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MrZayas1

Suggestions for a Duna Lander?

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Hey everyone, I need some tips, not because I suck at this game (maybe I do) but because I really need some help. I don't understand why but getting to other planets is very complicated, and only about 30% of my rockets are actually successful in getting to MINMUS! So I have no idea what I am doing wrong but is there some kind of ratio or some way to get a lander into space (I always run out of fuel before getting to Duna) and to Duna with fuel to spare? I would rather build my own spaceship so anything that serves as advice would help me very much! Thanks alot in advance!

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I would suggest putting lots of parachutes on the lander so that you wont need to use a powered decent.

Depending on how confident with docking, you may want to consider launching your lander into LKO then launching a tug and docking them together then use the tug to get the lander there. Undock, deploy parachutes, land and explore!

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Hi there, are you sure that you use a good trajectory to get to the Mun? Also, I would suggest using a mod http://forum.kerbalspaceprogram.com/threads/18230-0-22-Kerbal-Engineer-Redux-v0-6-1-4 for it to give you a basic info about your craft properties, so you could design it with a good amount of fuel and delta v needed for your tasks. And surely take a look at spacecraft exchange section too.

You could watch few videos of Scott Manley videos on a matter of planetary transfer on KSP.

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If you are having trouble getting to minmus my first thought would be that you aren't getting into Low Kerbin orbit efficiently (not putting you down, it takes a bit of practice). Are you playing in career mode or sandbox? Can you post a screenshot of your rocket? More information would be helpful to know how to help you.

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I recently went to Duna, (and nearly all the way home again!), a couple of times with differing craft.

There's this one here: http://forum.kerbalspaceprogram.com/entries/1080-My-mission-to-Duna-and-why-this-is-one-of-the-best-games-ever-made

My second attempt is documented here: http://forum.kerbalspaceprogram.com/threads/60009-The-harsh-realities-of-engineering-Home-Sweet-Home-Mk2-To-Duna-and-back

They should give you plenty of ideas. Basically you'll need a lifter and an interplanetary stage, probably using low thrust/high efficiency nukes. this will mean long burn times, to Duna, probably around 10 minutes or so, so start out the burn half way from your maneuver node, (so if it will take 12 minutes then start at t-6 minutes), and then the lander.

The best way to do it with a single launch is to work each stage with enough delta v and not a lot more. For this I'd highly recommend the Engineer Redux. It does all the maths for you and gives a nice read out of how much delta v you have at what thrust to weight. Incredibly useful.

You need around 4,400 m/s to get into LKO. From there it's 800 or so to escape the sun's SOI. From there around 1,500 ish I think, to get to Duna and a few hundred to slow down again once there. Then you'll need an injection burn of not a lot to get into the atmosphere. Parachutes will help but will not slow you down completely, you need some thrust at the start of the atmosphere and at the end to help you slow down.

To get home again you'll need around 2000 m/s to achieve Dunan orbit and around 1,800 or so to get back again. All of these numbers are approximate, but using those and the engineer you can build a much more accurate rocket that doesn't waste fuel or weight anywhere.

Good luck.

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@OP: I'ma thinkin' that your issue is more likely with how you're piloting rather than your overall design, but to be sure, could you post a pic of a rocket you've used to try to get to Duna?

Getting to other worlds differs from getting to Mün/Minmus in that you can't just go any time you want to. You have to wait for certain "launch windows" that correspond with the target being at a certain "phase angle" - if you don't, the delta-V requirements rapidly go up. You also want to set your maneuver node to eject either at Kerbin sunrise (for Moho/Eve) or sunset (for every other world, and hopefully I don't have that backwards). Finally, you need to plan to do a correction burn at some point along your route; usually this is best done at either the ascending or descending node, and like a docking maneuver you want to get that value down as close to zero as you can.

Think of an interplanetary transfer as a hole of golf - you do a long drive to tee off, you do one or more corrective drives to get you on the green, and then you put to get it in the hole. Same thing - a long drive to get you at least close to your target, correction burns to put you in the SOI, and then final corrective burns to put your periapsis where you want it. Naturally, the sooner you get your periapsis where you want it, the better (you spend less delta-V that way).

A good site for planning launch windows is http://alexmoon.github.io/ksp/ - it generates porkchop plots and tells you when you should go and how much delta-V you should plan for.

Credentials - I've been to Duna and back on kerballed missions three times now; the last time I took six Kerbals there...

Edited by capi3101

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... I don't understand why but getting to other planets is very complicated, and only about 30% of my rockets are actually successful in getting to MINMUS! So I have no idea what I am doing wrong but is there some kind of ratio or some way to get a lander into space (I always run out of fuel before getting to Duna) and to Duna with fuel to spare?...

The trick with getting to Minmus is matching planes either before you leave LKO or while you are on your way (It's easier to do it in LKO, but not necessarily dV efficient) I have a feeling you are doing the same thing for Duna, just kinda pointing your rocket in that general direction and hoping for the best. An interplanetary trip takes planning, and a fair amount of it. I won't tell you how to design your rocket (There are plenty of other places for that) but what I will do is give you the tools you need to plan an effective interplanetary trip.

http://mononyk.us/wherecanigo.php is a handy tool if you are running out of fuel. the math might be a little off (I don't know where he gets his dV numbers from) but it will get you a ballpark (And you should always pack extra dV anyway)

http://alexmoon.github.io/ksp/ This will show you when the optimum time to launch is. A Duna mission doesn't require much more dV than a Mun mission, if you launch it right.

http://i.imgur.com/UUU8yCk.png every Kerbalnaughts bread and butter, a dV map. This one is a tad more accurate than the one on the wiki, and it even includes the max dV you would use for a plane change maneuver.

http://alterbaron.github.io/ksp_aerocalc/ this will save you some dV. If you can aero-brake/aero-capture (They are not the same) at a planet you have the potential of saving thousands of m/s dV.

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It's also worth mentioning that doing an "apollo style" lander will help quite a lot in terms of fuel, if you're confident enough with docking. You need a fairly hefty chunk of fuel to get back home from Duna, and you probably don't want to have to cart all of that down to the surface and back to orbit again. Leave the return fuel in orbit around Duna while you perform your landing, then dock with it again when you want to come back. Ideally you can leave your lander behind around Duna too, to save even more fuel.

Note that I haven't actually tried a Dunan return mission yet, but the principle is the same

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Here is the one I have used for a couple missions already, 700NitroXpress helped clean up my original design. Further into the thread you can see the tug system I have it hooked to to get it there and back, it is fairly simple but works good. There is a .craft file in the thread of the lander, you are welcome to (though if it is not there let me know and I will load it up in here). You can land with only using the engine to get you into a landing setup as there are enough chutes to land without power assist.

http://forum.kerbalspaceprogram.com/threads/59747-My-single-crew-Duna-Lander-in-need-of-help/page2

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Make sure you build your space craft with a TWR of higher than 1 and a little more than 7500 m/s delta-v. You can double the delta-V if you want to return, so make sure you can land your ship halfway through your delta-V. Also you don't need as much thurst to get off of duna to return.

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Make sure you build your space craft with a TWR of higher than 1 and a little more than 7500 m/s delta-v. You can double the delta-V if you want to return, so make sure you can land your ship halfway through your delta-V. Also you don't need as much thurst to get off of duna to return.

Scratching my head a bit with the "double the delta-v to return" statement. Getting into Duna orbit from the surface takes ~1400 m/s and a transfer back to Kerbin is ~605 m/s.

So in total we have:

Kerbin Orbit: ~4500 m/s

Duna Transfer: ~1050 m/s

Duna Orbit: ~680 m/s (or ~0 if you use aerocapture)

Deorbit / Landing (with chutes): ~300 m/s

Return to Kerbin: ~2050 m/s

All told, if you use aerocapture and parachutes, you can do the trip with 8 km/s dV and have fuel to spare.

Some other words of advice:

- Use drogue chutes! Duna's atmosphere is much thinner than Kerbin's, so you will still be moving quite quickly when your main chutes fully deploy. Spontaneous lander disassembly may result!

- If you're having trouble getting your rocket into Kerbin orbit, it may be because you're wasting too much dV early in your launch. Try to keep your velocity under 100 m/s until you reach 3 km altitude, and under 200 m/s until you reach 10 km.

- Another common issue when putting large loads into orbit is using an accent profile that is too steep. Remember, the key to getting into orbit is getting up to orbital velocity, not just getting up to orbital altitude. Start your gravity turn early (8km is not too low to start a gradual turn), and don't be afraid to have the nose of your rocket pointing below to the horizon during the later parts of the accent.

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Rather then build a big complex ship, start simple and make Minmus your first lander target. It,s low gravity and seas make landing much easier. Then, go for Mun and finally Duna.

A simple Duna lander;

91CDoVl.jpg

Just be sure to fire the retro to reduce touchdown speed to avoid damage. Be sure to land in daylight.

jFY9onT.jpg

3i4rYC4.jpg

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