Which ship design is best for Eve?

[Silverwood]

Hello All,

Well I am playing in career mode, and have decided to have a go at Eve. I have tried a few modified rockets, but can't get enough fuel to make it!

Has anyone got a design using any features from the VAB up to 300 science. That is as far as I have got. Or is it too hard at this stage?

Keith

 

[Human Person]

You might not want to land on Eve without the Vector or the Aerospike engine. Those are the only ones with acceptable ISP at Eve-Sealevel.

 

It's possible to go with lower tech, but then you have to land on the highest mountaintops of Eve. Your best bets would be the Mainsail and the Twin-Boar engines in that case.

Edited July 10, 2017 by Physics Student

[Dafni]

Do you just want to get to Eve? (a fly-by mission, an orbital probe, an impactor, or one-way mission or something like that?)

Or do you want to make a return mission?

I am not very familiar with the tech tree these days, but I believe the first should be achievable with relatively low tech (only takes parachutes to land, and they work very well there BTW), and for the later see the post of @Physics Student above.

Edited July 10, 2017 by Dafni

[Weywot8]

It can take a lot of fuel, depending on when you leave. On the other hand, if you leave at the right time during an optimal transfer window, you won't have to design something different if all you want to do is get into orbit and return. You would have access to heat shields already so the best time to leave for cheap is given by this nifty tool assuming aerobreaking. All for only 1100dV. Optimal return is 1400dV. So your ship is going to be bigger to get into Eve orbit.

As Physics Student said though, returning from an Eve landing is a different matter altogether. Have you tried looking for inspiration at KerbalX?

 

 

[Silverwood]

Ok thanks.

At this stage it is just one way - and a probe only.

[Spricigo]

 

Reaching Eve, and even landing at Eve is actually easy at this stage. Its the return to orbit from the surface of Eve that is the big deal.

from the wiki:

Quote

It is especially notable for its extremely thick, dense atmosphere, which makes aerobraking and returning two of the most dangerous activities in the game. Additionally, Eve has the greatest surface gravity of all the planets, and the second highest escape velocity, second only to Jool.

In short: is (by far) the hardest planet to launch a vessel from.

My advice: explore Gily, Ike and Duna instead, maybe even the Jool system (and there is rumours about  another celestial that you can also visit). Or use one way probes. Eve is not a destination, its a challenge.

[Silverwood]

Oh, ok I thought it might be easier than that!

I shall take your advice then.

Thanks.

Keith

[Cpt Kerbalkrunch]

1 hour ago, Spricigo said:

My advice: explore Gily, Ike and Duna instead, maybe even the Jool system (and there is rumours about  another celestial that you can also visit).

Poor Dres. The Rodney Dangerfield of planets.

[Snark]

2 hours ago, Silverwood said:

At this stage it is just one way - and a probe only.

Eve is really, really easy to travel to and land on... and incredibly difficult to take off from the surface and get back to orbit.

But if it's just one-way, you're on easy street.  Just make sure you have a heat shield, because you will absolutely need it.  But as long as you have one, even a small parachute can land a fairly heavy probe on Eve, given how thick the atmosphere is.  You can send quite a low-tech probe to an Eve landing without much trouble.

 

As for taking off and getting back to orbit-- save that one for last, after you've mastered most of the rest of the solar system.  An Eve lander that can return to orbit is one of the biggest challenges in KSP.  You can't just "wing it"-- it takes careful and expert attention both to engineering and to piloting.  And it's going to need parts from the top end of the tech tree, and (if it's crewed) is going to be big-- getting a Mk1 command pod back up to orbit from the surface typically takes a lander that's at least 50-60 tons on the surface.

[Cpt Kerbalkrunch]

19 minutes ago, Silverwood said:

Oh, ok I thought it might be easier than that!

I shall take your advice then.

Thanks.

Keith

If you're only sending a one-way probe, and you have the 300-level science unlocked, than you can accomplish this pretty easily. A small probe, stocked with science instruments and an antenna, on top of an inflatable heatshield will get you to Eve's surface without much trouble or even too much cash. You can grab some good science this way and complete some contracts.

However, if you want to get back, the difficulty level jumps exponentially, even for an unmanned probe. As @Spricigo said, it's the toughest place to launch from. Even the most experienced players consider it a challenge, and extensive testing is often required. In fact, sending a manned vessel to Eve's sea level and back to orbit is probably the pinnacle of the stock game. At least IMO.

[Human Person]

56 minutes ago, Snark said:

Eve is really, really easy to travel to and land on... and incredibly difficult to take off from the surface and get back to orbit.

For small probes, yes. 

Reentry can be very hot though. Not only use a heat shield but also make sure it is attached to a quite heat tolerant part itself, as heat transmission is relevant too. If you attach a heat shield to a probe core, the probe core will most likely overheat, because its heat tolerance is only 1200K. I found that putting heat sensitive parts in a cargo bay and putting a heat shield on the cargo bay works best for little probes.

As for the ascent: I don't find it particularly difficult to build an ascent vehicle for Eve. Simply add boosters until you have 8 to 10 km/s of delta v, with a TWR of just over 1. The hard part is the atmospheric entry and the landing of such a massive vehicle. It's not a bad Idea to land it empty and to refuel it by mining the surface.

Edited July 10, 2017 by Physics Student

[Spricigo]

30 minutes ago, Physics Student said:

Reentry can be very hot though. Not only use a heat shield but also make sure it is attached to a quite heat tolerant part itself, as heat transmission is relevant too.

maybe just a silly idea, but when I see that comment I always think about attaching the heatshield....to a heatshield

[Cpt Kerbalkrunch]

57 minutes ago, Physics Student said:

As for the ascent: I don't find it particularly difficult to build an ascent vehicle for Eve. Simply add boosters until you have 8 to 10 km/s of delta v, with a TWR of just over 1. The hard part is the atmospheric entry and the landing of such a massive vehicle. It's not a bad Idea to land it empty and to refuel it by mining the surface.

I think that's part of the challenge, and what makes Eve so tough. In order to launch a vessel off the surface, you had to actually land it there in the first place. It's sort of an implied part of the deal.

As for minng to refuel; it really does work well. You're able to land an empty ship (which means lighter), so it makes things easier. It can also save money on your design, because you only need enough fuel to get to Eve (with a bit left to slow down just before touchdown). However, I did my first Eve ascent this way, and it left me feeling like I sort of got off easy. So, when I went back the next time, I did so with 2 Kerbals and no drills. That time, when I got back to orbit, it left me with that true feeling of accomplishment that this game bestows upon you and makes you keep coming back for more. Next I'd like to do the ascent with the Mk1-2 (my favorite command module). I think that'll be another "feel good" moment.

[foamyesque]

My own experience is that the best way to get truly massive Eve vehicles down in one piece is to put wings on them, but it takes extensive testing to get the aero- and thermo- dynamics of the entry correct.

[Snark]

3 hours ago, Physics Student said:

Reentry can be very hot though. Not only use a heat shield but also make sure it is attached to a quite heat tolerant part itself, as heat transmission is relevant too.

True, but with the caveat that actually, nearly all KSP parts are "quite heat tolerant".  Basically, the only parts that you're likely to be attaching to a probe that don't have a heat tolerance of at least 2000K are,

• lower-end probe cores (up to OKTO2)
• science instruments
• OX-STAT solar panels

As long as you ensure that none of the above are directly mounted to the heat shield, it's fine.  They have no problem with reentry at all, as long as they're in the heat shield's "shadow".  I just make sure that the thing sitting on top of the heat shield is something else, e.g. a battery, or mini reaction wheel, or the little 1.25m-to-6.25m adapter, something like that.  Works just fine, even without a service bay or the like.

3 hours ago, Physics Student said:

The hard part is the atmospheric entry and the landing of such a massive vehicle.

I've had pretty good luck with the 10m heat shield.  The main risk on landing is the G-shock of plopping down on hard terrain-- has a tendency to snap connections and disassemble the ship under its own weight like a load of jackstraws.  So, either a lot of parachutes, or a very brief retro-thrust to cushion the landing, or both.  Can be a bit finicky, make sure things are well-strutted.

The other challenge is to pick a good shape. You want something tall and skinny for good aero (because drag losses lifting off Eve are huge, that's where most of the dV budget goes)... but on the other hand, needs to be short and squat so it doesn't tip over.  My biggest challenge (other than just packing enough dV along with the insane TWR needed to lift off efficiently) is coming up with something that's aerodynamic enough to be efficient, while squat enough not to tip over, while light enough to make it out of the atmosphere, while sturdy enough to stand the landing.

YMMV, I suppose.  But I would say that lifting off Eve and getting to orbit is the hardest technical challenge I've experienced in the stock game, speaking personally.  Everything else seems easy in comparison.

One thing:  Eve will throw you curve-balls if you haven't done it before.  There are a lot ways things can go wrong, and if anything goes wrong, you're hosed.  Eve will teach you that things can go wrong in places where you didn't even know you had places.  Burn up on entry.  Or flip over and then burn up on entry.  Or stick out a little too far, burn off a piece, go lopsided and then flip over on entry.  Or can't jettison the damn heat shield after entry.  Or you jettison it and it smacks you and destroys something vital, i.e. any piece of equipment at all.  Or your ship falls apart when you land.  Or it tips over.  Or it starts scuttling downhill like a giant mad space crab.  Or it turns out not to have quite enough dV to take off again.  Or it flips during ascent.  Or it has not enough TWR.  Or the engines don't work as well as you thought they would.  Or burn up on ascent.  Or start your gravity turn too soon.  Or start it too late.  And the list goes on, and on, and on.

All of those things can be addressed-- but they're hard to address unless you've tried it out with a particular ship design.  So you really really need to test-- both descent from and ascent to orbit.  If anyone's putting together a land-and-return Eve mission, I'd strongly advise testing by first building just the lander, launching it, and using the Alt+F12 cheat menu to put yourself directly in low Eve orbit.  Then see if you can land.  Then see if you can get back to orbit.  You'll probably have to go through a dozen design revisions, discovering new foibles each time, until you get a lander that can pass the test.  And then you can worry about building a lifter that can launch that sucker from KSC to Eve in the first place. 

[XLjedi]

They should just rename the "Nuke Engine" tech node "Interplanetary Conquest" and be done with it...

[Spricigo]

50 minutes ago, XLjedi said:

They should just rename the "Nuke Engine" tech node "Interplanetary Conquest" and be done with it...

Sorry,  but that is a gross overestimate of NERVs. 

1. Good luck using NERVs in any atmosphere.  

2. You can go anywhere in kerbol system without ever touching that node (or ion propulsion for the matter).  Just the Swivel and the Terrier are enough to comfortable land and return from Duna,  Ike and Gily.

3 . There are still several reasons to not use nuclear engines even when the situation requires a high deltaV budget. 

Notice,  this don't mean nuclear engines are not useful (far from it) just that is not the solution to all problems in KSP.  It is a good option to solve some problems,  another tool in the toolbox. 

[foamyesque]

7 hours ago, Snark said:

I've had pretty good luck with the 10m heat shield.  The main risk on landing is the G-shock of plopping down on hard terrain-- has a tendency to snap connections and disassemble the ship under its own weight like a load of jackstraws.  So, either a lot of parachutes, or a very brief retro-thrust to cushion the landing, or both.  Can be a bit finicky, make sure things are well-strutted.

The other challenge is to pick a good shape. You want something tall and skinny for good aero (because drag losses lifting off Eve are huge, that's where most of the dV budget goes)... but on the other hand, needs to be short and squat so it doesn't tip over.  My biggest challenge (other than just packing enough dV along with the insane TWR needed to lift off efficiently) is coming up with something that's aerodynamic enough to be efficient, while squat enough not to tip over, while light enough to make it out of the atmosphere, while sturdy enough to stand the landing.

 

Wings, man, wings. Landing gear is stupidly sturdy, a horizontal landing keeps your CoG nice and low even if you're long and skinny so's you don't tip, all your bits and Bobs are within a single ladder's reach of the surface so's you can efficiently disembark/ISRU/go roving, and your launch TWR doesn't need to be ungodly huge.

Also, it looks pretty danged cool.

[Silverwood]

Ok thanks again. Lots to think about.

I also get the impression a lot of you are using add ons? I only have the basic game, no mods, also my experience of rockets is quite basic. Whilst I have manged to get to both the Mun and Minimus - it was more by luck I think. When you talk about Delta & thrust - I am getting lost! I don't suppose there is  a really simple guide? I have tended to use the same design - simple with just a few extra fuel tanks or boosters and copied the designs from sandbox.

Thanks.

Keith

 

Edited July 11, 2017 by Silverwood

[Weywot8]

3 hours ago, Silverwood said:

I only have the basic game, no mods, also my experience of rockets is quite basic. Whilst I have manged to get to both the Mun and Minimus - it was more by luck I think. When you talk about Delta & thrust - I am getting lost! I don't suppose there is  a really simple guide? I have tended to use the same design - simple with just a few extra fuel tanks or boosters and copied the designs from sandbox

The very Kerbal MOAR booster's approach! Jeb approves.. 

I usually just wait for Snark to give his most excellent answer/tutorial replies as I can't add much more to that level of completeness.  

But very short answer - there are efficient ways of building rockets and some governing equations that determine how much 'travel power' any rocket has depending on the amount of fuel, rocket engines used and how the rocket is staged using decouplers. That 'travel power' is called delta-V, or dV.  Every big maneuver uses a "typical amount' of dV, depending on how efficient the player is and there are functional mods that do the maths for you such as 

and also this one, that also does many other things as well

With that dV number in hand, maps such as this one become very useful as a guide on how much dV your spaceship should have to reach the desired destination.

It's also a shorthand for ship iinterchangeability- for example, a ship that can land on the Mun can definitely get you to Eve. It takes about 3400 dV to get into a 100km (Pe)x100km(Ap) parking orbit for a new player.  From there, maybe 850-900 dV to get to set up the transfer to the Mun. And another 300-400 dV to get into a nice low circular orbit. and 650-750dV to land. So that's 1800-2050dV from parking orbit. (Just bolded 'new player' for the benefit of other forum members who will notice that the numbers quoted here are rather on the high side)

Using a much simpler tool, with helpful visual aids on when and where to launch, you can easily get to the Eve orbit using aerobraking with a slightly larger ship than what you used to get to the Mun because an efficient player  uses only 1100dV to get to Eve, from parking orbit, when the planets are optimally aligned. Slightly larger because you probably want some extra dV the first time round. I reckon for a first go, if you swap out the command pod of the ship you use to send a Kerbal to the Mun for a cargo/supply(?, forgot what it's called) bay, probe core, extra batteries, solar panels and make sure to have that heat shield with 100% ablator...that should get you all the way there and then some.

Edited July 11, 2017 by Weywot8

[XLjedi]

8 hours ago, Spricigo said:

Sorry,  but that is a gross overestimate of NERVs. 

1. Good luck using NERVs in any atmosphere.  

2. You can go anywhere in kerbol system without ever touching that node (or ion propulsion for the matter).  Just the Swivel and the Terrier are enough to comfortable land and return from Duna,  Ike and Gily.

3 . There are still several reasons to not use nuclear engines even when the situation requires a high deltaV budget. 

Notice,  this don't mean nuclear engines are not useful (far from it) just that is not the solution to all problems in KSP.  It is a good option to solve some problems,  another tool in the toolbox. 

My purposefully short comment related to nukes was in response to the OP which mentions trying a few modified rocket designs but not enough fuel to make it to EVE.  I didn't pay much attention to the other follow-on posts in the thread... if it grew into a SSTO discussion and having to fly the rocket/plane in the atmosphere?  Aside from thinking that NERVs would have to be the only engine brought along on the trip (no multistages or specialized lander craft), what might be some of the reasons eluded to in item 3 not to use nukes for a high deltaV requirement?  Speed over fuel consumption possibly?

My current plan is to build an Orbital Command Vessel using nothing but nukes to make the trip between the planets.  ...and outfit it with mission bays for landers/equipment with suitable engines for each planet upon arrival.  Plan is to never take it out of orbit, refuel it in orbit, and occasionally pick up new equipment at Kerbin. 

 

Edited July 11, 2017 by XLjedi

[Spricigo]

4 hours ago, XLjedi said:

My purposefully short comment related to nukes was in response to the OP which mentions trying a few modified rocket designs but not enough fuel to make it to EVE.  

After the few first answers the OP made evident that he didn't get enough deltaV to land on Eve and return to orbit.  Unfortunately,  your well intentioned reply is not relevant in this context. 

Quote

I didn't pay much attention to the other follow-on posts in the thread... if it grew into a SSTO discussion and having to fly the rocket/plane in the atmosphere?

Considering the intention of landing on Eve and returning to orbit, the discussion naturally veered towards  atmospheric flight ( heat,  drag, ... ).  SSTOs was never the subject,  I'm afraid.. 

Quote

Aside from thinking that NERVs would have to be the only engine brought along on the trip (no multistages or specialized lander craft), what might be some of the reasons eluded to in item 3 not to use nukes for a high deltaV requirement?  Speed over fuel consumption possibly?

While NERVs have excellent Isp, the relatively low thrust and high mass may overcome the advantage in some circumstances.  Length maneuvers are less efficient (higher cosine losses and possibly less Oberth effect),  in this case low TWR can be a liability. 

Also there is the fact cost \F 10000 a piece.  If cost is a concern it may be cheaper to get the required performance with chemical rockets. 

Finally the issue of high required deltaV may be solved with other means (gravity assist,  refueling)  which make high Isp engines less necessary and  high TWR more useful. 

Quote

Quote

My current plan is to build an Orbital Command Vessel using nothing but nukes to make the trip between the planets.  ...and outfit it with mission bays for landers/equipment with suitable engines for each planet upon arrival.  Plan is to never take it out of orbit, refuel it in orbit, and occasionally pick up new equipment at Kerbin. 

Reusability and efficient engines are certainly advantageous.  But notice that you will make compromises to make it suitable for different tasks.  Using a vessel capable of reaching Jool when your destination is Duna means you are carrying a lot of mass needlessly. 

[XLjedi]

20 minutes ago, Spricigo said:

While NERVs have excellent Isp, the relatively low thrust and high mass may overcome the advantage in some circumstances.  Length maneuvers are less efficient (higher cosine losses and possibly less Oberth effect),  in this case low TWR can be a liability. 

If the craft is infintely reusable; not too concerned about the cost per engine; but your quote above I think is valid, and I touched on that mentioning the speed vs. fuel efficiency tradeoff.  I'll have to gauge it against how difficult (and time consuming) the calculations are related to hitting launch windows for planet encounters.  In which case, I may opt for two different drive systems.  One geared toward efficient cruising, the other a rapid intercept engine.  That initial wait time for the "apoapsis to grow" does kinda drag down the fun factor in gameplay.  I can see myself wanting to "punch it" and rapidly move along to the next planet when the window opens. 

Edited July 11, 2017 by XLjedi

[Weywot8]

8 hours ago, XLjedi said:

I can see myself wanting to "punch it" and rapidly move along to the next planet when the window opens. 

Another person who feels the need...the need for speed! Completely biased based on my own preferences of course. Are you playing pure/mostly stock? Part of my end goal is to be in a position to ignore optimal transfer windows because I would have raked in bucketloads of surplus cash by then and some mining bases set up to refuel stuff around various planets/moons (which then led to "why not Kolonize while I'm at it"). Much easier to do with advance tech mods but it got complicated with just stock parts - got as far as 'dockable in-SoI-use high TWR boosters/refuelers' for a nuclear mother ship which seems do-able given that more experienced posters on the forum have actually used this in practice on 'everyday' ships. 

Edited July 11, 2017 by Weywot8

[XLjedi]

8 minutes ago, Weywot8 said:

Another person who feels the need...the need for speed! Completely biased based on my own preferences of course. Are you playing pure/mostly stock? Part of my end goal is to be in a position to ignore optimal transfer windows because I would have raked in bucketloads of surplus cash by then and some mining bases set up to refuel stuff around various planets/moons (which then lead to "why not Kolonize while I'm at it"). Much easier to do with advance tech mods but it got complicated with just stock parts - got as far as 'dockable in-SoI-use high TWR boosters/refuelers' for a nuclear mother ship which seems do-able given that more experienced posters on the forum have actually used this in practice on 'everyday' ships. 

Yeah, for the most part, I consider myself a stock player... All my craft designs (including my yet to be developed OCV craft) are all stock designs.  I do use the KIS/KAS mods, but that's about it part-wise, and I never include KIS/KAS parts in craft files when posting to KerbalX.  I do have a few "quality of life" type mods that I use (Kerbal Engineering Redux, Hyper-Edit, Kerbal Alarm, MechJeb, Launch Window, etc.).  I also don't mess with any of the aerodynamic mods, so my stock craft are geared toward stock physics.

I think the only thing I really feel like I'm missing out on part-wise is something along the lines of stock robotics parts.  I kinda cringe at the idea of scraping together a makeshift stock workaround involving thermometer hinges and landing gear for something that should be as simple as a hydraulic lift.  I may end up breaking down and tinkering with Infernal Robotics, but I'm holding out some hope for a parts upgrade in the next "Making History" pack that might (fingers crossed) also include some historical parts from our space shuttle program to allow for the creation of a robotic arm.