Landing on Eve and Returning Back to Kerbin

[KerikBalm]

1 hour ago, Lt_Duckweed said:

With a sufficiently optimized ascent, you don't use rtgs.  Prop ascent phase should only take 12-15 minutes.  If you run the math, rtgs only beat batteries for ascents taking at least 35.5 minutes.  So if you use batteries you are looking at  2-3x less mass and about 7x lower part count vs rtgs.

Yea, but no batteries are visible either.

No power storage or supply parts are visible. The craft must refuel by doing its own isru, that takes power... How is he supplying the power for his 12-15 minutes ascent?

[Lt_Duckweed]

44 minutes ago, KerikBalm said:

Yea, but no batteries are visible either.

No power storage or supply parts are visible. The craft must refuel by doing its own isru, that takes power... How is he supplying the power for his 12-15 minutes ascent?

I mean, it's pretty obvious he's using batteries.  They are either in the fairing or under the skin of the craft.

In the initial launch from Kerbin you can see that he has 48000 electric charge.

[KerikBalm]

1 hour ago, Lt_Duckweed said:

I mean, it's pretty obvious he's using batteries.  They are either in the fairing or under the skin of the craft.

In the initial launch from Kerbin you can see that he has 48000 electric charge.

I mean... the craft I showed, about half the mass of his, had over double that, and was actively producing power with fuel cells, and nearly exhausted it's batteries after 7 minutes...

He must have at least some power generator for the ISRU. I suppose his more massive craft can use less EC through drag exploits (note the visible fairing bases with no visible fairing, and a sub obviously using part clipping to alter buoyancy which is also a way to do an exploit to get less drag), but I am suspicious, as he never shows EC status in flight, and flies around on props for a while before landing, and still does his ascent.

Even the fairing cargo is exploity (I work within constraints of the mk3 bay, or find a way to not need aero shielding, or accept single use fairings)

Some more transparency about how that works would be nice, because I don't think it's a great example for players who wouldn't build things that way because they seem exploity 

[GoSlash27]

On 6/28/2021 at 11:30 AM, ecyenskeyn said:

Hello people,

I started playing career mode  a while ago and after completing some easy peasy (Mun, Minmus etc.) missions, I have gotten stumbled by a mission that requires me to land on Eve surface and come back to Kerbin.

The thing is I feel OK with general controls and methods of interplanetary travel (I was even able to do a flyby near Eve and return back to Kerbin earlier), but after many attempts to build an adequate ship for this particular mission I failed mostly because having insufficient delta-V. I feel I have to note the most powerful tech I currently have access to;

1- RE-M3 "Mainsail" Liquid Fuel Engine

2- S1 SRB-KD25k "Kickback" Solid Fuel Booster

3- Rockomax X200-32 Fuel Tank

 

After building a 1400000 $ monstrous contraption (cannot upload image for some reason "https://imgur.com/a/Hka5y4d") and yet failing again because of insufficient delta-V, I started to consider if I was doing something wrong and looking for online material. Only videos I could find about this mission involved more powerful tech than I currently have, so I need your help.

What I need is a video tutorial or some thorough example that shows how it should be done with my current tech or similar (FOR CAREER MODE). All help is appreciated.

Thank you in advance.

You inadvertently accepted the most difficult challenge in the game. I did manage to pull it off years ago, but that was with a more forgiving aero model and liberal application of asparagus staging. I also did it with a combination of kraken drive and infiniglide, but that's about as exploit-ey as you can get without blatant cheating.

 My advice is to 'live and learn'. Career mode can be fun, and part of the challenge is recognizing a bad contract when you see it.

Best,

-Slashy

[Blaarkies]

The easier way i found was to start cutting down on payload mass for the accent vehicle.

I wanted to get a kerbal from Eve surface to orbit? 
So why send a command pod with when they only need a lawnchair inside a fairing?

If you have the Breaking Ground DLC installed, such a lifter can mass less than 10t. I can't find the craft file anymore, but I remember using ducted propellers up to about 30 km altitude. From there, I left them running and decoupled the propeller section, pulling itself away from the craft which then fire it's engines. I didn't even need to use the Kerbal EVA jetpack to insert into orbit, so there was even more mass that could be cut.

I'm not saying throw your own ideas away and just do this (it was fun for me too the first time figuring out how to do it with rockets only, it took about 50t at surface). But the smaller, lighter and simpler you make the craft, the easier it becomes to get that thing down through Eve re-entry in one piece.

I wish there was some achievements tracker in KSP (regardless of platform) just to see what percentage of players actually achieve this for real in stock...I bet it is less than 5%

[cerberusti]

If you still wanted an eve ascent vehicle, this is the one from my recent career (I built and flew it last night).  It has generous margins, a full science package, three crew, can land and take off from land or water, moves decently fast in the lower atmosphere to get from point to point, and is relatively cheap and small at 230k credits and 218 parts.

https://steamcommunity.com/sharedfiles/filedetails/?id=2604415070

 

I decided to play through again as this is the last patch, so I deleted all my old saved games which mostly no longer work well and made a "Final" game.  I am mostly only doing the progression missions and general science, and doing each progression mission as presented.  Eve is the first planet, and after the flyby I had the mission to return a craft from the surface.  Minmus and the Eve flyby (with as science lab) provided enough science to entirely run the tech tree prior to this mission, and after buying facilities I had a couple million to build the return craft and a general use tug to get it there.

The progression mission itself is:

Splash down into the oceans of Eve

Walk on the surface of Eve

Return to Kerbin from the surface of Eve

 

Another goal was to hit each biome if possible to get a nice full science load to return for reputation and cash, and I also had a contract for one volcanic rock, so it needed to be able to move a bit.

There are a few options here, from multiple minimal drops, to suborbital hops with an ISRU, to a separate ascent vehicle and plane they can use to run around the globe then return, to spaceplanes in both the SSTO and staged variety.  I went with a staged spaceplane, mostly due to the visit to each biome taking a while and saving inside the atmosphere not being ideal (so you do not want to screw up a landing).  SSTOs are marginal enough that you cannot really carry niceties easily, such as science, extra crew members, safety margins, etc., and going large to compensate for the mass is kraken bait under Eve conditions.  I prefer a small craft which does not cause any additional lag.

Not being a masochist, I designed it in the mission builder first.  There are no mods installed and nothing clips, it is entirely stock.  It works with all settings, including g forces (nothing will be destroyed or crash, although everyone will pass out during Eve entry with plenty of time to recover before landing.)

 

Only fill three crew, one of which should be a pilot.  It will initially make orbit from Kerbin by flying to 5km or so on propellers (action 1 to start and stop propellers, action 2 opens and closes the cargo bays, custom slider 1 is propeller angle, hit F12 to see the aero display to make takeoff easier, and pin a rotor and a propeller to see useful metrics), then close bays and use the attached boosters from there, staging them when empty, and expending most of the fuel on the craft to reach orbit. 

It is marginal without the boosters, and may be able to SSTO itself on Kerbin using just the one vector plus a full fuel load.  I wanted an easy ascent without redesigning anything so I just strapped on a couple of small boosters to get it off Kerbin into orbit intact.  Press action hotkey 2 to close the bays, and 3 in order to disable fuel crossfeed on the top decoupler once in orbit, so later during the ascent it will not move on automatically to the last stage of fuel.  I did not need this fuel during my ascent from Kerbin, but if you do you can use it.

The standard docking port on the top is aligned with the center of mass once fueled, so your space tug of choice can dock, refuel it, and push or pull it to Eve.  It should be in an Eve orbit between 100km and 200km when detached.  

Once in a suitable low Eve orbit, turn retrograde and open a fuel tank menu on the outer wing structure then carefully use all the the fuel in the wing structure to get down to a safe entry speed.  It has twice the DV for this purpose than I managed to do this with in testing, and that makes it a fair bit easier and more reliable to survive reentry.  Do not use the fuel in the ascent vehicle, which you need to manually watch and stop as while fuel priority uses what is should first, it will not cut you off automatically before using the ascent fuel, as it is using the engine for the ascent vehicle to deorbit. 

I vaguely turned towards the horizon and up side up before hitting the atmosphere, but I am not sure how necessary that is.  The spin on entry may be destructive without it as the g load will increase rapidly.  Cut sas once entry effects show up and let natural aerodynamics take over.

It will orient itself so it is against the wind and slowing at nearly max speed (CoA is above CoM), so it will lose speed very quickly.  Nothing should overheat although it will show the bar, and if the g forces setting is on everyone will pass out from this.  It will fall until about 20k, where it will naturally start reorienting towards prograde, by 15k it will mostly be stable and you could start flying if desired.  Letting it fall to 1km or so then turning on sas and landing is faster.  Once on the surface or in the ocean, stage the fairing off of the science package.

Fly around doing science, the container at the tip can store it for ascent easily and it can go decently fast.  If you need to use the ladder on land, the gear should be raised to lower the ladder into reach.  All experiments which need to be cleared between uses are in range from the ladder.  When ready to ascend transfer the kerbal into the cabin, make sure any science is collected, and stage the science package off.

You can ascend at a 70 degree angle at over 100m/s on propellers, until you reach about 16km, at which point you should stage the wings off and max out the engine, keeping the 70 degree up heading until the vector runs out of fuel (which it will if you hit 3 earlier to disable crossfeed).  Stage the vector off to enable the terrier and aim for the horizon, there is plenty of time to ap to make the burn.  Once in orbit undock the docking port to leave just the cabin, command pod, and docking port, which can be dragged back to Kerbin, attached to a landing pod, and dropped into the atmosphere to return the craft.

[Curtis]

Maybe I'm just lazy, and I haven't landed/returned from Eve yet, but I plan on putting a space station in orbit around Eve first.  It'll have plenty of ore and a fuel converter, and that should provide adequate refueling for my Eve lander.  I did the same for Jool.  Refueling space station is in orbit and I'm ready to explore all the moons!  

[Scarecrow71]

Take a look at the Kerpollo Challenge thread.  That might give you some ideas as to how to design an Eve ascent vehicle.

 

[AndCar]

Hi, after working hard on it, I was able to design and build a ship capable of landing ready to leave.

The problem is that as soon as I touch the surface the landing legs bounce a lot, knocking over the rocket.

The same thing happens even with a small capsule while deactivating all the reaction devices.

Can someone help me.

Thanks for the replies

[Axelord FTW]

With Advanced Tweakables (I think), you can play with spring strength and damper. Find something suitable, and test it on Kerbin.

[AndCar]

On 12/9/2021 at 3:14 AM, Axelord FTW said:

With Advanced Tweakables (I think), you can play with spring strength and damper. Find something suitable, and test it on Kerbin.

Thank you!

I don't know it!

I'll try

 

[jclovis3]

On 6/29/2021 at 11:00 AM, paul_c said:

The contract system is 'flawed' or 'works' in that if you land on a body, it will give you contracts "to" and "from" that body (ie tourist trips, where to be successful they need to safely return to Kerbin). And also it will come up with "extract ore from...." contracts where its a huge amount of ore to get into orbit or somewhere else.

Another indirectly related one is where a space station is specified, but with a huge amount of liquid fuel or ore on it, and/or a piece of equipment which will never be used (resource scanners not in polar orbit, etc).

I went back in to KSP recently waiting for KSP2 and decided to try playing on one of the harder difficulties. I still allow reverting flights however. Currently, I am working on my second land and return ship. The first was a single seater that I messed up and forgot to add a way to move science back up to the departing ship, so I have to go back for that Volcanic Rock. I found this discussion because of your statement about the contract system being flawed. It does not pay well enough for any of the contracts requiring you to land and escape into orbit.

As for how to do it, and this is purely vanilla with the DLCs but no mods, the concept is that you use the cheat menu for testing steps only while you design, but then use your design for the actual mission. First build a ship that takes off rather quickly and can escape the sun purely on launch from Kerbin and test that. You will want stages and expect to have barely any parts left by the time you set your orbit. My ships all have a docking port on the base of the command module so I can release that last tank and then dock with the "taxi" shuttle. This taxi shuttle has the larger liquid fuel engines and refinery for visiting Minmus and Gilly on the way there and back. In my second build, I am using the Mk1-3 command module as it seats 3 and I am preparing for tourism and training for my own Kerbals. I have completed all my testing on descent and landing to take off and orbit already so its good to go.

Once you have a tested ship for takeoff, you have to add on everything you need for landing and anything you might want to do on the ground. Stuff has to be ready to be released either before or as you launch from the surface, and expect to release everything you don't need to ascend (including parachutes). I advise having a girder structure to build a cage for having 10m inflatable heat domes at both ends of the ship. The end you want to enter into the atmosphere first should be concealed behind just one of these, centered. You can use smaller heat shields around it as necessary for your cage as I did to protect the vertical frame and parachutes. The tip of your ship, if you are entering retrograde should have 3 or 4 of these and opened up like an umbrella to slow you down. The frame of your cage will have any parachutes you need and landing gear. If you plan to refuel from the surface (Eve has rich ore), your cage will have to support that too, but then plan to descend with empty tanks to make up for the weight of the converter and drills.

In my latest rig, I have just an X200-16 fuel tank and RE-J10 "Wolfhound" engine to push me gently into the atmosphere from under 110 km Pe/Ap. You want to skim for good aerobraking rather than trying to dart straight down so expect to set a maneuver node and quick save so if you miss your target landing area, you can reload from that to adjust the location of your maneuver. More direct descents can be done if you have fuel and engines to burn on your way in, but this will require rethinking your heat shield situation.

My newest ship has 16 S3 KS-25 "Vector" engines around the first detachable parts and a RE-M3 "Mainsail" down the center. The four detachable side stacks are installed in pairs so I don't have to carry all of them for a long ride up. Staging a pair off at a time keeps you balanced and you can have six or eight outer columns depending on what size tanks you're using. I started with Mk2 tanks at the top and used the adaptors to work my way down to a X200-32 fuel tank on the bottom of each of those four outer columns. Then the TVR-400L Stack Quad adaptor supports four Vector engines. The side columns on mine remain in a single unit with only the vectors at the bottom but some ship designs used several stages to drop lower tanks and use engines higher up the stack. I did that only for the center column. I wanted more time with good control surfaces to stabilize my heading in case of a sloped landing (high chance of that on Eve).

In my testes, the speed actually gets up so high so quickly, that if I don't turn down the thrust, I'll run out of fuel in the last side pair before getting high enough to remain stable after release, which means the center column flips back. I also realized that once reaching over 750 m/s with this design, I can cut the thrust back as I'll be reaching a high Ap already and use some of that to help with setting my orbit, but ultimately, the "Wolfhound" engine will be my last stage to push me into orbit because of the high ISP (70 ASL - 380 Vac). It has only 375 kN of thrust in the vacuum, but that is sufficient to push a single X200-32 fuel thank and the attached command module and probe core out into orbit.

The "Taxi" is just a separate ship which uses a bunch of Nerv Engines and has a refinery for refueling. It is one of my reusable ships so the expense of all those Nerv engines is made up for in the long run. It uses the largest docking port on the top to join my command module after getting back into orbit and the full ship with cage will have a large docking port at the bottom for the taxi to connect with for traveling in route. The taxi does not launch with the Eve lander as it may already be in orbit of Kerbin or Minmus waiting to tag up with it. I have another reusable booster ship that pushes the Eve lander into orbit of Kerbin and then drops back down for collection by the KSC. Having such a reusable liquid fuel ship for this purpose saves a lot of money as well.  This kind of ship uses plenty of parachutes and some braking heat shields on the sides to return safely and land or splashdown without losing a single part.

What I find messed up about these contracts though is that even without counting any reusable taxi ship or launcher, just the Eve lander itself will cost way more than the contracts will pay. Mine is at about 442k funds with full tanks. Oh, that's another point. To aid the taxi in getting my ship there, I drained the Oxidizer of all my tanks and set up a fuel piping system to push liquid fuel from all the tanks down to the taxi upon hookup. The taxi comes with some cargo boxes containing more struts and fuel lines that the engineer can attach after docking if need be. These fuel lines can be set to disconnect with an action group, and to ensure I don't accidentally do this early, I use one of the alternate set groups. I plan to run dry of oxidizer all the way to Gilly, then refuel there using the docked Taxi and release those extended fuel lines to ensure the ship for descending keeps all the needed fuel to take off. My first ship, the single seater, did not have this and I pushed full tanks all the way there. Uh that was tough.

One more thing. If you do decide to stage both laterally and vertically while taking off, complete a full vertical stack first before moving on to the next as this will decrease your air resistance considerably. Using fuel lines rather than allowing cross-feed makes it easier to see when an engine runs dry and is ready to release, but you may want to allow the cross-feed in parts to keep those engines just a little bit longer, like half of the next tank or so, if needed for the control surfaces or extra boost. Just remember that the fuel lines are sensitive to the order you attach them, like struts. Struts should always be attached on the first part to leave and then connected to any other part so you lose them when the part leaves.

I won't be video recording the whole process from KSC to Eve and back because I am running several other missions at the same time and want to close this posting out now. I hope I gave you enough to think about in your design. In my first single seater design, I had column stacks of the smaller tanks with "dart" engines along the way as they were the appropriate size for those tanks.

[bigcalm]

Yeah, it should be noted that Eve-ascent is probably the hardest challenge in the game.  There are so many phases that you need to think about, and you kind of have to do it in reverse order and it's easy to end up in a situation where what you've designed just won't work and you need to start again.

So let's talk about the phases in reverse order --

The ascent:  You will need a vessel with roughly 8k delta v to go from the surface of Eve at sea level to orbit around Eve.  It needs to be as aerodynamic as possible, and needs to have as little payload as possible - including doing the stuff that you always forget to do like removing monopropellent from the capsule.  Save every gram you can!  You want a separate craft to rendezvous with the orbital craft, either to pick up the crew, or dock with it to take it back to Kerbin if you want.  Don't try and design it to get all the way back to Kerbin from the surface of Eve -- you'll be adding a lot of additional complexity to an already mammoth task.  If you have MechJeb installed, use its delta v calculator in the VAB, set the body to Eve and pay attention to the SLT number - this is the surface-level-thrust and takes into account the atmosphere.  It should be above one for every stage within your rocket (except possibly the final orbital-insertion burn).

Because of Eve's gravity and soup-like atmosphere, you'll need big powerful engines that work well in atmospheres - the Vector, the aerospike, and if you've gone really big, the Mammoth.  You also want it as aerodynamic and as slippery as a fish whilst in the atmosphere as the drag from that atmosphere will huuuurt your chances.  My typical ascent profile tends to be straight up for the first 35k of atmosphere and *then* do the gravity turn.  And seriously, think about aerodynamics when designing.  I had a rocket that could make it from sea level with ~1k delta v to spare, I added some stabilising standard fins to it because the gravity turn was a bit hairy to pilot and just the addition of those fins made it such that the rocket would then not even get close to orbital velocity.  With Kerbin, you can brute-force stuff, use reaction wheels, not worry about aerodynamics all that much, but with Eve you very much have to care,

We also want to talk here about staging, which you will have to do in some way to get to 8k delta v.  I have often designed my Eve ascender where ejected stages just end up crashing into the rocket, and no amount of separatrons fixed it.   You should carefully consider the aerodynamic forces that will be at play when you eject stages -- is the atmosphere going to push on it on one side after ejection, and cause a rotation that smashes it into the active stages?  

Stuff that can help:  Tail fins are the best stock aerodynamic surface in the game.  Use them for aerodynamic stability, not just on your Eve ascenders but on every rocket that goes in an atmosphere.  Try to make the rocket relatively tall and thin.   It's kind of cheaty but a closed air-intake is the most aerodynamic thing you can put in an airstream.  When doing the gravity turn be *gradual* - it's easy to cause flip-out, ruining your chances of reaching orbit.   Make sure to eject every gram of weight off your ascent stage before ascending - don't take the landing legs or the deflated parachutes with you.  If you want more than a one-man ascender, consider using the aircraft cabins as they're the lightest crew-to-cabin ratio you can get.  Don't be afraid to throttle back when in the lower atmosphere - in the dense soup below about 20k, trying to go above about 250ms means that almost all of your thrust is going to be effectively used by aerodynamic drag and not accelerating your rocket.

The ground:

So you managed to land!  Congrats!  You thought about how the Kerbal was going to get from the capsule high up on the rocket to the ground to plant a flag and get back didn't you?

Before moving from the ground-phase to the ascent phase, you should be able to eject everything that is unnecessary for the ascent phase - parachutes, ladders, science gear, ISRU, ore tanks, etc.  If it's not needed for the ascent get rid of it before you start ascending.

With the kerbal-to-the-ground problem, there's two basic ways - either have a capsule low-down near the ground, where you can then 'transfer' crew from the bottom capsule to the one that they'll be sitting in when they launch (disadvantage - you lose science experiments), or have a Acme corporation ladder-style arrangement from the top capsule to the ground that can be ejected before take-off.

Stock landing gear suuucks on Eve.  You can easily end up with situations where it vibrates, explodes, judders or simply doesn't hold it steady, and blows up in bad ways if you shift focus to another vessel and back again.   This just generally means extra testing, careful placement, lots of strutting and possibly fiddling with some damper / spring settings in advanced tweakables,  For particularly large landers it can sometimes be worth trying just landing everything on girders rather than landing gear, as they're pretty sturdy and don't suffer from the same issues as stock landing gear (they suffer from DIFFERENT issues!).   The other issue will be slow movement - you can perhaps use ground tether to fix this which should work most of the time but may also occasionally cause some of your landing gear to explode either immediately or when shifting focus from to another vessel and back.   When a vehicle is moving, even very slowly, a Kerbal on a ladder will not have the option to 'climb out', which gives rise to certain scenarios where a kerbal can get out, reach the ground to plant the flag, and then not be able to return to the capsule, so if possible, have your ladder array such that a Kerbal can go round something circular, let go and simply be standing on something rather than always requiring 'climb out' to be available.

The descent:

From a low orbit of Eve, you will be hitting the atmosphere at approximately 3km/s.  For an interplanetary intercept, you'll be hitting at least 4 km/s and also won't have much choice on *where* you land.   Both are dangerous and extremely likely to make things blow up on atmospheric entry without heatshields.

However, just sticking a big heatshield on the bottom is unlikely to work, because to make it aerodynamic in the ascent phase, the rocket is now tall and thin, meaning that the centre of mass of the rocket is a long way from the heatshield.  Which means as soon as you start hitting the soupy atmosphere, the craft will then spin round to face the titanic heat of atmospheric entry and blow up.

The way to fix this is to add extra heatshields at the top of your rocket, at an angle, like the following image.  What this will do is make it a little like a very draggy dart - the heatshields acting as the flights on a dart to keep it firmly planted in the direction of travel, and all the fragile explodey-bits safe from the air-stream.   Continually rotating the craft during atmospheric entry can also help as it allows different bits to heat up at different times, possibly preventing an explosion.

 

Naturally, if you go with the configuration in the image, your entire rocket *must* fit above a 10 metre heatshield, which may involve redesigning the ascent or ground stages.  If you find you need the upper heatshields, you will also need the ability to eject them as soon as you reach a low enough speed (500ms ish).

After ejecting the upper heatshields, you then need to inflate the parachutes, which I only tend to do once I'm below 10k in altitude - it's easy to end up with a situation where you eject the top heatshields, inflate the parachutes and then because you no longer have the draggy things at the top have Eve's gravity accelerate you to the point where the parachutes go poof.  Which isn't great.  Then, after the parachutes have fully deployed, you should be able to eject the bottom heatshield without crashing into it (adding weight / separatrons can help here - if it's too light, i.e. just the heatshield it's easy to crash into it and have your precious engines destroyed).  Don't forget to deploy your landing gear after this and hope you don't land on a steep slope !

Off Kerbin / to Eve:

Given the amount of effort involved in designing the Eve-portion of the craft, I'd recommend just brute-forcing it however you can to get it there.  You have mammoths available on Kerbin and can refuel vessels in orbit - do it and don't care about the cost!  I also try to get the vehicle in a relatively low orbit around Eve before attempting descent/ascent, as this will mean I can more easily pick a landing spot and I'll be hitting the atmosphere at the lowest speed.

Testing

If you're not adverse to it, design and test it in Sandbox mode, use debug F12 cheat menu to put it in orbit of Eve for testing, and only copy the craft over to your "real" game when you're happy.

If you want to test in sandbox mode at Kerbin, there's a few bits of "simulation" that you can try which will get close to the conditions you'll experience at Eve:   By putting the craft in a highly elliptical orbit and then adjusting the periapsis to hit the surface, the craft will hit Kerbin's atmosphere at roughly the same speed as you enter Eve's at from low orbit.  The ascent phase you design should be able to lift off from Kerbin, get to orbit, de-orbit, get close to the ground (you won't have landing gear to actually land) and then make it back into orbit a second time.  You should also test whether the kerbal can successfully get out of the capsule, to the ground, and back up to the capsule and safely eject all of the parachutes/landing gear/etc.