Need help to encounter and orbit Duna

[MinasGodhand]

Damn, sorry, I wanted to post this in questions, not tutorials.

 

I need help with flying to other planet, such as Duna.

• I have a fuel ship in a Minmus Orbit. The plan is to fly to a space station orbiting Duna and back, depositing some fuel. 
• The ship has 43'560 Liquid Fuel loaded.
• It has roughly 3500 Total DeltaV.
• I'm leaving Minmus/Kerbin Orbit, when Duna Phase Angle is close to 44.3°.
• When creating the maneauver node the problem starts. It takes me 15 minutes to fiddle around the controls until I get an enounter with Duna with a low Periapsis (around 6'000km), usually I can't get any closer, because even carefully pulling one of the levers, it is sooo sensitive, it will throw it my plotting so far off course, I have to begin again.

1. Question: Is there a trick to get this done better?

• After creating the node, I need about 850m/s to get an encounter with Duna, which isn't a problem for the ship, this uses up about 27% of my fuel.
• I reach Duna, but then I need another 800 m/s to slow down to get decent orbit (1'000 km), so that's another 27% of my fuel gone.

2. Question: I believe this is because I am overshooting when reaching Duna, but I'm not sure how I can plot my course, so I have to slow down only a little. Is there a way, that I don't need almost as much DeltaV to slow down, as I do when I speed up?

3. Question (somewhat unrelated): Sometimes I reach Duna and I'm able to slow down to get an orbit, but instead of having a counter-clockwise orbit, I have a clockwise orbit. Is there a trick that this does not happen?

 

Thank you

 

Edited July 10, 2018 by MinasGodhand

[Vanamonde]

Moved to Gameplay Questions. 

Transits are subtle things. For example, the math usually assumes that you're doing your whole burn in a single instant, or you may be starting your burn at a sub-optimal point in departing orbit. Rather than try to get it ideally perfect, I usually get reasonably close, wait until the mid-point of the transit, and then do a correction burn. Because the effect is magnified over such a long arc, even gentle taps on RCS can be enough to move the periapsis dozens of kilometers. And if you're arriving retrograde, simply adjust the periapsis to be to the right of Duna rather than the left.

[bewing]

Welcome to the forums.

As Vanamonde said, it's generally best to not worry about precision on your first node. Nobody can match it precisely anyway. Burn when you are at the right spot. Get your Ap close. Then do a tiny midcourse correction to get your Duna Pe nice and low.

You may want to try sweeping your maneuver node forward and back a bit around your Kerbin gate orbit. Your Ap should be just as high as Duna's orbit to get there with good fuel efficiency. The higher your Ap is above Duna, the more speed you are going to have when you arrive, that you will have to counteract with burning.

Also as Vanamonde said, if you are arriving retrograde then you came in with too much speed (alternately, you arrived too soon). Burn a little retrograde and your Pe will move to the other side of the planet.

 

Edited July 10, 2018 by bewing

[Gargamel]

An additional way to save a bit of fuel is to aerobrake through the atmosphere of Duna.    I haven't done this in a log time, so the specifics escape me at the moment. 

[Reactordrone]

For fine control of the manoeuvre nodes try mousing over the handle and slowly using the scroll wheel on the mouse . Once you have an initial encounter click on the target planet and select focus to see where your path is in that sphere of influence. You can then click on the manoeuvre node again to embiggen it and do fine scroll adjustments. Duna's usually not too bad to do from Kerbin orbit but with planets at different  inclinations you  might be better off with a mid course correction.

[Mark Kerbin]

Ok so obvious the smart people ksp nerd brigade  have already arrived, but I’m going to chuck my two cents in just because I can.

1.Aerobrake into Dunas atmosphere. Bring a heatsheild and don’t go too deep. Other than that there’s not much else you can do to improve performance. I mean you could try using Ike to slow you down once you get there...

2. Congratulations, you have figured out out to encounter duna , at least in theory. That means you are almost there. Go ahead and do that burn. Then once you get on your way, add another node a fiddle around with that to try to fine tune it. You can do this multiple times to get better encounters, ie into the atmosphere or use Ike’s gravity. Or to make sure you come in on the right side of the planet. Your orange post node line indicates where your going to be and what direction, so try using that.

best of luck.  

 

[MinasGodhand]

On 7/11/2018 at 2:39 AM, Reactordrone said:

For fine control of the manoeuvre nodes try mousing over the handle and slowly using the scroll wheel on the mouse . Once you have an initial encounter click on the target planet and select focus to see where your path is in that sphere of influence. You can then click on the manoeuvre node again to embiggen it and do fine scroll adjustments. Duna's usually not too bad to do from Kerbin orbit but with planets at different  inclinations you  might be better off with a mid course correction.

This seems like a good suggestion. I didn't know you can zoom in to the target planet, I always set the course from the zoomed out overview. I'll try that. thanks

[StrandedonEarth]

If you’re going to aerobrake, don’t be afraid to abuse quicksave and quickload. It can be hard to get just the right Pe for a good aerobrake.