The Grumman F4F Wildcat was an American carrier-based fighter aircraft that began service with both the United States Navy and the British Royal Navy (as the Martlet) in 1940. Although first used in combat by the British in Europe, the Wildcat was the only United States Navy or Marine fighter in World War II 1941–42 in the Pacific Theater besides the brief appearance of the F2A Buffalo. With a top speed of 318 mph (512 km/h), the Wildcat was outperformed by the more nimble 331 mph (533 km/h) Mitsubishi Zero, but its ruggedness and 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
The Thach Weave or Beam Defense Position is an aerial combat tactic developed by naval aviator John S. Thach of the United States Navy soon after the United States' entry into World War II.
Thach had heard, from a report published in the 22 September 1941 Fleet Air Tactical Unit Intelligence Bulletin, of the Japanese Mitsubishi Zero's extraordinary maneuverability and climb rate. Before even experiencing it for himself, he began to devise tactics meant to give the slower-turning American F4F Wildcat fighters a chance in combat. Every evening while he was based in San Diego, he would think of different tactics that could overcome the Zero's maneuverability, and tested them in flight the following day.
Working at night with matchsticks on the table, he eventually came up with what he called "Beam Defense Position", but which soon became known as the "Thach Weave". It was executed either by two fighter aircraft side-by-side or (as illustrated) by two pairs of fighters flying together. When an enemy aircraft chose one fighter as his target (the "bait" fighter; his wingman being the "hook"), the two wingmen turned in towards each other. After crossing paths, and once their separation was great enough, they would then repeat the exercise, again turning in towards each other, bringing the enemy plane into the hook's sights. A correctly-executed Thach Weave (assuming the bait was taken and followed) left little chance of escape to even the most maneuverable opponent.
The basic Thach Weave, executed by two wingmen.Thach called on Ensign Edward "Butch" O'Hare, who led the second section in Thach's division, to test the idea. Thach took off with three other Wildcats in the role of defenders, Butch O'Hare meanwhile led four Wildcats in the role of attackers. Trying a series of simulated attacks, Butch found that in every instance Thach's fighters had either ruined his attack or actually maneuvered into position to shoot back. After landing, Butch excitedly congratulated Thach: "Skipper, it really worked. I couldn't make any attack without seeing the nose of one of your airplanes pointed at me."
The tactic was first tested in combat by Thach during the Battle of Midway, when his flight of four Wildcats was attacked by a squadron of Zeroes. Thach's wingman, Ensign R. A. M. Dibb, was attacked by a Japanese pilot and turned towards Thach, who dived under his wingman and fired at the incoming enemy aircraft's belly until its engine ignited.