This was sent to me by a very kind person after seeing the very rough images of the book that I had previously posted. This and the other design book are the only actual artbooks I've seen for Yukikaze. This looks to have been scanned at 400-600dpi, the images haven't been resized, just cropped down to the actual page.
Blue & Purple - Nawomotsukazenohon - Ikuto Yamashita
This is a rough scan I found on eMule.
Fairy Air Force at War
Sento Yosei Yukikaze - Mechanical Design Works
Here's all of the DVD booklets/covers for Yukikaze:
Sento Yousei Yukikaze - DVD Booklet 1 - 5