Eve 3000

[Laie]

Whoa! and I haven't even found the time to install v1.5 to try your previous craft. Seriously, I wasn't even aware that a new version had dropped until I was unable to load your vessel.

[ManEatingApe]

49 minutes ago, Laie said:

Whoa! and I haven't even found the time to install v1.5 to try your previous craft. Seriously, I wasn't even aware that a new version had dropped until I was unable to load your vessel.

The new burn time indicator is pretty neat. I used custom action groups to disable/enable engines without staging and it's smart enough to update the burn time numbers before it's too late!

[Laie]

Finally got around to updating the front page.

@ManEatingApe : I've been messing around a little the past few days and it seems as if you found the sweet spot. Your set of engines produces the most bang for the buck, by a considerable margin.

It may still be possible to save a few hundred bucks here or there, but I don't think one can trim it down so much as to shave a single LFB from your combo.

I think some congratulations are in order. Well done!

Edited December 24, 2018 by Laie
removed some redundant double repetitions, which was rather redundant (not to say repetitive) and also quite unnecessary.

[ManEatingApe]

Thanks! This is an engaging challenge and a great way to push the boundaries of Eve lander design.
The variety in the various entries is interesting and should provide inspiration for future missions.

I feel everyone who participated so far has conclusively shown that an Eve ore contract is not just possible* but actually profitable!

* Having seen some of the inspired lunacy that happens on these forums perhaps I should say probable instead ;-)

Edited December 22, 2018 by ManEatingApe

[jinnantonix]

Hats off to you @ManEatingApe that was too good.  You are the deserved winner of this challenge.

Edited December 22, 2018 by jinnantonix

[herbal space program]

I want to say that even though this challenge has already been thoroughly plastered by the usual suspects, I still find it intriguing, as one of the few common challenges I had never done before in this game was to mount an Eve sample return mission.  After 20-odd hours of work I  ended up with a craft that bristles with ugly struts and costs $400,000 and change, but it can survive a ballistic Eve re-entry at 500 tons and then make orbit again with 2000 m/s dV to spare, which for me is an achievement, even though my original version was not carrying anywhere near 15 tons of dead weight to orbit.  Having gotten that far, I was scrolling through the challenges forum looking for Eve Rocks when I found this thread. Of course what I have now does not constitute a valid entry for this challenge, nor do I think that I could outdo @ManEatingApe's excellent submission based on  straight-up, one-piece sea level lifter, even if I redesigned it to purpose. However, more devious approaches occur to me, and I wonder if OP  @Laie might entertain them to keep this challenge alive a bit longer. It occurs to me that you could in theory land a wheeled craft near sea level, use it to extract the required ore, and then drive it to a higher elevation for takeoff. You could also land a mother ship at high elevation, detach said rover from it to retrieve the ore from near sea level, then dock up the ore tank and take off from the higher site. Anyway, would you consider such a submission? It's the only  way I can see of significantly beating what's there now, and I'd love to give it a shot.

Edited February 6, 2019 by herbal space program

[Laie]

7 hours ago, herbal space program said:

It occurs to me that you could in theory land a wheeled craft near sea level, use it to extract the required ore, and then drive it to a higher elevation for takeoff.

The purpose was to make everyone play the same challenge. Not that it was strictly necessary... without the requirement for sea level everyone would have gone to the same mountaintop, I presume. Anyway, the point was not that ore has to come from the lowlands, but that the lifter is supposed to be sea-level capable.

There was an attempt to reboot Eve Rocks, but not much has come of it.

For one thing, I don't think an Eve Return is as hard as it used to be; the other, it takes a special kind of person to keep a challenge like that running for years. You have to look at every entry with a critical eye. After half a year they all started looking the same and I found it hard to still pay attention. On top of that, for something as involved as Eve Rocks or Jool-5, checking a submission is easily an hour of work. Boolybooly or Ziv or (these days) JacobJHC don't get nearly as many kudos as they deserve.

[Aeroboi]

On 12/22/2018 at 9:38 PM, ManEatingApe said:

Thanks! This is an engaging challenge and a great way to push the boundaries of Eve lander design.
The variety in the various entries is interesting and should provide inspiration for future missions.

I feel everyone who participated so far has conclusively shown that an Eve ore contract is not just possible* but actually profitable!

* Having seen some of the inspired lunacy that happens on these forums perhaps I should say probable instead ;-)

 

5 hours ago, Laie said:

The purpose was to make everyone play the same challenge. Not that it was strictly necessary... without the requirement for sea level everyone would have gone to the same mountaintop, I presume. Anyway, the point was not that ore has to come from the lowlands, but that the lifter is supposed to be sea-level capable.

There was an attempt to reboot Eve Rocks, but not much has come of it.

For one thing, I don't think an Eve Return is as hard as it used to be; the other, it takes a special kind of person to keep a challenge like that running for years. You have to look at every entry with a critical eye. After half a year they all started looking the same and I found it hard to still pay attention. On top of that, for something as involved as Eve Rocks or Jool-5, checking a submission is easily an hour of work. Boolybooly or Ziv or (these days) JacobJHC don't get nearly as many kudos as they deserve.

 

There are also mission contracts that require you to return a stranded Kerbal from Eve including the wreckage.

I think a good challenge would be to retrieve a wrecked ship. The general challenge rule could be to retrieve a specific vessel from Eve surface using a specific savegame file and the one who uses the lightest and cheapest vessel wins.

Or divide the challenge into weight or volume classes and the best winner wins.

Various ways of retrieving cargo using a pusher or puller rocket or a internal Mk3 cargo bay. One should make a mechanism to dock with a stranded vessel. One should find a way to lift the cargo into a aerodynamic position. So a stranded mk2 vessel that doesn't fit into a mk3 cargo bay should be lifted vertically while resting horizontally on the ground.

I won't organize this challenge but maybe it inspires somebody else.

Edited February 6, 2019 by Aeroboi

[herbal space program]

1 hour ago, Aeroboi said:

There are also mission contracts that require you to return a stranded Kerbal from Eve including the wreckage.

I think a good challenge would be to retrieve a wrecked ship. The general challenge rule could be to retrieve a specific vessel from Eve surface using a specific savegame file and the one who uses the lightest and cheapest vessel wins.

What comes to mind for me is an out-of-fuel Mk3 capsule/uppermost stage combo with a docking port,  that is splashed down somewhere in the ocean at least 10 km from land. There would be no rule about the elevation from which you can ultimately ascend back to orbit, but of course you have to devise a way to get your cargo to the launch site from the sea. It would be like an Eve Triathlon -- swim, drive, fly.  I guess I would have separate leader boards for lowest launch weight, lowest mission launch cost, and maybe lowest part count. I think that is a challenge that would not necessarily converge to one winning solution so quickly, but like you I don't know if I'm up for organizing it. The last time I did one, there were some initial positive reactions and then no entries at all, and it was a way quicker and easier mission than this one would be. I'll give it some thought anyway....

[Aeroboi]

2 minutes ago, herbal space program said:

What comes to mind for me is an out-of-fuel Mk3 capsule/uppermost stage combo with a docking port,  that is splashed down somewhere in the ocean at least 10 km from land. There would be no rule about the elevation from which you can ultimately ascend back to orbit, but of course you have to devise a way to get your cargo to the launch site from the sea. It would be like an Eve Triathlon -- swim, drive, fly.  I guess I would have separate leader boards for lowest launch weight, lowest mission launch cost, and maybe lowest part count. I think that is a challenge that would not necessarily converge to one winning solution so quickly, but like you I don't know if I'm up for organizing it. The last time I did one, there were some initial positive reactions and then no entries at all, and it was a way quicker and easier mission than this one would be. I'll give it some thought anyway....

Considering this challenge currently runs it might be a good idea to launch one sooner then later. Perhaps further interest will follow. By the looks of it people are both interested in amphibious vessels plus rockets and rovers no mind construction to get it done so I bet a lot of people will be interested in this.

[herbal space program]

7 hours ago, Laie said:

The purpose was to make everyone play the same challenge. Not that it was strictly necessary... the point was not that ore has to come from the lowlands, but that the lifter is supposed to be sea-level capable.

I guess it hinges on whether or not you consider driving your several hundred ton lifter up a mountain under its own power "launching" it. Anyway you gave me the answer I expected on that score, but I still thought it was worth asking 

[herbal space program]

3 hours ago, Aeroboi said:

Considering this challenge currently runs it might be a good idea to launch one sooner then later. Perhaps further interest will follow. By the looks of it people are both interested in amphibious vessels plus rockets and rovers no mind construction to get it done so I bet a lot of people will be interested in this.

OK,  I'm going to take a stab at it this evening. I agree that with well-contrived rules and sub-challenges it could appeal to a fair number of people, even though it's a pretty tall order all around. I think I'll have categories for both lowest launch cost and lowest launch weight, with the stipulation that you must at least reach LKO before you can mine any resources. I might throw in fastest recovery time as well, since that would be a completely different sort of challenge and might generate some entertaining craft. If you guys can think of any other categories that seem viable, please let me know!

[Laie]

This feels like a necro, but still.

I've been messing around, on and off, with recoverable Eve-300 craft. The idea was to bring down cost by returning  expensive hardware (and not to worry about using expensive stuff in the first place, because recovery). Given how @ManEatingApe could easily modify his winning vessel to recover 15k, I figured that I need to bring the price tag down to under 300k. Which is hard. The above is the first vessel that could do it at all, and only by the slimmest of margins (both dV as you can see, and budget: rollout 390k, recovery 95).

Not enough to warrant a full submission, but making it at all seems like a major breakthrough. Wanted to share.

[Laie]

Extending the above... it's by now means obvious how one best saves money using a recoverable vessel upper stage.

Putting Vectors on that one should help, shouldn't it? Those can work their way from the ground up, after all. But I find that this doesn't automatically translate into savings. Each Vector adds 4t, that's about 10% more "dry" mass as you make orbit, and thanks to the rocket equation those 10% add so much more fuel on the ground that the Vectors are totally occupied with lifting their own mass. They don't replace anything on the LV.

TL;DR: if you replace the Skiffs on the above Vessel with vectors, you still need the same amount of boosters to get off the ground. Savings: zero.

Be that as it may, I have more to report.

I guess the dotted line will be the most interesting: that is speed@altitude of an overpowered rocket running at infinite fuel, only throttling down to prevent the nosecone from overheating. I can't help the waviness, it's the closest I could get within my capabilities.

I think that the difference between good and excellent performance lies in how closely you scrape past the speed limit. You want to approach it as early as you can, never exceed it on threat of immediate destruction, and eventually cross the 45km mark at an angle that's suitable for your upper stage.

The solid lines are simply pitch and airspeed versus altitude of three rockets.  All three rockets had virtually the same mass and set of engines, had the same gravity turn dialled in early and then followed prograde. The only difference was how much fuel was on which stage. Of these, #3 (black) performed best overall, but I'll spare you the details.
 

[herbal space program]

2 hours ago, Laie said:

Extending the above... it's by now means obvious how one best saves money using a recoverable vessel upper stage.

Putting Vectors on that one should help, shouldn't it? Those can work their way from the ground up, after all. But I find that this doesn't automatically translate into savings. Each Vector adds 4t, that's about 10% more "dry" mass as you make orbit, and thanks to the rocket equation those 10% add so much more fuel on the ground that the Vectors are totally occupied with lifting their own mass. They don't replace anything on the LV.

<snip>

I think that the difference between good and excellent performance lies in how closely you scrape past the speed limit. You want to approach it as early as you can, never exceed it on threat of immediate destruction, and eventually cross the 45km mark at an angle that's suitable for your upper stage.

<snip>
 

That's all pretty consistent with my experience. Vectors are by far the best option for getting you off the ground in a manner that hugs your dotted line, but once they've done that their weight and relatively poor ISP up high makes them rapidly become a big burden. In my own attempts to address this question, what I ended up doing was just staging off the engines:

 

 

All that comes off of this craft is the 8 outer Vectors and their 2-way adapters, leaving  4 Vectors and 5 Wolfhounds on orbit. So non-recoverable launch costs here are only ~150,000, albeit with a higher launch altitude, much smaller payload, and disallowed engines viz. your challenge. I still however think there's a good chance this general strategy could be used to get a qualifying lifter to orbit for under 300,000....

Edited March 14, 2019 by herbal space program

[bayesian_acolyte]

At long last I've completed this challenge with a ship costing barely less than 300k, excluding return value. 

Imgur album: https://imgur.com/a/m4gkADk

Craft file: https://kerbalx.com/Bayesian_Acolyte/24-Asparagus-Flavored-Boars

I used 12 twin boars for most of the fuel storage and engine power, trying to take full advantage of their low cost. 3 Darts served as my main interplanetary engines as well as my upper stage on Eve ascent. One notable difference between my strategy and others was my decision to exclude parachutes for cost saving purposes. This worked out in the end but was quite frustrating and is not something I would repeat. My route was the same as others, Minmus -> Eve orbit -> fuel drop -> Eve touchdown -> re-fuel in orbit after ascent -> Gilly -> home. Details are in the imgur album linked above.

Thank you @Laie for the cool challenge and @ManEatingApe for the inspiration for the design. Your cost reduction by decreasing the use of Mammoths and increasing the amount of Twin Boars is what inspired this design.

[ManEatingApe]

7 hours ago, bayesian_acolyte said:

I used 12 twin boars for most of the fuel storage and engine power, trying to take full advantage of their low cost. 3 Darts served as my main interplanetary engines as well as my upper stage on Eve ascent. One notable difference between my strategy and others was my decision to exclude parachutes for cost saving purposes. This worked out in the end but was quite frustrating and is not something I would repeat. My route was the same as others, Minmus -> Eve orbit -> fuel drop -> Eve touchdown -> re-fuel in orbit after ascent -> Gilly -> home. Details are in the imgur album linked above.

Awesome mission and craft design! Over 100 aero--braking passes and a pure propulsive landing is both very crazy and very Kerbal

(...also your ship name is making me oddly hungry )

 

Edited March 29, 2019 by ManEatingApe

[Laie]

8 hours ago, bayesian_acolyte said:

I used 12 twin boars for most of the fuel storage and engine power, trying to take full advantage of their low cost. 3 Darts served as my main interplanetary engines as well as my upper stage on Eve ascent.

I've spent a lot of time trying to one-up ManEatingApe and couldn't do it, so. Phew. Whoa. Color me impressed. Major kudos for making the Aerospikes work -- all my attempts along these lines fell short (literally), there's lot of stability issues and I came to the conclusion that whatever the Darts are worth, they soak up in additional drag for the mountpoints.

In a stock context, at any rate. I eventually managed to make them work together with MH engines, stay tuned.

8 hours ago, bayesian_acolyte said:

One notable difference between my strategy and others was my decision to exclude parachutes for cost saving purposes.

Oh boy. I've done that back in the day... once. Won't ever do it again. My favorite failure mode was getting it right for once, then running out of fuel just above the surface.

Even a single small parachute works wonders in reducing speed, giving you a wider time window to do your braking; it also takes care of keeping the vessel pointed retrograde, so you don't have to worry about control and can concentrate on the throttle.

IMO, control is the major problem at that point. MJ takes some time to get things properly set up... with a total burn time of just a few seconds at constantly-changing throttle, it tends to make matters worse. I have an inkling that a lot of the sideslip you've been experiencing has been induced by MJ.

A bit sorry about the shortage of pictures of the ascent, and the MJ dV chart is pretty useless. I'll have to download your craft and play around with it in order to figure out how it works. Do you always drop tanks/stages as soon as they're empty, or do some stay attached for longer? If your last stage had nothing but the three Aerospikes and started as soon as the lower tanks were spent, TWR must have been under 0.5 with >2500m/s of delta-V -- I don't think it's possible to launch into a low orbit in such a vessel, you need to raise AP quite high or there's not enough time to circularise.

[Laie]

Making History to the rescue, the Mastodon really has some bang for the buck:

I have to admit to not having flown it... not quite. I have spent the past week taking a very similar vessel to Eve, Gilly, and back. As I've had my eyes on saving cost through recovery, I put on a few huge solar panels and an RTG for extra convenience, at a rollout cost of 320k, about 75k of which would be recovered. Gallery and tech talk here.

It just occured to me that it would qualify for cheapest vessel if I drop all the expensive gear. A single fuel cell will suffice, after all... then again, this challenge has been stock-only so far. MH was allowed but, to the best of my knowledge, not being used until now.

[bayesian_acolyte]

4 hours ago, Laie said:

Even a single small parachute works wonders in reducing speed, giving you a wider time window to do your braking; it also takes care of keeping the vessel pointed retrograde, so you don't have to worry about control and can concentrate on the throttle.

Ya, I figured this was the case, and I regret not doing this, but the realization came too late. I came very close to asking in this thread if I could hyper-edit a new craft into the same Eve orbit and fuel situation as my old one with the addition of a small parachute. But I wanted to minimize the use of H, and without it I figured it would take more time to get the new craft into position (including the aerobreaking) than it would to just land the craft I had.

 

4 hours ago, Laie said:

A bit sorry about the shortage of pictures of the ascent, and the MJ dV chart is pretty useless. I'll have to download your craft and play around with it in order to figure out how it works.

I can upload the ~120 save files I made if that helps. The shortage of ascent pictures was largely because there were a number of failed attempts and I didn't know which would work, and I wasn't sure how useful the failed attempt pictures would be. And then the ones I did get, I forgot to show the fuel tab. But the launch shouldn't be too hard to reproduce, I think I ended up making stable orbit like ~5 times loaded on ore if you include a few test launches, and I'm not the best pilot.

4 hours ago, Laie said:

Do you always drop tanks/stages as soon as they're empty, or do some stay attached for longer?

This is an interesting question, the short answer is that I did detach them as soon as they emptied. In my initial testing (before the official launch) I was mixing it up with both strategies, and the two times I achieved orbit I was dropping them immediately, so I just went with it. However I don't think I ever got the right ascent profile when I was holding the tanks longer, and there's a good chance the success of the former strategy was just due to chance. The TWR is around 1.4 at launch, and then goes up to around 1.75 before the first tanks are released, then goes back down to 1.4 after they are released. The TWR would continue to climb above 2 depending on how many tanks are held. It's an interesting theory question, is the extra drag and weight worth the higher TWR? Initially I suspected it would be but I never took the time to investigate properly, since I had verified I could achieve a successful launch that met my goals and that was good enough.

 

4 hours ago, Laie said:

If your last stage had nothing but the three Aerospikes and started as soon as the lower tanks were spent, TWR must have been under 0.5 with >2500m/s of delta-V -- I don't think it's possible to launch into a low orbit in such a vessel, you need to raise AP quite high or there's not enough time to circularise.

The dV of the final Eve ascent stage is around 1650m/s including the ore, which is much more manageable than 2500m/s. In one successful test launch my initial AP never made it out of the atmosphere and I fell past it. but was able to raise the far-side PE past the atmosphere to the new AP and then circularize on the other side. And then on the official launch I used, my initial AP was raised to 130 km, so I know a wide variety of launch profiles are possible. I suspect the more shallow launch is optimal, freezing time-to-ap just before reaching it, as it gives a lot of burn time for the final stage and minimizes waste thrust. The craft is quite controllable in this stage so you can tilt up as soon as the the stage is activated to slow the time to AP, and if you can freeze it without too steep of an angle that is going to be a successful launch. Here's a picture of a launch that achieved stable orbit (but with not enough remaining dV to meet the depot) despite AP being only 6 seconds away and 65km with 1150m/s dV remaining in the final stage, because I was able to freeze time-to-AP with a 45 degree angle.