I haven't seen a shmup-related design on KSP yet, but these are sure worth mentioning:
http://www.youtube.com/watch?v=4jPdEMwd ... e=youtu.be
http://imgur.com/a/2QBMK
Slightly related: On the other side I found some people made Ace Combat's X-02 Wyvern and ADFX-01 Morgan.