日本は戦争中彼らの航空機の品質を改善し、航空機エンジンの推力を多いに増加して、最終的に火力で
アメリカ戦闘機を上回り、終戦時、設計と実験段階で第一級の航空機を持っていた。しかしながら、航続距離、
性能、耐久性を増した信頼できる航空機の大量生産でアメリカに匹敵する広範囲な技術と工業的熟練に欠けていた。

The Japanese improved the quality of their planes during the war, greatly increased the power of their aircraft engines,
ultimately exceeded United States fighters in fire power and had first-class aircraft in the design and experimental
stage at the end of the war. They lacked, however, the widespread technical and industrial skill to match the United
States in quantity production of reliable planes with increased range, performance and durability.
http://www.anesi.com/ussbs01.htm