Kerbin circumnavigation

[lewisd]

I just wanted to share something I accomplished on the weekend, and see who else has ever tried it. (stock or otherwise)

I built a plane that can circumnavigate Kerbin without landing or refueling. It took about 5 hours to fly all the way, at Mach 1, give or take a bit. I wasn't able to use physics acceleration, since it gets unstable and the autopilot isn't able to hold it's heading any more.

I didn't want to have to spend 5 hours flying it myself, so I needed some kind of autopilot. Using stock SAS doesn't work over that length of time, as the heading it holds isn't relative to the surface, so as you fly forwards, your pitch relative to the surface increases. Instead, I used MechJeb's SAS in surface mode. I set a 90 degree heading, 0 roll, and ~4 degree (I think) pitch angle. The throttle was barely on once it reached cruising altidude, around 15km.

There's a bit of intake spam (3 intakes on the end of each wing) but I think it would work fine without them. It wasn't flying overly high, and the engine was barely on, so it shouldn't need much intake air. The solar panels also aren't necessary. It does need all the struts, to keep the wings from flapping like crazy, and the body from flexing. Without the struts strengthening the body, any pitch change makes the body flex back and forth, which makes it virtually impossible to land.

After landing, it still had 70% of it's fuel left, so it could probably have done another couple circles around Kerbin. I'm not sure what it's stability charactaristics are like when empty though, so I don't know if it would actually fly.

Done with KSP 0.23.5, and some mods (as best I can remember):

- FAR (I much prefer the more realistic drag model)

- MechJeb2 (as an autopilot)

- Engineer (didn't really need it, just added it out of habit)

- RealChutes (drag chutes for landing, not really needed)

- TAC Fuel Balancer (keeping the tanks all balanced to keep it stable)

EDIT: I should add, the ability to quicksave while in the atmosphere that was added in 0.23.5 was absolutely essential for pulling off this flight. Otherwise when I crashed the first landing attempt, that would have been 5 hours down the drain. Thanks Squad!

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Edited April 22, 2014 by lewisd