(1:144) Henschel GT 1200

The Henschel GT-1200 used a low powered rocket to extend the gliding range. When touching the water, wings and empennages jettisoned, a more powerful second rocket ignited in order to propel the device underwater and, thanks to a magnetic fuse, automatically exploded when under the vessel's hull.

Source :
"Die Geheimen Wunderwaffen des III. Reiches" book by J.Miranda and P.Mercado