Question: What engine was used in the aircraft intended to replace the F4F Wildcat?

Context paragraphs:
VMF-155: Marine Fighting Squadron 155 (VMF-155) was a fighter squadron of the United States Marine Corps in World War II.  During the war, they flew the SBC Helldiver and, after reconstitution in 1943, the F4F Wildcat.  Later in the War the squadron also flew the F4U Corsair.  One of the squadron's pilots who went on to great distinction later in his career was Lieutenant John Glenn.  The squadron, also known as “Ready Teddy” was deactivated shortly after the war and is still inactive.

Grumman F4F Wildcat: The Grumman F4F Wildcat is 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.  First used in combat by the British in Europe, the Wildcat was the only effective fighter available to the United States Navy and Marine Corps in the Pacific Theater during the early part of World War II in 1941 and 1942; the disappointing Brewster Buffalo was withdrawn in favor of the Wildcat and replaced as units became available.  With a top speed of 318 mph , the Wildcat was outperformed by the faster 331 mph , more maneuverable, and longer-ranged Mitsubishi A6M Zero.  However, the F4F's ruggedness, coupled with tactics such as the Thach Weave, resulted in a claimed air combat kill-to-loss ratio of 5.9:1 in 1942 and 6.9:1 for the entire war.

Pearl Harbor Trilogy – 1941: Red Sun Rising: Pearl Harbor Trilogy – 1941: Red Sun Rising is a trilogy of air-combat action games where players fly World War 2 era aircraft such as the P-40 Warhawk, F4F Wildcat, A6M2 Zero.  The first title in the trilogy is called "1941: Red Sun Rising" and includes missions from 1941 and 1942 such as Guadalcanal, Pearl Harbor and the Battle of Midway.  It was released on Nintendo's WiiWare download service in North America on July 5, 2010 and in Europe on July 16, 2010

Grumman F3F: The Grumman F3F was the last American biplane fighter aircraft delivered to the United States Navy (indeed, the last biplane fighter delivered to any American military air arm), and served between the wars.  Designed as an improvement on the single-seat F2F, it entered service in 1936.  It was retired from front line squadrons at the end of 1941 before it could serve in World War II, and was first replaced by the Brewster F2A Buffalo.  The F3F which inherited the Leroy Grumman-designed retractable main landing gear configuration first used on the Grumman FF served as the basis for a biplane design ultimately developed into the much more successful F4F Wildcat.  When it entered combat, the Wildcat quickly replaced the Buffalo as the primary fighter of the Navy and Marines in the first part of World War II, and continued to be produced throughout the conflict.

Fairey Gannet AEW.3: The Fairey Gannet AEW.3 was a variant of the Fairey Gannet anti-submarine warfare aircraft intended to be used in the airborne early warning (AEW) role on aircraft carriers of the Royal Navy.  It was introduced to service in 1959 to replace the obsolete Douglas Skyraider, and was intended as an interim solution until the planned introduction of a new, purpose built AEW platform for use on the planned CVA-01 aircraft carriers.  Neither the new aircraft carriers nor the new AEW aircraft were proceeded with, and the Gannet AEW remained in service until the last aircraft carrier that could operate it was retired.

Brewster F2A Buffalo: The Brewster F2A Buffalo was an American fighter aircraft which saw service early in World War II.  Designed and built by the Brewster Aeronautical Corporation, it was one of the first U.S. monoplanes with an arrestor hook and other modifications for aircraft carriers.  The Buffalo won a competition against the Grumman F4F Wildcat in 1939 to become the U.S. Navy's first monoplane fighter aircraft.  Although superior to the Grumman F3F biplane it replaced and the early F4Fs, the Buffalo was largely obsolete when the United States entered the war, being unstable and overweight, especially when compared to the Japanese Mitsubishi A6M Zero.

Deflection (ballistics): Deflection is a technique used for effectively propelling a projectile at a moving target, also known as "leading the target", i.e. shooting ahead of a moving target so that the target and projectile will collide.  This technique is only necessary when the target will have moved a sufficient distance to fully displace its position during the time the projectile would take to reach the target's range.  This can become the case over long distances (e.g. a distant target for a skilled sniper), due to fast moving targets (e.g. an opposing aircraft in an aerial dogfight), or while using relatively slow projectiles (e.g. a crossbow bolt or a basketball thrown to a running teammate).  During World War II, U.S. Navy pilots were taught explicitly about the concept in order to capitalize on the advantages of the F4F Wildcat.

Republic P-47 Thunderbolt: The Republic P-47 Thunderbolt was a World War II era fighter aircraft produced by the United States between 1941 and 1945.  Its primary armament was eight .50-caliber machine guns and in the fighter-bomber ground-attack role it could carry five-inch rockets or a bomb load of 2,500 pounds (1,103 kg).  When fully loaded the P-47 weighed up to eight tons (tonnes) making it one of the heaviest fighters of the war.  The P-47 was designed around the powerful Pratt & Whitney R-2800 Double Wasp engine which was also used by two U.S. Navy fighters, the Grumman F6F Hellcat and the Vought F4U Corsair.  The Thunderbolt was effective as a short-to-medium range escort fighter in high-altitude air-to-air combat and ground attack in both the World War II European and Pacific theaters.

USS Flatley (FFG-21): USS "Flatley" (FFG-21) was the thirteenth ship of the "Oliver Hazard Perry" class of guided-missile frigates.  She was the first ship of the U.S. Navy to be named for Vice Admiral James H. Flatley (1906–1958), a leading Naval Aviation tactician from World War II who flew the Grumman F4F Wildcat in the Battle of Coral Sea and subsequently commanded the VF-10 Grim Reapers taking them into combat for the first time.

Grumman F6F Hellcat: The Grumman F6F Hellcat is an American carrier-based fighter aircraft of World War II.  Designed to replace the earlier F4F Wildcat and to counter the Japanese Mitsubishi A6M Zero, it was the United States Navy's dominant fighter in the second half of the Pacific War.  The Hellcat competed with the faster Vought F4U Corsair for that role and prevailed, as the Corsair had significant issues with carrier landings.  The Corsair instead was primarily deployed to great effect in land-based use by the U.S. Marine Corps.

Supporting paragraphs: Republic P-47 Thunderbolt Grumman F6F Hellcat
Answer: Pratt & Whitney R-2800 Double Wasp engine