“A number of these experimental aircraft featured designs so innovative and outlandish they call out for recognition even now, more than 70 years later.”
MORE AIRPLANES rolled off assembly lines during World War Two than in any other period in the history of aviation.
Between 1939 and 1945, Allied factories cranked out a staggering 633,000 aircraft. That’s 288 a day – or one every five minutes for six years straight. For their part, Germany, Italy and Japan manufactured more than a quarter million machines.
In all, at least 750 distinct models of aircraft were in production during the war years. And amazingly, more than 250 additional designs, from fighters and bombers to trainers and transports, were evaluated and rejected by the world’s air forces. Some of these also-rans were passed over for being too expensive, others were too slow, ungainly or not safe for combat. Yet despite their unsuitability, a number of these experimental aircraft featured designs so innovative and outlandish they call out for recognition even now, more than 70 years later. Let’s take a look at some.
Despite its decidedly lopsided appearance, the German Blohm and Voss Bv-141 might have been a capable tactical reconnaissance aircraft for the Luftwaffe. The single-engine machine featured a three-man cockpit and observation pod positioned away from the fuselage on the starboard wing. With the exception of a blind spot created by the engine nacelle, the design did afford the observation crew and rear gunner a surprisingly wide field of view. Despite the fact that the plane had a rather high-profile champion in flying ace and Luftwaffe luminary Ernst Udet, Berlin passed on it in 1940 citing the feeble engine as the chief drawback. By the time the manufacturer upgraded the power plant, the German air force had already settled on the Focke-Wulf Fw-189.
Airborne Anti-Aircraft Gun
The concept of placing aircrew away from the fuselage wasn’t just a German idea. The Bell Aircuda YFM-1 had similar wing mounted crew cabins – two of them. Developed in the late 1930s as a sort of flying anti-aircraft battery for use against enemy bomber formations, the YFM-1 featured manned forward-facing gun turrets on both wings, each packing a 37mm cannon. To make room for the cabins, the plane’s engines faced aft. The U.S. Army ordered 13 of these curious “bomber destroyers” for evaluation purposes in 1940, but withdrew them from service within two years after the design’s many shortcomings became evident. With a top speed of only 275 mph (450 km/h) the YFM-1 was far too slow to catch most bombers of the day. Also, its “pusher” style engines made for unstable handling and risky bailouts. All models were eventually broken up for scrap.
Failure to Launch
Less of an airplane and more of a flying shotgun, the rocket-powered Bachem Ba-349 Natter interceptor was designed to overtake Allied bombers and pepper the enemy formations with salvos of up to 33 unguided explosive-tipped projectiles. Natters required no runways for take off; they could be launched vertically from just about any flat surface. The plane’s powerful rocket engine was designed to hurtle it 30,000 feet (9,000m) into the air in under a minute. Once at altitude, the pilot could easily overtake and destroy adversaries and then glide back to earth. Both the Luftwaffe and SS expected to add the Natter to their inventories. But by the time the Ba-349 was ready for service, Nazi Germany was mere days from defeat. Only 36 were ever built – none saw action.
Taking the Edge Off
Designers of the McDonnell XP-67 Moonbat hoped that by smoothing the edges of their twin-engine, long-range interceptor, they could create a futuristic fighter that could outfly anything in the air. And while the prototype, which first took the skies in early 1944, certainly looked fast and agile, performance was wanting. With a top speed of just 400 mph (640 km/h), the Moonbat was altogether too slow and its handling mediocre at best. But had the XP-67 entered production, its battery of six 37 mm cannons would have made it a fearsome ground attack machine. The only working model was lost in an accident after only nine months.
“Round” was also the watchword for the Vought V-173 Flying Pancake – a twin-engine demonstrator that looked more like a frisbee than an airplane. Despite its solid handling at low speeds (as confirmed by test pilot Charles Lindbergh) and its ability to take off and land in extremely small spaces, the V-173 never advanced beyond the demonstration phase. Only one was ever manufactured.
A number of wartime designers toyed with the concept of twin fuselage fighters and bombers. North American sought to increase the range of its workhorse escort fighter, the P-51 Mustang, by joining two of the plane’s air frames together. The results were promising. The P-82 Twin Mustang was as nimble as a conventional P-51 but could fly from Hawaii to Manhattan without refueling.  The war ended before the aircraft could be delivered in large numbers; it went into limited production in the late 1940s. Germany took a similar approach with its experimental Messerschmitt Bf-109Z, which included two conjoined fighters with the cockpit situated in the port fuselage.
Strange But True
Speaking of envelope-pushing designs, consider Britain’s Miles M.39 Libellula, a swept-wing, twin-engine, medium bomber demonstrator that flew in 1943. The three-man attack aircraft was designed to deliver a 2,000 lb. payload more than 1,500 miles (2,400 km) at 400 mph (640 km/h). Despite the fact that the sole working prototype displayed impressive handling characteristics, the RAF passed on the unconventional aircraft.
At almost the same time, American engineers at Curtis Wright were also dabbling in swept-wing combat aircraft with the XP-55 Ascender. The pusher-style fighter interceptor was equipped with a rear-facing, three-blade propeller. Up front was a suite of 20 mm cannons and .50 caliber machine guns. The military balked at the design and its underwhelming flight characteristics.
Stranger still was the Vultee XP-54 a single-engine twin-boom fighter demonstrator that the military tested in 1943. The single-seat warplane featured a nose section that could be pivoted several degrees vertically, allowing the plane’s two 37 mm cannons to be easily trained towards the ground during level-flight strafing runs. This odd feature earned the XP-54 the nickname the “Swoose Goose” after a popular song of the time. With a top speed of only 380 mph (600 km/h), it’s no surprise that the War Department passed on this ugly ducking.
(Dis) Honourable Mentions
Resembling a giant paper airplane, Nazi Germany’s delta winged Lippisch P.13a rocket plane certainly looked futuristic; yet ironically it ran on a decidedly old fashioned power source: coal. Hitler’s engineers could never really get the idea off the ground in time to save the Third Reich however and none were built.
XP-56 Black Bullet was a stubby, delta-winged experimental American fighter plane first tested in 1943. With aluminum in short supply, developers built the two prototypes using magnesium. While the Black Bullet could reach speeds of up to 460 mph (740 km/h), the military rejected the space-aged design in favour of emerging jet aircraft.
And what list of outlandish experimental aircraft would be complete without mentioning the Hafner Rotabuggy? A British-built “rotor kite” or autogyro, it was essentially a helicopter air frame built onto an ordinary Jeep. Designed to be dropped onto enemy territory during airborne operations, in tests the Rotabuggy managed to fly for several minutes at speeds of more than 60 mph (100 km/h) reaching an altitude of several hundred feet. Only one was manufactured in 1944. None were ordered.