Top 10 Forgotten Prototypes and Experimental Aircraft of WWII

World War II was a period of rapid technological advancement, particularly in aviation. This era saw the birth of designs that pushed the boundaries of what was possible with aircraft, with many nations experimenting to gain an upper hand. Here, we highlight ten unique experimental airplanes that, while they never made it to full-scale production, completed at least one flight, exhibiting the ingenuity and ambition of wartime engineers.

Fisher XP-75 Eagle

An ambitious American experiment, the XP-75 Eagle was developed to meet the need for a plane that could climb quickly and cover long distances. Its design borrowed elements from the Bell P-39, incorporating a mid-engine configuration. Despite showing initial promise, the prototype faced numerous challenges during testing, and by 1944, it was overshadowed by more successful designs like the P-51 Mustang, leading to its cancellation.

Caproni Campini N.1

Italy’s foray into jet-powered flight resulted in the Caproni Campini N.1. Before the wider recognition of Germany’s He-178 as the first jet aircraft, there was a moment when the N.1 was considered the forefront of jet propulsion. Despite this, the two prototypes saw limited action due to the Allied invasion of Italy in 1943 which halted further development.

Heinkel He 100

Germany’s quest for air superiority gave rise to the Heinkel He 100, a fighter that aimed to outpace all others with a top speed of 416 mph. Competing against the BF-109 for the top spot in the German Air Force, the He 100’s impressive speed was not enough to change the course of its destiny, and the project was eventually abandoned.

Douglas XB-42 Mixmaster

The American Douglas XB-42 Mixmaster was an experimental bomber that sought to marry the range of a B-29 with a smaller, more nimble design. Achieving speeds of up to 410 mph, it was a testament to innovative thinking. A surviving example of this prototype is under restoration and will eventually find a home at the US National Air and Space Museum.

Piaggio P.119

Unique for its mid-mounted radial engine, the Italian Piaggio P.119 was an experiment that differentiated itself with its engine placement and the potential for increased maneuverability and space for armament. Unfortunately, the Italian Armistice of 1943 cut the project short.

Blohm & Voss BV 141

The German Blohm & Voss BV 141 reconnaissance aircraft stood out due to its asymmetrical design, which, while unconventional, performed admirably well. Nonetheless, it never entered full production, leaving it as a curious footnote in aviation history.

Flettner FL 282

As one of the few helicopters of the era, the German Flettner FL 282 provided a glimpse into the future of rotary-wing aircraft. Though a handful were used for transport and observation, it fell short of its envisioned scope due to production being halted by the war’s events.

Bereznyak-Isayev BI-1

The Soviet Union’s Bereznyak-Isayev BI-1 was a rocket-powered endeavor that aimed to bring new capabilities to the interceptor role. Although it flew a dozen times, it never made it into regular service and was retired in 1945.

Vultee XP-54

The Vultee XP-54, with its peculiar appearance and downward-firing ejection seat, was a bold American experiment in aircraft design. Built to explore the limits of a twin-boom pusher configuration, it remains a remarkable attempt at breaking the mold.

Antonov A-40 Flying Tank

Perhaps the most unusual of all, the Soviet Antonov A-40 took the concept of air mobility to an extreme, attempting to create a tank that could glide into the battlefield. Tested in 1942, this innovative idea proved too ambitious for the technology of the time.