Why Radial Engines Were Preferred in World War II Aircraft

During World War II, radial engines were widely used in aircraft despite their inferior performance at higher altitudes compared to inline or V-type engines. Contrary to popular belief, the most successful fighter aircraft of the United States, the P51 Mustang, was originally equipped with a V12 Allison engine, only to later be fitted with the more powerful Rolls Royce Merlin V12 engine under license. However, radial engines were favored for specific reasons and in particular aircraft types, as explored in this article.

Overview of Engine Types in World War II

Engines of various types were used during World War II, encompassing both air-cooled radial and liquid-cooled inline engines. Some aircraft, including the B-17 Flying Fortress, B-29 Superfortress, and P-47 Thunderbolt, were equipped with radial engines. The F4U Corsair, another notable aircraft, also utilized radial engines. These engines were favored due to their reliability and robustness, making them suitable for combat conditions and certain types of aircraft design.

The U.S. Perspective on Engine Types

While the U.S. Army Air Force (USAAF) did use radials and liquid-cooled inline engines, the emphasis was often on the technologies they knew best. The P-38 Lightning, P-39 Airacobra, P-40 Warhawk, and P-51 Mustang all utilized liquid-cooled V12 engines. The exception was the P-47 Thunderbolt, which employed a large radial engine with an extensive turbocharging and intercooler system. This choice influenced the aircraft's design and performance.

Technological Complexities and Choices

The use of turbocharged engines, both radials and inline designs, was a significant technological advance during World War II. Turbocharging allowed for the operation of these engines at higher altitudes, overcoming some of the performance limitations of radial engines. The P-38, for instance, would have benefited from supercharged Merlins, as studies suggested this would have resulted in a lighter aircraft and simpler plumbing systems.

After the war, the P-82 vested with supercharged Allisons demonstrated the continued efficiency of this technology. However, the P-82’s successor would have required supercharged Merlins, but this was ultimately hindered by the financial difficulties faced by Packard, the U.S. manufacturer of these engines. Additionally, the Navy predominantly chose radial engines, citing their lower maintenance requirements and better suitability for shipboard operations.

Conclusion

In conclusion, the preference for radial engines in various aircraft during World War II was driven by a combination of reliability, robustness, and operational requirements. While these engines may not have performed as well as modern inline or V-type engines at higher altitudes, they remained a critical component in the air fleets of many nations, particularly the United States and the Navy. Understanding these choices and their impact is essential for a comprehensive analysis of the era's aviation technology.