Complex sentence: The experiment had been successful, inasmuch as the aircraft had been carried out to sea and safety floated off the submarine's deck, however, it was obvious that some improvements were obviously needed in the procedure and setup.
Split into simpler sentences: The experiment had been successful, inasmuch as the aircraft had been carried out to sea and safety floated off the submarine's deck. However, it was obvious that some improvements were needed in the procedure and setup.