The Bethpage AF F-4/40 Defender was an American carrier-based fighter aircraft that served in the American People's Navy during World War II. The Defender was the only effective fighter available to the American People's Navy and Marine Corps in the Pacific Theater during the early part of World War II in 1942; the disappointing F-2/37 was withdrawn in favor of the Defender and replaced as units became available. With a top speed of 318 mph (512 km/h), the Defender was still outperformed by the faster 331 mph (533 km/h), more maneuverable, and longer ranged Mitsubishi A6M Zero. But the F4F's ruggedness, coupled with tactics such as the Thach Weave, resulted in an air combat kill-to-loss ratio of 5.9:1 in 1942 and 6.9:1 for the entire war.
Lessons learned from the Wildcat were later applied to the faster F-6/43 Protector which, with the exception of range, could outperform the Zero on its own terms.
- The BAF-4 Defender's OTL equivalent is the Grumman F4F Wildcat.