Landing on Eve

[The Notorious Y.C.R.]

I have been trying my hardest to design a lander that is capable of surviving an Eve re-entry, and being able to return from sea level. My main problems are first that the lander needs to be quite big and so I need big rockets to haul them into orbit. Sometimes they are not light enough to get into LKO. The second issue is that I am trying to at least land on actual land and not the ocean so Jeb can plant a flag and the rocket can stay upright on landing legs. The problem with that is mainly that I don't know how to do atmospheric precision landings on Eve. Any tips?

Edited April 22, 2019 by The Notorious Y.C.R.

[Foxster]

You don't need a big craft...you need an efficient craft. 

Three things to consider in achieving this:

You should get the payload you are returning to orbit to the absolute minimum. That means dumping absolutely everything you don't need to make orbit before lifting off: chutes, airbrakes, landing gear, experiments, struts, etc. Don't be tempted to throw on extra crew, unneeded solar panels, RCS, reaction wheels, batteries and such.

You need the best engines for isp and low drag to suit Eve. This will likely mean Vectors and/or Aerospikes for the first stages and a Terrier for the final stage. 

For Eve the biggest challenge is drag, so you want to keep it skinny! You want a small number of thin mk1 stacks. You also want to eliminate absolutely anything that sticks out and is otherwise not essential. 

A final thought on your craft design for Eve: If you get the urge to add something to gain just a little more dV then you are likely wrong - you need a "what else can I take away" attitude instead.  

As for landing on land...There are some very large land masses in the equatorial region. Do a couple of orbits and you should spot one. Set your Pe so that the orbit end is to the eastern edge of the land and you will almost certainly land in an area to the west of that.  

 

Edited April 22, 2019 by Foxster

[jost]

In my experience it's quite helpful to use a mod which shows trajectories when trying to land on planets with an atmosphere:

 

 

[Laie]

4 hours ago, The Notorious Y.C.R. said:

My main problems are first that the lander needs to be quite big

"Big" is in the eye of the beholder... I don't want to throw screenshots at you without asking (maybe you want the challenge of designing your own Eve lifter from first principles), but to give you a ballpark figure: the most lightweight ESL single-person lifters come at about 20t. Those are tricky to fly with no room for error, but, well, just to give you an idea of what's possible.

If your lifter (the barebone lifter, discounting all landing gear, chutes & c) masses more than 40t for a single person, or over 100t for four Kerbals in proper crew cabins, it's much heavier than it has any right to be.

4 hours ago, The Notorious Y.C.R. said:

The problem with that is mainly that I don't know how to do atmospheric precision landings on Eve. Any tips?

Depends on what kind of precision you're after.

Do a de-orbit, see where you end up, then saveload and try again with a differently timed de-orbit burn. This will get you to within 10km after three or four saveloading iterations. Using tools like the Trajectories mod will speed this up so you can get to within a few km on the first try. However, I find that precision under 1km is pretty hard to achieve merely by timing the burn.

But! After all the reentry fire effects stop, you've still got a minute or three of falling through the atmosphere, which is getting dense and denser. At this stage, even a small amount of airbrakes or control surfaces (which you probably carry anyway) will allow you to steer a quite bit. Here's a video of one example, the relevant bit starts at about 2:40. It's from the Eve-3000 challenge, i don't think it will spoil you in any way.

You can already achieve similar effects by deploying a single airbrake (so it doesn't fall quite straight), and rolling your vessel to control the direction of the drift. This allows for pinpoint precision, though i usually need several tries for every new vessel just to get the hang of it.