Eve Experts?

[KerrMü]

Hello KSP-Players

I´ve got a little question.

Recently the Plant-a-flag-on-Eve Contract popped up in my carrer save.

And this:

... was a complete and utter failiure a few months ago. Really, it was a disaster.

So I´m a bit scared of Eve. But now I´m tempted to try again.

So far I sent out 2 drones, and they found a plateau like spot at the hight of about 4500m about sealevel.

At the moment my Evetta rover is on its way to look for a relatively flat spot to land on. It also got a little landing beacon aboard.

From an altitude of 4500m I need about 11000dV I think. So this is what I came up with:

It´s a much more simple and lightwight approach to the problem. Just one passenger this time.

The landing cage carries all the equipment that isn´t necessary during the launch phase (probecore, chutes, landing legs etc) and shall protect the ascend vehicle at impact.

It also should be able to finetune the point of touchdown via horizontal thrusters, and set the vehicle upright by raising single legs.

Tests on Kerbin went pretty well and the whole thing takes an unpowered impact at 15m/s with no problem. I´m guessing on eve this would be more like 10m/s at that altitude.

Now the launching vehicle:

As said,I guess I´ll need round about 11000m/s dV, so I´m pretty close to that, right? And I think the TWR isn´t too bad either.

So here is the question. Do you see any major flaws with this craft?

Otherwise I would try to get this thing into Eve orbit at the next transfer window. And then try to get it down to the surface in one piece.

The Crew and scince equipment would follow.

The mission shall be completed with stock aerodynamics and stock parts (with one exeption: I´ll use mechjeb for the landing predictions, long rover rides and as backup. So if I mess up, I´ll give MJ a try)

Thx for reading and feedback would be appreciated.

Cheers Mü

Edited October 30, 2014 by KerrMü

[EdFred]

Your vehicle may be too tall, and might end up tipping over if you don't get a really flat spot to land.

Look at the two Eve adventures in my signature for some "squattier" ideas.

[Stratzenblitz75]

I see radial rockomax 24-77s. You should replace them all with the stack-mounted rockomax 48-7Ss as they get much better efficiency and they have a better TWR ratio. That is, unless you feel that rockomax 48-7S are too cheaty.

Other than that, I don't see any major design flaws. You could increase the width of your landing base, but that isn't necessary.

(BTW very nice looking crafts, I really like your Eve probe glider)

Edit:

Just noticed the seperatrons, you should probably get rid of those. They add a lot of mass and I don't even think you need them.

Edited October 30, 2014 by Stratzenblitz75

[Starman4308]

It depends a bit: stock aero or FAR/NEAR aero? Also, take my stuff with a grain of salt, because I haven't done an Eve ascent yet.

In stock aero: bump up the TWR to be closer to 2.0 in the bottom stages. The most efficient vertical ascents stay at terminal velocity: faster, and you waste fuel fighting atmosphere, and slower, and you waste fuel fighting gravity. To get a wide landing base, consider making your ascent stage an asparagus-staged, thrust-plate pancake.

In FAR/NEAR: probably still 2.0 TWR in the lowest stages (the beginning of a FAR/NEAR ascent from Eve will be identical to a stock ascent, albeit at much higher terminal velocity), with decreasing TWR once you start getting to Mach velocities and have to worry about getting into your gravity turn, aerodynamic stresses, and possible DRE burn. No asparagus-staged pancakes: have a slender ascent rocket which lands on a wide but short base. If it's hard to get the entire rocket to orbit with such a weird shape, you might have the bottom attached via a docking port. Once you ditch the base, ascent through lower atmosphere should go a lot quicker than stock, with correspondingly less delta-V loss to gravity and aero drag.

[KerrMü]

Wow, that was fast

@ EdFred: Jep, I´ll consider that when my rover doesn´t find any flat spots in the area. thx

@ Stratzenblitz75: you may have a point there. I just tested it. Changing the 24-77s to 48-7Ss gave me 7 more dV and a bit better initial TWR. THX. I use them on the last 2 stages, so I don´t find them too cheaty.

And thx for the compliment. I love that little plane. It replaced my spacestation as desktop picture. And it flies surprisingly well.

@Starman4308: Stock aero. the depicted TWRs are for Eve. On Kerbin the TWR is well above 2 for the first 6 stages. In principle that is an asparagus pancake. I just put the outer tanks on top to fit with my landing cage idea.

Edit: updated the VAB-pic

Nope, those tanks with the 48-7Ss on are ejected first. Tested it, without the seperatrons they just sit on the lower tanks and lead to mayhem.

And now I´ll try to get some sleep and dream of purple explosions.

Edited October 30, 2014 by KerrMü

[GoSlash27]

I agree with the others; an Eve LV needs to have a low aspect ratio for landing stability, especially in the uneven terrain of higher altitudes.

The atmosphere is like soup, so you don't need much in the way of 'chutes to stick the landing.

But short and wide has gotten me good results.

Good luck!

-Slashy

[Starman4308]

@Starman4308: Stock aero. the depicted TWRs are for Eve. On Kerbin the TWR is well above 2 for the first 6 stages. In principle that is an asparagus pancake. I just put the outer tanks on top to fit with my landing cage idea.

I did catch that. For any body with a thick atmosphere*, vertical ascent TWR should be 2.0 for that body, and your vehicle seemed a little short. The math which says "terminal velocity is the best speed to ascend vertically on Kerbin" is just as valid on Eve, though trying to shave engine mass at the cost of TWR will be a greater concern for an Eve ascent than a Kerbin ascent.

*Duna's atmosphere is so thin that your ascent is more like something from an airless world.

Another way to think about it: staying at terminal velocity will require TWR of slightly > 2.0 (1.0 TWR to fight gravity, 1.0 TWR to fight air resistance, a little bit more to accelerate as terminal velocity increases), and the most delta-V efficient ascent is one which remains at terminal velocity throughout. It might not be the most mass/fuel efficient ascent: factors like mass of engines and staging equipment tend to favor less TWR, but in pure delta-V land, you want to stick to terminal velocity.

Edited October 30, 2014 by Starman4308

[DrMonte]

With TWR of ~1.3 you'll fail to launch. I've tried exactly the same approach and didn't make to 50km. Had to send a rescue mission. As others noticed the TWR of lower stages must be near 2.0 (>1.8).

Legs might brake on EVE. Though that wouldn't affect your lifter much. You can try testing this by putting an orange tank on top of your lander and dropping it down at ~7m/s.

[AlexinTokyo]

I've never done an Eve return, so I can't really comment on the overall mission, although I think it looks pretty good.

Would you be willing to share the craft file for that probe glider? I would love to add it to my upcoming Eve exploration mission.

[Laie]

With TWR of ~1.3 you'll fail to launch. I've tried exactly the same approach and didn't make to 50km. Had to send a rescue mission. As others noticed the TWR of lower stages must be near 2.0 (>1.8).

On my launch, it took me 90seconds at TWR=2 to get from 4000 to 14000m; another ninety seconds to reach 60km (with a gravity turn starting at 25km). My last stage then had a TWR of ~0.7, which turned out to be not quite enough. 4000m/s ain't much if you have to keep your pitch at 60 degrees.

If you start from ~5km, your design might possibly work, but I have my doubts.

Your vehicle may be too tall, and might end up tipping over if you don't get a really flat spot to land.

I consider it doable, especially as you have a rover to scout out a good spot. Be aware that flat surfaces are common, but level ones are not. On a slope, the legs will work against you, with the ones on the downhill side settling deeper in their suspension. You may want to lock the suspension on every fourth leg, then quickly unlock the ones on the uphill side as soon as you know where uphill is going to be.

I suggest you try your lander by putting on some extra weight and landing it in the wild on Kerbin. The high grassland west of KSC should do. This will give an idea of what kind of slope your lander can still handle.

[Redshift OTF]

Hmmm, I think that lander might work. I'm sure you only need 8500 DeltaV if you are taking off from 4500m as you don't have to contest with the really thick part of the atmosphere. You may have some issues with controlling the craft during ascent due to atmospheric effects. One thing you may find useful is to attach a barometer to you drone, (which looks awesome btw), and you can find which heights are equivalent to Kerbin's atmospheric thickness. I think 1 atmospheres of pressure starts at 13km up?

[metaphor]

That craft should have enough delta-v to reach orbit from 4000m, even with the low TWR. It looks like it would be relatively stable on landing as long as you don't land on a big slope.

The sepratrons aren't really needed, and they might be put on the wrong stages.

I would say just try it out and see how it goes. One of the harder parts will be landing at your target on Eve.

[KerrMü]

Hey Folks

Ok, first here is the file for the subassembly of this:

http://www./view/vwftdcn4xt8kisq/Solar_Glider_mediafire.craft

Retrorockets are included.

Warning: If you detach the nose section, it won´t attach again. The attachment points get lost. (subassemblys...)

Also the staging gets messed up a bit. sry.

And now... too late, I´ve launched it.

Hell yeah! that was expensive.

I admit I felt the urge to revert the flight, but meeeh, at least it looked pretty. (walks off and does some science missions to earn some funds)

Thank you for your supports and doubts.

I´ll keep this thread up to date, so if anyone is interested, you can see me fail miserably. (may take some time, cause I´ll be probably away for the weekend)

Have fun, cheers, Mü

[Kobymaru]

About your first lander: I feel your pain.

About your current lander: as mentioned by others, the TWR is way too low.

Happened to me too

You have to take into account that the atmosphere reduces engine thrust A LOT, especially for non-aerospike engines. Just look at how sad he is

[KerrMü]

Hello Ladies and Gentlemen

My Eve mission made some progress over the last few days.

First I took the Evetta rover down to the surface and cruised around a bit to find a suitable landing place for Leia (the ascend vehicle).

The widest almost flat area I could find at a reasonable altitude was at 4390m. I still think that could work, so i deposed the landing beacon and drove the rover to a save distance.

Then I landed Leia.

Wow, that was the most nerve wracking experience I had in this game for a looong time. The piloting was done manually, but with the readouts from MJ.

It actually took me 3 trys, but with a little practice I could keep the landing prediction marker over the target, and the horizontal thrusters did the finetuning while parachuting down.

I touched down pretty close to the beacon (that little bug between the landing legs is it)

Now I just have to get a Kerbal there.

Just before the weekend I´ve already designed the ship for that mission (still hasn´t got a name).

So today I assembled it in orbit, docked a landing capsule and a gilly lander/rescue-tug (to hopefully catch Leias head in low orbit), and then filled the whole thing up.

In this pic my asteroid tug is still clawed to the ship. It turned out that it is very versatile and so I use it for fuel transfers, deorbiting debris etc.

Tomorrow I´ll take the crew up (Bill, Jeb, Bob and Rayden) and send them on their way to Eve.

So long, Mü

( I think this thread morphed into a mission report, so if any moderator decides to move it, it´s fine )

[Laie]

Been watching 2001 a lot, maybe?

Anyway, good-looking ship you got there.

[KerrMü]

Been watching 2001 a lot, maybe?

Anyway, good-looking ship you got there.

That movie is definitely in my top 5, and thx.

Small update:

I have arrived

and landed

Collecting all the sweet science right now. Gonna make a rover-ride to the seaside, and then try to get in orbit again.

I´m away for the weekend again, and I just can´t wait so long to see if I can make it or not.

[KerrMü]

YEEEEEEESSSS!

It worked! At my try I messed up the gravity turn a bit and hadn´t got enough oomph to circularize. Then I gave Mechjeb a try, and he got Jeb into a nice 100km orbit with a bit of fuel left. And that gave me some time to take some screenshots.

I´m gonna try this again manually, but for tonight it´s enough.

Game on, cheers, Mü

[Raptor9]

KerrMu, awesome thread. I've been struggling to find a solution to Eve using just stock parts. I never considered building two vehicles, one optimized for ascent and one for descent; don't know why, it's such a simple idea. I'm going to see if I can get a Mk1-2 Command Pod off the surface in the ascent vehicle so I don't have one lonely Kerbal exploring the purple surface. If I do, I'll post the screenshots here. Kudos

PS: do you have anymore screenshots or another thread showing those Duna landers in your signature. They kinda look like DC-X/Delta Clipper rockets.

[Raptor9]

UPDATE: So I've tested the second version of my ascent vehicle. As of this post, I launched from an elevation of 5691m above sea level, and was able to make a 102km apoapsis with 1553m/s delta-V remaining (at fuel exhaustion) on the gravity turn to circularize the orbit. My ascent vehicle still sports a Mk1-2 Command Pod, which I know is the heaviest, but I'm intent on sending three Kerbals to the surface and back. Logic would dictate landing three smaller ascent vehicles on the surface (one for each Kerbal), but I know this design can work. It's just a matter of getting into the grinder about getting the right engines for TWR vs ISP at certain points along the trajectory, weight-saving, and making sure I keep it as close to terminal velocity as possible.

Call me stubborn, but I know I can make this concept (proven by KerrMu) work on a 2.5m pod as heavy as the Mk1-2. It's not impossible, I just haven't quite figured it out yet.

EDIT: My favorite part of the testing process is the initial launch, seeing the gantry towers explosively blow away as the ascent vehicle lifts off is so cool

Edited November 16, 2014 by Raptor9

[SgìobairOg]

KerrMü, KSP is telling me there are some non-stock parts in your Glider, is that the case or no?

Also, how did you get it to Eve?

[EdFred]

More importantly, how do you keep that thing from tipping over? I can never find a level enough place to land something that top heavy.

[KerrMü]

UPDATE: So I've tested the second version of my ascent vehicle. As of this post, I launched from an elevation of 5691m above sea level, and was able to make a 102km apoapsis with 1553m/s delta-V remaining (at fuel exhaustion) on the gravity turn to circularize the orbit. My ascent vehicle still sports a Mk1-2 Command Pod, which I know is the heaviest, but I'm intent on sending three Kerbals to the surface and back. Logic would dictate landing three smaller ascent vehicles on the surface (one for each Kerbal), but I know this design can work. It's just a matter of getting into the grinder about getting the right engines for TWR vs ISP at certain points along the trajectory, weight-saving, and making sure I keep it as close to terminal velocity as possible.

Call me stubborn, but I know I can make this concept (proven by KerrMu) work on a 2.5m pod as heavy as the Mk1-2. It's not impossible, I just haven't quite figured it out yet.

EDIT: My favorite part of the testing process is the initial launch, seeing the gantry towers explosively blow away as the ascent vehicle lifts off is so cool

http://i1356.photobucket.com/albums/q737/raptor_9000/Placeholder%20Photos/screenshot93_zps4b150151.png

Hey Raptor

If you can do that, then you´re my hero.

Fiddeling with the engines, weight, staging might get you quite a bit more dV. 1500m/s is still a little mountain to climb, though.

As I know, you want to build your own lander, here is the craftfile for my Princess Leia. Just in case you wanna check out my staging sequence. That way turned out to be the most efficient for my craft.

http://www./view/5zboemh6odhyeu4/Princess_Leia_Mediafire.craft

Good luck Pal, and keep us up to date.

KerrMü, KSP is telling me there are some non-stock parts in your Glider, is that the case or no?

Also, how did you get it to Eve?

Hello SgìobairOg

I just doublechecked the file on a stock version of 0.25.0. It works here, so I am sorry, but I don´t know what´s the issue there.

And here is how I got it to Eve:

I´m gonna have to test it on duna soon.

More importantly, how do you keep that thing from tipping over? I can never find a level enough place to land something that top heavy.

Jeah, that was not easy. Took me 1.5h driving around in that little rover to find that spot. And landing on it was (like I wrote above) the most difficult thing I´ve ever done in this game. Got square eyes, cause my nose was glued to the monitor that evening.

Hilltops are often pretty falt.

--------------------------------------------------------------------------------------------------------------------------------------------

On another note:

I finally found some time to play today.

So after my first manned landing on Gilly ever

I attempted to rescue Jeb from Low Eve Orbit.

My original plan was to take both vehicles back home to kerbin (that´s why the gilly lander´s got chutes). But the inclination of the target was to steep, and the little tug didn´t have enough juice. (I had to mess up something on that mission ) So I had to send it out unmanned to refuel Leia. And so Jeb safely got back to the mothership.

And after a huge Snackparty they all set off on their way home to Kerbin.

The end of that story is near.

Cheers Mü

Edited November 17, 2014 by KerrMü

[Raptor9]

KerrMu, that first screenshot is awesome!

UPDATE: I'm on Mk3.1 now (yes, design modifications have taken to sub-Mk numbers now ). I've managed to knock off a couple hundred remaining delta-V remaining at the apoapsis. I'm gonna take a page out of your book with that lander in your signature and use a Hitchhiker storage container instead of the Mk1-2, it'll save me a couple tons, and give me the option to return four Kerbals instead of three. Among a number of other small revisions....getting closer.

EDIT: Mk4 down to 880m/s delta-V left

Edited November 17, 2014 by Raptor9

[Redshift OTF]

Welcome to the club Kerrmu! Escaping Eve is one of the hardest challenges in the game.