Could the Pratt Whitney R-4360 Wasp Major Have Kept WWII Airplanes Exceeding 500 MPH?

The quest to determine if the Pratt Whitney R-4360 Wasp Major engine, being fitted into the P-47 Thunderbolt or F4U Corsair, would have allowed these aircraft to exceed 500 miles per hour (mph) during World War II (WWII) is an intriguing one. Let's explore the potential and challenges of such an endeavor.

The P-47J: A Specialized High-Performance Variant

One notable example of a high-performance P-47 variant was the P-47J, which claimed to be the first piston engine plane to exceed 500 mph. This achievement, however, was made possible by several modifications: a unique R-2800 engine, a specially designed cowling for improved aerodynamics, and the removal of two machine guns for reduced weight. While impressive, it remains uncertain if the R-4360 would have managed such a feat.

Theoretical Feasibility

Shoving a R-4360 into a P-47 or Corsair involves substantial challenges. The R-4360 is significantly heavier than the R-2800, and increasing the engine's power would necessitate a new propeller design. This combination would likely destabilize the aircraft, making it difficult to achieve the desired speed of 500 mph.

The XP-72: A Crucial Prototype

Republic's XP-72 was conceived as a P-47 with the R-4360 engine and necessary modifications to the propeller and balance. Despite reaching a peak speed of 490 mph, it did not exceed 500 mph. The XP-72's unsuccessful pursuit further underscores the complexity of integrating the R-4360 into existing airframes.

Testing and Actual Performance

Despite the theoretical challenges, it's worth noting that a test P-47 model, designated the XP-47J, managed to exceed 500 mph in a WWII context. This model featured a specially designed R-2800 engine, a more streamlined cowling, and reduced its armament to enhance aerodynamics and weight. The success of the XP-47J with an R-2800 hints that it might have been possible to achieve similar results with the R-4360, but the practicalities remain unclear.

The F4U Corsair with the R-4360

The F4U Corsair, one of the most iconic fighter planes of WWII, did see modifications with the R-4360 engine. While these modifications paled in comparison to the XP-47J, they did show some promise. One particular version, the Goodyear-built F4U-4, reached a top speed of 448 mph, slightly higher than the original F4U-1 (431 mph), but still well below the potential of the R-4360. An even more modified variant, the F4U5, utilized the R-2800-32E engine and reached a top speed of about 470 mph.

Race Performance and Real-World Testing

During wartime, testing through air races provided further insights. An R-4360-42W powered "Super Corsair" participated in air races, including one at Reno, where it achieved an average speed of about 438 mph per lap. This performance remains impressive for a WWII fighter, despite not rivalling the usual top speeds of 500 mph in specialized racing configurations.

While the R-4360 was a powerhouse engine, its integration into existing fighter planes like the P-47 and F4U Corsair presents significant engineering challenges. However, real-world tests and prototype development demonstrate the potential for these planes to achieve remarkable speeds, even with existing tweaks to weight and aerodynamics.