To Eve and Back

[Hornet18]

Hello, so I have played KSP for a relatively short period of time, and was looking for some advice when it comes to getting to Eve and back with a crew of any size. Since I have never landed at Eve before I don't know a lot about it other than it has a really think atmosphere, and higher gravity that Kerbin. Would a space plane or rocket be the base option? Please share some of your designs and tips!

Thanks

-Nick

Edited June 18, 2015 by Hornet18
Answered

[OddFunction]

You have two real options. Only one is really feasible.

Firstly you could launch a massive, multi stage rocket. Burn through Kerbins atmosphere and drop your biggest tanks and engines in the process. Then transition to medium engines and tanks to get into a Kerbin orbit. A nuclear engine will get you to Eve, though I'm not sure which is the best for in-atmosphere. I'd avoid this strategy if possible.

The second and more reasonable method in my opinion is to send a fully functional space station with everything you need (or just extra fuel if you are mod-less) to orbit Eve. Then you send a lighter, more reasonable craft to Eve orbit to meet up with the space station and refuel. You should at that point have enough to land and take off again into Eve orbit for a second refueling. Or you could just get your lander back into orbit and send a third vehicle to rescue the second.

But that's just logistics. You're going to need specifics on in-atmosphere engines for Eve... because the return-ascent is the hardest part.

[Red Iron Crown]

... because the return-ascent is the hardest part.

Very much this. An Eve return mission is built around the ascent-from-Eve phase of the mission.

Spaceplanes are pretty much right out. Jets don't work there, single stage is virtually (if not still mathematically) impossible, and the thick atmo means lots of drag from those wings. Wings that are dry mass taking away from the large delta-V budget needed for ascent.

A multistage rocket is the most practical ascent. If you can land at high altitude the ascent is much easier. Pick engines with good atmo stats (aerospike, Mainsail), and have a small upper stage to complete the insertion. Drop your landing gear and chutes immediately after takeoff. Leave your return vehicle in orbit so you don't have to lug it back up.

I don't have a craft to share as the last Eve ascent I did was under the old aero, with a superwide asparagus design (though the delta-V requirements were higher then, too).

[Snark]

Yeah, Eve ascent is a brute. I haven't gotten around to doing it in 1.02 yet... in 0.9, the smallest I ever got my lander was a bit under 200 tons at the surface-- and that was just to loft a single Mk1 lander can to orbit. (Not to "escape from Eve and return to Kerbin", mind you. Just to low Eve orbit.)

Will be interesting to see what it's like in the new post-1.0 world... looking forward to i.

But basically, what Red Iron Crown said.

Also: Test, test, test. There are so many things that can go wrong with an Eve mission. For example, just landing: hitting the ground at even just what seems like a moderate speed can cause your ship to break apart like a jumble of jackstraws, snapping struts and popping engines off their fuel tanks (this is a combination of the heavier gravity, and the fact that your lander has to be big and big things are highly vulnerable to their own inertia). Just trying to come up with landing gear that won't snap under the strain is a challenge.

[Foxster]

One tip (from someone who has actually done this a few times now): Land your Eve craft nearly empty of fuel. Take along a disposable set of mining and fuel processing kit and refuel on the surface before lifting. Alternatively, put down a rover probe with refueling capabilities first and use that to refuel your return craft. You don't have to do this but it means less mass to lift from Kerbin.

You are looking for about 8500 dV from the surface to 100km orbit. It is possible to do it with less but there is a lot of drag from Eve's atmosphere and if your craft is anything less than optimal then you will lose dV.

Typical ship mass will be in the order of 150t. So plan to land it with plenty of 'chutes and some air brakes.

Here's a couple of examples that work:

Use hyperedit to land your craft for testing. You will lose a lot of craft in testing and you don't want to do a whole mission to Eve every time.

Your Kerbin ascent profile will definately not work on Eve. You will want to go straight up for at least 25km and then bank over sharply to gain orbital velocity. Any weak stage (TWR close to 1.0) will kill your lift.

The atmosphere is very dense near Eve's surface. Engines with poor sea level thrust will be useless for the first and probably second stages. Even a Poodle as a third stage is marginal. This will severely limit your engine choices.

Edited June 18, 2015 by Foxster

[Scarecrow88]

I very recently did my first successful manned mission to Eve. I sent 3 craft; the actual lander which relied mostly on parachutes for a safe landing, a refuelling craft that was used to replace the fuel on the lander that was burnt during the transfer from Kerbin, and a crew support vehicle that was used to bring the lander pilot back to Kerbin.

[selfish_meme]

As others have said, plan around the ascent. Mesklins Eve for Valentine mission is exemplary.

[A_name]

One tip (from someone who has actually done this a few times now): Land your Eve craft nearly empty of fuel. Take along a disposable set of mining and fuel processing kit and refuel on the surface before lifting. Alternatively, put down a rover probe with refueling capabilities first and use that to refuel your return craft. You don't have to do this but it means less mass to lift from Kerbin.

You are looking for about 8500 dV from the surface to 100km orbit. It is possible to do it with less but there is a lot of drag from Eve's atmosphere and if your craft is anything less than optimal then you will lose dV.

Typical ship mass will be in the order of 150t. So plan to land it with plenty of 'chutes and some air brakes.

Here's a couple of examples that work:

http://i.imgur.com/GPIibhM.jpg

http://i.imgur.com/jIZ6Qir.jpg

http://i.imgur.com/jt5UO3U.jpg

Use hyperedit to land your craft for testing. You will lose a lot of craft in testing and you don't want to do a whole mission to Eve every time.

Your Kerbin ascent profile will definately not work on Eve. You will want to go straight up for at least 25km and then bank over sharply to gain orbital velocity. Any weak stage (TWR close to 1.0) will kill your lift.

The atmosphere is very dense near Eve's surface. Engines with poor sea level thrust will be useless for the first and probably second stages. Even a Poodle as a third stage is marginal. This will severely limit your engine choices.

What advantages did you see in the landing gear vs landing legs?

[Prepper-Jack]

What advantages did you see in the landing gear vs landing legs?

The impact tolerance of the large aircraft landing gear is 70 m/s. Top of the line rocket landing struts is around 12 m/s, IIRC.

[Hornet18]

Thanks guys for all of your ideas and tips. I think i will take a whole space station type design to eve, with a rover or two, to scout the areas out, find a possible landing sight. Then il land the lander/launcher hopefully somewhere above 3000 feet since I am still a rookie, got to make it a little bit easier on myself!

[selfish_meme]

The impact tolerance of the large aircraft landing gear is 70 m/s. Top of the line rocket landing struts is around 12 m/s, IIRC.

It's not just that, the normal landing gear is quite saggy and cushioned, when you are trying to stop heavy tall things on uneven ground you need a multitude of them. The gear is lighter and stiffer. We mostly burn on landing to soften it so impact speed is not really a problem. Pre-1.0 a parachute calculator told me I needed 14 chutes to land a 100t lander at 6m/s, thats a lot of chutes and infrastructure to support them, better a small tank. Post 1.0 the chutes seem better, I can get 12m/s landings with 3 chutes.

[Perry Apsis]

One thing I recommend very highly: While developing your Eve ascent stage, use Hyperedit to transport it to the surface. You don't want to go through a bunch of trial and error where each trial costs you an hour or two. As was said earlier in the thread, perfect the ascent stage (surprisingly difficult all by itself), then (again, I'd use Hyperedit to put it into Eve orbit) the landing stage, and so on. Maybe it's time to revisit with the new aero and see how it works...

[Foxster]

Curious how others use hyperedit.

I HE the craft to 100km orbit. Get it upright. Then HE it to 20m. Dropping the last few meters.

Problem is that I never get the same spot twice. If I try to save and reuse the coordinates from a previous drop then the craft is not upright and I can't land it. So I end up having to use the relatively lengthy two-stage approach.

How do others do this?

[Red Iron Crown]

HyperEdit has an autolander function that will set you down gracefully at a specified lat/long.

[Foxster]

HyperEdit has an autolander function that will set you down gracefully at a specified lat/long.

Yes, I appreciate that. But (and I must be missing something here) it only lands the craft OK if I use Ship Lander if the craft is upright wrt the ground while in orbit. If it's not upright then when I do Ship Lander it is at an angle to the surface and I can't seem to right it before it hits - attitude control seems to be either disabled or very very sluggish.

[Red Iron Crown]

You could be right (been a while since I used that function and I vaguely remember having to do something tricky to get it to work). Sounds like it's easy enough to work around, just set the navball to surface mode and point radial, then hyperedit down.

[Foxster]

You could be right (been a while since I used that function and I vaguely remember having to do something tricky to get it to work). Sounds like it's easy enough to work around, just set the navball to surface mode and point radial, then hyperedit down.

Err, yes, as I said, that's kinda what I do. What I'd ideally like to do is be able to HE to some previously stored coordinates and just drop the last 20m or so. Either being correctly orientated already or to be able to quickly get upright while dropping.

Its hard to explain I know.

[SAI Peregrinus]

I first hyperedit a pod there and plant a flag where I want to do my landing tests. I get the coordinates of that site and write them down.

Then I HE my lander to an orbit that passes directly over the flag. When the lander is over the flag, I set navball to surface, point radial, and hyperedit down to the coordinates. Since I'm over the landing point I'm vertical, and since there's the flag it's the same point every time.

[Windspren]

I remember reading that the only engines that work on Eve are the Mainsail and the Mammoth. SQUAD really needs to un-nerf the Aerospike.

[Francesco]

Curious how others use hyperedit.

I HE the craft to 100km orbit. Get it upright. Then HE it to 20m. Dropping the last few meters.

Problem is that I never get the same spot twice. If I try to save and reuse the coordinates from a previous drop then the craft is not upright and I can't land it. So I end up having to use the relatively lengthy two-stage approach.

How do others do this?

1. Load craft on launchpad

2. Hyperedit to 100 km Eve circular orbit

3. Autolander with saved coordinates at an altitude that lies outside of the atmosphere (100km)

4. Use reaction wheels/whatever you've got on board to turn the craft upright

5. Autolander with saved coordinates again, this time at a convenient altitude for landing (100m above ground)

[Signo]

It's not just that, the normal landing gear is quite saggy and cushioned, when you are trying to stop heavy tall things on uneven ground you need a multitude of them. The gear is lighter and stiffer. We mostly burn on landing to soften it so impact speed is not really a problem.

Due to this I am trying a completely gearless/legless design atm. I am flying the first Eve mission during this week end. It is working on Kerbin so, based on my previous experiences I think it will on Eve too. If anybody wants to give it a try I uploaded the craft here.

[Foxster]

1. Load craft on launchpad

2. Hyperedit to 100 km Eve circular orbit

3. Autolander with saved coordinates at an altitude that lies outside of the atmosphere (100km)

4. Use reaction wheels/whatever you've got on board to turn the craft upright

5. Autolander with saved coordinates again, this time at a convenient altitude for landing (100m above ground)

Excellent. Just what I needed. Thanks!

[selfish_meme]

Excellent. Just what I needed. Thanks!

I also hyperEdit to a couple of hundred meters high in Landing, pop a chute and let that drag my nose skyward. If a bit higher you can turn landing on and off, this rotates your ship faster.