Another efficiency challenge? Bring Criske Kerman home on the cheap.

[Gordon Fecyk]

With the experience of a couple of gravity turn efficiency challenges, maybe this might be a reasonable one to submit. I haven't found it after a short search, however, if it's been done before please let me know and I'll ask a moderator to delete, lock or merge this one.

Take the Stock Refuel at Minmus scenario, and get Criske Kerman and her modified Aeris 4B safely back to Kerbin, while leaving the most resources possible at the Bowser 1 tanker for other visitors to use. It's too easy to just take everything from Bowser 1, so how much do you really need to get home?

Rules: Use the stock scenario "Refuel at Minmus" from KSP 1.1 or 1.2. This being my first attempt at hosting a challenge I'm not going to dispute any shenanigans. As long as you're not hacking the game physics or parts, or hacking the scenario, let's see what you can come up with. I'd say stick with the stock physics, but I'm also curious what Principia and Ferram Aerospace would change, so I'll allow those mods.

I'll rate each attempt based on resources left at Minmus, mission duration, and landing or splashdown distance from KSC. Multiple submissions per participant are permitted and I'll put your favourite attempt on the table. Document your attempt here with numbers, and ideally with pictures or video. This one seems simple enough but presents some challenges for the thrifty.

Here's a video example. Spoilers ahead, so don't look if you want to challenge yourself first.

Spoiler

 

Participants table:

Participant	LF at Minmus	OX at Minmus	Distance from KSC	Duration
Eidahlil	354 (untouched!)	432 (untouched!)	150 km (? Guessed from map)	2y 58d 2h 54m
Gordon Fecyk	360 (topped up tank)	338	0 (landed on runway)	25d 3h 27m

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Edited December 3, 2016 by Gordon Fecyk
Added participants table and rules

[Eidahlil]

-Stuck in orbit? Me? Girl, I could probably make it to Duna with what I have in the tanks.
-Did you not say exactly that just minutes before getting yourself into this situation?
-Oh, get off my back. Look, I'll just do a quick Kerbin gravity assist, and be home for lunch.
-Command advises that orbital mechanics do not work that way, Criske. Just refuel and get this over with, before you get into a bigger mess.
-Watch me.

2 YEARS LATER:

Made it home mostly fine (lost one poorly placed solar panel on reentry) on only 81.85 units of monoprop. I also wasted all the jet fuel when already on Kerbin. I'm sure it can be done more efficiently by, for example:

• Using the side (in-line) RCS instead of the bottom RCS. I think the thruster blocks are slightly crooked and waste fuel.
• Splitting the Minmus escape burn into parts.
• Planning a better trajectory and executing the nodes more precisely.
• Not forgetting to turn off RCS when rotating the craft.

But it looks good enough for me.

 

[Gordon Fecyk]

1 hour ago, Eidahlil said:

-Look, I'll just do a quick Kerbin gravity assist, and be home for lunch.
-Command advises that orbital mechanics do not work that way, Criske. Just refuel and get this over with, before you get into a bigger mess.
-Watch me.

2 YEARS LATER

...I don't suppose Criske is related to Pierre Trudeau in your head-canon?

/me ducks

I'm also surprised you didn't explode aerobraking at 50 km up. Nice job! I figured we were in for a treat with that prologue.

So we have Ediahlil on the board with a mere zero resource usage from Bowser 1. Anyone looking to improve on that should instead top up Bowser's liquid fuel tank...  and I thought this would be a simpler challenge for us n00bs.

--

[John FX]

On 30/11/2016 at 3:51 AM, Gordon Fecyk said:

Take the Stock Refuel at Minmus scenario, and get Criske Kerman and her modified Aeris 4B safely back to Kerbin, while leaving the most resources possible at the Bowser 1 tanker for other visitors to use.

Does the `Stock Refuel at Minmus` scenario leave you with full or empty tanks?

You may want to change the rules so you have to fill up your craft and use the least fuel to return as the most fuel has already been left around Minmus on the first response. Also make it so there is no monoprop on the craft or say it should not be used.

 

Major props to @Eidahlil for doing it with no fuel though that sort of breaks the challenge.

[Gordon Fecyk]

1 hour ago, John FX said:

You may want to change the rules so you have to fill up your craft and use the least fuel to return as the most fuel has already been left around Minmus on the first response. Also make it so there is no monoprop on the craft or say it should not be used.

I like the ingenuity exhibited, I have to admit. I already 'cheated' somewhat when I noticed some liquid fuel aboard the 4B but no oxidizer. Also, RCS proved rather handy during aerobraking so it doesn't seem right to disallow that.

How about we see what other attempts come up? Don't let Ediahlil discourage you. Shenanigans aside, I'm impressed he survived re-entry from interplanetary speeds when I nearly melted just coming from the Mun.

What if we factor in resource use, closeness to KSC, and duration together? Two years is a long time to be cramped in a Mk1 cockpit after all.

I forgot to answer the first question, sorry. It seems the modified 4B in this scenario has slightly more than 89 units liquid fuel but no oxidizer, and just over 90 units monopropellant. Oddly, the RCS tank on that craft has no capacity defined, hence the 91 / 0 display we're seeing in the resources tab. All other tanks appear to be empty except for the bit of fuel in the Mk1 fuel fuselage toward the rear of the craft. Bowser 1 appears almost completely full.

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Edited December 2, 2016 by Gordon Fecyk
Added answer to first questions

[Eidahlil]

3 hours ago, Gordon Fecyk said:

...I don't suppose Criske is related to Pierre Trudeau in your head-canon?

I'm also surprised you didn't explode aerobraking at 50 km up. Nice job! I figured we were in for a treat with that prologue.

She was not. While I have heard of his son, I suppose I'm not as well versed in the histories of the countries on the other side of the pond as I should be. Thanks for that reference.

Also, I did explode aerobraking at 50.7 km up (I came in in the opposite direction than Kerbin is spinning. so no surprise there). Then I quickloaded, and changed that to 57 km.

3 hours ago, Gordon Fecyk said:

Anyone looking to improve on that should instead top up Bowser's liquid fuel tank

Well, the Bowser has 354/360 fuel and 432/440 oxidiser. The Aeris has 83.95 fuel and 95.32 monoprop. Leaving an extra 6 fuel in there has almost no impact, apart from the 2 units of monoprop spent to dock. Leaving more would reduce the mass of Aeris and make things easier.

In all honesty, I was trying to do something else, but this happened, and I thought it was good too.

There are all kinds of alternative solutions, like pushing Aeris in an EVA suit; docking with Bowser, then spinning and releasing, using centrifugal inertia to gain a boost; burning off some fuel from Bowser to have more space for liquid fuel, and probably many more I cannot think of right now. And then somebody might bring Bowser to Kerbin as an anti-solution (if you think you can do it without using any fuel from it, consider it a challenge ).

I think it's better to ban the obvious abuses (and it's your call whether escaping from Kerbin SOI is an abuse), rather than trying to come up with a formula to discourage that. Though until somebody does push Aeris all the way in an EVA suit for free, perhaps it's all cool.

[Gordon Fecyk]

On ‎12‎/‎2‎/‎2016 at 11:39 AM, Eidahlil said:

There are all kinds of alternative solutions, like pushing Aeris in an EVA suit; docking with Bowser, then spinning and releasing, using centrifugal inertia to gain a boost; burning off some fuel from Bowser to have more space for liquid fuel, and probably many more I cannot think of right now. And then somebody might bring Bowser to Kerbin as an anti-solution.

Aside from modding parts, invoking the cheats menu or otherwise modifying the stock physics, all of these alternate solutions show the same ingenuity that saved Apollo 13 and probably countless other real-life land or sea-based missions where lives were at stake. OK, maybe getting out to push is cheaty because of the stock game's infinite EVA fuel, but if someone's going to do that they have a lot more time on their hands than most of us, and I'd love to see the footage.

Seriously though, your entry reminded me that there isn't always a 'set' way to solve a problem. Like trying to measure the height of a building with a barometer by dropping it off the top floor, I'd consider your solution valid especially since it demonstrates efficiency and proficiency in orbital mechanics.

At least these aren't as absurd as trying to get an orange tank to orbit using monopropellant. Sheesh.

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Edited December 4, 2016 by Gordon Fecyk

[Gordon Fecyk]

I made one more attempt at this, topping up the Bowser 1 tanker with liquid fuel and only using about 125 m/s delta-v for the return trip. This time I succeeded in landing at KSC, while leaving 360 LF and 338 OX behind and the mission timer at 25 days, 3 hours, 27 minutes. I probably could have gotten away with 50 units less oxidizer, but I won't count it as credit since it wasn't left at Minmus.

Spoiler

 

I'll put up a leader board on the original post in a moment, showing resources left behind, distance from KSC, and mission time for each participant. Good luck.

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Edited December 3, 2016 by Gordon Fecyk