10 of the Rarest Experimental Aircraft of WWII

When we think of World War II aircraft, common models like the Spitfire or the B-52 Bomber often come to mind. However, there was much more taking off from airfields and design tables worldwide. This is a dive into ten unusual and rare experimental planes which did not make it into mass production yet left their mark in aviation history. To qualify for our list, these aircraft had to exist, complete at least one flight, and not have been mass-produced. From the USA to the Soviet Union, creative minds pushed the limits of aircraft design.

1. Fisher XP-75 Eagle

In the realm of unique concepts, the Fisher XP-75 Eagle takes flight with its distinctive design. Born from a 1943 expectation for a high-climbing, long-range aircraft, the XP-75 was armed with a similar configuration to the single-engine Bell P-39 but fell short of expectations during testing. Despite its potential, recurring faults and rapidly evolving fighter technology led to its cancellation in 1944.

2. Caproni Campini N.1

Italy’s foray into jet propulsion manifested in the Caproni Campini N.1. Italy’s aviation experts were neck and neck with German innovation, thinking they had made history with the first jet turbine-propelled aircraft in 1940. However, the He-178 had already claimed that title. The ambitious N.1 underwent several tests until the Allied forces’ advances in Italy ended further development.

3. Heinkel He 100

Engineers at Heinkel, not satisfied with the performance of the German BF-109, sought to break speed records by creating the He 100, a swift contender that soared to 416 mph. Yet, even with its significant velocity, surpassing the early Spitfire’s 362 mph, it remained a prototype, as the established BF-109 continued its service.

4. Douglas XB-42 Mixmaster

The Douglas XB-42 Mixmaster was a rare bird with speed in its DNA, boasting a high-speed pusher configuration. In 1944, this experimental bomber had the speed (410 mph) to impress, born from a private endeavor by Douglas to create a smaller counterpart to the B-29 with comparable range. A surviving XB-42 is being restored for future display, honoring its place in aviation progress.

5. Piaggio P.119

A novel design came from Italy’s Piaggio P.119 with its mid-mounted radial engine—a stark contrast to other fighters of its day. Designers hoped the engine placement would increase maneuverability and enable a larger arsenal. However, the turning points of the war, including the Italian Armistice, brought the P.119’s development to an end.

6. Blohm & Voss BV141

An innovation in asymmetry, the German-designed Blohm & Voss BV141 reconnaissance aircraft, performed admirably despite its uncommon shape. While the machine’s performance was solid, the odd design did not make it off the drawing board into full-scale production.

7. Flettner FL 282

The Flettner FL 282 stood out as one of the few helicopters considered for WWII operations, tasked with reconnaissance and transport. The German helicopter was little-known because most were not ready for wartime action. A production order was placed, yet only a fraction was built before a bombing raid halted progress.

8. Bereznyak-Isayev BI-1

Further east, the Soviet Union’s Bereznyak-Isayev BI-1 stretched the imagination with its rocket-powered design meant to counteract enemy fighters. After a mere dozen flights, the ambitious interceptor project faded away by 1945 as other technologies took precedence.

9. Vultee XP-54

The Vultee XP-54 catches the eye with its unusual look and advanced features, such as an ejection seat that fired downward. Its pioneering twin-boom, pusher configuration was cutting-edge in 1943. The fighter aircraft also featured an electrically lowered pilot’s seat, which at the time seemed straight out of science fiction.

10. Antonov A-40 Flying Tank

The Antonov A-40 was unlike any other—the epitome of unconventional. This Soviet-built machine was a tank that could glide, a literal “flying tank,” trialed in 1942. It was intended to deliver battlefield vehicles directly to the front lines. While it proved the concept feasible, it was never deployed in combat.