What's the better way to make an Interplanetary Ship?

[p14082003]

I've tried to figure a way to get to Duna, but I don't seem to know how to do it. I've tried ion engines but they are really slow. I mean, I know that, but I'm not shure if these are enough to slow the orbit down. I never get the right amount of fuel for nuclear engines, and I can't even do it by docking several parts together. How can I make a vessel with an interplanetary stage that can go to duna and back, and a simple lander? I really master docking, but I suck at landing. Help please! I love this game but I hate the fact that I can't reach Duna!

Edited May 21, 2015 by p14082003

[peachoftree]

I understand your concern with ions, but the nukes should be working. have you drained all the oxidiser out of the tanks and could you post a screenshot of it please.

[p14082003]

Yeah well.. the last one I tried was in 0.90. I know nukes don't use oxidizer anymore. Still, what would be a great design?

[Wanderfound]

You want to take:

1) A lander.

2) A moderately large fuel tank.

3) One nuke engine or one poodle engine.

The nuke will have three times the range of the Poodle, but LKO -> Duna is only about 1,000ÃŽâ€V anyway. That's around the same as a trip to the Mun. So, you can do it with a small-medium tank and the nuke, or a large-medium tank and the Poodle.

Duna's atmosphere is thin, but it's enough to aerobrake, so you don't need any ÃŽâ€V for capture or descent. Aerobrake into orbit, then drop your lander on parachutes with a bit of engine thrust to assist at the last moment. Leave the nuke in orbit and recollect it on the way back.

Edited May 20, 2015 by Wanderfound

[p14082003]

I'm a complete noob at this, so please help :$

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Thanks wander! Should I have them docked first or do a kind of apollo stile docking?

[Wanderfound]

I'm a complete noob at this, so please help :$

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Thanks wander! Should I have them docked first or do a kind of apollo stile docking?

Whatever works for you; one big launch or two moderate launches.

You could even ditch the transfer engine entirely; just dock a big fuel tank onto the front of the lander and then use the lander engine itself (presumably an LV-909 or Poodle, depending on the size of the lander) for the transfer.

Whack a heat shield on somewhere for the interplanetary aerobrake. Make sure you tune your parachutes for Duna's atmospheric pressures.

Edited May 20, 2015 by Wanderfound

[p14082003]

Thanks Man! I was just looking at your wanderful designs. I assume you know a lot, so I'm going to try it tomorrow. (It's 23:15 here in Argentina)

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One last question for today. How high should the starting kerbin orbit be?

[Jonboy]

Thanks Man! I was just looking at your wanderful designs. I assume you know a lot, so I'm going to try it tomorrow. (It's 23:15 here in Argentina)

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One last question for today. How high should the starting kerbin orbit be?

You can use any height orbit you like, but for a more efficient burn that takes advantage of the Oberth Effect, do it closer to Kerbin. 100 km is good, 75 is even better.

[Streetwind]

Just don't be so low in orbit and have an engine so weak that you dip into the atmosphere during your burn!

A good piece of advice for interplanetary ships - for all rockets actually: downsize! This is something I personally did wrong a lot in the beginning. In my mind, going interplanetary was this huge step, and naturally, I thought it would require a huge rocket. But this is not so.

The rocket equation says that a rocket with 8 tons of fuel and 2 tons of dry mass flies exactly as far as a rocket with 800 tons of fuel and 200 tons of dry mass. And as Wanderfound says, Duna requires only about 20% more fuel than the Mun. So you can easily do simple Duna flyby/orbiting missions on all 1.25m parts. In fact, people have done single-launch, Duna landing and return missions on all 1.25m parts before.

Of course, nobody expects amazing feats of rocketry from a beginner, and I too tend to load up my interplanetary missions with instruments and utilities like a passenger train in india is loaded with passengers so I only need to fly one mission ever, but it's still always a good idea to be on the lookout for situations where you can do the same thing with less mass, less bulk, less size, fewer launches. The dry mass of your mission defines the amount of fuel (and therefore the size of the rocket) that will be required; the more dry mass you can cut out, the smaller your ship will be.

[LordFjord]

Another little advice: it is possible to get to Duna with 1k dV, however, on your first trip (and probably no idea about transfer windows), rather count with 2-3k dV. And maybe 1.5k for the return trip.

My first trips to Duna were horrendously ineffective, the mission needed a rescue which also needed a rescue but it could reuse some parts that I left in orbit, so 3 flights to get there and to bring everyone home again.

To your engine questions:

go with an orange tank and a poodle, that should get a small lander to duna and hopefully also back.

Good luck with the mission!

[SlabGizor117]

I'm also an interplanetary noob, but here's what I did: I started with an orbiter probe, just to get practice for interplanetary transfers. It was just a core, SAS, Power stuff, a bunch of jet fuel, and a nuke. I had two core jet fuel tanks, and 4 jettison-able tanks, and I made it to Duna without even having to get rid of one. Now, since it also has a docking port, it's sitting in Duna orbit as a refueler. What I would suggest is an Apollo mission, but if you don't have much practice like me, then send your CSM equivalent(return stage, basically) but with more fuel. Get that in Duna orbit, then send your lander module seperately so you don't have as much to push with one little nuke(I forgot to say, for me, nukes are the way to go). Then you don't have to worry about having enough Delta-V in one launch to get there and back, and it simplifies orbital lift stages. What I did, is, I'm planning a rover landing now, and so I got my transfer stage, and rover, descent stage, etc. and bundled it all up in a fairing, and said, "Ok, this is what I need to get into LKO." and it made it a lot simpler with guesswork of whether I had enough Delta-V, and it turns out I have more than enough!

[LordFjord]

Another hint: the Duna journey was wonderfully described by trevize1138 on reddit.

Has some nice "rule of the thumb" hints for interplanetary transfers.

[cicatrix]

1. You will need a plan and a dV map (like this, for example). A thorough plan about what you are going to do. For example:

a. Transfer from LKO to Duna's SOI (1100 m/s) - I leave some margin for errors

b. Decide - full powered circularization on LDO (650 m/s) or Aerocapture (ideally 0-100 m/s) but incidents can happen.

c. Ike gravity braking assist (rather difficult)

d. Decide - land or not (landing can be unpowered on parachutes you only need a few m/s for deorbit) and taking off back will cost you ~1100 m/s of dV

e. Visit Ike? (Duna - Ike transfer 580 m/s)

f. Land on Ike? ( Land 390 m/s Take off 390 m/s total 780 m/s)

g. Transfer back to Kerbin ~1100 m/s

f. Circularize on LKO (aerocapture?) or go straight to landing (reentry at 3+ km/s)?

Now, sum this all: 1100 + 650 + 100 + 1100 + 580 + 780 + 1100 = 5410 m/s dV (make it 5700-5800 m/s).

Now, grab a Kerbal engineer and make a craft.

Decide about whether you will make a dockable lander or land the whole craft. Both methods have its pros and cons. Your lander should be able to withstand reentry on Duna (and back on Kerbin) and have enough dV for landing assist if necessary (Duna's atmosphere is very thin so the parachutes might not kill enough speed as you descend) and taking off. The same for Ike (watch the TWR - it should be >1 for taking off from the relative body). Your transfer craft should have enough dV to do 2 interplanetary burns and maneuvering around in the Duna system (transfer from Duna to Ike and back if necessary + possible corrections, plane changes, circularizations etc).

Finally, when you finished with your craft, the rest is easy - build a lifter to get it to LKO and launch.

If you have a detailed and thorough plan you're 80% done.

[KerbMav]

And if docking is easy for you: should the whole thing be to heavy to lauch, empty every tank and refill them in orbit.

[p14082003]

Thanks to you all! I'm going for an unmanned, nuke powered and small lander. I use Space-Y mod so launching it all together should not be a problem. I guess that a jumbo tank and a nuke plus some solar panels should be enough. Also, 1m lander to kill some mass. I'm gonna go for it a post a pic once landed.

[Anglave]

I did my first 1.0.2 Career mode Duna land-and-return mission before unlocking the LV-N nuclear engines. You can absolutely do it with conventional engines, and a very reasonably sized craft.

Here is a step by step breakdown of how I planned and flew the mission, and here is the craft itself.

There's plenty of room for improvement (you could put parachutes on and recover the solid boosters, you could adjust the staging of the Duna-landing parachutes and expend much less delta-v in landing than I did, etc.) Feel free to try it, modify it, or just use it as an example for your own design.

I'm collecting a general KSP knowledge base, tips and tricks for playing the game successfully. If you're interested, take a look and let me know what you think!

[SRV Ron]

For stock, play with Sandbox to get a design that works in the restriction of your career mode. Consider sending a probe first before attempting a Kerbal mission.

Like Mun, straight land and return missions are possible. Also, you should have enough tech unlocked by this time to send probes to do the mission before committing to a Kerbal one.

Better is to send a small fleet of ships. Have one designated for landing and returning to orbit from Duna. Have a second ship that orbits and collects crew and science from the landers. The Landers could then be left as orbiting satellites. A third could be used to land on Ike and intercept the return ship. It wouldn't have to be manned as an EVA could be used to recover the data. Leave probes behind in orbit or on the surface. Take advantage of aerobraking to save fuel for entering orbit and landing. Use Slingshot maneuvering to get an Ike intercept and orbit.

And, as always, while ships are on their way to Duna, you could always be doing contracts, more exploration of Mun and Minmus, and send one way probes to Eve and the Jool system.

With Mods, things can become much easier. With the Hooligan Lab mod, landing and return from Eve is possible without the need to build a massive lander.

Edited May 20, 2015 by SRV Ron

[p14082003]

Changing to answered as soon as I make to Duna. alredy have the ship. 4200 dv for transfer stage. i will post a picture soon.

[Warzouz]

The first time I went to Duna I sent 2 distinct missions with nearly the same payload mass.

The first one was a lander for Ike (able to do 1 hop) and the second one was a lander for Duna (no hop). Both landers were derived from my mun lander and able to do the return to Kerbin on their own. The middle stage was a bit bigger.

Of course landers weren't exactly the same. The one for Duna had chutes and science experiment for one spot. The Ike's one had doubled experiments. Flying 2 missions in the same time is quite fun, I liked it very much. You can see what consequences very small node variations can have in the end.

It was so fun that I flew a 14 flights mission to Jool's system next...

PS : that was in beta 0.9.

I'll very soon go to Duna (window is in 28 days), but I'll send a space station, fuel and landers to explore in one shot.

[p14082003]

Thank you all! you're the best!! I made it to Duna. I'm not going back because I don't want to *COUGH* no fuel... *COUGH* pics in a second!!

--EDIT--

I don't know how to share a whole imgur album, but here's the link:

http://imgur.com/a/prBCi

check it out and tell me what you think! its all the pictures I took in KSP 1.0

Edited May 21, 2015 by p14082003

[Warzouz]

Well done. Now time for rescue mission

[p14082003]

Not actually necesary because it is an unmaned ship. i think the lander can go to the mun and minmus in a single mission.

anyways, that might be the first part of a Duna station.

i have to say, I made it to Duna and i had NEVER landed safely on the moon

Edited May 21, 2015 by p14082003