Difference between revisions of "Talk:Tutorial:How to get to Duna"

Revision as of 07:18, 16 October 2014

Launch to Kerbin Orbit

I'm a little confused by the following in step 3, launching into Kerbin orbit:

…heading east instead of the usual west.

The normal ascent to orbit from KSC is going east, taking advantage of the small amount of rotational velocity you start out with from Kerbin's own rotation, into a counter-clockwise orbit (this is also mentioned just after the above quote). So, either step 3 is incorrect in some way, or it needs more explanation to clarify the intention.

I'm not claiming expertise here, but I'm struggling to see why you'd do anything other than a standard east / 090° ascent from KSC, at least as your initial launch to orbit when keeping it simple. An advanced departure might try to do something like matching the solar orbital plane, I guess, but that's easy enough to do either as part of the later Hohmann transfer, or fine tuning the intercept once in solar orbit. Matching Duna's plane wouldn't account for an opposite launch.

So, should this just be a standard launch to orbit heading 090°, or what am I failing to see here?

--Murph (talk) 02:30, 23 November 2013 (CST)

I had the exact same question and came to discussion to see if there was a discussion/explanation. I'm going to edit it; if we're missing something, please do add a clarification while reverting.

Kenberto (talk) 02:05, 14 January 2014 (CST)

Edit: Very helpful instructions. Just wanted to say that the numbers described are accurate only if your orbits and alignments match up. Initially, I had problems understanding the clock references, because when I tried to follow the instructions, I couldn't get my burns to reach a good intercept with Duna, and then back to Kurbin. I've read forum threads having questions about how to use the clock and whether it was changing orientation each time it was mentioned. But after a lot of trial and error, I think they are correct. It was just not working out exactly right because it's not possible to measure the angles without some tools and to drag the maneuver nodes into intended positions. The size and shape of the starting orbit probably also affects the result of the node predictions. Anyway, it seems like the description of the sun being the center of the clock, and Kerbin ALWAYS being the 3 o' clock position is what's being used as references whenever the angles and clocks are mentioned. Just got to try moving the maneuver node back and forth in the general area of the instructions to find the best burn. I've only played a few days but it seems like adjusting your course just after escaping the origin planet/moon is very important to easily get a low periapsis. If you make them early enough, it takes very small. The RCS was helpful with making these tiny adjustments. For example, a change in like 10 m/s sun-ward was enough to change a periapsis of 5 million meters to 25 km. I also found that if my velocity into Duna was higher than ideal, I had to get my periapsis on Duna aerobaking to as low as 11km in order to produce an apoapsis. Username is Hodor, October 15, 2014