herbal space program

Eve oceanic rescue/salvage challenge: A KSP Triathlon

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Intrepid Kerbals are in distress!

Flash: During Valentina's 78th attempt to land her Mk3 capsule-based Eve 3000 Challenge lifter from orbit,  engineer copilot Bill finally fell asleep and spilled his coffee all over the console! The resulting short circuit caused every action group to go off simultaneously, instantly jettisoning all but their uppermost stage! Legendary pilot that she is, Valentina was able to safely re-enter her historically significant, record-setting command/service module "Jeb" under power, but it required every resource she had, and left her and the now wide awake Bill bobbing in the Drink, totally helpless, and miles from shore.

In light of this emergency, your mission, fellow Kerbonauts, is to Rescue Valentina, Bill, and Their Historic Ship from the Eve Ocean and return them to Kerbin!

The debate in Mission Control on how to accomplish this was lively, and unfortunately no consensus on the best approach was reached. Some argued that getting the rescue accomplished ASAP was the highest priority, while others reasoned that Valentina and Bill still had plenty of snacks according to the ship manifest, and moreover that since they had just blown the most incredible amount of funds jettisoning their massive Eve lifter,  their rescue should cost as little as possible. In the end, Werner couldn't really make up his mind either, so he decided to fund both projects...

So!

While your mission in either case is to return both ship and occupants to Kerbin, there are two ways to play: You can get it done either as quickly or as cheaply as possible. For the "quickly" challenge, money/mass is no object and you just need to do it in the shortest time possible, from launch to recovery on Kerbin. For the "cheaply" challenge, there are two three sub-categories: lowest launch cost, lowest total cost, and lowest launch weight.

The rules:

What is required: You must return both the stranded Kerbals (alive), as well as their ship (in one piece, without staging, burning, or breaking anything off) from some location at least 10km offshore in any of the major seas of Eve to the ground on Kerbin. The ship to be rescued must include a MK3 capsule and two Large Ore Holding Tanks, and have a dry weight of at least 10 tons and a total weight at the time of rescue of not more than 20 tons. The cost of this vessel will not be charged against your overall mission cost. Pretty much anything within those constraints is allowed, with the proviso that it must not have any resources on board that are consumables for control or locomotion, nor can it have the intrinsic capability to create those without docking to another craft. That means all on-board fuel/RCS tanks must be empty, and all reaction wheels must be either deactivated or without power. You may furthermore not have any solar panels, RTGs, or ore converters on board the vessel to be rescued. Having said that, you may place ore in the tanks of the vessel to be rescued, but any ore that you actually convert after docking to the rescue craft cannot be counted as part of the "dry" weight of the craft to be rescued. The point here is that the rescue craft must actually bring the capability with it to create these resources, and that no matter what you start with, you must lift to orbit and deliver to Kerbin a craft that weighs at least 10 tons during all phases of this process.  As long as you obey that rule, you may actually use unconverted ore purely as ballast.

What is not allowed: For me, the goal of this challenge is to elicit the broadest variety of competitive solutions possible, so the rules are pretty loose. However, having said that please don't cheat. I define cheating as anything that violates the intended physics of Stock KSP.  This obviously includes exploiting any and all clear bugs in the vein of Infiniglide, Ladder Drive,  Kraken Drive, etc. This also includes non-Stock parts that violate the basic Stock parameters in terms of mass, TWR, ISP, etc, as well as any part clipping into non-hollow structures that significantly cheats the drag model.  That is, you can clip batteries, reaction wheels, etc. into hollow adapters and nosecones, so long as they are not clipped into each other, but not into fuel tanks or other non-hollow parts, nor can you clip non-hollow parts into each other. If you want to clip backwards intakes into engines to reduce back-end drag, I guess that's OK with me.  As to Alt-F12/Hyperedit, that is totally OK for testing, but for submission I expect all key phases to be fully flown and/or driven by the submitter and duly documented.  That means that using MechJeb, etc. to fly the hard parts for you is expressly forbidden. Having said that, if your mission depends on some repetitive resource extraction/conversion/refueling process that would take an eternity to execute by hand, you may demonstrate just the first cycle of that explicitly and then refuel your craft fully using Hyperedit, etc. Lastly, ore extraction/processing can only be carried out by any particular launch package after it reaches LKO.

What is allowed:  You can place the vessel to be rescued any way you want, so long as it is floating at least 10 km offshore.  Any and all purely informational mods such as KER are also fine. You may use any strategy within the constraints spelled out above to get the mission accomplished. This includes all sorts of detachable rovers/ships, reaction wheel-powered copters/ships, etc. Any way you can transport the vessel to be rescued back to Kerbin in one piece is OK,  provided it does not violate Stock physics. You may use whatever engines/tanks/wheels/etc are present on your rescued module to get back home, provided that all the consumables required are brought/created by the rescue craft. 

The Categories:  At this point, I am scoring four categories: Lowest Launch Cost: The lowest cost on the VAB indicator right before you launch, combined for all the separate modules you may launch. Lowest Total Cost: the lowest total net expenditure of funds, meaning that whatever parts and/or resources you may recover on Kerbin at the end can be deducted from your total launch cost as defined in the previous section.  Lowest Launch Weight: Smallest combined mass of all modules launched from Kerbin, at the time of launch. Fastest Rescue: The shortest time elapsed from the first Kerbin launch to touchdown of the rescued craft on Kerbin, regardless of any other parameter. Note that the vehicle to be rescued itself does not count towards any of these measures.

My submission: Since AFAICT this challenge is clearly possible given past challenges, I will not be submitting my own entry immediately. I will instead work on my entry in parallel with (hopefully) those of the other contestants. If there is any clear objection about feasibility based on the posted rules, please post it to this thread and I will address it as warranted. Leader boards will be created as appropriate when submission are received....

One more thing: Given that this contest will (in most cases) require at least three major design exercises, please feel free to post any intermediate steps that you're willing to share! 

 

Edited by herbal space program
more clarifications to the rules about the craft to be rescued

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Some questions about the rules... is the vehicle to be recovered allowed to have a docking port (makes attaching it to a rescue vehicle easier), and can it be used as the vehicle that Kerbin re-entry is made in?

The section in the rules about the rescued vehicle states that it "must not have any resources on board that provide control or locomotion". The part in bold might force a re-entry to Kerbin of the rescued pod to have another means of control attached to it, for that last part of the journey.

I've got some ideas on approaches to this challenge, and as a frequent visitor to the purple kerbal eater, I might give this challenge a go.

 

Additional:

Damm you Herbal... I got home and immediately started planning how an entry to the challenge would be done.

Well that's my weekend gone :)

Edited by purpleivan

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12 hours ago, purpleivan said:

Some questions about the rules... is the vehicle to be recovered allowed to have a docking port (makes attaching it to a rescue vehicle easier), and can it be used as the vehicle that Kerbin re-entry is made in?

The section in the rules about the rescued vehicle states that it "must not have any resources on board that provide control or locomotion". The part in bold might force a re-entry to Kerbin of the rescued pod to have another means of control attached to it, for that last part of the journey.

I've got some ideas on approaches to this challenge, and as a frequent visitor to the purple kerbal eater, I might give this challenge a go.

Howdy and welcome to the challenge!  The answer to both of your questions is yes. You may make your craft out of whatever parts you want excluding solar panels, ore converters, and RTGs, provided it includes the three required ones and is empty of all fuel/monoprop/xenon,  and has either no electrical charge or all reaction wheels disabled. That is, it must be completely dead in the water at the time of rescue. If you can successfully dock your rescue ship to it while it is in that state, you may refuel it with whatever resources you brought with you, and then have it do whatever it is capable of doing under its own power thereafter, including processing whatever ore it may have had on board at the time of rescue, although I am going to update the rules at the top to clarify that  the total weight of the craft on rescue must be between 10 and 20 tons rather than the dry weight, so that Valentina's historic pod is not reduced to a fuel barge. The upper weight limit is also there to insure that cheeky contestants don't trivialize the cost/parts challenges by dropping an entire unfueled Eve lifter into the water for free and then just tagging it with a token rescue ship.

Anyway, definitely included in all that is ultimately using the rescued craft as an upper stage/Kerbin re-entry vehicle, provided you don't stage/break/explode anything off of it in the process. That is, it must make it back to the ground on Kerbin in one piece, as found on rescue, regardless of whether that is in a cargo bay or under its own power. Within those rules you can devise and use it any way you want, and I'm hoping that this will lead to some creative entries.

Happy flying!

Edited by herbal space program
added new rule about panels, converters, and RTGs

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I have some more questions.

1. I'm confused about this part of the rules that state that " The ship to be rescued must include a MK3 capsule and two Large Ore Holding Tanks, and have a dry weight of at least 10 tons and not more than 20 tons. Does the dry weight rule allow for filling the ore tanks with sufficient ore to bring the weight up to the minimum of 10 tons, or do these have to be empty and other parts added to bring the total weight up from the 6.72 tons for the pod and ore tanks, to 10 tons?

2. Can the ore tanks on the ship to be rescued, be used by the ascent vehicle as part of ISRU to provide fuel, rather than sending tanks to Eve for that purpose. The rules don't explicitly rule this out, but your intention might have been that the ship to be rescued be treated at all time as just dead weight.

Just saw your new post and I think these questions might be answered by it... the answer seems to be that yes, ore can be part of the "dry weight" of minimum 10 tons, and yes the ore tanks can be used once the vehicle is recovered by the rescue team.

Edited by purpleivan

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28 minutes ago, purpleivan said:

I have some more questions.

1. I'm confused about this part of the rules that state that " The ship to be rescued must include a MK3 capsule and two Large Ore Holding Tanks, and have a dry weight of at least 10 tons and not more than 20 tons. Does the dry weight rule allow for filling the ore tanks with sufficient ore to bring the weight up to the minimum of 10 tons, or do these have to be empty and other parts added to bring the total weight up from the 6.72 tons for the pod and ore tanks, to 10 tons?

2. Can the ore tanks on the ship to be rescued, be used by the ascent vehicle as part of ISRU to provide fuel, rather than sending tanks to Eve for that purpose. The rules don't explicitly rule this out, but your intention might have been that the ship to be rescued be treated at all time as just dead weight.

Just saw your new post and I think these questions might be answered by it... the answer seems to be that yes, ore can be part of the "dry weight" of minimum 10 tons, and yes the ore tanks can be used once the vehicle is recovered by the rescue team.

1. You are right that there is a bit of ambiguity/loopholes here, so I tried to clarify it at the top. I changed to "a dry wight of no less than 10 tons" so that people must deal with returning at least that much mass back to Kerbin, and a "total wight of no more than 20 tons" so that people can't drop entire lifters in the drink or make their craft into an ore barge. IOW, ore may be part of the total weight but not  the dry weight.* So the bottom line is you can have up to 10 tons of ore aboard that you may convert to fuel upon rescue, or else you can use that weight to add fuel tanks to your vessel that you may later fill using ISRU at some other site.  I hope I get to see which strategy will prove more economical!

2. Just to be completely clear, you may use the rescued vessel any way you want, so long as you return it to Kerbin completely intact. What you may not do is ballast a 5-ton ship with 15 tons of ore and then burn that all up so that you're only lifting 5 tons to orbit.

Anyway, I hope that's now clear to everyone. Coming up with clear and balanced rules is always a challenge with these kinds of challenges!

 

* I have now further refined this to say that if people want to use the ore just as ballast they may, but it must be lifted to Eve orbit and returned to Kerbin unconverted.

Edited by herbal space program

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12 hours ago, purpleivan said:

Damm you Herbal... I got home and immediately started planning how an entry to the challenge would be done.

Well that's my weekend gone :)

Awesome! I hope to spend a good portion of this cold, rainy weekend the same way. Since you are jumping right in, please note that upon some reflection I updated the rules to disallow solar panels, ore converters, and RTGs from the craft to be rescued, to prevent people from just tagging it with a tiny token rescue vessel and then having it ISRU its way to the mountaintop under its own power. Without that rule it seems like it would not be much of a Triathlon.

Edited by herbal space program

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On 2/9/2019 at 2:06 AM, herbal space program said:

Awesome! I hope to spend a good portion of this cold, rainy weekend the same way. Since you are jumping right in, please note that upon some reflection I updated the rules to disallow solar panels, ore converters, and RTGs from the craft to be rescued, to prevent people from just tagging it with a tiny token rescue vessel and then having it ISRU its way to the mountaintop under its own power. Without that rule it seems like it would not be much of a Triathlon.

Ok, I'll need to take off the the 3 small solar panels I put on my stranded ship, but it'll only be running on it's own power for very last part of ascent from Eve and then Kerbin re-entry, so not a big deal, but I'll throw an extra battery on it to be safe.

Edited by purpleivan

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I've been working for a few days now to create the set of vehicles that I planned to use to create an entry for this challange, but I've hit a snag that I think that breaks one of my vehicles and therefore my entry.

My plan for the mission was to use a boat to recover the stranded ship to the shoreline, then take a wheeled transporter into the breakwater, mount it on its back, then drive to a nearby ascent vehicle. This way I would avoid having to land an ascender on and launch from the sea, as well as the issues of transporting ISRU sourced fuel from a land based refinery.

All parts of this work fine, even in the 1.7g of Eve, except the transporter. It's a long time since I've used a wheeled vehicle on Eve, and certainly on that weighs about 20 tons, even without the ship on its back. I'm using the TR-2L wheels on the vehicle in the image below, but they're just not up to the task of handling 1.7g.

The picture below is actually a slightly earlier version with 10 wheels, whereas now I'm using 12.

EUrYHG0.png

On the flat terrain of the KSC, with the gravity cranked up to 1.7, they are "mostly" fine, but on natural terrain with any kind of bumpiness, the wheels constantly shatter. Even on a save reload, an undamaged vehicle will have 3 or 4 damaged immediately and repairing them just causes the vehicle to hop around and others to break. I could crank up the number of wheels to reduce the stress on them, but I think I'd have have to get into silly numbers (maybe double the 12 I have now) to be sure of reliability.

For now my attempt is going to have to go on hiatus, certainly until I can face dumping my entire mission plan and designing a sea based ascender mission.

BTW... here are a few pics of the othe vehicles that I planned to use.

 

Almost final version of the recovery vehicle. I later removed the raised forward wings to improve aerodynamics. Nice vehicle and quite fun to drive around in, with about an over 25km range, even towing the stranded ship.

92UUFiA.png

The ascent vehicle, transport (with drive section detached) and the stranded ship laying on the erector section.

Nb136uI.png

The stranded ship docked to the ascent vehicle. After I use the erector, I found the alignment wasn't quite right, so nudged the thing around with the drive section of the transport until it was close enough to alignment to raise the landing legs and dock. At that moment the physics went haywire, the pad exploded and the ascent vehicle (with the ship attached) spun into the air.

Miraculously the thing landed right side up and intact.

DZCv4Oq.png

The ascent vehicle was more powerful than I expected. I did a test run from a 600m high location on Eve and made orbit with about 2000 dv to spare. Then again it is a pretty big ship :)

Edited by purpleivan

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4 hours ago, purpleivan said:

I've been working for a few days now to create the set of vehicles that I planned to use to create an entry for this challange, but I've hit a snag that I think that breaks one of my vehicles and therefore my entry.

My plan for the mission was to use a boat to recover the stranded ship to the shoreline, then take a wheeled transporter into the breakwater, mount it on its back, then drive to a nearby ascent vehicle. This way I would avoid having to land an ascender on and launch from the sea, as well as the issues of transporting ISRU sourced fuel from a land based refinery.

All parts of this work fine, even in the 1.7g of Eve, except the transporter. It's a long time since I've used a wheeled vehicle on Eve, and certainly on that weighs about 20 tons, even without the ship on its back. I'm using the TR-2L wheels on the vehicle in the image below, but they're just not up to the task of handling 1.7g.

The picture below is actually a slightly earlier version with 10 wheels, whereas now I'm using 12.

 

On the flat terrain of the KSC, with the gravity cranked up to 1.7, they are "mostly" fine, but on natural terrain with any kind of bumpiness, the wheels constantly shatter. Even on a save reload, an undamaged vehicle will have 3 or 4 damaged immediately and repairing them just causes the vehicle to hop around and others to break. I could crank up the number of wheels to reduce the stress on them, but I think I'd have have to get into silly numbers (maybe double the 12 I have now) to be sure of reliability.

For now my attempt is going to have to go on hiatus, certainly until I can face dumping my entire mission plan and designing a sea based ascender mission.

Wow, it looks like you've  gotten pretty far on this! I'm actually at very close to the same stage with my entry, which has components fairly similar to yours. I have a working lifter, a stranded ship that actually has its own wheels, and an amphibious rescue vehicle. The wheeled vehicles all seem to work fine driving around Kerbin, but I had not actually gotten around to testing them on Eve yet. I hope that doesn't turn out to be a showstopper! The next size of wheels up is going to be pretty, well,  unwieldy.  If as I suspect I'm going to have the same problem, I might see if I can use some number of passive landing gears to mitigate the overall wheel stress. I guess at least I know now what to expect in terms of my next design hurdle....

PS: Your lifter is indeed pretty big! Mine is a fair bit smaller, but it won't make orbit from anywhere near that low, which is an idea that could end up on the scrap heap if wheels just won't work at all...

Edited by herbal space program

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On 2/14/2019 at 12:46 PM, purpleivan said:

On the flat terrain of the KSC, with the gravity cranked up to 1.7, they are "mostly" fine, but on natural terrain with any kind of bumpiness, the wheels constantly shatter. Even on a save reload, an undamaged vehicle will have 3 or 4 damaged immediately and repairing them just causes the vehicle to hop around and others to break. I could crank up the number of wheels to reduce the stress on them, but I think I'd have have to get into silly numbers (maybe double the 12 I have now) to be sure of reliability.

For now my attempt is going to have to go on hiatus, certainly until I can face dumping my entire mission plan and designing a sea based ascender mission.

 

So I spent a little time working on this problem today, since it is a major issue for me as well, and what I discovered, against all intuition, is that lowering rather than raising the spring/damper strength on the wheels is what prevents them from bugging out in high gravity. At first I kept  taking them off "auto" and raising one or the other, and my ship would just do the phantom force jumping bean dance until it flipped and blew up or enough wheels broke that it was stuck to the ground. Finally I tried going the other way and presto! All the buggy forces are gone and the wheels behave more or less reasonably, although the loping gait of the resulting suspension is a bit comical. I do hope you'll give that a try before you give up after doing so much great work!

PS: In the wake of all this testing, I am also coming to the conclusion that there is no terrestrial brake more powerful than a broken rover wheel! I am going to have to try that some time when I need to make a short landing of some kind...

Edited by herbal space program

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I know this challenge is some months old, but since it has not been closed here is my submission:

My rescue crafts are the heavy lifter 'Hydra' and the small fuel transporter 'Hermes'. I did not ditch any stages, but Hydra cannot go back to orbit, but stays on the surface on Eve. My historic craft weighs 12.999 tons empty and does not have any fuel or ore in its tanks.

The historic craft lies 11km away from shore in the water:

nZUX5pb.jpg

Hydra:

SprSrTf.jpg

Hermes:

YKGYvcT.jpg

Mission completed:

YkraIcd.jpg

A gallery with images of the whole mission can be found here: https://imgur.com/gallery/5TWdwD5

Mission description:

After docking Hermes and Hydra on the runway, they fly together to the surface of Minmus. After refueling on Minmus, the two craft make their way to Eve. The transfer from low Minmus orbit to an Eve intercept is very efficient and costs only 380m/s. I achieved thy by going into an elliptical Kerbin orbit first and then burning at Kerbin-Periapsis. This also includes a ~50m/s normal burn after leaving Kerbin SOI to make sure the descending node is at the place of the Eve encounter. By saving the fuel, I have enough fuel to capture and circularize at Eve using retro burning. I also have enough fuel left for the deorbiting.

I land Hydra and Hermes on the highest mountain of Eve. There Hermes undocks and flies down to the historic craft. The remaining fuel is enough for both Hermes and the historic craft to fly to land. There I dock all three craft together and fly back to the mountain top. One by one I push Hermes and the historic craft back to orbit. Hydra can push the upper stage into a suborbital trajectory. After circularizing the upper stage I can switch back to Hydra and land Hydra back on Eve. With 2-3 hops I can fly Hydra back to the highest mountain of Eve and repeat the process.

When docked in orbit, Hermes and the historic craft do not have enough delta-V to go back to Kerbin. So Hermes shuttles fuel from the surface of Eve to orbit. Hermes has around 250-300 liquid fuel plus corresponding oxidizer when in orbit. It needs 100 liquid fuel plus oxidizer to deorbit. So I perform 7 refueling runs until I have enough fuel in orbit. I decided to fly all refueling runs instead of using Hyperedit because as far as I know this is the first mission that uses repeated reusable missions to Eve surface for refueling. Deorbiting is the hardest part because of the low heat tolerance of the solar panels and the grabbing unit. One time I overshot the landing position and landed Hermes 22.6km off shore. To rescue it, I used Hydra as a speed boat and docked with Hermes. After that I just had enough fuel to fly back to land.

After flying back to Kerbin I captured at Kerbin using a Mun assist, aero capture and a small bit of retro burning. After aero braking to a circular orbit, I landed the historic craft and Hermes together on the runway.

Mission duration: 14y 401d 1:17

Mass at launch: 413.975 tons (Hydra) + 11.73 tons (Hermes) = 425.705 tons

Cost at launch: 241 398 (Hydra) + 13 028 (Hermes) = 254 426

Recovered cost: 12 294 (Hermes, empty on fuel)

Edited by EveMaster

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Oh this is good! I dont care if it's old or if entries are still accepted or not, but I will start planning this tomorrow.

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Crafts

So, I have now designed an Eve lifter (Walrus) and the craft in need of rescue (Manatee).

Walrus can land to Eve's surface from orbit and once docked with the Manatee can assist Manatee to a stable 100x100km orbit from ~sea level. Ascent profile is very sensitive though and I am usually left with less than 100m/s dv.

Next I need to design a refueling craft (Otter) that will also bring Manatee from ocean to solid ground. It will be docked to Walrus (in place of the Manatee) at the beginning of the mission and it will leave a fuel tank to low Eve orbit for refueling so Manatee can get back to Kerbin.

Whole mission plan is roughly the following:

1. Walrus + Otter combo launches from kerbin and achieves orbit.

2. Next stop is refuel at minmus (Walrus might need some modification to be able to land there).

3. Then refuel at Gilly if needed and leave a fuel tank in orbit for the return journey.

4. Land the rest of the craft to Eve near the Manatee.

5. Refuel everything.

6. Undock Otter and get to Manatee.

7. Dock to Manatee and convert ore in Manatee's tank to LF/Ox so you can get back to Walrus.

8. Refuel Manatee once right next to Walrus. Undock Otter from Manatee and dock Manatee to Walrus. 

9. Launch Manatee to low Eve orbit.

10. Refuel from the fuel tank left behind earlier.

11. Go home.

EDIT: I am mostly going for the lowest mass category but launch cost won't be too insane either. Altough vectors are so expensive... 

Edited by tseitsei89

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Nice to see the progress in your rescue plan, @tseitsei89.

I decided to bring fuel instead of a converter to the craft in rescue. The problem with bringing a convertor is, that you can have 600 ore (6tons), if your craft has 13 tons. The next higher slider value is 750 ore would exceed the 20 tons total mass. If you bring a Convert-O-Tron 125 then this ore converts to only 1.2 tons of LF+Ox. The Convert-O-Tron alone has 1.25 tons, so it is not worth it. If you bring a Convert-O-Tron 250 you could get 6 tons of fuel, but this large converter weights 4,25 tons. If you also account for solar panels, radiators and batteries you also don't gain much, as the dry mass of your rescue craft will also be much higher.

In my opinion the rules of the challenge should be changed to allow to fully fill the two large ore tanks to encourage bringing a converter.

I developed a new craft to be able to bring back every single part back to the Kerbal space center. To get my lifter 'Hydra' back into orbit, I launch from the highest point on Eve to a suborbital trajectory with 150km apoapsis. The orbital speed at apoapsis is only around 2200km/s. When I'm out of the atmosphere I switch to the orbital tug, slow down to rendezvous and dock with Hydra and accelerate back to orbital speed before I would fall back into the atmosphere. The docking should be completed around the apoapsis, so that the that circularization can be done without too much antiradial component. This leaves me around two minutes for rendezvous and docking from an initial speed difference of close to 1000m/s. The tug is designed to have a high TWR and has many reaction wheels and RCS thrusters to allow this.

 

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22 minutes ago, EveMaster said:

Nice to see the progress in your rescue plan, @tseitsei89.

I decided to bring fuel instead of a converter to the craft in rescue. The problem with bringing a convertor is, that you can have 600 ore (6tons), if your craft has 13 tons. The next higher slider value is 750 ore would exceed the 20 tons total mass. If you bring a Convert-O-Tron 125 then this ore converts to only 1.2 tons of LF+Ox. The Convert-O-Tron alone has 1.25 tons, so it is not worth it. If you bring a Convert-O-Tron 250 you could get 6 tons of fuel, but this large converter weights 4,25 tons. If you also account for solar panels, radiators and batteries you also don't gain much, as the dry mass of your rescue craft will also be much higher.

In my opinion the rules of the challenge should be changed to allow to fully fill the two large ore tanks to encourage bringing a converter.

I developed a new craft to be able to bring back every single part back to the Kerbal space center. To get my lifter 'Hydra' back into orbit, I launch from the highest point on Eve to a suborbital trajectory with 150km apoapsis. The orbital speed at apoapsis is only around 2200km/s. When I'm out of the atmosphere I switch to the orbital tug, slow down to rendezvous and dock with Hydra and accelerate back to orbital speed before I would fall back into the atmosphere. The docking should be completed around the apoapsis, so that the that circularization can be done without too much antiradial component. This leaves me around two minutes for rendezvous and docking from an initial speed difference of close to 1000m/s. The tug is designed to have a high TWR and has many reaction wheels and RCS thrusters to allow this.

 

Yeah, I havent actually built my "recovery/refueler" yet so I dont know exactly how it will work but I'll see what is most efficient. I'll have to bring a converter to the surface of Eve anyway but we'll see. 

I dont have patience to travel to the highest peak from sea leve :D nor the docking skills required for your mission profile. Impressive and will result in a really low total cost if you can return everything. You would only pay for the initial fuel needed...

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Getting from sea level to the highest peak was one of the easier tasks. It is not that far and the fuel in the tanks is more than enough for that hop. Avoiding the overheating or breaking apart during reentry was a harder part. If Hydra lost her 'heads' during reentry, it grew them back by the magical use of 'F9'.

Here is a picture of Hydra docked with the orbital tug:

 

W9EX51K.jpg

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I have decided to integrate mining equipment (and claw to refuel Manatee at sea) to Walrus itself and use the whole ship to get to Manatee instead of building a detachable craft. This turned out to be an interesting engineering problem without robotic parts from dlc. But I think I got it now.

I still have problems with Eve re-entry and plenty of testing to do before the actual mission

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