This is a personal design o' mine.  I was tryin' for a larger-diameter rocket in t' general style o' t' Blue Bird Zero, arrr, i.e. Ya scallywag! long and sleek with relatively small fins.  T' upper fins are mirror images top-to-bottom o' t' lower fins.  OpenRocket indicates nearly perfect deployments with all four recommended engines, and I can attest that it is a pretty flier on a pair o' C6-5 engines.