[Tutorial] Duna For Dummies: How to get there without math

[RoboRay]

Moho for Morons?

[Chev]

Jool for a fool.

[Markus Reese]

Gilly for the silly

Great guide, though only challenge I have is the need to send multiple ships to try and capture. While if you are going for maximum efficency, it is a way to do it. However, I use a different way that has a very high success rate, though can result in long mission times.

I never try to capture on a direct single transfer. Too much frustration of save and reload or messing around with the multi rockets etc. When I launch, I plan to arrive early for outer orbit transfers. Arrive a little late for the inner planets. Main point of the strategy is to let the planet intercept you. when you escape kerbin SOI, align your orbit plane to target, and do your burn. Make sure you do your transfer burn to arrive at orbit a bit ahead. Keep a slow burn to have your orbit pass past the target orbit. What will happen is the planet will catch up to you or for inner planets, you catch up to it. By continuing your slow burn, you just need to watch the map for your orbit capture on trajectory. If you are well off the mark, at apo or per can decel/accel if you have the fuel to elongate your time at the different speed.

It works every time as long as you have your planes aligned, which is needed anyways for any capture.

Edited September 27, 2012 by Markus Reese

[Piotrburz]

Im trying for like 2 days and landed just once on that friggin planet. I have enough of this, im using protractor and its useless, i always arrive too late at intercept point.

What phase angle and ejection angle are you using guys?

[RoboRay]

Im trying for like 2 days and landed just once on that friggin planet. I have enough of this, im using protractor and its useless, i always arrive too late at intercept point.

What phase angle and ejection angle are you using guys?

The angles are going to vary with the elliptical nature of the orbits. There is no hard & fast "always correct" answer.

That said, Protractor is the best solution I've found. It will get you as close as any other method that assumes circular, non-inclined orbits.

[Piotrburz]

So if i arrive too late i should start prograding burn when phase angle is lower than protractor values, right?

[Trebuchet-Launch]

If you are going to arrive too late then you want to burn inwards, to move your apoapsis along Duna's orbit, then burn prograde a little, because your apoapsis will move inwards somewhat during this correction.

[Grizzlol]

Instead of doing a retrograde burn within the SOI as an orbital capture, I prefer to correct my trajectory very early, so much that my ship goes right into the target body's atmosphere, which slows the ship down enough to have the same effect as burning retrograde but using far less fuel. As far as I can see, this will always be more fuel efficient, provided of course that the target body actually has an atmosphere.

In your example scenario, it is still possible to do aerobraking after you entered the SOI, but that is not my point. Point is, why waste fuel doing retrograde burns in the SOI when you can do this 1 billion km away. The only case in which doing corrections that great within the SOI is effective is when the relative speed at the point of entering it is close to zero, which rarely happens, if ever, unless you are doing a rendezvous, or when the target body does not have an atmosphere.

However, I am no expert, so please correct me if I am wrong.

Edited September 27, 2012 by Grizzlol

[draeath]

If you are going to let MechJeb do everything, you may as well just watch KSP videos on Youtube.

By that logic you'd want them to fly the Apollo missions without the guidance computer? It's basically the same thing, just with some archaic VERB NOUN data entry scheme instead of a GUI.

[Piotrburz]

If you are going to arrive too late then you want to burn inwards, to move your apoapsis along Duna's orbit, then burn prograde a little, because your apoapsis will move inwards somewhat during this correction.

I don't understand. By saying inward you mean a 0 point direction[going upward from orbiting body]?

I found that best phase angle for Duna is 40.

[Trebuchet-Launch]

I don't understand. By saying inward you mean a 0 point direction[going upward from orbiting body]?

I found that best phase angle for Duna is 40.

No. This is a means of correcting a bad trajectory, not setting it in the first place. Reread the section on flying to Duna on course corrections. You have an orbit which reaches Duna's. If you want to move your apoapsis forward along Duna's, you burn inwards, STRAIGHT DOWN. Burning outwards, STRAIGHT UP, you slide your apopasis backwards along Duna's orbit. This corrects for slightly bad ejection or phase angles in your launch.

[Piotrburz]

No. This is a means of correcting a bad trajectory, not setting it in the first place. Reread the section on flying to Duna on course corrections. You have an orbit which reaches Duna's. If you want to move your apoapsis forward along Duna's, you burn inwards, STRAIGHT DOWN. Burning outwards, STRAIGHT UP, you slide your apopasis backwards along Duna's orbit. This corrects for slightly bad ejection or phase angles in your launch.

Inward like the center of orange part of navball? So down through a perpendicular vector to the sun surface, that start in the ship and end at sun surface?

[Commander Zoom]

Yes, point your craft's nose right at the sun and burn.

[EatVacuum]

The angles are going to vary with the elliptical nature of the orbits. There is no hard & fast "always correct" answer.

That said, Protractor is the best solution I've found. It will get you as close as any other method that assumes circular, non-inclined orbits.

I'm not a big fan of doing all sorts of math to figure out the launch angles but I do use two tools. First is a phase angle chart that is out there. The second is the Alarm clock addon. It can be programmed to tell you when a transfer window is coming; I like to leave myself a day's warning. When that pops up I launch my ship and while I wait for the window, I use the maneouvre node thingy to figure out the trajectory.

Like going to the Mun you want to leave orbit when Duna is coming over the horizon to gain the advantage or Kerbin's orbit and rotation, so place the node at that point in your orbit. Then pull the prograde arm until your planned trajectory reaches Duna orbit. You won't likely get an encounter right away but you will probably be close enough that you will get the closest approach markers. At that point you can start adjusting the prograde/retrograde arms and the two arms that point towards and out from your orbital plane and see what effect that has on the closest approach markers. Keep fiddling until you get an encounter. Any encounter will do, you can fine tune doing course correction when you are out of Kerbin's SOI. And don't forget you can also grab the maneouver node and drag it prograde and retrograde in your Kerbin orbit to adjust your trajectory. Once you have it set, you can do your ejection burn using the navball to guide you. Or if you use Mechjeb, just hit "execute next node" and away you go.

[Javster]

Useful. I'll use it.

PS: This: * is an asteriSK, Asterix is the gaul.

[Javster]

There are those of us who take pride in accomplishing things the hard way.

If I do something using MechJeb, I do not post that I accomplished it- because I didn't actually do anything.

The computer did all the work and I just sat around and watched it happen.

Not necessarily. I use MechJeb for boring, basic, repetitive things like getting to orbit.

[Javster]

My method:

1. Acquire Dunebug II

2. MechJeb to orbit (cos I can't be bothered)

3. Wait for rough planetary adjustment

4. Manoeuvre node to Duna

5. ???

6. PROFIT!!

No way back due to Mulbin's flaw of rockets: never enough fuel to get back.

Edited October 27, 2013 by Javster

[EnteroTuna]

Very helpful.

[Surimi]

Lots of useful information here. I think (as usual) I've built my Duna ships too big, but I suppose that's part of the learning curve too. Will be trying some of these hints out once the flight window opens.

[SurfinRainbow]

Hey Trebuchet,

Nice guide! Although, I have gotten to Duna with one ship- Just put the rocket on VERY low thrust, and then look for that encounter!

Make sure you use Maneuver Nodes for it though.

[Mulbin]

My method:

1. Acquire Dunebug II

2. MechJeb to orbit (cos I can't be bothered)

3. Wait for rough planetary adjustment

4. Manoeuvre node to Duna

5. ???

6. PROFIT!!

No way back due to Mulbin's flaw of rockets: never enough fuel to get back.

Its a poor workman that blames his tools.. ive been to duna and back many times in dunebug.

[Mitchz95]

Thanks for this great guide! Though I don't see what the problem is with aerocapture - all you have to do is shift the encounter with your RCS until the periapsis is around 10km. Saves a ton of delta-v for the journey home.

[celem]

Aerocapture is indeed smart and saves buckets of fuel. Yet this is a tutorial tilted towards the noobier end of the playerbase, and fills that roll in spectacular fashion.

He could have had them all editing files and setting conic mode 0, then hit a Duna aero-cap trajectory with ease while still way back in Kerbin's SoI.

But lets face it, this technique he has posted works just fine, with the .craft file he helpfully included. It doesnt assume any understanding of how the game really works, which again, is the niche it was aimed at. Once you run this mission profile and get your guys back to Kerbin, well, then you can edit his ship, remove some fuel, add RCS, whatever and go for a more efficient mission profile.

If you already knew all this stuff and regularly aero-cap, then the tutorial wasn't really aimed at you. Still worth people commenting on it, those reading this thread will find all the useful hints added by readers and be able to design a mission they are happy with.

Excellent tutorial. Baseline, off-the-shelf, Duna land and return for dummies. Does exactly what it says on the tin.

EDIT: Whuups, slight necro here. Still feel it was worth posting since I tried out his ship and mission profile

Edited December 5, 2013 by celem

[SoldierBoy027]

Great guide, easy and informative! great guidance for an eyeball mission!

[Steve-S]

Thanks for the guide. I was googling for a Duna guide as I was having fits trying to figure out the Dv needed. I built my ship based on your directions and have 12,434m/s as it sits ready to launch. I'm planning on lithobraking so prolly have extra. I like extra. :-) Looks like I have 3,252m/s for my xfer stage and 3,828m/s for my lander/orbit/return vehicle. I feel prepared to risk 3 Kerbals in this attempt thanks to your guide.

WOW!. 376 day mission cause I missed my departure from Duna just a tad. Only by .2 degrees or so. Oh well. I got there, planted flags, left 2 Duna Buggies and got back in time to see the kids graduate from college. Thanks for the guide. What a blast of 7.5 hours of gameplay.

Edited March 29, 2014 by Steve-S