Long trip to Duna?

[Chrysoprace]

Hello,

Relative newbie here. I just attempted my first trip to Duna and I ran into a couple of questions that I couldn't find answers to that didn't amount to "install a mod and let the game do it for you."

First question: 

Is there some way that I am missing like a dummy to look at specific places on the map? Specifically, I can't get in close enough to my Duna encounter to make fine adjustments until I am almost there. The result of this is while I got my peri to an acceptable altitude, I could not tell that I was coming in low and ended up in a polar orbit on arrival. 

Second question:

I followed the directions of a couple of tutorials because this was my first trip outside of Kerbin's SOI. They amounted to: 

Wait until Duna is at about 1:30 when Kerbin is at 3:00.

Get into orbit.

Put a maneuver at about 5:00. 

Pull prograde until you get solar orbit that meets up with Duna orbit.

Fine tune until you get a Duna encounter.

Make another node on the way to fix any small problems (like in my first question). 

This worked out fine apart from being low and ending up in polar orbit. 

However, the tutorials said that the trip should take about 70-120 days. I couldn't get mine below about 260 days. Any idea what went wrong? 

This isn't a super big problem, except that those same tutorials recommend returning when Duna is at 5:30 to Kerbin's 3:00, and on arrival Duna was more like 4:20. 

Thanks in advance! 

Edited November 30, 2016 by Chrysoprace

[FullMetalMachinist]

8 minutes ago, Chrysoprace said:

First question: 

You can zoom out enough to see Duna, and then click on it and select 'focus view'. That will show you what your orbit through Duna's SoI will look like. From this view you can still adjust the maneuver node to fine tune things. An alternative is you can press Tab to cycle the map view through all the celestial objects. Press Backspace to return focus to your ship. 

8 minutes ago, Chrysoprace said:

Second question:

A screenshot showing your ejection orbit from Kerbin will help answer this. Not sure why your transfer orbit is so long without more specifics. 

Edited November 30, 2016 by FullMetalMachinist

[Chrysoprace]

Thanks, so if I focus on Duna it will show future encounters that occur after the SOI transfer? If so that is extremely helpful. 

I am not home now and didn't take any screen shots but can load an older save and try to replicate it later on. 

[Snark]

1 hour ago, Chrysoprace said:

However, the tutorials said that the trip should take about 70-120 days. I couldn't get mine below about 260 days. Any idea what went wrong?

It didn't. 

A perfectly-executed Hohmann transfer from Kerbin to Duna (i.e. minimum dV, nailing the launch window just right) should actually take about 302 days or thereabouts.  So 260 is actually a pretty good number, reasonably close to the optimum.

(If you're wondering where I got that number from:  Take the average of Kerbin's semimajor axis and Duna's semimajor axis.  Plug that into the orbital period equation, using the sun's standard gravitational parameter.  Then divide by 2, since the transfer is only half an orbit.  Divide by 21600 (length of a Kerbin day) to convert from seconds to days.  There you go.)

Certainly it's possible to make the trip in less time... but you have to spend a lot more dV to do that, i.e. it's not a Hohmann transfer.

1 hour ago, Chrysoprace said:

Wait until Duna is at about 1:30 when Kerbin is at 3:00.

Get into orbit.

Put a maneuver at about 5:00. 

Incidentally... you may find this tool useful:

http://ksp.olex.biz

...just tell it your origin, your destination, and the height of your parking orbit, and it'll tell you all of the above as well as the dV requirements, with a nicely intuitive visual display of the relative positions.  (There are other orbit calculators too, that one just happens to be my personal favorite.)

1 hour ago, Chrysoprace said:

This isn't a super big problem, except that those same tutorials recommend returning when Duna is at 5:30 to Kerbin's 3:00, and on arrival Duna was more like 4:20.

Correct.  After you arrive at Duna, you have to wait there a long time (months) until your window opens up to return to Kerbin, if you want to make a minimum-dV transfer back again.  If you don't feel like waiting the better part of a year, you don't have to wait, you just have to spend more dV.

[Chrysoprace]

Thanks Snark, that is not only informative and helpful, but also makes me feel better about not having done something so blatantly wrong that it doubled my flight time, but rather having accidentally done it almost optimally. 

Edited November 30, 2016 by Chrysoprace

[FancyMouse]

4 hours ago, Chrysoprace said:

However, the tutorials said that the trip should take about 70-120 days. I couldn't get mine below about 260 days. Any idea what went wrong? 

Are you looking at some super old tutorial where the "day" there equals 24 hours, i.e. 4 Kerbin days?

[Chrysoprace]

Could be. Looked again and I noticed that the ship they screenshotted was aerodynamic like a flying Winnebago.