If I ever make it back from Eve

[Reinhart Mk.1]

Wow thank you for all the responses and advice! I'm working on something new and i'm gonna try to work all those tips in. Eeeeeeesh wish me luck

[Foxster]

57 minutes ago, herbal space program said:

There is no way a sea level Eve ascent is possible with only 5.8km of vacuum dV.  Even as actual atmosphere-adjusted dV that claim seems pretty iffy to me. That's because if Eve had no atmosphere, you would need to expend at least around 4 or so km/s of vacuum dV just to get going fast enough to stay in orbit. And that's only if you take off horizontally in vacuum, accelerating to that speed instantaneously, i.e. that is a hard theoretical limit and not any kind of practical one. And even setting that aside, there is no way you are pushing anything that size through all that soup for just an extra 1.8km/s over that  limit. If however what we are talking about what the dV indicator says when you are sitting on the ground, then that sounds about right.

 

For an example, here's a sea-level Eve lifter I made that can survive a ballistic re-entry fully fueled and then take off to orbit again, which was one of the hardest design exercises I've ever taken on:

https://imgur.com/a/7jFsTG2

 

You can see that the dV indicator reads 5.3 km/s while it's descending through the upper atmo, but reads only 1.4km/s when it's near the ground (OK, that particular time it actually went in the Drink, but that's beside the point!). Its actual vacuum dV when staged as intended is something like 12km/s, and configured as shown it makes Eve orbit from sea level  with around 2km/s dV to spare in low TWR orbital maneuvering ability.

I'm one of those that don't worry about the maths, I just build stuff and I can assure it's very possible. 

One of the huge differences is the scale of my craft and yours. Mine has just two engines and masses less than 25t.

[herbal space program]

21 minutes ago, Foxster said:

I'm one of those that don't worry about the maths, I just build stuff and I can assure it's very possible. 

One of the huge differences is the scale of my craft and yours. Mine has just two engines and masses less than 25t.

If you "don't worry about the maths",  then on what do you base the claim that your craft made orbit from Eve SL with only 5.8 km/s dV? That's the claim I'm taking issue with, not the one that your craft, whatever it was, made orbit per se. The dV tool we have in the game now is far from infallible, as I demonstrated above.

[Laie]

I can't really recall the best I've got... It was incredibly nasty to fly as you had to dial in the gravity turn quickly and then were very much locked in that trajectory. It was a hair's breadth between burning up and falling short.

My takeaway was that 6km/s are certainly possible if one is willing to try hard enough. Or at least that's what I remember... it has been a while. Do we need a proper challenge?

[herbal space program]

44 minutes ago, Laie said:

I can't really recall the best I've got... It was incredibly nasty to fly as you had to dial in the gravity turn quickly and then were very much locked in that trajectory. It was a hair's breadth between burning up and falling short.

My takeaway was that 6km/s are certainly possible if one is willing to try hard enough. Or at least that's what I remember... it has been a while. Do we need a proper challenge?

I'm rather busy with my own challenge right now, but it would be interesting to see what people come up with. If it's like similar Kerbin-based challenges I've participated in, I would expect that Mammoth-based designs would do the best, since that engine has the best TWR on Eve, and the larger diameter stack should have a more favorable mass/drag ratio. It seemed to boil down to getting as much vertical velocity as quickly as possible out of the gate, maintaining a pretty aggressive rate of ascent  relative to TV early, then making an early gravity turn at a high TWR, skirting the edge of exploding behind the lowest-diameter heat shield you can use.

Edited February 17, 2019 by herbal space program

[Foxster]

1 hour ago, herbal space program said:

If you "don't worry about the maths",  then on what do you base the claim that your craft made orbit from Eve SL with only 5.8 km/s dV? That's the claim I'm taking issue with, not the one that your craft, whatever it was, made orbit per se. The dV tool we have in the game now is far from infallible, as I demonstrated above.

I meant I don't bother with calculations myself, relying on mods for that sort of thing. It's the vac dV reported by MJ. 

Not at my PC at the mo. When I'm back I'll check the numbers but it's about what I quoted, certainly nowhere near 8k.

39 minutes ago, herbal space program said:

It would be interesting to see what people come up with, although I'm rather busy with my own challenge right now. If it's like similar Kerbin-based challenges I've participated in, I would expect that Mammoth-based designs would do the best, since that engine has the best TWR on Eve, and the larger diameter stack should have a more favorable mass/drag ratio. It seemed to boil down to getting as much vertical velocity as quickly as possible out of the gate, maintaining a pretty aggressive rate of ascent  relative to TV early, then making an early gravity turn at a high TWR, skirting the edge of exploding behind the lowest-diameter heat shield you can use.

No, Mammoths and their tanks are way too draggy for an efficient Eve craft. You want mk1 engines, which means Vector or Aerospike for atmos work. 

 

1 hour ago, Laie said:

Do we need a proper challenge?

There is a long running lowest-mass Eve orbiter challenge but I don't think anyone has posted in a while. Comes down to pretty much the same thing as minimum dV when you are heading towards 20t. 

Update: I actually over-estimated it...

It's a tad cheaty because the fairing used like that means that the lander can is considered shielded and I used some dodgy offsetting of the drop tanks but the dV requirements holds and it is quite orbit-capable.

Here it is going to orbit (at 2x speed)...

 

Edited February 17, 2019 by Foxster

[Reinhart Mk.1]

I hate Eve, so much.

[Superfluous J]

1 hour ago, Foxster said:

It's a tad cheaty because the fairing used like that means that the lander can is considered shielded and I used some dodgy offsetting of the drop tanks but the dV requirements holds and it is quite orbit-capable.

Why is there a decoupler on top of the right side drop tank, and a nose cone (only) on the bottom of the left tank? At the very least, I'd think those tanks should have 4 nose cones.

I ask because I'm building this now to see what it says and how it flies.

EDIT: I see now. It's more shenanigans. Not that I'm against shenanigans, so long as the challenge accepts them.

Edited February 17, 2019 by 5thHorseman

[Superfluous J]

1 hour ago, Foxster said:

It's a tad cheaty because the fairing used like that means that the lander can is considered shielded and I used some dodgy offsetting of the drop tanks but the dV requirements holds and it is quite orbit-capable.

I don't have the mod that allows offsetting anywhere, so I couldn't rebuild your craft exactly. However I think I corrrectly counted 15 Oscar tanks on each side, so just made it with decouplers and no fuel lines. KER basically agrees with you, enough to guess that the differences are just due to the slightly different configurations.

I then teleported it into a 9999Gm orbit and was going 342.4m/s . After exhausting the side tanks, I was going 1502.6. After the Vector was done, 2759.0. Finally, the Terrier got me to 5716.4. Minus 342.4 on each means the stages had 1160.2, 1256.4, and 2957.4 respectively, for 5374 m/s.

My guess is that the 8km/s estimate is based on the stock game, where you literally cannot build your rocket. A downloaded craft file will run in the stock game, so if the challenge accepts it that's fine, but you can't really use it to set the standard that people who don't take such measures can expect.

And it's probably not helpful in a thread where someone is obviously struggling with their first attempt at getting off of Eve.

[Foxster]

33 minutes ago, 5thHorseman said:

Why is there a decoupler on top of the right side drop tank, and a nose cone (only) on the bottom of the left tank? At the very least, I'd think those tanks should have 4 nose cones.

I ask because I'm building this now to see what it says and how it flies.

There's a small nosecone surface attached to the upper tank and then offset into the fairing. Attached to the bottom of that is the little decoupler you see, which is then offset to the position you see it at. The small tanks are then stacked below that with another small nosecone on the bottom. Half those tanks are then offset to the left of the craft. This creates a single stack of tanks with nosecones at the top and bottom split by "magic" to either side of the craft for balance. 

The other "trick" is to place and build the fairing on top of the lander can first so it's just a bit taller than a lander can. Then with it still built, relocate (i.e. pick up and re-place, not offset) it to under the lander can so it sticks up through the lander can. Then put the tank, Terrier etc below that. This makes the lander can shielded and so have zero drag. 

You can build something less cheaty for about 3-5t more with a little more dV. 

11 minutes ago, 5thHorseman said:

My guess is that the 8km/s estimate is based on the stock game, where you literally cannot build your rocket

Infinite offset is in the stock game. Just hold shift whilst offsetting. 

11 minutes ago, 5thHorseman said:

And it's probably not helpful in a thread where someone is obviously struggling with their first attempt at getting off of Eve.

True, I did kinda sideline things. Was just reinforcing the point though that 8KdV is only needed if your craft is draggy. Reduce the drag and you can get away with less. 

I can't find a craft at the moment but something with a mk1 capsule, a Terrier upper stage, a Vector middle stage and a couple of Aerospike lower stages is fairly easy to build without resorting to Mammoths, Mainsails or such. 

Edited February 17, 2019 by Foxster

[Reinhart Mk.1]

OKAY, i took everyone's advice and made something smaller the lander is in multiple stages with the last stage just being one vector engine with what seems to be plenty of fuel, pray for me

[Reinhart Mk.1]

new design, whatchyall think?

https://jumpshare.com/v/MVFGyrWkaJ5on4LxrWhT

[herbal space program]

1 hour ago, Foxster said:

There's a small nosecone surface attached to the upper tank and then offset into the fairing. Attached to the bottom of that is the little decoupler you see, which is then offset to the position you see it at. The small tanks are then stacked below that with another small nosecone on the bottom. Half those tanks are then offset to the left of the craft. This creates a single stack of tanks with nosecones at the top and bottom split by "magic" to either side of the craft for balance. 

The other "trick" is to place and build the fairing on top of the lander can first so it's just a bit taller than a lander can. Then with it still built, relocate (i.e. pick up and re-place, not offset) it to under the lander can so it sticks up through the lander can. Then put the tank, Terrier etc below that. This makes the lander can shielded and so have zero drag. 

Impressed as I am, for my challenges, that craft would be disallowed because it's basically using both extreme part offsetting and structural/backwards part clipping to cheat the heating and drag models. That's the only way you can reach such absurdly high velocities so low in Eve's atmo. That and given the extreme aerodynamic forces and flipping potential, there's also no way you could fly that thing except with McJeb, which I always disallow as well. But it still is pretty remarkable. I'd like to see how it performs in the current version, just so we know how it really compares.

6 minutes ago, Reinhart Mk.1 said:

new design, whatchyall think?

https://jumpshare.com/v/MVFGyrWkaJ5on4LxrWhT

It looks like you're not using asparagus staging there.  Unless you're going to do that, it's better to put everything in one stack.

[Reinhart Mk.1]

20 minutes ago, herbal space program said:

asparagus staging there

oh no i am! i just mean like aerodynamic wise, staging wise i think i got it

[Superfluous J]

15 minutes ago, Reinhart Mk.1 said:

oh no i am! i just mean like aerodynamic wise, staging wise i think i got it

Aerodynamically it looks fine. I can't tell the dV from looking at it though. I'm a much bigger fan of Vectors than Aerospikes. My first Eve lifter was Aerospikes and then I tried Vectors and never went back.

[Reinhart Mk.1]

Just now, 5thHorseman said:

Aerodynamically it looks fine. I can't tell the dV from looking at it though. I'm a much bigger fan of Vectors than Aerospikes. My first Eve lifter was Aerospikes and then I tried Vectors and never went back.

SAAAAME, from the last video i posted i was just trying to be careful to not overdo it, i honestly might have to replace them. rn im on approach with this design so lets see what happens

[Tw1]

Embrace the purple. This is your home now.

Why would you ever want to LEve.
 

[Foxster]

55 minutes ago, Reinhart Mk.1 said:

new design, whatchyall think?

https://jumpshare.com/v/MVFGyrWkaJ5on4LxrWhT

Looking good. 

Coupla thoughts...

Use autostruts rather than real struts. Real struts are very heavy and draggy.

Find a way to dump the science stuff etc. before lift off.

Use a mk1 capsule. Better heat tolerance and weighs less.  

[Reinhart Mk.1]

Just now, Foxster said:

Use a mk1 capsule. Better heat tolerance and weighs less.  

and i couldn't put the inflatable heatshield on it :'( had to switch to mk.1

also HOWWW do i use auto struts again??

15 minutes ago, Tw1 said:

Embrace the purple. This is your home now.

Why would you ever want to LEve.
 

REAL TALK i was thinking about just leaving a kerbal there and planting a flag just to be done with the mission hahaha

[Foxster]

1 minute ago, Reinhart Mk.1 said:

and i couldn't put the inflatable heatshield on it :'( had to switch to mk.1

also HOWWW do i use auto struts again??

Oh, errr...A game setting somewhere to turn on advanced tweakables and then right click on a part will show the autostrut option.  Or something. Been a while. 

1 hour ago, herbal space program said:

Impressed as I am, for my challenges, that craft would be disallowed because it's basically using both extreme part offsetting and structural/backwards part clipping to cheat the heating and drag models. That's the only way you can reach such absurdly high velocities so low in Eve's atmo. That and given the extreme aerodynamic forces and flipping potential, there's also no way you could fly that thing except with McJeb, which I always disallow as well. But it still is pretty remarkable. I'd like to see how it performs in the current version, just so we know how it really compares.

If you think that craft is dodgy you should see my lighter one that uses an extending docking port as a capsule  

[Reinhart Mk.1]

12 minutes ago, Foxster said:

extending docking port as a capsule

i just found out you can literally just throw kerbals in the service bays but W H  A T

[Tw1]

Alternatively (note, this video is out of date and this trick probably no longer works)  : 

If we allow for it being a few versions ago, and uh, a few other things, I still hold the record for the lightest ever pure stock, not-technically cheating Eve ascent vehicle.

Edited February 18, 2019 by Tw1

[Reinhart Mk.1]

Okay so I'm sorry for the bad mic quality/volume (and language... it's frustrating ) but here's my NEW design which could've maybe worked with more reaction wheels IDK. Trying a new one with less vector engines but the aerospike ones don't seem to be cutting it. I KNOW I'm getting close...

 

https://www.youtube.com/watch?v=zNTjfkpSw_k

also uhhh idk how to embed either i'm sorry

Edited February 18, 2019 by Reinhart Mk.1

[I_Killed_Jeb]

On 2/16/2019 at 1:55 PM, Gargamel said:

With some testing, and patience, it's not that hard.  I mean, it's difficult, but do able. 

One option to consider is to have the lander land empty, and refuel via ISRU.   Save some mass that wayIn this pic, the 6 man return vehicle landed on it's own, empty, and the rover with the crew landed somewhere else, drove to the lander, refueled it, and then they went home.  But it would be pretty trivial to change the design a bit to have the ISRU under the lander, and have it drop off during launch. 

Spoiler

 

 

This is my solution as well

 

[GRS]

Well...my best Eve Lander was capable of orbiting from like 2161 Meters ASL and Delta v DIDN'T EVEN REACH 7000 m/s (a little smaller actually yet still has around 100 m/s in orbit) and is like 44 tons, No MechJeb, your designs are nice, you only need to get rid of most of the mass as booster stages so you can have massive TWR and massive delta v, one FL T-800 to fuel core stage is in fact...enough, and you'll need 4 FL T-800, 4 FL T-400 boosters (put the big tanks below the small tanks and use 4 simetry) with at least 2 Aerospikes, orbital stage only need one Terrier fueled with one FL T-400 tank, you can still use landing legs instead of Fairing Base, and try aiming higher grounds, like That Mt.You-Know-What.

That Lander, Sorry if it's too dark.

Edited February 18, 2019 by GRS