i need help with eve landers

[Xenon2462]

i built an eve lander and sent it to eve it had asparagus staging and aerospike rockets but when i landed it on eve and tried to take off it tipped over. please help

[Red Iron Crown]

Aerospikes don't vector their thrust for attitude control, which is what I suspect is causing your troubles. Add more reaction wheels, put a thrust vectoring engine like the LVT-45 at the center, add some fins, or some combination of all three.

Got a picture of what you built? That will help troubleshoot it a bit better.

[WooDzor]

pics? Top heavy maybe, not enough trust to get it up (that's what she said) or winglets above your COG can mess things up too..

[WooDzor]

'more reaction wheels' = more weight.

[NecroBones]

Reaction wheel weight isn't too big of a deal as long as you don't go overboard with them, and if you put them on the outer stages, so that they're ejected as your mass goes down. As long as the symmetry is good, you won't need them too much more, once you get some good velocity going.

I'd also double-check that all of the engines engaged, and that it's not a staging problem. Also, if you ejected your landing gear or parachutes, also double-check that none of those got stuck on something and threw off your weight balance.,

[Lukaszenko]

My Eve lander was also highly unstable. I couldn't thrust all the way, especially in the lower atmosphere, and I couldn't even think about starting the gravity turn until waaaay high, like 30 km up. And even then that was after adding multiple reaction wheels.

[Xenon2462]

This is the best i have also to note it does have a center gimble engine and it tipped over when i launched it off the sufice

[GoSlash27]

http://fc02.deviantart.net/fs71/f/2014/183/c/3/screenshot187_by_xenon2462-d7oy5yf.png

This is the best i have also to note it does have a center gimble engine and it tipped over when i launched it off the sufice

That's a very high center of gravity for a lander, and I suspect it's also going to be underpowered for Eve. Some food for thought:

An early version of my "drumset" Eve lander design. Normally short wide rockets are bad for stability, but the upside is that you can put a reaction wheel right at the CoM and it makes for a very stable landing platform.

The latest version looks very similar to this, but is more mass efficient (no pics yet)

Regards,

-Slashy

[NecroBones]

http://fc02.deviantart.net/fs71/f/2014/183/c/3/screenshot187_by_xenon2462-d7oy5yf.png

This is the best i have also to note it does have a center gimble engine and it tipped over when i launched it off the sufice

Did you land on a slope? A high center of gravity, and a sloped surface, will make it important to correct your angle immediately after leaving the ground. You may be getting some induced rotation just from the landing legs being in contact at different angles. In fact, I'm pretty sure this is it:

1. Because it's slightly tilted on a mildly sloped surface: As the thrust starts to lift the lander, some of that thrust turns into horizontal (lateral) motion.
   
2. Lateral motion starts while landing legs are still touching the ground, because the legs are springy and soft.
   
3. Legs are still grabbing, so the top of the spacecraft is thus able to move horizontally faster than the bottom, and so rotation begins.
   
4. Legs come off the ground, with not enough SAS torque to stop the rotation
   
5. You lose control and smack into the ground.
   

The fix is more SAS torque and/or RCS thrusters, to get control very quickly after leaving the ground. Once you're flying straight, you don't need all of those reaction wheels so much anymore, so they can be on the first stage to be ejected.

And don't worry about trying to compensate for that lateral side-slipping directly. Just get the nose pointed straight up.

--

As one more thing to check (which I alluded to in previous post): I can't tell from the image how your landing gear is set up. Are the legs on decouplers? That caused my Eve lander to go shooting off to one side, one time. The gear ejected, but one of the legs got caught on the side and didn't fall away, so the weight balance was wrong. I hit F9, and tried again, and it worked great. So it's something to look for.

Edited July 3, 2014 by NecroBones

[NecroBones]

That's a very high center of gravity for a lander, and I suspect it's also going to be underpowered for Eve. Some food for thought:

http://i52.photobucket.com/albums/g13/GoSlash27/KSP/1a_zpsc3f79a6f.jpg

An early version of my "drumset" Eve lander design. Normally short wide rockets are bad for stability, but the upside is that you can put a reaction wheel right at the CoM and it makes for a very stable landing platform.

The latest version looks very similar to this, but is more mass efficient (no pics yet)

I like it! Eve definitely encourages you to build wide, rather than high, just because of TWR problems.

I may try something lighter at some point. My most successful Eve lander so far, was a typical asparagus lander:

Full mission:

Javascript is disabled. View full album

[EdFred]

Landing legs? Who needs landing legs.

This was my lander for the Eve Challenge. Other than the large boosters, the rest of the lander was Aerospikes and the 48-7S engines.

Trip documentation:

www.sidnaw.org/kerbal/EveChallenge.htm

Edited July 3, 2014 by EdFred

[Xenon2462]

thank you all for your help i did not expect this much help

[GoSlash27]

Duplicate post...

Edited July 4, 2014 by GoSlash27

[Tortoise]

Eve has an atmosphere, could'nt you just land with parachutes, then re-pack them after landing?

[EdFred]

Eve has an atmosphere, could'nt you just land with parachutes, then re-pack them after landing?

Yes, you can chute to the surface. I think I landed at 7m/s with no engine deceleration.

[GoSlash27]

@NecroBones,

Woof! That's a big'un. I imagine it's designed for 12,000 DV. I found that the mass balloons pretty rapidly above 9 grand or so, so here's what I'm working on:

It only gets 8,900 DV, but it's off-road ability allows it to climb to a suitable launch altitude. Weight is 52 tons and it has very docile handling through all phases.

The idea is to do a deorbit and landing, drive overland to the launch site, and then use tylo rovers to refuel it on the surface.

Still in alpha testing, so I'm not ready to release it just yet...

Taking a breather to recharge the batteries during the hill climb test. Jeb's feeling daring...

Yeah, you can use parachutes during the descent, but the atmosphere is so heavy that it's not worth the weight and headaches IMO. The atmospheric drag will get you pretty slow before touchdown and it doesn't take much DV to make up the difference.

[NecroBones]

Eve has an atmosphere, could'nt you just land with parachutes, then re-pack them after landing?

Yep, parachutes work really well. The gravity at the surface is 80% higher than on Kerbin, but the atmosphere is really thick, so parachutes overcome that pretty well.

The difficulty is entirely with getting back off the planet. Since the gravity is so high, and the atmosphere is very thick (and lacks oxygen, so you can't use jet engines), you have to make these big landers with a lot of delta-V and a lot of thrust.

[Tortoise]

Yep, parachutes work really well. The gravity at the surface is 80% higher than on Kerbin, but the atmosphere is really thick, so parachutes overcome that pretty well.

The difficulty is entirely with getting back off the planet. Since the gravity is so high, and the atmosphere is very thick (and lacks oxygen, so you can't use jet engines), you have to make these big landers with a lot of delta-V and a lot of thrust.

Oh, I was looking at the screenshots. I just noticed people were trying to leave eve, not land on it with engines.

[Dispatcher]

If you can get this to Eve, depending on where you land, you may be able to return to Kerbin with it. It would need parachutes to descend to Eve's surface:

The TWR was optimized for Eve; hence why its high for Kerbin.

[Mesklin]

Best engines for Eve is Rockomax 48-7S, it is very light and powerful. And also wings is better for eve then parachutes: wings are lighter and you can choose your landing place

Bottom view for my Grand Tour ship

On Eve just after landing (then I moved to really high mountain >6000 m, more then 60 km roved)

[Stratzenblitz75]

You definitely want to build short and wide for Eve. A short and wide lander is less prone to tipping over, can have a higher TWR because of its increased surface area, and its easier to set up your ladders to allow your Kerbals to get on and off the lander. Of course, the best way to go short and wide is with an asparagus-staged pancake shaped lander. Now, if you simply want to return a command chair to Eve orbit, asparagus staged Rockomax 48-7S are your friend. They are extremely light, have a lot of trust and decent efficiency so they are perfect for small Eve landers. However, if you aren't so found of the "ride a lawn chair into the hottest planet in the Kerbol System" idea and want to return a command pod to orbit, then things get more complicated. When you need to push more mass around, 48-7S engines become far less useful. Instead, I recommend you use Aerospikes for the first stage, as they have good efficiency in atmosphere and decent thrust, then use 48-7S engines for the final stage once the lander is out of the thicker parts of the atmosphere. Landing the lander is pretty easy with Eve's thick atmosphere, just slap a bunch of parachutes on a few decouplers, parachute down to the surface, and detach them before launch. For the landing legs, I recommend you use rover wheels, specifically, the TR-2L Ruggedized Vehicular Wheel. Not only are these wheels tough and can take a landing, you can use them to drive around the surface of Eve and find a suitable launch site, preferably at the top of a tall mountain. Be warned though, the wheels will often "pop" on touchdown, so you need to take a Kerbal out to fix them. For example, here is my Eve lander than I built around these principles. It is an asparagus staged 48-7S pancake carrying a command chair. The engines are mounted beneath every FL-T200 fuel tank.

Eve is, without a doubt, the hardest planet to land on and return from. Hopefully, my advice helps you build a capable Eve lander to overcome the purple planet. Good Luck!