How to Get to Duna. Am I doing it right?

[jordanlane93]

Hey guys!

I'm using Mechkeb to get to duna. Am I doing it right?

• First I'm making duna my target.
• launch at interplanetary window
• get into orbit around the sun
• Then use Redezvous autopilot to get me to duna. 

 

Is there a better way to do it?

[WanderingKid]

Yes.  You burn to intercept directly from Kerbin Low Orbit.  Because of the Oberth effect this is much more efficient on your Delta V costs.  I don't use MechJeb, however, so someone would have to walk you through that technique.  I only know how to do it manually (-ish) with Maneuver Nodes and timing using these sites:

http://ksp.olex.biz/

http://alexmoon.github.io/ksp/

The first one helps you locate where in the orbit of Kerbin you want to put your maneuver node, the second helps you plan your dates and delta V requirements.

[HebaruSan]

This is more or less what my mod is for. Click the maneuver icon on the row labeled Duna, and it'll create a maneuver node with approximately* the right time and delta V to get you there. You can then use the stock "Warp to Next Maneuver" option to fast forward to it.

* Some manual adjustment will be necessary to get an encounter in most cases. Pull gently on the prograde and retrograde handles of the maneuver node in whichever direction reduces the distance of closest approach.

 

[Vanamonde]

Thread moved to modded support, since it's specifically about mod use. 

[jordanlane93]

4 hours ago, HebaruSan said:

This is more or less what my mod is for. Click the maneuver icon on the row labeled Duna, and it'll create a maneuver node with approximately* the right time and delta V to get you there. You can then use the stock "Warp to Next Maneuver" option to fast forward to it.

* Some manual adjustment will be necessary to get an encounter in most cases. Pull gently on the prograde and retrograde handles of the maneuver node in whichever direction reduces the distance of closest approach.

 

Thanks man! You guys all were a big help.

4 hours ago, HebaruSan said:

This is more or less what my mod is for. Click the maneuver icon on the row labeled Duna, and it'll create a maneuver node with approximately* the right time and delta V to get you there. You can then use the stock "Warp to Next Maneuver" option to fast forward to it.

* Some manual adjustment will be necessary to get an encounter in most cases. Pull gently on the prograde and retrograde handles of the maneuver node in whichever direction reduces the distance of closest approach.

Also, what is the most accurate Delta V map now?

Thanks man! You guys all were a big help.

Whats the most accurate Delta V map?

[jordanlane93]

6 hours ago, HebaruSan said:

This is more or less what my mod is for. Click the maneuver icon on the row labeled Duna, and it'll create a maneuver node with approximately* the right time and delta V to get you there. You can then use the stock "Warp to Next Maneuver" option to fast forward to it.

* Some manual adjustment will be necessary to get an encounter in most cases. Pull gently on the prograde and retrograde handles of the maneuver node in whichever direction reduces the distance of closest approach.

I'm having trouble getting an encounter. Am I missing a step. I'm getting into orbit and then using that mod as you suggested. No matter what I do with the nodes I'm not getting an encounter.

 

[HebaruSan]

2 minutes ago, jordanlane93 said:

I'm having trouble getting an encounter. Am I missing a step. I'm getting into orbit and then using that mod as you suggested. No matter what I do with the nodes I'm not getting an encounter.

Are you getting close approach markers? The easiest way is to right click them to pin them as visible, then experiment to see which of the maneuver node handles reduces the close approach distance the quickest.

[jordanlane93]

12 hours ago, HebaruSan said:

Are you getting close approach markers? The easiest way is to right click them to pin them as visible, then experiment to see which of the maneuver node handles reduces the close approach distance the quickest.

I'm getting those markers just can't seem to get them close enough to get an encounter. Maybe I just need to try harder. It usually creates to maneuvers right?

[artwhaley]

I frequently find that I need to make the first burn as suggested by either Atrogator or mechjeb's 'advanced transfer to another planet' mode in the maneuver planner, then warp until I leave Kerbin's SOI....  then tweak the second mid course correction node to get the encounter to show up.  It's easier to get the map to acknowledge an encounter when it's only one SOI change away..   I think I could fiddle with my patched conic settings to get around this perhaps... but I find it easy enough to just warp until I'm in the solar SOI and then adjust course.  If it doesn't show up easily- you can delete Astrogator's mid course correction node and use the Mechjeb Maneuver Planner's "fine tune closest approach to target" button.   I wouldn't use the rendezvous autopilot...  it will absolutely get you there as you described it...  the transfer will be fine, but letting 'match velocities with target' to get capture is probably not going to be the most efficient possible maneuver.   

Flying it mechjeb only... I would 

1. Launch to 85km parking orbit on the right day for transfer (to avoid slow time warp!).   
2. Use Mechjeb's maneuver planner to plot the transfer - either with the 'transfer to another planet' button or the 'advanced transfer to another planet.'   Either way, if I picked a transfer window in step 1, I just choose the ASAP option, then execute the node.
3. Warp to edge of Kerbin's SOI then plan course corrections.  If our planes are substantially off, match planes first.  After that, or if planes are fine, use the 'fine tune closest approach to target' button.. .set to 50km or so as a target closest approach  If not even THIS node gives you an encounter...  something way's wrong.  Tweak the handles a little but...  you might want to revert to launch and try again if you don't have a lot of delta v and time to waste. 
4. Warp to the destination planet's SOI.  As soon as you enter it, burn radial + or radial -  (or use the maneuver planner's 'change periapsis after 0s' option) to set the periapsis you want.   This is also the right time for a final plane change maneuver if you don't like the inclination you're coming in on.
5. If you're just doing a capture burn, burn at periapsis to circularize...  or at least get eccentricity below 1.  If you're doing something fancier than a capture burn... well.. do that..  

Astrogator doesn't do anything Mechjeb can't do.  But I keep it installed anyway because I love the simplicity of it.   Even and perhaps especially when working in the kerbin system...  if you're running a half dozen launches to the mun or minmus...  having a single click to plot the transfers is so convenient!  

[jordanlane93]

2 hours ago, artwhaley said:

I frequently find that I need to make the first burn as suggested by either Atrogator or mechjeb's 'advanced transfer to another planet' mode in the maneuver planner, then warp until I leave Kerbin's SOI....  then tweak the second mid course correction node to get the encounter to show up.  It's easier to get the map to acknowledge an encounter when it's only one SOI change away..   I think I could fiddle with my patched conic settings to get around this perhaps... but I find it easy enough to just warp until I'm in the solar SOI and then adjust course.  If it doesn't show up easily- you can delete Astrogator's mid course correction node and use the Mechjeb Maneuver Planner's "fine tune closest approach to target" button.   I wouldn't use the rendezvous autopilot...  it will absolutely get you there as you described it...  the transfer will be fine, but letting 'match velocities with target' to get capture is probably not going to be the most efficient possible maneuver.   

Flying it mechjeb only... I would 

1. Launch to 85km parking orbit on the right day for transfer (to avoid slow time warp!).   
2. Use Mechjeb's maneuver planner to plot the transfer - either with the 'transfer to another planet' button or the 'advanced transfer to another planet.'   Either way, if I picked a transfer window in step 1, I just choose the ASAP option, then execute the node.
3. Warp to edge of Kerbin's SOI then plan course corrections.  If our planes are substantially off, match planes first.  After that, or if planes are fine, use the 'fine tune closest approach to target' button.. .set to 50km or so as a target closest approach  If not even THIS node gives you an encounter...  something way's wrong.  Tweak the handles a little but...  you might want to revert to launch and try again if you don't have a lot of delta v and time to waste. 
4. Warp to the destination planet's SOI.  As soon as you enter it, burn radial + or radial -  (or use the maneuver planner's 'change periapsis after 0s' option) to set the periapsis you want.   This is also the right time for a final plane change maneuver if you don't like the inclination you're coming in on.
5. If you're just doing a capture burn, burn at periapsis to circularize...  or at least get eccentricity below 1.  If you're doing something fancier than a capture burn... well.. do that..  

Astrogator doesn't do anything Mechjeb can't do.  But I keep it installed anyway because I love the simplicity of it.   Even and perhaps especially when working in the kerbin system...  if you're running a half dozen launches to the mun or minmus...  having a single click to plot the transfers is so convenient!  

Thanks! 

Also, how can I get set up so I can transmit from Duna back to Kerbin?

[artwhaley]

I haven't taken the time to get really into playing with commnet.  So I just overkill it.  I have a couple of the big relay antennas on satellites in kerbin orbit...  and I put a big relay into orbit around any planet I'm going to visit.  If it's a single trip.. - that's often just mounted on the transfer stage so it goes 'along for the ride.'  Even if it gets discarded before the orbiter or lander captures into a final orbit...  the relay stays in range long enough to be used during my operations time.    If I'm going to conduct several missions to a planet then I bother to preposition a couple of relays in orbit.   My last campaign was with USI Life support...  which makes planetary travel require a LOT more stuff...  so at the transfer window before I wanted to send a manned mission I would preposition a supply and fuel tanker in the planet's orbit, and often put a large relay antenna on that so it would help out that way too.