• 0
hhatch

Duna orbital adjustments

Question

I've managed to get into Duna orbit a couple of times but I think I just had some luck.  I'm confused about making orbital adjustments. Below are 2 screenshots at different points on way to Duna.

One shot shot shows things after doing an initial burn and correcting inclination. I could not get an encounter initially so I went ahead and did the burn. I did another maneuver and burn about half way to Duna and got an encounter. The other shot shows the ship ready to burn to go into Duna orbit.  I'm a long way off and the burn is almost 4 minutes.  How can I make better adjustments so I can get closer and not burn so much fuel ?

 

 

WWeZYYK.png

 

 

WWeZYYK.png

Share this post


Link to post
Share on other sites

7 answers to this question

Recommended Posts

  • 0

Does your ship have RCS?

You'll want to get it as close as you can, but burning doesn't make that easy.  You can try knocking your thrust limiter on your engine way down, pointing prograde or retrograde depending on which way you need to go, and just throttling up a little bit with shift.  Get an encounter, then focus in on Duna, and do the same to get it where you want.

RCS is handy for this too.  Turn RCS off.  Point your ship prograde or retrograde, RCS on, then tap 'H' or 'N' to make small adjustments to your orbit.  Make sure you always have RCS off when re-orienting your ship, or it will change your orbit.

Depending on how far out you are, even RCS may move it too much.  You might need to turn down the thrust limited on all your RCS ports.

Share this post


Link to post
Share on other sites
  • 0
6 minutes ago, Geonovast said:

Does your ship have RCS?

You'll want to get it as close as you can, but burning doesn't make that easy.  You can try knocking your thrust limiter on your engine way down, pointing prograde or retrograde depending on which way you need to go, and just throttling up a little bit with shift.  Get an encounter, then focus in on Duna, and do the same to get it where you want.

RCS is handy for this too.  Turn RCS off.  Point your ship prograde or retrograde, RCS on, then tap 'H' or 'N' to make small adjustments to your orbit.  Make sure you always have RCS off when re-orienting your ship, or it will change your orbit.

Depending on how far out you are, even RCS may move it too much.  You might need to turn down the thrust limited on all your RCS ports.

No I do not have RCS on this one.  I'm assuming I burn prograde or retrograde based on whether I left too early or too late

Share this post


Link to post
Share on other sites
  • 0
Just now, hhatch said:

No I do not have RCS on this one.  I'm assuming I burn prograde or retrograde based on whether I left too early or too late

From the looks of it, you'll need to start by burning prograde.  You might need to flip a few times to get it right.

Turn your thrust limited waaay down, and you should be able to pull it off just fine.

Share this post


Link to post
Share on other sites
  • 0
17 minutes ago, Geonovast said:

Does your ship have RCS?

You'll want to get it as close as you can, but burning doesn't make that easy.  You can try knocking your thrust limiter on your engine way down, pointing prograde or retrograde depending on which way you need to go, and just throttling up a little bit with shift.  Get an encounter, then focus in on Duna, and do the same to get it where you want.

RCS is handy for this too.  Turn RCS off.  Point your ship prograde or retrograde, RCS on, then tap 'H' or 'N' to make small adjustments to your orbit.  Make sure you always have RCS off when re-orienting your ship, or it will change your orbit.

Depending on how far out you are, even RCS may move it too much.  You might need to turn down the thrust limited on all your RCS ports.

If advanced tweackeables is enabled, you can Skip turning on/off RCS if you configure well the RCS thruster (enabling RCS only for traslation)

 

 

  • Like 1

Share this post


Link to post
Share on other sites
  • 0
Posted (edited)

@hhatch Don't just "assume" and start burning in some random direction. Instead,

- Make a maneuver node some short distance (20-30 minutes) ahead of your ship's current position.
- Then, focus your view on Duna.
- Turn your camera to find the maneuver node you made, and (if necessary) click it to bring the controls back up.
- Start pulling gently (!) on various arms, and observe how your trajectory near Duna changes.
- Tweak your encounter into something with a low, but not too low periapsis (60-70 km is good), and decide whether you want to come in over the poles for a polar orbit, or equatorial. Both have their own advantages.
- Beware of Ike. You can't swing a cat around Duna without accidentally encountering Ike. You too will probably encounter Ike. Don't sweat it, so long as you don't have a collision course.
- Execute the node you just made. You don't need to wait for the correct time here, anywhere within half an hour of it is fine.
- Executing your node, which will likely be an extremely small amount of dV, will get easier if you first set the thrust limiter on your engine(s) really low.
- You should execute the node while in map view, focused on Duna. That way you can see the result of your burn playing out live, and you can stop based on when things look right without having to rely on the node dV counter.

This should reliably yield the result you want, without guesswork or having to correct repeatedly. :) 

Edited by Streetwind

Share this post


Link to post
Share on other sites
  • 0

Also, that orbital insertion burn is huge ... part of that is because you're so high up, but I think part is due to the previous burn.  Remember to seek to go TO the planet's orbit, not PAST it.  Generally, radial in will get you there faster, and radial out slower, but you don't want more of either than you need.

Share this post


Link to post
Share on other sites
  • 0
Posted (edited)

I figured out why I had so many problems getting an encounter with Duna. After experimenting,I found that the phase angle I got from the  transfer calculator was not correct (Olex).I don't know if this is related to the recent updates or maybe  just user error. So using some of the suggestions I got here I can now put my craft as close as I want. I'm still working on trying to do a better job of shaping my orbit and I am still not very efficient at using fuel. However, after 400 hours I am starting to get a better understanding of how to use orbital mechanics. I don't know about the experiences of other people but for a non science person like me learning orbital mechanics is very hard. This "game" is very hard. It is also very addictive. That and this forum have kept me going.  Thanks.

Edited by hhatch

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now