Eve One - Soliciting advice for an Eve Ascent Vehicle

[gilflo]

The cost in parachutes and landing legs for unpowered descent is around 40T to eject before take off. Landing between 4 and 5m/s

[Red Iron Crown]

I would recommend against this. I mean it's up to you, but my experience was the amount of parachutes and landing legs (though you have custom ones) required for a consistent unpowered descent was too much. In the end I found it much easier to just spend a bit of fuel on landing (my 300t lander has 12 drogues and 12 radial parachutes). I could land at 3 m/s, so the parachutes would put me to around 10 and then under 50m I'd use the engines for a safe landing. Only costs about 100 dV, could even just throw a couple drop tanks on the sides for the landing fuel and drop them when you launch, though that does mean debris.

You might be right. I could add four FL-T800 drop tanks on some of the points of my hexagon of boosters and add them to the asparagus flow without adding much to the part count. A powered descent for the last few meters is probably a good idea anyway as when I tried landing on a slope the flex in the landing legs allowed it to "walk" down the hill. Plus, any fuel left over after touchdown could be used to help the ascent. I'm not really worried about debris left on the surface, just in orbit.

[cerberusti]

I just strapped a few small fuel tanks to my landing gear on the large craft. It does not take much fuel to burn for the last ten or twenty meters in order to soften your landing (I also used it to push out of the water to some extent, as I was not sure how staging the gear off underwater would go.)

The walk on landing is probably not due to impact speed. I thought that was the case with mine, but it still did it even when very carefully landing at 0.1m/s. You probably need a very flat site to land it (which is hard to find on eve as it turns out... and why I ended up landing in the water.)

[WhiteKnuckle]

Holy spiderweb Batman!

I tried tweaking my design to a lander can, but it's just too much extra weight and I can't get the dV back up. It would have to be a clean sheet redesign. So I gave up and tried to build a spaceplane and the game froze.

I found going for a spaceplane style was much easier than a gigantic lander, it does away with the standard Eve problems of parachutes, landing legs, and T/WR.

Just a hair over 30 tons, not exactly easy to fly and it doesn't have much of a margine of error on the accent profile, but it sure beats crashing yet another big lander into the surface.

[ScottyDoesKnow]

I found going for a spaceplane style was much easier than a gigantic lander, it does away with the standard Eve problems of parachutes, landing legs, and T/WR.

http://i.imgur.com/JUpgEvu.png

Just a hair over 30 tons, not exactly easy to fly and it doesn't have much of a margine of error on the accent profile, but it sure beats crashing yet another big lander into the surface.

This requires kethane though, stock jet engines can't breathe on Eve.

[WhiteKnuckle]

This requires kethane though, stock jet engines can't breathe on Eve.

True. Other people have used the thermal turbojets from KSP Interstellar, but as far as I know there is no way to do an airplane design completely stock (although it would be neat to see someone try to land a 150t aircraft on Eve)

[Red Iron Crown]

Not sure it would work without FAR, either. As I understand it, FAR reduces delta-V requirements for ascent (Kerbin surface to LKO possible for about 3500m/s).

Edit: On perusing the Flying off of Eve challenge, it looks like some have done it with Kethane but no FAR.

Edit again: I see great minds think alike.

Edited March 31, 2014 by Red Iron Crown

[WhiteKnuckle]

Not sure it would work without FAR, either. As I understand it, FAR reduces delta-V requirements for ascent (Kerbin surface to LKO possible for about 3500m/s).

I thought that as well, but it doesn't seem to be the case.

http://forum.kerbalspaceprogram.com/threads/73048-Flying-(off-of)-Eve!

Check out SV-ESK's entry, he didn't use FAR and got from sea level to a 780km orbit (!) with an 9 ton ship.

[cerberusti]

I tried an eve ion plane a few times, but the upper atmosphere is a problem (it requires that I lift real fuel or a lot of wings, which makes it too heavy.) Maybe with the next patch it will become possible.

I would expect FAR and kethane to make it much easier, but with a stock craft the only engine which can even get the DV to do it in one stage is an ion engine (drop tank planes have their own problems, and it seems like the lower TWR requirement is not enough to make up for the much longer ascent time.)

The easiest way to do an eve ascent in stock is probably still a classic lander, as far as I know nobody has done it with an unmodded plane.

[Technical Ben]

So I'm not just the only one with spagetification/pancakefication when trying to land on Eve? I can land rovers, but anything bigger just collapses under it's own weight.

PS. I managed to get a landing! Lost my main battery though (note to self, do not put under rocket next time). So I cannot drive it to the launch location (up a mountain). So one final attempt and if I keep the battery, I should be good. Else I'll try for a launch from low altitude!

Edited March 31, 2014 by Technical Ben

[ScottyDoesKnow]

So I'm not just the only one with spagetification/pancakefication when trying to land on Eve? I can land rovers, but anything bigger just collapses under it's own weight.

PS. I managed to get a landing! Lost my main battery though (note to self, do not put under rocket next time). So I cannot drive it to the launch location (up a mountain). So one final attempt and if I keep the battery, I should be good. Else I'll try for a launch from low altitude!

I just responded to you in your thread, but just note that altitude plays a big role in launching from Eve. Launching from 0 takes around 12000 dV while launching from the highest mountain takes at least 8000: http://wiki.kerbalspaceprogram.com/wiki/Eve#Orbital_statistics

[Technical Ben]

I'll see if I can get the lander up to the mountain. I landed low altitude to save on landing rockets, and due to mountains being hard to hit targets.

I'll then launch it for effect, but will need an adjusted replacement with your added tweaks, to get the kerbal back.

PS, yep, TWR is totally different when I reach Eve. Rather more confusing than most launches. Any rough idea what TWR I should aim for without mods to tall me the kerbin/eve differences?

Edited March 31, 2014 by Technical Ben

[ScottyDoesKnow]

PS, yep, TWR is totally different when I reach Eve. Rather more confusing than most launches. Any rough idea what TWR I should aim for without mods to tall me the kerbin/eve differences?

Here's the Kerbin vs Eve TWR for my lander. This is in atmosphere, if you have 11.5k vacuum dV you won't make it back from 0 altitude.

[chemieglennie]

Finally did my Eve return mission. I used a big rover so I could drive up a mountain. Used the wide short fuel tanks rather than the tall thin ones with mostly aerospikes and some little tanks and engines for the top stages. This gave a low centre of gravity, which made the rover much more stable. I had a lot of problems with tall rovers swaying and breaking.

Take off is so much easier when you start from high ground. This seemed a good way of reliably getting there.

It had 9,700dv and made it from 4000m height with just under 200dv left. (Just noticed it says 8924dv in picture, that must be atmospheric dv)

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[Red Iron Crown]

*snip*

Nice mission. I especially liked launching the nuclear transfer stage upside down to avoid fairing issues, clever!

[Technical Ben]

Finally did my Eve return mission. I used a big rover so I could drive up a mountain. Used the wide short fuel tanks rather than the tall thin ones with mostly aerospikes and some little tanks and engines for the top stages. This gave a low centre of gravity, which made the rover much more stable. I had a lot of problems with tall rovers swaying and breaking.

...

Ahhh. Similar to what I'm doing but half the height, and twice the length/width. So I need to trim it down that way...

PS, less/no spontaneous explosions with the latest build. So might try upping the design a bit.

Edited April 2, 2014 by Technical Ben

[jBeta]

I've been following this, and made a first manned attempt at Eve. He's just sitting in Eve orbit at the moment waiting for me to send a better lander/ascent vehicle. Well, the lander part is fine. Today's patch may have made things a whole lot easier, at least in terms of heavy lifters, and less parts to break. Back to the drawing board!

[ScottyDoesKnow]

I've been following this, and made a first manned attempt at Eve. He's just sitting in Eve orbit at the moment waiting for me to send a better lander/ascent vehicle. Well, the lander part is fine. Today's patch may have made things a whole lot easier, at least in terms of heavy lifters, and less parts to break. Back to the drawing board!

I just redesigned my eve ship from close to 2200 parts to 865, and that's pretty much just swapping out the launcher and removing struts. You can see the lander in my signature, but it's a triple asparagus (6, 12, 18 tanks) that doesn't even have struts along the paths of the radial decouplers now. The only struts are a single strut from each tank to the one beside it (so 3 rings of struts). It holds up fine, and even stays together when you open all 12 parachutes at once when I used to have to open 2 at a time.

Edited April 2, 2014 by ScottyDoesKnow

[capi3101]

Yeah, I've been wondering what kind of effects the new parts will have. I haven't had much of a chance to get in there and look at them to compare stats just yet. If I can get something comparable to the Skipjack in one part, that'd be frickin' awesome. Makes me wonder if the challenge of Eve will become "do it with pre 0.23.5 parts"...

[ScottyDoesKnow]

Yeah, I've been wondering what kind of effects the new parts will have. I haven't had much of a chance to get in there and look at them to compare stats just yet. If I can get something comparable to the Skipjack in one part, that'd be frickin' awesome. Makes me wonder if the challenge of Eve will become "do it with pre 0.23.5 parts"...

I don't think it'll be too bad. I think the big thing is the structural integrity change more than the new parts. I doubt people will be using the new size parts in an Eve lander, so it really just helps with getting the lander into Kerbin orbit (which was never that bad, you could always send it up empty and refuel it).

The structural integrity changes will make it so you don't try to land and have the parachutes rip your ship apart. Which I think is a good thing, cause if it weren't for hyper edit to test with I would never have finished this mission.

[capi3101]

Decided to try a re-design of my Eve One craft utilizing some of the new parts, in particular the LFB KR-1x2 - just something appealing about having your tanks and your engines together as one part. Basically just took the same design I was using, swapped out the tanks and engine clusters and added an outer ring of drop tanks. Wound up with an 11.6k delta-V ship with too much thrust, having reduced the part count from over a thousand down to just 67 parts.

I still need to add the extra accoutrements of course (lander legs, chute clusters, ladders), but that's not as big of an issue as it was previously (the part count was really prohibitive for Eve One).

Thoughts, comments on the Eve Two?

[Red Iron Crown]

I still haven't mentally adjusted to the new joint strength, at first glance it looks like the drop tanks should pull the ship apart. Hopefully the increased strength makes the chutes easier to manage, too.

The TWR seems higher than is strictly necessary in the later stages, but there's not really a penalty for it so why not? The part count reduction is fantastic, too. The SRBs in your staging list are sepatrons, I take it? Did the LFBs not separate cleanly without them?

It's going to take a lot of lander legs for a ship of that mass, I'm interested to see what you come up with.

[jBeta]

capi3101,

Did you say you were going for a mountain landing or not? I ask because my design with the new 23.5 parts might be a bit bigger... Wait, I think that image is just "squished" maybe. If those are the large (6480) tanks, then it's similar to my design. I may be overdoing it though, and I also decided to send the Mk1-2 Pod down, because I realized that the new parts probably made it SLIGHTLY easier. That being said, I used maybe 60 percent of its fuel on launch, and I have sent up 4 refueling missions to LKO after that, even with my humongous heavy lifter. I also am creating hack parts to fix some design flaws I discovered, rather than relaunching... (some ill placed ladders on a decoupler!)

I got enough fuel to test an Eve Landing, but not Ascent yet (although I hacked the ship there in the early design phase.)

A trick I've been trying on Kerbin Is rotating to 45 degree ascent immediately after launch, then down to about 22.5 between 10-12km. I already know it isn't a match for Eve, but If I make it to orbit without (loosing velocity on) any stages, plus enough remaining fuel to roughly go to the Mun and back without landing, I think that the ship will make the eve ascent.

Also, It seems to me that once you hit 10-12km altitude on eve, the ascent becomes more like launching from sea level on Kerbin... Does anyone agree? that means a ship with about 60 percent more power than necessary on kerbin should do fine at that point... the trick of course is getting to that point.

On a side note, that new LES makes a convenient way to get rid of your science package once not needed, or deposit a rover... or both

I am also not using mechjeb or any addons, and really this is the only forum thread I have read about Eve attempts.

Anyway, I picked a few pictures out. If you want the craft file ask, but It has several design flaws in it I'd like to revisit eventually.

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Edited April 7, 2014 by jBeta
left out some words

[capi3101]

I still haven't mentally adjusted to the new joint strength, at first glance it looks like the drop tanks should pull the ship apart. Hopefully the increased strength makes the chutes easier to manage, too.

Yeah, I'm not wholly convinced I've got enough strutting on the thing either. I suppose somebody needs to play the guinea pig; might as well be me...

The TWR seems higher than is strictly necessary in the later stages, but there's not really a penalty for it so why not? The part count reduction is fantastic, too. The SRBs in your staging list are sepatrons, I take it? Did the LFBs not separate cleanly without them?

I'm absolutely thrilled about the part count reduction, frankly; that and lack of time were what had kept me from making the attempt up until this point. My calendar still hasn't cleared up...

Yes, those SRBs are seperatrons, yes I added them because the LFB's did not seperate cleanly (that flaring bottom kind of complicates matters) and I'm not convinced I have enough of them as yet.

It's going to take a lot of lander legs for a ship of that mass, I'm interested to see what you come up with.

The plan had been to use the same set up I had for the Eve One (the pair on a fat, short I-beam on a decoupler), just to add a few more. I'll have to test that idea out of course.

capi3101, Did you say you were going for a mountain landing or not?

Nope. My assumption is that I will aim for a mountain and botch it so badly that I land in the ocean. I'm a pessimist. 11.6k actually seems a bit anemic to me but it occurred to me that I could move some of the fuel from the outer ring to the inner one, because obviously I've got thrust to spare there, and that fuel would get expended later in the flight - which should improve the delta-V unless I'm very much mistaken.

I am using TAC, which I plan to use to override the fuel lines during the launch from Kerbin. I plan to send a supply mission ahead which will also include the return module. Dock in Eve orbit, refuel, land, do my buisness, try to take off. Wont be left with much besides Jeb in the Can if all goes according to plan. Have the return stage rendezvous with Jeb and bring him home.

Edited April 7, 2014 by capi3101

[Red Iron Crown]

I am using TAC, which I plan to use to override the fuel lines during the launch from Kerbin. I plan to send a supply mission ahead which will also include the return module. Dock in Eve orbit, refuel, land, do my buisness, try to take off. Wont be left with much besides Jeb in the Can if all goes according to plan. Have the return stage rendezvous with Jeb and bring him home.

That's almost exactly the mission plan I've been working up to, with the minor difference of refueling in LKO rather than at Eve. TAC makes a specialized launcher unnecessary in my testing, just balance all tanks and don't stage anything away and it should make orbit easily.

I couldn't see your final stage of Eve Two very well in the pic, is it similar to the small one you used on Eve One?