you've gotta look at the progression of planes coming out of design, test and manufacturing timelines, facts and stats. when the pacific war started, the u.s. had a bunch of brewster f2a buffaloes and grumman f4f wildcats which were totally outclassed by the zeros. of course, airmen piloting these "deathtraps" would whine and complain. when the f6f hellcat replaced the wildcat, praises started pouring in. same pilots, different planes. even more so, young navy pilots who just graduated from training flew and fought better than veteran pilots from the ijn. there were also other factors, such as better training, better organization, better strategy, better command, better recruitment, better this better that. but you cannot deny the obvious - better planes. also contributing to this was the u.s. navy's vital need to rescue and save pilots who were shot down in the sea. this increased the total veteran experience in the (valuable and limited) pool of pilots, while the ijn were losing their veteran stock cumulatively... and quickly when better planes were flown by the usn. the u.s. has a knack of improving technology, equipment and weapons on the fly so to speak when push comes to shove. the japanese were slow to adapt. why was the hellcat so much more superior than its predecessor, the wildcat, and its direct opponent, the zero? you have to look at the specifications and facts. it was the first naval fighter to incorporate design lessons from battle losses incurred by its predecessor. besides engine performance, maneuverability, and a better rate of climb, the hellcat continued one advantage that the wildcat had over the zero. the pilot compartment and fuel tank section were heavily armored, ensuring high survivability of the most important resource of a fighter aircraft - the pilot.