My first attempt at an Eve Lander. A 1700 ton monstruosity?

[juanml82]

I've got the game a few months ago and I've been lurking here. So far, I've landed in Duna, Dres, Eeloo, have ships going for Jool and missed Moho (not enough deltaV). And I want to tackle an Eve landing with return in the same ship. AFAIK, I should design a lander with a DeltaV 12 Km/s (is that vacuum deltaV?) , so I based it on my heavy lifters. And the second/interplanetary/lander stage thus includes 16 Mainsails in a two ring asparagus configuration (is that onion staging?) with a Skipper in the middle, which weights almost 1,700 tons. Here's my first version of it in Kerbin orbit

I've deorbited it after checking the ksp parachute calculator, which indicated I needed 600 parachutes to land the monstrosity without firing the engines.

So I went back to the drawing board and to plan the mission again. Here are some screenshots of the... thing, on the VAP, so you can get an idea on what I'm building

Now, I have some issues with the design and the way to carry out the mission.

I've read it's a good idea to detach the chutes and even the landing gear while taking off Eve, to save on weight. However, I've tested separating the chutes (they have separatrons on the decouplers) on the launching pad and it doesn't work. The small rockets fire but the gravity still keeps the quad adapters with the chutes in place, so I guess that would only work for radial mounted parachutes?

The only way I thought of putting the landing gear so they extend beyond the Mainsails is to put them in the end of the beams. They do hold the lander on the pad, so I guess I'll have to land very softly to avoid damaging the engines

The manned capsule is at the bottom, just above the center Skipper. I should try it, but I guess a Telus mobility enhancer is enough to put my Kerbal on the ground and allow him back inside

On mission planning, I'm thinking several approaches:

To reach LKO, I'm not jettisoning the emptied tanks and engines, as I want to use them again at Eve. With all the rockets I've put as a first stage, it manages orbit with three engines running. Which is good, because the Skipper can't lift the thing on its own (and that's also a reason to launch it with the center line tanks with only 1/4 of the fuel to save weight). So I'll have to refuel it in orbit to fill all tanks and use the 16 inefficient Mainsails for the interplanetary burn. I don't think a tug with nuclear rockets will be practical to push such a beast into Eve, but I might be wrong.

This also means I'll have to refuel on Eve's orbit. I'm thinking to send a tanker and/or using the Kethane mod to refuel through a mining base on Gilly.

Landing, that's the tricky part, I guess, since this "lander" is huge. My last version has 32 drogues parachutes and 32 mk16 chutes. Is there an ideal proportion between them? If the only parachute calculator is right and my landing gear isn't sturdy enough (which I don't think it is), I could go down with parachutes and use the engine below 100m AGL to soften the landing. Since I'm apparently unable to detach them, I guess I'll have to make an action group to cut them and carry on with the weight during Eve's take off.

I was also thinking in attaching a "parachute tug" on top for landing: a small probe with an insane amount of radial parachutes which I can detach before take off. Maybe I could even replace all the onboard parachutes for that madness? The issue is, I guess, that so many parachutes on top of a docking port could cause the ship to break apart. Maybe not at the dock, but below.

The other, more complicated option, is to land on dry tanks. I don't refuel on Eve's orbit. Even more, I use the fuel to refuel a twin-like tanker with wheels. The dry weight is 280 tons, which shouldn't pose a problem for the parachutes. The twin-tanker-rover won't be taking off, so I could fill it with as many radial chutes as I can fit - the additional weight to an already heavy ship would be only a problem while taking off from Kerbin. And then I use the parts of the KAS mod to transfer fuel and fill the tanks. I would also probably need 2 or 3 tankers to be sure to fill them, so it seems rather complicated.

I've also seen posts of people showing far lighter, and more reasonable landers. I don't know how the fit enough deltaV for take off, though. And I'm now also curious about trying to land and take off in this monstrosity.

Thoughts, opinions? Is it too big?

Edited August 4, 2014 by juanml82

[csanders]

What's it's TWR on Eve? It doesn't look like it will be high enough.

[MockKnizzle]

While I admire your audacity in terms of part count (that monstrosity is approaching Whackjobian proportions), you can certainly make an EAV that is faaaaaar, far smaller than that. For example, something I whipped up the other day:

Weighing in at just a hair over 33 tons, you can easily achieve 11k+ dV with a minimal part count. The number one rule of construction: NO UNNECESSARY MASS. That means no command pod, no RCS, no batteries, no docking ports, nothing. By minimizing your final-stage mass, you can exponentially decrease the size of your rocket. Additionally, only use the most efficient engines for the job: Mainsails have terrible atmospheric ISP, and Skippers aren't much better. For my boosters and first core stage I'm using Aerospikes which have the highest atmospheric ISP in the game, and for my second and third core stages I'm using the 48-7S (in a dual-engine configuration on the second stage and just a single engine in the third stage), which has a reasonable ISP in the upper atmosphere (same as a Skipper) but has the highest TWR of any engine in the game. All parachutes and landing legs pop off when ascent begins, and I'm carrying a bare minimum of control surfaces up with me while I'm burning the Aerospikes.

Edited March 9, 2014 by MockKnizzle

[Claw]

Wow. That thing has almost double the number of parts my computer can handle. I admire your ability to build something so massive that can make it to orbit.

You ought to lurk less on this forum and watch for people who want to build massive rockets. There are often posts from people who's large scale rockets experience unintentional spontaneous disassemble. I'm certain you could help with that.

Good luck!!

[Jouni]

Weighing in at just a hair over 33 tons, you can easily achieve 11k+ dV with a minimal part count. The number one rule of construction: NO UNNECESSARY MASS. That means no command pod, no RCS, no batteries, no docking ports, nothing. By minimizing your final-stage mass, you can exponentially decrease the size of your rocket.

The decrease is only linear, not exponential. By building a 10x bigger rocket, you can lift 10x the payload. Exponential scaling would increase the size of the rocket by a constant factor for each additional kilogram of payload.

[marauder78]

Surface TWR of 1.53@kerbin isn't going to get you off the ground on Eve, sorry but i don't think your 16 mainsail ship is going to get off the ground until it expends so much fuel that it doesn't get back into orbit.

Delta-V isn't the only value you have to watch when you try to launch from eve, you have to watch your TWR as well. As for dumping chutes and landing gear, this is because its much easier to get a light ship into orbit.

[MockKnizzle]

The decrease is only linear, not exponential. By building a 10x bigger rocket, you can lift 10x the payload. Exponential scaling would increase the size of the rocket by a constant factor for each additional kilogram of payload.

Yes, according to the rocket equation you're right. There's still penalties for multiplying payload beyond just a linear increase in initial mass though, since in KSP you can't just scale the size of engines and tanks and support structures. To get 10 times the thrust on your first stage, you'd need to either use the bigger, less-efficient engines or cluster smaller ones, which adds structural mass. Additionally, your structural joints are experiencing 10 times the stresses, which often necessitates extra reinforcement and again, added mass.

Not to mention a larger rocket means a larger part count and a lower framerate

[juanml82]

Thanks to everyone for the replies. I've checked with Kerbal engineer redux and it wouldn't take off from Eve

I wonder what can I do with Monstruosity. Tylo perhaps? It's so heavy that it would fall like a rock. Then again, I could try to see how fast a gentle deorbit burn causes it to crash.

I'm building with aerospikes now, and it's far smaller. I still want to try to carry a larger payload, if possible: some science (No goo or lab, though), and the ability to plant the flag, take a sample and go back. So my design is just above 10 km/s, so if I'm correct, that should allow me to take off from Eve if I land in a mountain.

The first version was this

To which I've added pocket beams to separate the fuel tanks and allow a Kerbal to actually use the ladder (all which, unfortunately, shaves deltaV). I still have some kinks in the design to work out.

Here's how it landed at Kerbin

The centerline engines crashed with the ground when my Kerbal got in the ladder (or into the command seat, I don't know), half the engines broke apart when the chutes activated at 500m and the craft descended tilted, causing the landing struts to break.

[m4rt14n]

I love how realistic this game is. Eve has massive gravity and atmosphere. Yet the Kerbal pilot survives re-entry and orbital procedure just by using a seat, instead of an actual command pod...

[Ghost13]

I complete my Eve challenge back in 0.21 and going to repeat it some time later with FAR and DeadlyReentry installed thus I will have to think about re-entry heat and aerodynamics of my craft for Eve decent and accend. So I will probably go for a smallest lander possible since I will need to be in size with heatshields. As for accend I will probably just put the noze cone on top of the seat. So yea, designing a spacecraft is not only about MOAR BOOSTERS you need to take the weight and TTWR into account, I suggest you to use the Kerbal Engennering plug-in or MechJeb that will do just the same for the ship info. Then you can carefully design your spacecraft with maximum dV and keep yourself within 30 tonns.

[Jimbimbibble]

Go with the 1.25m parts only. You honestly don't need to use any 2.5m parts for an Eve lander if you're only flying with 1 kerbal, so the bigger parts only complicate things and force you to use less efficient engines.

[kurja]

I did this once, with a one man capsule. 1.25m parts, lots of stages, lots of aerospikes. Around the whole thing, I put another asparagus layer of small tanks & tiny engines, idea with those was that I had science parts, parachutes, landing legs and things like that on them, idea ofc being that they get dropped very soon after liftoff.

As for dropping parachutes, did you have them on decouplers? Sepratrons alone can't yank them off your rocket, you need to decouple the chutes first, separating rockets are there just to toss them out of the way.

edit - re-read your post, you had decouplers. but it should work though.

Edited March 10, 2014 by kurja

[Nedal]

I completed an eve rescue, rescuing 3 kerbals from around 1600m above sea level. The ship was a bunch of Aerospikes on the tall skinny 360 fuel tanks until those burned up almost instantly. The beginning stages were quad Aerospikes on the 1440 Rocomax tanks, so they didn't burn as fast. It had delta v to spare for DE orbiting and landing. An earlier iteration was probe controlled and I had a hard time landing efficiently without the radar altimeter in the cockpit. As sticking enough chutes on the thing was way too many parts. I finally got rid of the drogues and went all small chutes and thrusted before deployment. Was basically orbit kerbin without staging, refuel, go to eve without staging, refuel. Land then take off.

[breakthrough]

-impressive looking Eve ascent vehicle, except for one little detail-

I'm curious as to how that attaches to the transfer stage, or the launcher to get off of Kerbin for that matter.

[celem]

Well he's showing it in the VAB, so it may well be the top section of a regular rocket attached to a transfer stage via decoupler on the central aerospike.

On the OP, yeah that first ship is a monster, the newer attempts look more promising. When building an eve ascent dont overlook the tiny stages up top. I like to take a lander can rather than the external seat of silliness, i leave the monoprop in and stick rcs thrusters directly to it which makes it a final stage. a decoupler below, then a tiny 1.25m tank and the little rocko engine, decoupler, next a slightly larger 1.25m tank, lvl-909, decoupler then the aerospike tanks. By breaking the top bit into multiple parts like this you can get a lot of your dV from the fact that you are always pushing a tiny weight, it also makes the aerospike stack beneath much smaller. When climbing off Eve its all about dropping dead-weight, and thats not just stuff like panels and landing legs, it also means spending as little time as possible with big empty spaces in fuel tanks. Many smaller stages over fewer large ones.

Edited March 10, 2014 by celem

[MockKnizzle]

I'm curious as to how that attaches to the transfer stage, or the launcher to get off of Kerbin for that matter.

Very carefully

That miiiight have been a small detail I overlooked, seeing as I threw it all together in a couple minutes more as a proof-of-concept than anything else. But thinking about it now, I can see a few ways of getting it to Eve. The first and easiest one is to remove the command seat and mount the thing upside-down on top of a conventional lifter, bringing the seat along in a KAS container and attaching it on top just before de-orbit. The second way is to attach a small L-shaped structure to the bottom of the core stage that curves underneath the Aerospike to give it a node, and then strap the whole thing on top of a lifter with space tape.

Edited March 10, 2014 by MockKnizzle

[juanml82]

The thing about 1.5 m is that they don't give me enough deltaV, maybe because of the heavier payload. This 300 ton creature has enough thrust and deltaV

The issue is that it breaks apart upon splashing down on Kerbin's oceans. Eve ground might be more forgiving, so I'm still thinking in either a careful burn at the last time during landing or a dry landing and refuel with KAS and a few tankers (those filled with as many parachutes as I can fit, as they aren't coming back).

The other problem is, how do you control it without thrust-vectoring or SAS module? Ascend it fine, but I'm tipping over trying to do the gravity turn. Maybe it's a matter of making it very, very slowly? I've tried separately adding a SAS module or a bunch of the small radial orange engines, but neither provides enough control (and cut the deltaV)

[magnemoe]

I love how realistic this game is. Eve has massive gravity and atmosphere. Yet the Kerbal pilot survives re-entry and orbital procedure just by using a seat, instead of an actual command pod...

Note you can have an lander with an command pod, just leave it on ground then you take off.

This also brings an rover and a lot of science stuff.

[Jouni]

I'm always using a real command pod in my atmospheric landers, because kerbals are not supposed to survive the trip in external seats or lander cans. It's a bit arbitrary choice, as I'm not otherwise caring about re-entry heat and similar things, but it's the place I put the limit on silliness.

This was my first and only Eve lander:

A bit more asparagus staging would have allowed it to land below 3 km, but setting up fuel lines is so boring that I didn't want to do it. There were also a couple of trivial errors that forced the pilot to abandon ship and circularize with his jetpack, but they would have been quick to fix, had I noticed them early enough.

[sdj64]

Don't overlook the need for landing legs. I've seen Eve landers that are much smaller than that with more than 25 heavy landing legs, because of Eve's high gravity. Another solution would be structural parts like girders, which can survive a higher impact speed, like on Jouni's lander.

[MarvinKitFox]

Don't overlook the need for landing legs. I've seen Eve landers that are much smaller than that with more than 25 heavy landing legs, because of Eve's high gravity. Another solution would be structural parts like girders, which can survive a higher impact speed, like on Jouni's lander.

Structural members are better than landing legs in every way:

*They are Stronger

*They are more impact-resistant

*They are uglier

Also remember the extraordinary usefulness of cubic-octagonal-strut crumple zones.

You can land on a bed of (zero weight!!) cubic struts, have them blow to smithereens under you, thereby conforming nicely to the terrain below while cushioning your 50m/s landing!

{disclaimer: this bed-of-struts has other useful functions, such as making toasted cheese on your CPU, due to part count....}

And lastly:

Correctly configured structural-girder legs can allow your lander to crawl on legs, downhill.

Simply connect your legs as one long girder, with a short girder on the end in 110degree angle. (sample image below)

Use alt-> and alt-< to activate/deactivate this nifty feature.

Example: my tech-zero bunnyhopper

Also works on Eve, my Kethane airbreather lander had a top crawling speed of 22m/s!

The parachute-ejection mechanism might be of interest to you.

(truth is, I just want to show off my vacation photo's, and you gave me an excuse to do so)

Javascript is disabled. View full album

Edited March 10, 2014 by MarvinKitFox

[Skorpychan]

I'm considering one myself, with FL-T800s asparagused around a Rockomax X200-8 tank, and aerospikes all around, with a FL-T200 tank and a 48-7s engine pushing a Mk1 Lander-can into orbit. Chutes and legs on decouple-able girders. However, how would you get the kerbal up onto the top of the lander again after collecting surface samples?

Ladders add weight, which has to be balanced as well. And you have to get them over a wide tank.

[MarvinKitFox]

... how would you get the kerbal up onto the top of the lander again after collecting surface samples?

.

Where exactly in the Rule Book does it say that your capsule has to be at the *top* of the lander?

Make the middle stack of your lander be capsule at ground level, then all the other non-propulsive bits above that. Or attach the can to the side of the central stack, with a suitable counterweight offsetting the balance, or attach the ladder to a chunk that will stay on the ground, or include a lil' 1-kerbal jetpack "rover" on your lander, or...

As down-mass is not very relevant, only your up-mass in the ascent stage needs to be finely optimised.

Edited March 10, 2014 by MarvinKitFox

[Skorpychan]

Where exactly in the Rule Book does it say that your capsule has to be at the *top* of the lander?

Make the middle stack of your lander be capsule at ground level, then all the other non-propulsive bits above that. Or attach the can to the side of the central stack, with a suitable counterweight offsetting the balance, or attach the ladder to a chunk that will stay on the ground, or include a lil' 1-kerbal jetpack "rover" on your lander, or...

As down-mass is not very relevant, only your up-mass in the ascent stage needs to be finely optimised.

Still has to be relatively balanced for launch from Kerbin, however.

Maybe I can just balance extendable ladders with rotation, and dump them off the side with decouplers.

I've also got to land a few probes and a rover around it to get the whole whack of science, and maybe a lab and habitat later for a permanent science outpost.

Or rover-probes that do science on the way down, and then simply roam over to wherever the kerbal lands.

[technion]

While I admire your audacity in terms of part count (that monstrosity is approaching Whackjobian proportions), you can certainly make an EAV that is faaaaaar, far smaller than that. For example, something I whipped up the other day:

eighing in at just a hair over 33 tons, you can easily achieve 11k+ dV with a minimal part count. The number one rule of construction: NO UNNECESSARY MASS. That means no command pod, no RCS, no batteries, no docking ports, nothing. By minimizing your final-stage mass, you can exponentially decrease the size of your rocket. Additionally, only use the most efficient engines for the job: Mainsails have terrible atmospheric ISP, and Skippers aren't much better. For my boosters and first core stage I'm using Aerospikes which have the highest atmospheric ISP in the game, and for my second and third core stages I'm using the 48-7S (in a dual-engine configuration on the second stage and just a single engine in the third stage), which has a reasonable ISP in the upper atmosphere (same as a Skipper) but has the highest TWR of any engine in the game. All parachutes and landing legs pop off when ascent begins, and I'm carrying a bare minimum of control surfaces up with me while I'm burning the Aerospikes.

The majority of the Eve ascent is done in an atmosphere. One of my Eve rocket had a similar design to yours in its core, and it still took a lot of extra tanks outside that to get it moving. I don't believe your rocket could manage an Eve ascent, even if you did land it on the tallest mountain.