Rescue from Sun Escape

[metaphor]

Bill is in trouble. His ship has reached Sun escape velocity but with no fuel left to get back. He is now stranded out past the orbit of Duna and rapidly getting further away. Your mission is to get him safely back to Kerbin.

Use this > save file <.

Scoring: by fastest time that Bill is back on the surface of Kerbin.

Proof required: Screenshot from the tracking station showing Bill Kerman on Kerbin's surface and the game time. Also any other screenshots you want.

Rules:

- no aerodynamic surfaces with infiniglide

- no mods besides info/piloting mods like Mechjeb

- no using the debug menu

Fastest times:

1.

2.

Unfortunately, the game doesn't seem to show closest approach to a spacecraft on escape trajectory. So Mechjeb or Kerbal Engineer are very useful. They aren't required but it would be amazing if someone could pull it off without them.

< Posting my own attempt here. >

Edited August 1, 2013 by metaphor

[Sean Mirrsen]

Why no jet engines? A rocket with jets ascends no faster than a regular rocket, and a spaceplane would take extra time to get up.

Likewise, ion engines won't set any speed records - let people use them if they want. I mean, you only score by time taken, not by design or efficiency, after all.

I don't mind rules, I just like it better when the rules make sense.

[Stochasty]

Mmmm... for this challenge, ion engines /will/ set speed records. You can get a lot more delta-v out of an ion engine than anything else, and nobody is going to by flying brachistocrones out past Duna orbit so thrust doesn't matter.

As far as jet engines, I agree with you; they don't make enough difference to be worth banning.

[metaphor]

OK, I'll allow jet engines. I'm not allowing ion engines because I don't want people to spend hours doing burns for this challenge, which is what would be required to get the most delta-v.

[Tw1]

OK, I'll allow jet engines. I'm not allowing ion engines because I don't want people to spend hours doing burns for this challenge, which is what would be required to get the most delta-v.

Long burns with Nuclear engines it is then!

[metaphor]

Long burns with Nuclear engines it is then!

Yep but still many times shorter than with ion engines.

[TouhouTorpedo]

Why would you not allow ion engines since people could set up long burns, but allow mechjeb (Automatic long burns with LV-N)? Its not like ion engines would even be a undisputable solution to this, since they can't accelerate quite so well. Infact for a large enough return craft they probably aren't going to work well at all, but it seems wrong to limit the creativity here on even attempting to try that.

[metaphor]

I just don't want it to be too boring of a challenge. Don't want people spending hours to get the spacecraft somewhere and then figure out they didn't install a spare command pod or whatever. That would be way too frustrating. Without ion engines it requires more strategy and is less time-consuming in my opinion. I'm doing it right now and none of my nuclear engine burns are taking more than 5-6 minutes.

Well OK, I'll allow ion engines. If you want to spend the hour-long burns, go ahead =p

Also, unfortunately the game seems to not show close encounters with spacecraft on escape trajectories. So Mechjeb or Kerbal Engineer are very useful.

Edited August 1, 2013 by metaphor

[zapy]

Well, finally I ended this challenge. I found it interesting, but very long, and there's still lots of things that can be improved. I Mechjeb should be used to finish this although its not strictly needed.

this is the launcher the lower stages are in Asparagus and the upper tanks are for the nuclear engines, although Mechjeb says that has 15 Km/s deltaV, the fuel remaining when I reach orbit are transfered to the nuclear engines, so the real deltaV is more than 34 Km/s, but I only used 27.

I start leaving Kerbin SOI and I wait till I passed a the tangent point between the escape pod and Kerbin, in this way my hiperbolic escape trajectory crosses the Bill's one. In that point I burnt for about 7500 m/s to reach the pod faster. That also means that I had to burn retrograde for about 4000 m/s when I reached Bill. Then I tried to rendezvous, but the structure was too weak and after some attempts, I decided to transfered Bill on EVA.

After that I used the remaining RCS to brake the ship and then I used the remaining fuel to enter in orbit arroung Kerbol, but the orbital period was extremly long so I continue burning retrograde whit the ion engine, I thought I'll intercept Bill closer to kerbol, but at 285 Gm solar panels doesn't work, so I used the two RTG for reducing my speed more, but that meant more than 16 hours of burn (4h at 4x...).

When I reached AP I burnt to get my PE close to Kerbin's orbit. Then transfer to Kerbin and more burns to get in orbit arround Kerbin, then I realised that my ship can't land Bill (too much G force when the parachute deploys), so I built another small ship, I transfered Bill to that one (again on EVA), and I landed, to discover that the landing struts were too short, so the lander was damaged, but Bill managed to get out of it.

As I used two ships, the time in the screen is incorrect, so I captured this showing all the ships in the mission

http://imageshack.us/a/img547/1065/xp61.png

So that's it, two ships, one with 622 tons and more than 27 Km/s deltaV and the other 70 tons and 7Km/s deltaV.

Total time: 10 years and 45 days...

This time can be improved, in another try I reached the escape pod in 400 days instead of the 577 of this one. Also, you can reduce the return time more than I did (I was tired of waiting...) and the idea of using two vessels can be nice to reduce the weight of the rescue ship.

Edited August 13, 2013 by zapy