KSP Challenge: Eve Speed Challenge!

[Skystorm]

@Red Shirt You could do something like this:

1. Determine about how long you want the whole trip to last.  Say 120 days.  About half of this will be Kerbin to Eve and the other half Eve back to Kerbin.
2. Using the Transfer Window Planner, work backwards finding the transfer from Eve to Kerbin first.  Look for a transfer with a trip duration of 60 days using the least amount of fuel for that duration.  Make a note of the departure date, delta V requirements, and other parameters.
3. Then using the Transfer Window Planner again, find a transfer from Kerbin to Eve with a trip duration of exactly 60 days which arrives on your Eve departure date.  Make a note of the departure date, delta V requirements, and other parameters.

** Note that at least one or both of the transfers will require more, possibly significantly more, delta V than the ideal lowest fuel transfers.  You'll probably want to plan on having at least 4 km/s - 5 km/s of delta V available for each transfer for a total of not less than 10 km/s.

You might be able to get away with only needing the "fly by" delta V for the return trip from Eve to Kerbin, but you will need to reduce speed considerably to round Eve, then perform a second burn before leaving Eve to setup your transfer back to Kerbin.  Rounding Eve as close as you can may reduce your overall delta V requirements.  Aerobraking at Eve to reduce speed is also a possible option to reduce delta V.

Of course the more you lower your desired overall trip time the more delta V it will cost you.  Expect all of your burns will likely be in the 1,000's of delta V and perhaps 5 or more minutes in duration and plan your TWR accordingly.

[EpicSpaceTroll139]

I went the brute force method of packing somewhere between 80 and 100 km/s of delta-v into my rocket

I made the trip in 18 days, 5 hours, 4 minutes, and 6 seconds (Kerbal time) =  4 days, 17 hours, 4 minutes, and 6 seconds (Earth time). (either of these could have showed up in-game depending on which time setting is used)

I probably could have made it in 14 days if I had better optimized my trajectories. I ended up expending less delta-v on the Eve-ward leg and more on the Kerbin-ward leg than I should have ideally.

Edit: @Badie which time setting should we be using for this challenge? Kerbin time (6hr days, 426d years), or Earth time (24hr days, 365.25d years)? Because it's a legit setting in the menu.

Edited September 9, 2017 by EpicSpaceTroll139

[Terwin]

My attempt was an apparently sluggish 77 days even with > 20km/s at launch, so clearly I have no idea how to do this efficiently.  I use them so little in my main games, I completely forgot about ions and just used a lot of liquid fuel in a nerva.

 

https://imgur.com/a/Jt7UE

 

Edited September 10, 2017 by Terwin

[Darth Badie]

What do you think about giving 1 more week for this challenge? 

[Just Jim]

34 minutes ago, Badie said:

What do you think about giving 1 more week for this challenge? 

I'm game. With luck I'll have my power back on by then, so I still may be able to give it a shot

[Terwin]

I tried again, this time replacing the LFO booster stage with an ion stage, but I think I made a mistake

https://imgur.com/ZzBeVSS

So I reversed(most of) the ion engines and tried again.

https://imgur.com/a/Jt7UE

34 days 3 :10:04 total flight time from launch to below 150KM above eve and back to the kerbin SOI

Using > 60km/s mostly in ions.

Probably would have been faster if I waited until closest approach instead of launching on day 1...

 

Hmm, 136,500 xenon burned by 8 engines at 0.486 xenon/sec each, means I had 9.7 hours of ion burn in that flight...

 Even at 4x physical warp that is a lot of hours... I'm pretty sure I do not want to spend the > 4 hours of real time ion burns to do that again with twice the xenon to try for a ~18 day trip...

Edited September 14, 2017 by Terwin