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seaces

Get to Duna NOW!

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Hi people,

I have settle my mind to install some life supp. mod and before I do that I must return all my kerbals home so when the mod kicks in they do not die in space. 3 kerbals are on Duna north pole and those are furthest kerblas (other are around Mun in MPL and 1 on station orbiting Kerbin at 600km). So now the original plan for those guys on Duna is that they have to wait 1y and some days before their launch window opens for return trip. I cant get them earlier becouse of the lander dv limits. It wasnt designed for this and the time of design I had no intentions to start using lifes supp. mods until I have found out about deepfreeze mod so I do not have to make large ships bcs of food I would only freeze them and give them food for the time that they are planned to be active.

Now I cant wait to get them back to get my science and install the mods. I used windows planner (I have one in game that is mod, forgot its name) and if I would want to start now and get there as fast as I can, which is around 150 days, my ship needs around 13k-15k of dv just to get there and if I want to return them as fast as I can with the same ship I again need 13k-15k of dv for return. Well I did not have much time to play in VAB or SPH but initial drawings showed me that I need a monster. This is career game so I still gave to unlock engines and tanks above 2,5m. Those are I believe 550 and 1000 science point nodes. There I will get plenty of parts including the Space y parts that I have installed.

Now let me hear your ideas what would be the fastest way to get them back, as a part of this self imposed challenge I must launch now and also as soon as I land/recover them I must turn back. There is no waiting for better windows or something I want to abuse the engines and rockets :P

My first idea was ti create a space plane bcs I to make a simple capsule and land it near them would be exercise of my patience so I decided to use atmo on duna and once I get there to fly the ship to them. VTOL would be nice (it doesnt have to be Kerbin VTOL working only Duna would be fine).

Second idea is to maybe assemble something in the orbit..

Anyway lets see what are your ideas, these are mine for now

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Since this is rather an unfair limit that you are imposing on yourself, are you sure you aren't willing to cheat just a little and teleport your Duna Kerbonauts home? Or cheat just a little less and put a little infinifuel into your rocket tanks?

 

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6 minutes ago, bewing said:

Since this is rather an unfair limit that you are imposing on yourself, are you sure you aren't willing to cheat just a little and teleport your Duna Kerbonauts home? Or cheat just a little less and put a little infinifuel into your rocket tanks?

 

I would rather just continue to play as planned untill I get them back as per original plan if this insanity is impossible :D

The only allowance that I would make is that I would play around mun/minimus to get some 250pts more to get 550 points to unclok some more parts...I have new science mods that would get me a bit more science and a moho probe that will send its data once it lands in 120 days :D

Edited by seaces

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5 minutes ago, The Aziz said:

Time warp on maximum?

Would do it but first I have to get rid of running probes and cotracts many of which have correction burns or orbital injections to be done...I have many things running in my save :P

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I think this thread title is much funnier if you read it in an Arnold Schwarzenegger accent. Get to Duna NOW!

 

If you're impatient to start with the new mods, then finish the active contracts in as little as possible real time (not game time). You do that by finishing the Duna mission as planned. Finish all active contracts but don't accept new ones. When you've finally warped ahead 1 year, you bring the guys back. This will take by far the least of your time. Then you can indulge in the new mods with all Kerbals safe at the KSC.

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I agree. Building a rocket with 30 km/s dV is not impossible... but I wager that merely the effort of constructing and prototyping it in the editor would take you significantly longer than just timewarping until you can launch a regular vessel on a regular Hohmann transfer, timewarp until the return window, do a regular Hohmann transfer back, and timewarp until arrival.

If you do insist on roleplaying it out ingame as a high speed rescue mission: I hope you have nuclear rockets and ion drives unlocked, max level launchpad and VAB, a deep understanding of rocket construction and orbital mechanics, and a looooot of patience for long and staggered burns. :wink:

 

Edited by Streetwind

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46 minutes ago, Magzimum said:

I think this thread title is much funnier if you read it in an Arnold Schwarzenegger accent. Get to Duna NOW!

 

Hhahahha Magzimum :D

Yeah well I was thinking to do something like that but then thought if something like this is even possible.

11 minutes ago, Streetwind said:

I agree. Building a rocket with 30 km/s dV is not impossible... but I wager that merely the effort of constructing and prototyping it in the editor would take you significantly longer than just timewarping until you can launch a regular vessel on a regular Hohmann transfer, timewarp until the return window, do a regular Hohmann transfer back, and timewarp until arrival.

If you do insist on roleplaying it out ingame as a high speed rescue mission: I hope you have nuclear rockets and ion drives unlocked, max level launchpad and VAB, a deep understanding of rocket construction and orbital mechanics, and a looooot of patience for long and staggered burns. :wink:

 

Only nuclear I have and I have forgot to mention I do not have ISRU and the drills so that makes it impossible to make a 15k dv vessel and refuel it there.

Wonder if somebody has any design that has this much of dv to share? Just for inspiration and fun

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Can the Kerbals on Duna at least take off under their own power? Or does a rescue mission need to land there and take off again?

Maybe I'll try it out for fun when I get home, though I'm not sure if it'll fit in the VAB. Or if I'll have time.

 

(Do note: even with a 30 km/s rocket, you can't actually fly this mission, because you cannot aerocapture at Kerbin. At that speed, any periapsis deep enough to capture will destroy your craft through dynamic pressure. Not even heat, just straight out "you shatter because air is like a concrete wall at these speeds". So you'll need a largely propulsive capture, which I assume is not yet budgeted in? And adding two more stages to a rocket that probably doesn't fit into the VAB creates a rocket that absolutely doesn't fit into the VAB.)

Edited by Streetwind

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11 minutes ago, Streetwind said:

Can the Kerbals on Duna at least take off under their own power? Or does a rescue mission need to land there and take off again?

Maybe I'll try it out for fun when I get home, though I'm not sure if it'll fit in the VAB. Or if I'll have time.

 

(Do note: even with a 30 km/s rocket, you can't actually fly this mission, because you cannot aerocapture at Kerbin. At that speed, any periapsis deep enough to capture will destroy your craft through dynamic pressure. Not even heat, just straight out "you shatter because air is like a concrete wall at these speeds". So you'll need a largely propulsive capture, which I assume is not yet budgeted in? And adding two more stages to a rocket that probably doesn't fit into the VAB creates a rocket that absolutely doesn't fit into the VAB.)

I did not yet think how to stop it at Kerbin so yes that is without breaking with engines. The lander is capable to return to Kerbin by itself. It has 3 kerbals so we are talking about big capsule for 2,5m rockets. If you insist I can send you maybe picture of the lander and maybe .craft file of the lander after when I get home.
I am just trying to do this to get them back faster then I would by wating 1 more year for transfer windows Duna-Kerbin and the trip itself. Yes I could time warp and other shocrtcuts I could use but for the sake of game play and challenge I was thinking is it possible to make express ship that would get them back ASAP.

So there you go, I cant wait to see your idea if you ever make it. Good luck! :wink: 

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For that matter, you know how much the departure burns are, have you budgeted for the capture burn at Duna?  It's going to be pretty huge too!  Unfortunately, these things happen when you're well out of the transfer window...

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I have used window planer. there I have set starting planet and destination Kerbin-Duna-Kerbin and typed in starting orbit altitude and the one at duna and also inserted these numbers for back trip. So I suppose those 30k of dv are taking in account to get from kerbin-duna and get in orbit of duna then get from duna and get into orbit of kerbin. If I am not mistaken

 

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Yeah, if you didn't check the "no capture burn" box then that budget should include propulsive captures and even circularization. That's good news for the feasibility :)

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2 minutes ago, Streetwind said:

Yeah, if you didn't check the "no capture burn" box then that budget should include propulsive captures and even circularization. That's good news for the feasibility :)

Yeah that's how I did it...I hope I wasnt too drunk not to notice that I have turned that on by accident :D

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You will need to build an extremely small return capsule, three lander cans on top of a nuke and whatever fuel tanks you will need. I am on spreadsheet now, so I cannot check the numbers in VAB with KER, but assuming 15k dV and 2.5 t payload, you can do the return vehicle for 33t on dual nukes. That again means a 412 t ship from LKO with 21 nukes if you want TWR at 0.2. Careful staging will of cause reduce that number quite a bit, but still you are looking at hundreds of tonnes to orbit.

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16 minutes ago, Freshmeat said:

You will need to build an extremely small return capsule, three lander cans on top of a nuke and whatever fuel tanks you will need. I am on spreadsheet now, so I cannot check the numbers in VAB with KER, but assuming 15k dV and 2.5 t payload, you can do the return vehicle for 33t on dual nukes. That again means a 412 t ship from LKO with 21 nukes if you want TWR at 0.2. Careful staging will of cause reduce that number quite a bit, but still you are looking at hundreds of tonnes to orbit.

15k of dv to get to Duna and circularize. Then it is possible to use the lander what is on surface to bring Kerbals close to the ship and EVA them to other ship. Return from duna to kerbin and to circularize at kerbin you need another 15k of dv. In total around 30k of dv. Actual number is maybe 26-28k of dv

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2 hours ago, seaces said:

15k of dv to get to Duna and circularize. Then it is possible to use the lander what is on surface to bring Kerbals close to the ship and EVA them to other ship. Return from duna to kerbin and to circularize at kerbin you need another 15k of dv. In total around 30k of dv. Actual number is maybe 26-28k of dv

About 400t will get a payload of 33t 15000 dV. 33t of vehicle will take 2,5 t payload 15000 dV, you _really_ don't want to haul the entire ship back. My personal sanity limit is about 8-9k dV for a single stage.

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You shouldn't plan for circulation at Kerbin, which will save a lot of dV. Go straight for re-entry. This will go fine with just a capsule, chute and heatshield. 

I suggest this to return the crew...

GgkBDdU.png?1

Its a light 3-man solution, with enough chutes to land on Kerbin. You can remove all but about 40 ablator and the monopropellent. The three Elevon 4s are there to help keep it retrograde during re-entry. 

 

The other thing to think about to save time and dV is to try for a "Watney" recovery at Duna. That would mean having the recovery craft do a fly-by of Duna (rather than enter orbit) and rendezvous with it with the lander. It would depend on the capabilities of the lander and your own skills. 

Edited by Foxster

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My spreadsheet was not sturdy enough to meet the real world, in VAB I came out with 473t @ 0.1 TWR to meet your required dV, using stock parts. This was with asparagus staging of both trip and return trip. But given that you have quite some dV sitting on Duna, I agree with @Foxster. There is a lot to save by doing an rendez-vous without circularization, but aligning the two craft will be difficult. What is the current date in your save asnd how much dV is in your lander?

 

Edited by Freshmeat
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So my save time is Y2D169-1h:42min
and here is the pic of the lander with KER readouts:

Hegg8Wf.jpg

 

Edited by seaces

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Have you ever tried an asteroid rendezvous? Catching a rescue craft as it does a fly-by of Duna is the same thing. 

Doing a "Watney" with what you have looks do-able with your 3.2KdV. I've just tried it with something surprisingly similar to your lander and made it OK...

pyOdlqt.png?1

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Never did asteroid catching I hve upgrade the tracking station. But it it looks like it is possible to make fly by adn get them to the other craft

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I am thinking to do it with fly by on duna and while the craft is going for duna I will put the lander on orbit around duna and play with manouver node untill I get encounter

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