In 1943, the US Army Air Corp began manufacturing a new propeller-driven, single-engine fighter aircraft: the P-38 Lightning. At the time, the P-38 was the most technologically advanced fighter plane in existence, and boasted a host of innovations that made it one of the most capable aircrafts ever designed. However, aside from its impressive speed and maneuverability, the P-38’s greatest feat was its ability to shoot down 20 German Me-109s in one single engagement. This was no easy feat, as the Me-109 was equipped with a powerful 20mm cannon turret.
The B-17 Flying Fortress is an iconic American warplane that was introduced in 1935 as part of a burst of new bomber designs for the US military. Although the B-17’s size and shape were futuristic, it was actually a simple, conventional design. This airplane was powered by a single Packard 890 engine, had a pressurized cabin, and was the first American aircraft to use hydraulically operated flaps.
In the late 1930’s, after the horror of Pearl Harbor, the US Air Force scrambled to put together a plan to counter Japanese aircraft. The main idea was to put bombers in the air which could be sent over Japan and launch missile attacks at the enemy. They could also act as a decoy for the American air force so as to draw away the Japanese fighters and bombers. The next problem was the number of planes that would be needed. The aircraft of the day weren’t capable of carrying the bombs, missiles and fuel necessary to deliver a good payload to Japan, so this was a major problem.
Forward-swept wings were featured on the Luftwaffe’s first jet-powered medium bomber test-bed.
The Junkers Ju-287V1, a flying test-bed for a jet-powered medium bomber that could outrun the fastest Allied fighters, was one of the most odd aircraft to emerge from German drawing boards in the latter stages of World War II. Early in 1943, the task of development fell to the Dessau-based Junkers Flugzeug und Moterenwerke A.G., which formed a design team for the project led by Hans Wocke.
Wocke first put up a design for a jet aircraft with a 25-degree wing sweepback, which, in principle, could exceed 550 mph in level flight, using research data from the Deutsche Versuchtsanstalt für Luftfahrt (a government aeronautical research and testing organization most frequently referred to as DVL). Wocke became concerned about the poor flying characteristics of sweptwings at low airspeed, particularly the loss of aileron control associated with tip stalling, while the design was still in the early phases. Wocke came up with the notion of reversing the wing planform in order to increase the critical Mach number of the wing while also avoiding the problem of wingtip stalling.
The forward-swept wing, at least in theory, would have the same effect as a sweptback wing by reducing the thickness-to-chord ratio, but its peak lift coefficient would be at the wing’s root. As the lift coefficient declined toward the tip, the tips were the last to stall, and aileron control was retained after airflow broke away from the major sections of the wing. Wind tunnel experiments later validated Wocke’s findings, but they also showed a fundamental flaw: the wing’s aeroelasticity, or its ability to flex and deform due to aerodynamic loads. However, Wocke and his team believed that the problem could be mitigated.
The German aviation ministry ordered Junkers to start with a full-scale flying test-bed to analyze flight characteristics while the final design of a production bomber was being worked out since the design was so unconventional. The test-bed was built using off-the-shelf airframe components, including a fuselage from a Heinkel He-177A bomber, a tail group from a Ju-388L reconnaissance plane, nose wheels from a salvaged American B-24 Liberator, and main landing gear from a Ju-352 transport plane. The landing gear was left fixed and the wheels were encased in enormous spats since retraction of the wheels into the test-thin, bed’s forward-swept wings was not structurally feasible.
The Ju-287 was a strange assemblage of what was available to Junkers’ designers, including a tail assembly from a Ju-388L, fuselage from a He-177A, and landing gear from a captured American B-24. (From the National Archives)
The all-metal, two-spar wing with a particular Junkers reverse-camber, high-speed airfoil section was a thin, high-aspect-ratio structure. The wings were fitted with fixed slats at the inboard leading edges to postpone root stalling, as well as huge slotted trailing edge flaps and ailerons that would droop to 23 degrees, providing camber throughout the whole span. The test-bed would be powered by four Junkers Jumo 004B-1 axial-flow turbojet engines, each rated at 1,984 pounds of static thrust (the same engines planned for use on Messerschmitt Me-262s), arranged in four individual nacelles, one under each wing at about 30% span and one on either side of the forward fuselage.
The ultimate product, the Ju-287V1, was definitely one of the strangest-looking aerial contraptions of WWII. The wingspan was 65 feet 1134 inches, the length was 60 feet, and the total wing area was 656.6 square feet. Wing loading was 67.2 pounds per square foot at a maximum takeoff weight of 44,092 pounds, almost identical to the contemporaneous Me-262. The Ju-287V1 was transferred from Dessau to Brandis Field, near Leipzig, for flight testing in the summer of 1944, and it was first flown on August 22 by Flugkapitän Siegfried Holzbauer. Two Walter 2,645-pound-thrust rocket packs were mounted below the wing nacelles to provide takeoff power during that flight, but they were ditched shortly after takeoff. The test-bed employed one of the first instances of a drogue parachute launched from the tail cone to lessen landing roll.
The Walter rocket packs, which can be seen behind the engine nacelles, added 2,645 pounds of thrust to each launch. (From the National Archives)
The Ju-287V1 from Brandis completed sixteen further flights. The only severe problems observed during testing, unrelated to aerodynamic arrangement, were periodic flameouts with the finicky Jumo 004B turbojets and, on one occasion, the explosion of one of the Walter rocket packs. The Ju-287V1 was highly stable in slow flight mode, requiring few trim changes during flap operation, as predicted. With the flaps extended, the plane reached a speed of 150 mph on approach and 118 mph on landing, which isn’t too fast by today’s standards. During testing, wool tufts were placed on the upper surface of the wings to allow a camera set immediately front of the vertical fin to capture the pattern of airflow. The results of this experiment backed up Wocke’s expectations about the consequences of forward sweep: Airflow breakaway extended outward from the root to the tip at low airspeeds, with a nose-down pitching moment occurring only when the breakaway reached the ailerons.
The Ju-287V1 was nosed over at full power to reach a top speed of 404 mph during testing at greater speeds, at which point the wing’s aeroelastic limitations became apparent. The main drawback was a loss of elevator control when maneuvering, but longitudinal stability was unaffected. At 19,685 feet, the highest level speed reached was 347 mph. Following that, the Ju-287V1 was sent to the Luftwaffe assessment center at Rechlin, where it was destroyed during an Allied bombing strike and was no longer able to fly.
In the meantime, Junkers began work on the Ju-287V2, which would serve as a follow-on testbed for the planform’s high-speed characteristics. The wing remained mostly intact from the V1, but the body was based on the Ju-388 (a further evolution of the Ju-88 design), which had fully retractable tricycle landing gear. Four experimental Heinkel-Hirth 011A turbojets, each with a projected thrust output of 2,866 pounds, were to be slung in paired nacelles under the wings to provide power. Simultaneously, Junkers began work on the Ju-287V3, which would become the ultimate bomber prototype. Due to delays in the construction of power plants, Junkers had to rely on the less powerful but more easily accessible BMW 003A-1 turbojets, each rated at 1,760 pounds of thrust. Under the wings, six of these engines would be pod-mounted in threes.
When the Dessau facility was captured by Soviet forces in late spring 1945, final construction of the Ju-287V2 was in progress. Not surprisingly, the captured prototype, as well as its tools, jigs, parts, and design team, which included Wocke himself, were sent to the Soviet Union. The Ju-287V2 was purportedly finished and flown in 1947 at Podberezhye, south of Leningrad, but no performance data is available. The Ju-287V3, which had full operational equipment and weapons, had also begun component construction, but the Soviets abandoned the project once the V2 was completed. The Ju-287V3 was expected to have a top speed of 537 mph at 16,400 feet, a cruise speed of 493 mph at 23,000 feet (80 percent power), and a range of 985 miles with an 8,800 pound bombload or 1,325 miles with 4,400 pounds, according to the manufacturer. The Ju-287V2 would have flown in 1945 if the Soviets hadn’t intervened—a remarkable achievement given that the first postwar Allied jet-propelled medium bomber didn’t fly for another two years (the North American XB-45, which had its initial flight on March 17, 1947).
When World War II ended, most of Germany’s research and test data on transonic flight prompted some American airframe builders to change their plans for new jet aircraft. Convair’s XB-53 tactical bomber—a tailless, tri-jet design with 30 degrees of forward wing sweep—was one of the most unusual concepts developed by the stolen German technology, but the project was terminated in 1948.
The forward-sweep planform was inactive until 1964, when West Germany’s Hamburger Flugzeubau developed the HFB-320 Hansa Jet, a twin-engine executive transport capable of carrying up to 12 passengers. The Grumman X-29A, which flew for the first time in 1984, coupled forward sweep with canards and solved the problem of aeroelasticity using wings made of exceptionally hard composite materials. The two X-29s were retired in 1994 after extensive testing.
The Sukhoi Su-47 (S-37) Berkut (“Golden Eagle”) fighter, designed by Russians, flew for the first time in 1999. The Russian government has set aside cash for testing this latest forward-sweep design, but no production plans have been declared as of this writing.
The original version of this essay was published in the September 2004 issue of Aviation History. Make sure you don’t miss an issue by subscribing!
In the early months of World War II, Nazi Germany’s military machine was firmly on top of the world, having recently conquered France, the Low Countries, and Poland. But in early April of 1940, the Nazis were shocked by a sudden defeat at the hands of the Allies: the Battle of the Netherlands.. Read more about 20 of the most useless planes ever made and let us know what you think.
The worst plane of WW2 was the Boeing B-29 Superfortress."}},{"@type":"Question","name":"Was the P 39 a good plane?","acceptedAnswer":{"@type":"Answer","text":"
The P-39 was a good plane."}},{"@type":"Question","name":"What was the biggest dogfight in WW2?","acceptedAnswer":{"@type":"Answer","text":" The Battle of Britain."}}]}
Frequently Asked Questions
What was the worst plane of WW2?
The worst plane of WW2 was the Boeing B-29 Superfortress.
Was the P 39 a good plane?
The P-39 was a good plane.
What was the biggest dogfight in WW2?
The Battle of Britain.
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