RedactedNarrative: OPERATOR STATED HE LAUNCHED V1 AND WAS TRAVELING EAST WHEN HE HEARD A POP IN THE ENGINE COMPARTMENT.  OPERATOR OPENED THE ENGINE COMPARTMENT AND SAW SMOKE COMING FROM THE EXHAUST AREA OF THE ENGINE BUT NO FIRE.  HE THEN SAW WATER BEGIN TO RUSH IN THE ENGINE COMPARTMENT AND HE TRIED TO HEAD TOWARD THE SHORE. HE WAS ABOUT 50 FEET FROM THE SHORE WHEN HE ABANDONED V1.  ONCE ON SHORE HE LOOKED BACK AND SAW THAT V1 HAD COMPLETELY SUBMERGED.  V1 SUNK IN THE ARKANSAS RIVER AND HAS NOT BEEN RECOVERED.