Fairey Swordfish. It was so slow (139mph top speed) that the Bismark's fire control could not calculate the AA guns. It also flew so low many of the AA guns could not angle low enough to hit it. It helped sink the Bismark and was in service until the end of WW2. The stringbag.
Blueprint Art of Plane Fairey Swordfish Mk2 Technical Drawings Engineering Drawings Patent Blue Print Art Item 0006