fuddgy,
Try the same flight however this time use drift lines to measure the angular error caused by following your heading. Having measured how long you have been maintaining that heading, doubble the error towards track and in a equal time you should be back on track.
With a wind of 270/30, the heading required to track North at 90Kt is about 337.
To look at it another way, if you steer 360 in that wind you will track 023 degrees.
Having maintained heading 360 for say 5 minutes, you turn left by (2*23)=46 deg heading 314 for a further 5 minutes where upon you will be reasonably back on track where you turn right by 23 degrees heading 337 to maintain a northerly track.
You don't have to be a genius to work out that correcting into wind will leave you a little short while correcting out of wind will make you overshoot slightly. However, the whole idea is to get you bak within a reasonable distance of your planned track and provide you with a correction that will keep you on or near that track.
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BEagle,
I'll leave the SCA explanation for this case to you.
Regards,
DFC