Eve Liftoff Ideas

[Zosma Procyon]

I need help designing a rocket to get kerbals off Eve. My attempts either don't have enough Delta-V to enter orbit after liftoff, or keep breaking up on the way down. My only stimulations are I don't like space planes, and would like it to have a capacity of 16 or more kerbals.

[sevenperforce]

1 hour ago, Zosma Procyon said:

I need help designing a rocket to get kerbals off Eve. My attempts either don't have enough Delta-V to enter orbit after liftoff, or keep breaking up on the way down. My only stimulations are I don't like space planes, and would like it to have a capacity of 16 or more kerbals.

Good thing you don't like spaceplanes, because they are useless on Eve.

Getting 16 Kerbals off Eve is roughly the equivalent of getting the VAB off of Kerbin. It's NOT going to be easy.

Your best bet is parallel staging, and LOTS of it. Take it slow. There are no gravity turns on Eve; expect to expend at least the first half of your stages burning straight up. You need a lot of thrust; try using a Rhino as your final stage.

Do not try direct ascent, either. You need to dock in low Eve orbit afterward.

If you have trouble with your ascent vehicle breaking up on the way down, try coming in empty (or burning retrograde all the way down) and using ISRU to refuel. It really helps. 

RCS does not work on Eve. You need reaction wheels and steerable fins.

[Zosma Procyon]

1 hour ago, sevenperforce said:

Good thing you don't like spaceplanes, because they are useless on Eve.

Getting 16 Kerbals off Eve is roughly the equivalent of getting the VAB off of Kerbin. It's NOT going to be easy.

Your best bet is parallel staging, and LOTS of it. Take it slow. There are no gravity turns on Eve; expect to expend at least the first half of your stages burning straight up. You need a lot of thrust; try using a Rhino as your final stage.

Do not try direct ascent, either. You need to dock in low Eve orbit afterward.

If you have trouble with your ascent vehicle breaking up on the way down, try coming in empty (or burning retrograde all the way down) and using ISRU to refuel. It really helps. 

RCS does not work on Eve. You need reaction wheels and steerable fins.

I prefer Vectors. 1 MN of thrust packed into a small surface area easily clustered.

[Ultimate Steve]

1 hour ago, sevenperforce said:

Getting 16 Kerbals off Eve is roughly the equivalent of getting the VAB off of Kerbin. It's NOT going to be easy.

It's not impossible, though.

This has been able to get 16 Kerbals off of Eve during testing with plenty of fuel to spare. It's en route to Eve. However, it's in a save I haven't touched in months.

[Zosma Procyon]

2 hours ago, sevenperforce said:

Getting 16 Kerbals off Eve is roughly the equivalent of getting the VAB off of Kerbin. It's NOT going to be easy.

I actually know a way to move 16 kerbals with almost no mass. You put them in the 2.5 meter cargo pods, with 16 external command chairs arranged radially on the top and bottom. I used this trick extensively in the past, but haven't recently because it shoots up the part count and that slows down computers. I'm leaning toward resurrecting it. The annoying thing you can't use the transfer crew function with external command chairs.

[Foxster]

Even going from one Kerbal in a capsule to two adds a lot of size to an Eve craft. Sixteen will mean a very large craft. Though, as pointed out above, using shielded command seats means much lighter. 

Some tips for an Eve flight to orbit are: Keep it streamlined (thinnest stacks and smallest number of them), dump every ounce and bump before lift-off, use the right engines (vectors and aerospikes usually), be prepared to try lots of launch profiles (just a couple of km difference before starting your turn can mean failure to make orbit),  if you have a mod that shows Q then watch it carefully to reduce drag losses resulting from going too fast in the mid section of the flight, keep your AoA close to zero to reduce drag. 

[Freds]

If you use Karbonite and MK2 Expansion mod, you can get off Eve using a small spaceplane.
There is lots of Karbonite in Eve's Atmosphere, so you can collect fuel as you fly.

 I found that the 'Sledgehammer' Air-Augmented Ramrocket of the MK2 Expansion are very effective in Eve once you get above Mach 1.5 and at high enough altitude, can be very useful to get off the atmosphere.

Even with this mods, is still very difficult to get to Eve Orbit.

[sevenperforce]

8 hours ago, Zosma Procyon said:

I actually know a way to move 16 kerbals with almost no mass. You put them in the 2.5 meter cargo pods, with 16 external command chairs arranged radially on the top and bottom. I used this trick extensively in the past, but haven't recently because it shoots up the part count and that slows down computers. I'm leaning toward resurrecting it. The annoying thing you can't use the transfer crew function with external command chairs.

Yes, the command seat approach works well.

My smallest Eve ascent vehicle used three Vectors, a Dart, a Spark, and a command seat, and I had to use the jetpack to circularize.

[sevenperforce]

I didn't realize this, but the Mk2 crew cabin is actually more mass-efficient than the Hitchhiker Container, and is significantly less draggy. Of course, the Mk3 Passenger Module edges them both out significantly. That's if you don't want to use command seats.

 

[sevenperforce]

This monstrosity will get 16 Kerbals and a pilot down to the surface of Eve (even to sea level, if you are a glutton for punishment) and back up into orbit again. Requires pretty steely nerves to fly.

Of course, getting it TO Eve is left as an exercise for the reader.

Spoiler

Protip: If you simply don't stage, it will SSTO easily enough thanks to those lovely Mammoths, from which point it can be refueled in orbit. Or, if you are very very good, you use your remaining fuel to get a gravity assist off the Mun and make it out to Minmus to get ISRU, then do the same at Gilly, then head to Eve. You do need nearly-full tanks for the Eve EDL to keep from burning up, though. If it were me, I'd slap a docking port underneath the bottom and have it rendezvous in LKO with a nuclear tug to take it to Minmus and then to Gilly.

 

Flown properly, you end up back in Eve orbit with more than enough fuel to rendezvous with a tugship, though the tug will need a Klaw or somesuch. An entry burn at Kerbin is recommended; propulsive landing will be necessary but not terribly challenging).

If anyone wants the craft file, let me know.

[Zosma Procyon]

Well I finally built a behemoth that can get through Eve's atmosphere, and should have had enough Delta-V to enter orbit, but I didn't position parachutes properly, and this happened.

[Zosma Procyon]

I got it down, but it did not have enough thrust to get back up again. I'll add more engines, but I think I'll experiment with 6 pylons, and  my cargo pod concept. I thought 22.5 m/s/s would enough. Nope.

[sevenperforce]

9 hours ago, Zosma Procyon said:

I got it down, but it did not have enough thrust to get back up again. I'll add more engines, but I think I'll experiment with 6 pylons, and  my cargo pod concept. I thought 22.5 m/s/s would enough. Nope.

On Eve, I've found propulsive landing and ISRU to be more reliable and more mass-efficient than chutes.

[Fearless Son]

On 1/24/2018 at 5:35 AM, sevenperforce said:

On Eve, I've found propulsive landing and ISRU to be more reliable and more mass-efficient than chutes.

Plus the thick Eve atmosphere means that you need fewer chutes to slow down than you would on Kerbin.  Clustering them near the top of the rocket will also help keep it oriented for landing.  Do be sure to pop them off with decouplers though.

[sevenperforce]

21 minutes ago, Fearless Son said:

Plus the thick Eve atmosphere means that you need fewer chutes to slow down than you would on Kerbin.  Clustering them near the top of the rocket will also help keep it oriented for landing.  Do be sure to pop them off with decouplers though.

Fewer to slow down, yes, but you have a higher terminal velocity despite the soupy atmosphere. Drag is linear to the drag medium density and quadratic to velocity. The higher air density on Eve means you need less drag area (fewer chutes) to slow down at high speeds, but you hit terminal velocity sooner and it's much higher than on Kerbin. Even if you don't use ISRU, propulsive assistance for landing is super-necessary.

The 16-kerbal ascent vehicle above doesn't actually use any chutes; I just use some inflatable heat shields up top to help with high-atmosphere drag and to keep the center of pressure as high as possible.

[mystik]

On 1/23/2018 at 3:32 AM, Zosma Procyon said:

I need help designing a rocket to get kerbals off Eve. My attempts either don't have enough Delta-V to enter orbit after liftoff, or keep breaking up on the way down. My only stimulations are I don't like space planes, and would like it to have a capacity of 16 or more kerbals.

Use this https://kerbalx.com/mystik/Dart-V30-Eve-Lander-with-Rover-and-return-Pod-to-Eve-orbit

You can remove the rover from the top and create it more aerodynamic and stuff. Add a larger cargo bay instead and add some more seats to a longer mini pod. You will need to edit the layout inside to make it fit lengthwise instead of the way I designed it. My design is crowded because I needed minimal stuff. You will do well with a larger tank, but only slighter. Just remember to disable fuel flow from the pod to the main rocket or your fuel will run out before getting to orbit.

Instead of the rover you can create a return vehicle instead. something with a nuke at the bottom.

This design requires refueling in Kerbin orbit and requires a return vehicle from Eve to Kerbin. It is only designed to tackle the high gravity demand of putting a few kerbals into orbit from Eve sea level. Otherwise check @Matt Lowne 's designs out of which this comes to mind: 

 

Edited January 29, 2018 by mystik

[septemberWaves]

On 1/23/2018 at 2:46 AM, sevenperforce said:

try using a Rhino as your final stage

Not going to work on Eve. A Rhino may have enough thrust for reasonable payloads on the surface of Kerbin, but it's still vacuum-optimized and it'll lose far more I_sp and far more thrust at the surface of Eve. Even at Kerbin's sea level it loses 2/5 of its maximum possible thrust, which is way more loss at Kerbin's surface than you'd want from an Eve ascent engine. Vectors and aerospikes are the only really good stock options.

If you're willing to use mods though, try the Deliverance or Scylla engines from Kerbal Atomics. They're both huge nuclear aerospikes with I_sp in the thousands and thrust to match. The larger of the two retains 86% of its vacuum I_sp at Eve sea level, which I think is far better than anything the stock game has to offer (its maximum thrust is also more than that of a Mammoth). I'll be relying on both to get anything off of Eve in 3.2x scale, but I'm certain they'd be helpful for your 16-kerbal Eve ascent at the stock scale too.

Edited January 29, 2018 by eloquentJane

[sevenperforce]

6 hours ago, eloquentJane said:

Not going to work on Eve. A Rhino may have enough thrust for reasonable payloads on the surface of Kerbin, but it's still vacuum-optimized and it'll lose far more I_sp and far more thrust at the surface of Eve. Even at Kerbin's sea level it loses 2/5 of its maximum possible thrust, which is way more loss at Kerbin's surface than you'd want from an Eve ascent engine. Vectors and aerospikes are the only really good stock options.

If you're willing to use mods though, try the Deliverance or Scylla engines from Kerbal Atomics. They're both huge nuclear aerospikes with I_sp in the thousands and thrust to match. The larger of the two retains 86% of its vacuum I_sp at Eve sea level, which I think is far better than anything the stock game has to offer (its maximum thrust is also more than that of a Mammoth). I'll be relying on both to get anything off of Eve in 3.2x scale, but I'm certain they'd be helpful for your 16-kerbal Eve ascent at the stock scale too.

Rhino as your final stage if you have one serial staging with everything else parallel.

[eagle92lightning]

My plan (when I finally have the guts) is a reusable system that I can simply use mods to actually reuse the rocket and leave it abonded until the next mission is ready to leave in which they will try to find the rocket (hopefully succeeding) and then thanks to KRE and my knowledge of super heavy launch vehicles (I have successfully gotten payloads in excess of 100,000tons to orbit) you could viably build something akin to a Falcon 9 and succesfully get off the planet.