How do I get this to go to Duna?

[Profound]

So I built a 70ton lander for Duna: http://www./?rg5pq790iggatkh (it's not particularly good)

My problem is actually getting it to Duna now.

This is my current attempt. I'm not sure what I can do to make my ship larger. http://www./download/al7klhgeq00rnc0/Duna_2.craft

At the moment I have to use lander engines to get me into Kerbal Orbit.

My other issue is that I don't have the tech tree completely unlocked. (otherwise this would be more trivial, especially with mainsails and jumbo tanks)

I have all the 90 science techs unlocked plus Heavier Rocketry, Specialized Control, Advanced Electrics, Advanced Exploration, Advanced Landing, Electronics, Field Science, and Advanced Science Tech. (First two and bottom 3 of 160 science level, bottom 2 of 300, and 2nd to last 550.)

I'm not particularly attached to anything but the lander if someone has a random sub-assembly that works with my technology.

[KvickFlygarn87]

Could you actually upload the image to an image site (or whatever it's called) like imgur? Would help a lot!

[kurja]

http://forum.kerbalspaceprogram.com/threads/33381-0-20-2-Zenith-rocket-family-(modernised-for-0-20-x-with-perfect-subassembly)

Look at the two largest lifters (you'll need to lift your transfer stage + 70 ton lander + return). Can you do something similar with the parts that you have? If not, add docking ports and lift the lander, transfer and return stages separately, dock them together and refuel if needed.

[el_coyoto]

I don't have pictures right now, but I have a career heavy lifter that compensates the lack of Mainsails by using Skippers and LV-30 strapped to the booster with a tail connector (to avoid clipping).

It is an asparagus set-up, with a central booster using a Skipper and 4 LV-30 and the booster "stalk" pairs have 1 Skipper and anywhere between 1 and 3 LV-30 to optimize the Delta V / TWR ratio. It boosts a 80 tons Duna atomic lander to LKO while keeping ~1000 m/s in the central booster for shorter ejection burns. I only use 2 asymmetrical "stalk" booster pairs, but I'm already happy with the performance of my launch vehicle so I don't feel the need to add a 3rd booster pair.

I did tests in 0.21 on heavy payloads and came to the conclusion that Mainsails can be replaced by the "Skipper + LV-30" combo without losing too much lifting capability : Mainsail-based rockets simply use more fuel (less ISP) and have less parts.

I'll try to post pictures when I get home, because I don't know if the above explanation is clear enough...

Edited October 22, 2013 by el_coyoto
words

[capi3101]

70 tonnes for Duna, sans nukes. Tricky, yes...

Fortunately you've got the Poodle, Skipper and the X200-32, so that's something...I've made it to Duna before without Nukes.

Okay, so you've got your lander. Delta-V map says 1,788 m/s is 125% of the delta-V needed to get to Duna. Let's go with a Poodle for that job...it has a 390 Isp in space. Add the decoupler. You need 70 tonnes of fuel for the job; four X200-32s will cover you. Set one up in the center, three outboard, strut them together and run fuel lines from outboard to center. That oughta do that.

Now you've got 142.5 tonnes of payload...

Oof. You need somewhere between 14,911.2 - 15483.15 kN of thrust to lift that, assuming asparagus. You'll need 23-24 Skippers for that job (or 23-24 three-motor clusters of LV-T30s/LV-T45s).

Okay...if you were to lift the two separately and dock them in orbit...but you don't have Specialized Construction yet. You'd only need 12 Skippers, though, and that would be doable. You could get away with nine skippers asparagus if you can accept a 1.28 TWR (bit low for asparagus but it'd still get you into space). All that hinges on being able to dock.

Not sure what to tell you in this case. Large Control and Specialized Construction need to be your next tech tree priorities; with large control and Heavier Rocketry, you unlock Very Heavy Rocketry and the Mainsail Engine. 1110 Science total to unlock those techs.

[Profound]

Could you actually upload the image to an image site (or whatever it's called) like imgur? Would help a lot!

Here's a picture of what I have so far. I added on a bit. My asparagus randomly falls apart and I can't get into orbit.

Example:

I think I might just have bad strutting or something?

updated craft file: http://www./?al7klhgeq00rnc0

Edited October 22, 2013 by Profound

[Elsig]

Have you got docking ports unlocked?

If so, I would assemble this in orbit and then take it to Duna

[capi3101]

I'd put some higher efficiency engines on that transfer stage. The Skipper's a good engine but for interplanetary travel you need efficiency, not thrust. And the Mk-55 just plain sux. Wiki even says "It is recommended to not be used in atmospheric landings."

You also need MOAR FUEL. Remember I suggested 23-24 Skippers this morning? Well, I meant that. Five of those need to comprise your core stage, so you're looking at a nine-stage to orbit asparagus booster, and for the mass you're lifting, you're going to need Jumbo 64s. And unfortunately, the Skippers won't provide enough thrust.

Yeah, I'm sticking to my original suggestion; you're going to have to dock the lander to a transfer stage. Or reduce the mass of the lander somehow - 70 tonnes is a hell of a lot of payload to be taking to Duna without Mainsails.

[el_coyoto]

70 tonnes for Duna, sans nukes. Tricky, yes...

Ooops, didn't parse the tech tree description properly. Tricky but doable, and this is a nice "green" solution...

Here's a picture of what I have so far. I added on a bit. My asparagus randomly falls apart and I can't get into orbit.

I think I might just have bad strutting or something?

I wonder, maybe a few struts between your lander fuels tanks and the stage below could help?

(The symmetry mode difference between each stage might make this easier said than done though...)

Does the rocket wobble a lot before breaking? Did you try to disable gimbaling on some of your Skippers?

I got home and took a picture of the cheap trick that I use when I don't have access to Mainsails :

Central core : 1 Skipper + 4 LV-30. Each booster : 1 Skipper + 1 LV-30

The LV-30 are not gimbaled, so the rocket flies straight without messing around with the trust vectoring setup. The lander itself is light (35 tons, much less than in my memories lol), but the central booster is lifted in 80x80 LKO with a sizable delta-v reserve (~400 m/s if i remember correctly).

(And I should really stop posting about my rockets while at work, because it seems that I have a bad memory and really overestimate their performance. )

Now, back to the game, and let's see how much more fuel I can lift with a few more strategically placed LV-30...

Good luck and I hope this helped a bit...

[capi3101]

Hmm...that's doable. Tail connector's available with Aerodynamics - a 90 sci tech, so OP should be able to build the same.

I've had problems with the Tail Connectors before, though...how do you keep the top end from coming loose? Parts clipping or struts?

I'll have to re-calculate at 1510 kN thrust per booster. The Isp would be impoved too...

140 tonnes is within the capabilities of Temstar's Supernova asparagus booster, so yes this is doable. Still going to be tricky, but not as tricky as before. Good suggestion, el_coyoto.

EDIT: Looking at the Supernova, it's 12 stacks at 4 X200-32 tanks equivalent. 4STOa with three stacks in the center and the outboard boosters released in triplets. There's a stack of 1.25 meter tanks in the center feeding into the triple stack. Rebuilding it exactly would be tricky but you could set up something similar. It would definitely get you into orbit.

Edited October 22, 2013 by capi3101

[Sirrobert]

For one I'd suggest launching the transfer stage and the lander seperatly, docking them in orbit, and refueling if needed (with a third ship).

Should save alot some trouble

[Profound]

I'd put some higher efficiency engines on that transfer stage. The Skipper's a good engine but for interplanetary travel you need efficiency, not thrust. And the Mk-55 just plain sux. Wiki even says "It is recommended to not be used in atmospheric landings."

You also need MOAR FUEL. Remember I suggested 23-24 Skippers this morning? Well, I meant that. Five of those need to comprise your core stage, so you're looking at a nine-stage to orbit asparagus booster, and for the mass you're lifting, you're going to need Jumbo 64s. And unfortunately, the Skippers won't provide enough thrust.

Yeah, I'm sticking to my original suggestion; you're going to have to dock the lander to a transfer stage. Or reduce the mass of the lander somehow - 70 tonnes is a hell of a lot of payload to be taking to Duna without Mainsails.

The mark 55 is my only choice for the lander, and it actually works pretty good. I originally had poodles, but they would explode on impact. I tested the lander by landing on Kerbin and taking off into orbit, so I know it has enough fuel.

I made a video of my....lameo attempts at taking off. I will work in some more changes. Note: I accidentally pressed stage once. But you'll notice that there's like these huge explosions and stuff in the asparagus design when I separate rockets and stuff... and I lost two lander legs.

http://www.youtube.com/watch?v=mdP_DeD_HvA&feature=youtu.be

The video is mostly just to show the problems are in the mid-section.

[UnthinkableThinker]

Well, from the video I can see you messed up when you decoupled a booster while it was still burning.

Regarding the stuff blowing up after you decouple, just use a few Separatrons, strap them on to the stuff that is going to get decoupled and put them in the same stage as when the decoupling happens. What they basically do is "push" the stuff you decoupled, away from your other parts (if placed correctly ). I'm sure you have those unlocked by now.

[Sirine]

http://www./download/n8n9tefsdjrs41u/Duna_2_(Fixed).craft

Fixed. Just add-in a few more struct.

[capi3101]

Tried to put together a proof-of-concept Supernova-substitute booster this evening. Had some parts clipping through one another, so it didn't survive the third staging event, but things were going reasonably well up to that point.

[el_coyoto]

Hmm...that's doable. Tail connector's available with Aerodynamics - a 90 sci tech, so OP should be able to build the same.

I've had problems with the Tail Connectors before, though...how do you keep the top end from coming loose? Parts clipping or struts?

I'll have to re-calculate at 1510 kN thrust per booster. The Isp would be impoved too...

140 tonnes is within the capabilities of Temstar's Supernova asparagus booster, so yes this is doable. Still going to be tricky, but not as tricky as before. Good suggestion, el_coyoto.

EDIT: Looking at the Supernova, it's 12 stacks at 4 X200-32 tanks equivalent. 4STOa with three stacks in the center and the outboard boosters released in triplets. There's a stack of 1.25 meter tanks in the center feeding into the triple stack. Rebuilding it exactly would be tricky but you could set up something similar. It would definitely get you into orbit.

Strange, I've had troubles with the lil' cubic connectors in the past and switched to tail connectors for this kind of tricks because they seemed WAY more stable on my rockets and felt less cheaty (they have a mass). I don't use part clipping in this instance and simply grab them, rotate so they are correctly aligned and place them. I don't even strut them to the booster. Rocksteady stable...

I used "Editor Extensions" and vertical snap in this case, but I've already used tail connectors without vertical snap and no problems.

The only precaution I take is strutting every fuel tank to the tank below to make the booster very stiff. It might be your problem : too much thrust and the fuel tanks start "dancing around" because of the high thrust+low stiffness if not strutted, thus messing around with the tail connector.

I had a similar problem yesterday when I worked on the "1000 m/s left in the central booster left when in LKO" and the added thrust required me to add struts to the tank on which the connector+engines were connected to avoid engine wobble...

[capi3101]

It might be how I'm trying to place them. Last night I got them attached to the sides of the X200-32 tank and the game didn't want to let me put the next tank on top. I had to turn on parts clipping to get it to finally work, and that's probably what ultimately caused the third stage meltdown I had. I plan to try again and put girders on the central stack this time around, just to get a little more space in between the tanks this time. Some Sepratrons too; they're part of the original Supernova design and it turns out they're necessary...

Edited October 23, 2013 by capi3101

[Oddible]

I'm very confused by this thread. You're using all that to get those 3 tiny cans to Duna and back? Seems like overkill, go simple.

[Nurph]

Your design can easily get to Duna. I was able to land on Duna and return to orbit with fuel still left in the Mk 55 stage, did not test Kerbin return but I'm sure there was enough dV left.

I would however recommend that you:

1. Ditch the reaction wheels on the first stage.

2. Add a set of winglets to the first stage.

3. A couple more sets of struts between the first and second stage.

4. Struts between the second stage and lander.

5. Set an action group to disable the gimbals on the outer two rings of Skippers.