EVE--how to?

[birrhan]

I've been having several problems with Eve. My first is with the forum: "eve" is too short a word to search, so "all these threads" about Eve landers aren't searchable.

That said, I'm trying to get a 3 man command pod down and back, and the lowest weight I can get for a reasonable dv (9300) is 589 tons:

I saw some very lovely pictures of vertical asparagus staged rockets weighing in around 28 tons, that you put a couple ladders on and have your Kerbals hold on to for dear life. During an ascent. out of the atmosphere. At many thousand of meters per second. A more realistic approach using an mk1 can get out for ~50 tons. Why does it take so much more to get the extra 3 tons back home????

That's mildly rhetorical. This thread should contain ONLY (a) links to other threads on 3 kerbal manned return mission to Eve, and ( images of stock Eve landers/return vehicles for a mk3 capsule, including approximate dv. I'm kind of tired of circling around the problem and talking about concepts without anything specific. So let loose with your specifics--show me your landers! Or improve on mine.

[Aphox]

Sweet mother of Kerbol that thing is terrifying. I think you might be over-thinking it.

Also this should probably be in the how-to forum ;D

Edited May 17, 2013 by Aphox

[TheDarkStar]

You should be using more efficient engines for the upper stages. Atmospheres thin out fast.

[birrhan]

Sweet mother of Kerbol that thing is terrifying. I think you might be over-thinking it.

Also this should probably be in the how-to forum ;D

Appreciated, but seriously, I'm kind of sick of the "dude, you're overthinking it....." answers. I get it. it's a problem. Improve on it, or else you're not really adding to the conversation.

This is kerbal science. We demand evidence. And explosions. but also evidence.

[Kurile]

If you are decent at docking, or just really want to try it, i would suggest you get that into orbit. Assuming you have fuel left, i would suggest not dropping any tanks on the way up, minus SRBs. Next, launch a repeat of the craft, and dock up and transfer fuel to fully fuel up your craft. If you have the NERVAs, use those as much as possible, transferring fuel from the outer tanks with the bigger and less efficient engines, to the NERVA tanks.

If Not, then you might need to design a few stages, and launch them up seperately, dock and combine them, then fuel missions til full, and set on out. Combine with Kethane pack for max longitivity of mission.

My personal fun recommendation is the second option. I love overly complicated missions that could be done easier. So does jeb. They tend to blow up faster.

[Aphox]

Eh, I don't really do return missions, so I might not even know what I'm talking about.

Just considering than in my experience, huge designs don't work very well. I used to make ENORMOUS rockets just to get to Duna until I really figured out what I was doing and was able to scale them down significantly.

Also, are you allowing refuels? I'd park refuel rigs everywhere I stop in orbit and try to rendezvous with them and see if that helps.

[Specula]

I know it seems crazy, but in KSP, less is more in almost every case.

I was able to get to the Jool system with a LOT of fuel left over with this:

You shouldn't have much of a problem getting to Eve with a much smaller craft. Take the approach that Lotus does with cars. Don't ask 'what extra can we do with?', but instead ask 'what can they do without'? It's a fine art that takes practice. Just play around until you find something. Best of luck!

[Temstar]

There are one man pod Eve return craft that weigh 50 tons? I don't think that's possible. All the below 50 ton crafts that I know of are open-air rockets. These 50 ton capsule'd crafts don't use the EVA jetpack with its 520m/s of delta-V as it's final orbital stage does it?

But suppose there was a 50 ton lander with an one man pod, that clearly shows somewhere in your design you have inefficiency. For one using tricoupler for your final stage and including those 1.25m - 2.5m adaptors seems like a waste of weight to me. Instead of tricoupler use the cubic strut trick as you would with clustered engines. Everything on your rocket, particular that final stage should only be there if it's absolutely critical. If taking away a part of the rocket doesn't cause it to fail catastrophically then it doesn't belong on a Eve return vehicle. Every kg of weight you save at the top translates to dozens of tons by the time its effect filters down to the first stage. So for example if you switch that ASAS for that spaceplane guidance package and your rocket manages to still fly straight you save another 40kg from the top. All the record breaking crafts such as that 18 ton open air two man Eve return rocket are hand flow or with MJ so as to ditch ASAS to squeeze even more delta-V out of the rocket.

One other hint - if you want to carry three guys back and you don't want to use the ladder trick for an open air rocket then using three one man pod is still lighter than using a 2.5m pod.

[Splode]

Is the craft pictured the whole rocket? Or just the lander? I've been looking at doing this myself, but I haven't worked out a good way of moving something with 15 000 dV through space. I would of course go for an apollo style set up, and leave my return to kerbin stage in orbit. Is this what you're doing? Or are you going for one enormous rocket.

[birrhan]

UPDATE:

9500 dv achieved on less than 200 tons.

Can you do better?

[Spatzimaus]

Sweet mother of Kerbol that thing is terrifying. I think you might be over-thinking it.

Actually, he's not. 9300m/s isn't actually enough to ascend from Eve; you need to be in the 11.5-12k range to get off the surface, even if you do the ascent perfectly. So if you're using conventional rockets then yes, it does need to be really big like that.

That being said, the trick is to NOT use just stock conventional rockets. The upper stages can use more efficient propulsion, like LV-Ns, and even in the lower stages you should prioritize efficiency over raw thrust unless you absolutely NEED that much thrust to keep a decent TWR. I've ascended from Eve using Kethane-powered turbines, which have the high ISP of jet engines, but you can even do it with stock parts if you design your ship as a large spaceplane. That way, you can use your wings' lift to offset the high gravity, and you don't need to waste a huge amount of fuel building up speed at low altitudes, where the terminal velocity is too low to be useful.

[Spatzimaus]

You shouldn't have much of a problem getting to Eve with a much smaller craft.

He's not trying to get TO Eve, he's trying to get OFF Eve. Ascending from Eve takes FAR more delta-V than getting to Jool.

[Temstar]

9300m/s is more than enough to get off Eve if you land on some kind of hill. At 6.5km mountain top a return trip to Low Eve Orbit can cost as "little" as 7500m/s. You only need 12,000m/s if you plan to get back to orbit from Eve's sea level.

With 9300m/s you can probably get back from 4600m altitude or higher, depending on your TWR and your Isp to atmospheric pressure curve of your rocket.

[birrhan]

Actually, he's not. 9300m/s isn't actually enough to ascend from Eve; you need to be in the 11.5-12k range to get off the surface, even if you do the ascent perfectly. So if you're using conventional rockets then yes, it does need to be really big like that.

That being said, the trick is to NOT use just stock conventional rockets. The upper stages can use more efficient propulsion, like LV-Ns, and even in the lower stages you should prioritize efficiency over raw thrust unless you absolutely NEED that much thrust to keep a decent TWR. I've ascended from Eve using Kethane-powered turbines, which have the high ISP of jet engines, but you can even do it with stock parts if you design your ship as a large spaceplane. That way, you can use your wings' lift to offset the high gravity, and you don't need to waste a huge amount of fuel building up speed at low altitudes, where the terminal velocity is too low to be useful.

You have no idea how upset I am right now. From my perspective, I see "oh, that's cool, but not good enough. you'll need to do better." Elaborate on better, please. I need a picture of your lander; these vague "oh, use LVN in your upper stage" mean NOTHING to me. Pics. or links. Text is useless--it says nothing about the totality of how your lander is constructed. you are likely forgetting things that you don't even think to include, that are critical. If you're intent on being helpful, please abide: pics or links ONLY.

[tavert]

Dude, calm down. If (well-intentioned) suggestions aren't helpful enough for you, ignore them. You also should have posted this in How To, not in General. One reason you're not finding much information about 3-man Eve ascent vehicles and most people's comments are non-specific is that it's an extremely difficult thing to do. Eve ascent with a 1-man capsule is tricky, trying it with a 5-times-heavier payload is going to be 5 times harder.

The fact that Eve is not searchable on the forums does suck. Google is your friend.

http://forum.kerbalspaceprogram.com/showthread.php/25329-Three-To-Eve-Mk-1-2-Command-Pod-Challenge

http://forum.kerbalspaceprogram.com/showthread.php/25468-SESRV-Smallest-Eve-Sample-Return-Vehicle/page2

Temstar, under 50 tons with a 1-man capsule from a mountaintop is doable with an SRB first stage. I think this http://imgur.com/a/ab3ly/#0 was Nao's first SRB-using Eve ascender, and he was able to take a couple tons off that design (can't find a link to his final version, it was around 45 tons).

[CalculusWarrior]

I know it seems crazy, but in KSP, less is more in almost every case.

I was able to get to the Jool system with a LOT of fuel left over with this:

You shouldn't have much of a problem getting to Eve with a much smaller craft. Take the approach that Lotus does with cars. Don't ask 'what extra can we do with?', but instead ask 'what can they do without'? It's a fine art that takes practice. Just play around until you find something. Best of luck!

Oh my god, that thing is massive! My Jool ion probe is just:

I suppose it's all too easy in KSP to add more and more fuel, but get smaller and smaller delta-v returns back.

And OP, I like your second design; especially how you used the tri-coupler and the three one-man pods! I'm sure that will save a lot of weight.

[1001sd]

A little (off-topic maybe) thing to say, is that you can in fact search the forums for short/common words using google. Just search for "site:forum.kerbalspaceprogram.com some text here to search for", and you will get search results on the forums only.

[Francesco]

I know it seems crazy, but in KSP, less is more in almost every case.

I was able to get to the Jool system with a LOT of fuel left over with this:

is that thing manned? and does it also come back to Kerbin from Jool?

[Spatzimaus]

these vague "oh, use LVN in your upper stage" mean NOTHING to me. Pics. or links. Text is useless

It's called a "hint". It's something people give you when you're better off figuring out the specifics for yourself, but when they want to put you on the right track towards a successful attempt. KSP is all about learning how to do things, and this is what we call a teachable moment. You've obviously learned how to construct a rocket, get your current mass, get your total delta-V, and so on, so you can do it without us handing you a perfect design. As long as the stage in question isn't activated until you're above 15000m or so (where the nuke's ISP reaches 500), the only reason to use the less efficient engines is if you still need the high thrust, so you should be able to figure out for yourself exactly which stages should be using those engines.

[superm18]

A little (off-topic maybe) thing to say, is that you can in fact search the forums for short/common words using google. Just search for "site:forum.kerbalspaceprogram.com some text here to search for", and you will get search results on the forums only.

That's gonna be sooo helpful

[tavert]

Spatzimaus, have you actually made a working Eve ascent vehicle using LV-N's? As far as I can remember I've never seen anyone post that kind of design, the TWR is lousy and as we all know Eve has the highest surface gravity in the game...

The Kethane jet is far from a fair comparison, as it is obscenely overpowered. (see https://docs.google.com/spreadsheet/ccc?key=0AvPJpCCRbRI3dG5aTTVUd2ZmczlOQXlrYkY3ejF2TlE#gid=0 - this is technically for a single stage, but is a useful way to compare engine capabilities. Make a copy and change Planetary Surface Gravity to 16.7 for Eve numbers)

Edited May 17, 2013 by tavert

[CoriW]

COMPLETELY REBUILT THIS SHIP, IT'S IN ANOTHER POST BELOW

Well, I decided to try my hand at this... And man the whole thing about it being 3 man and not 1 man is an absolute pain... But after 2 hours in the VAB, I present you with this...

IMAGE REMOVED

Now if you can actually get this thing to Eve, which I highly doubt, then I can almost gaurentee landing it would be near impossible... And even if you can do that, it'll probably either blow up in-flight or be just slightly short on DV for a proper orbit... Do you realize that those extra 2 capsules cost over 1200m/s DeltaV??? Without them this design sits around 12,000 m/s DeltaV but with them it's a mere 10800 m/s DeltaV. Oh and I avoided a decoupler because every time I added one it said I would lose over 3000 m/s DeltaV... P.S ~ It weighs in at 234 tons and has no landing legs or parachutes... That'd be too much DeltaV lost.

And the craft file: Completely re-built this ship, it's in another post below.

EDIT: Fixed the .craft file (Took off the Engineer Redux part) (Now Mk.3)

EDIT: After some testing, updated the ship with some struts (Now Mk.4)

Edited May 17, 2013 by CoriW

[loppnessmonsta]

Well, I decided to try my hand at this... And man the whole thing about it being 3 man and not 1 man is an absolute pain... But after 2 hours in the VAB, I present you with this...

Now if you can actually get this thing to Eve, which I highly doubt, then I can almost gaurentee landing it would be near impossible... And even if you can do that, it'll probably either blow up in-flight or be just slightly short on DV for a proper orbit... Do you realize that those extra 2 capsules cost over 1200m/s DeltaV??? Without them this design sits around 12,000 m/s DeltaV but with them it's a mere 10800 m/s DeltaV. Oh and I avoided a decoupler because every time I added one it said I would lose over 3000 m/s DeltaV... P.S ~ It weighs in at 234 tons and has no landing legs or parachutes... That'd be too much DeltaV lost.

And the craft file: Click Here

EDIT: Fixed the .craft file (Took off the Engineer Redux part) (Now Mk.3)

EDIT: After some testing, updated the ship with some struts (Now Mk.4)

I've never left Kerbin's SOI (Except for my first few launches, before I figured out that I needed to do a gravity turn) but I can already tell you one very important thing about your ship that you MUST fix immediately, else you'll never get there!

Flip the middle capsule upside down so it looks nicer!

[CoriW]

When I initially posted that... I hadn't tested the ship at all... And I very quickly found out it had about a million and one problems! So now I've rebuilt it and am going to re-post the new version.

Alright so here is my sort of completely rebuilt version of my previous design for an Eve Launch Ship (ELS, because it sounds cool)

The new version has quite a number of changes to it, hence why I stopped updating my earlier post.

- Only has 1 command pod (I know this thread asks for 3 but it's simply too much valuable DeltaV, you can re-add the other 2 if you want. Loss of about 1300 m/s DeltaV.)

- Changed the type of radial decouplers (The previous ones had a tendency to explode at stage.)

- Added ASAS

- Added more struts

- Added Parachutes (Action group "1" for Drogue chutes, "2" for Full chutes.)

- Added Landing Legs

- Added Decoupler

- Added Winglets as to hopefully no long spin wildly out of control

(Craft file link below the image.)

And the craft file: Click Here

EDIT: Fixed .craft file (Forgot to take redux off before uploading again.), Also fixed screenshot (Redux was set to Kerbin so TWR was wrong.)

Edited May 17, 2013 by CoriW

[Temstar]

So... How is the kerbonaut supposed to get up and into that lander?