit by extending an ellipse from your start orbit toward your target orbit.  You just pull the prograde handle to escape your home.  This is Step 2 but it is NOT enough.  Where are you going?  To the destination orbit but to intersect it PRECISELY when the target planet reaches the same point as you reach in the target orbit.  It's NOT enough just to go to Duna's orbit.  You have to go to its orbit at the same point Duna will be in that orbit WHEN you get there!  That is what the alignment step is all about.  The point in YOUR orbit that you execute the transfer maneuever determines where in Duna's orbit you'll arrive but you won't get an encounter unless that's the same point Duna will be when you get there.  That's the whole magic of this.

And, next, if it's taking 7 years, then, yes, you are not leaving in the "transfer window".  You can get there but it will take more time and fuel.  Leaving an inner orbit to go to Duna, you will be moving faster than Duna so, when you leave, it should already be ahead of you, but not too far.  Kerbal Alarm Clock can signal you when a transfer is due.  Also check out KSP Orbicalc, which you can get on your phone.  Or check out: https://alexmoon.github.io/ksp/

Basically it tells you 3 things:

1. how far ahead/behind in solar orbit your target should be
2. what prograde angle to launch[***]
3. how much dV you will need to extend your orbit to intersect the target orbit

[***] prograde angle.  The direction Kerbin is heading around Kerbol is 0 degrees.  Moving counter-clockwise, it unwinds from 360 back down to 0.  So leaving at 150 prograde ...  well, this is what we have been discussing.  It's not enough to leave; you have to pick the point in your orbit to leave such that the transfer heads in the right direction.  This actually makes the difference, for example, whether you leave toward an inner orbit (wrong way for Duna), or to an outer orbit...

One last tip: practice/experiment with all of this with a closer target, such as Minmus.  Minmus because it has an inclination from the ecliptic and because it's a bit further away than the Mun.  Just keep drawing out the maneuver node and experiment with where/how you do it until things become clearer...  it will.

Good luck.

Edited December 27, 2018 by Hotel26

[putnamto]

I  finally  got  it!! I  was  trying  to  leave  to  early, thanks  for  all  the  info @Hotel26

[Hotel26]

17 minutes ago, putnamto said:

I  finally  got  it!!

CONGRATULATIONS!

This is a HUGE MILESTONE!!

(Just wait till you catch first sight of it!)

Edited December 27, 2018 by Hotel26

[putnamto]

I  landed  and  did  some  sciencing, c

Failed 3 rescue contracts  while  waiting  on  the  time  warp  though, RIP

[Curveball Anders]

39 minutes ago, putnamto said:

I  landed  and  did  some  sciencing, c

Failed 3 rescue contracts  while  waiting  on  the  time  warp  though, RIP

Kerbal Alarm Clock ...

I use it all the time to do other stuff while waiting for longer missions to reach important points.

 

[eddiew]

12 minutes ago, Curveball Anders said:

Kerbal Alarm Clock ...

This is one of my mandatory mods, tbh. It's what makes parallel missions possible. (Although I kind of recommend not running parallel missions because you can go crazy with it and never reach your launch window to other planets.)

Another can't-live-without which I think the OP would benefit from is Transfer Window Planner - by the same mod author. Basically it'll tell you the right time to launch for highest efficiency. Both mods together give you a "todo" list of when to launch new vessels  

[FleshJeb]

@putnamto I noticed you're not using MechJeb's Maneuver Node Editor. You'll never pull on a maneuver node again.

[putnamto]

1 minute ago, FleshJeb said:

@putnamto I noticed you're not using MechJeb's Maneuver Node Editor. You'll never pull on a maneuver node again.

Haha  I  forgot  all  about  that, I  tried  to  use  it  once  when  I  was  still  a  young  kerbonaught  and  it  confused  me

[Epicdreamer]

Great to see your progress Putnamto! And all that in just a day. Soon you'll be planting a flag on one of Jools moons if you keep your progression going like this. Congrats!