The Focke-Wulf Fw 190 Würger (English: Shrike) is a German single-seat, single-engine fighter aircraft designed by Kurt Tank in the late 1930s and widely used during World War II. Along with its well-known counterpart, the Messerschmitt Bf 109, the Focke-Wulf 190 Würger became the backbone of the Luftwaffe's Jagdwaffe (Fighter Force). The twin-row BMW 801 radial engine that powered most operational versions enabled the Fw 190 to lift larger loads than the Bf 109, allowing its use as a day fighter, fighter-bomber, ground-attack aircraft and, to a lesser degree, night fighter.
The Fw 190A started flying operationally over France in August 1941, and quickly proved superior in all but turn radius to the Royal Air Force's main front-line fighter, the Spitfire Mk. V, especially at low and medium altitudes. The 190 maintained superiority over Allied fighters until the introduction of the improved Spitfire Mk. IX. In November/December 1942, the Fw 190 made its air combat debut on the Eastern Front, finding much success in fighter wings and specialised ground attack units called Schlachtgeschwader (Battle Wings or Strike Wings) from October 1943 onwards. The Fw 190 provided greater firepower than the Bf 109, and at low to medium altitude, superior manoeuvrability, in the opinion of German pilots who flew both fighters.
The Fw 190A series' performance decreased at high altitudes (usually 6,000 m (20,000 ft) and above), which reduced its effectiveness as a high-altitude interceptor. From the Fw 190's inception, there had been ongoing efforts to address this with a turbosupercharged BMW 801 in the B model, the much longer-nosed C model with efforts to also turbocharge its chosen Daimler-Benz DB 603 inverted V12 powerplant, and the similarly long-nosed D model with the Junkers Jumo 213. Problems with the turbocharger installations on the -B and -C subtypes meant only the D model would see service, entering service in September 1944. While these "long nose" versions gave the Germans parity with Allied opponents, they arrived far too late in the war to have any real effect.
The Fw 190 was well-liked by its pilots. Some of the Luftwaffe's most successful fighter aces claimed a great many of their kills while flying it, including Otto Kittel, Walter Nowotny and Erich Rudorffer.
Between 1934 and 1935 the German Ministry of Aviation (RLM) ran a contest to produce a modern fighter for the rearming Luftwaffe. Kurt Tank entered the parasol-winged Fw 159 into the contest, against the Arado Ar 80, Heinkel He 112 and Messerschmitt Bf 109. The Fw 159 was hopelessly outclassed, and was soon eliminated from the competition along with the Ar 80. The He 112 and Bf 109 were generally similar in design but the 109's lightweight construction gave it performance edge the 112 was never able to match. On 12 March 1936 the 109 was declared the winner.
Even before the 109 had entered squadron service, in autumn 1937 the RLM sent out a new tender asking various designers for a new fighter to fight alongside the Bf 109, as Walter Günther had done with his firm's follow-on to the unsuccessful He 112. Although the Bf 109 was an extremely competitive fighter, the Ministry was worried that future foreign designs might outclass it, and wanted to have new aircraft under development to meet these possible challenges. Kurt Tank responded with a number of designs, most based around a liquid-cooled inline engine.
However, it was not until a design was presented using the air-cooled, 14-cylinder BMW 139 radial engine that the Ministry of Aviation's interest was aroused. As this design used a radial engine, it would not compete with the inline-powered Bf 109 for engines, when there were already too few Daimler-Benz DB 601s to go around. This was not the case for competing designs like the Heinkel He 100 or twin-engined Focke-Wulf Fw 187, where production would compete with the 109 and Messerschmitt Bf 110 for engine supplies. After the war, Tank denied a rumour that he had to "fight a battle" with the Ministry to convince them of the radial engine's merits.
At the time, the use of radial engines in land-based fighters was relatively rare in Europe, as it was believed that their large frontal area would cause too much drag on something as small as a fighter. Tank was not convinced of this, having witnessed the successful use of radial engines by the U.S. Navy, and felt a properly streamlined installation would eliminate this problem.
The hottest points on any air-cooled engine are the cylinder heads, located around the circumference of a radial engine. In order to provide sufficient air to cool the engine, airflow had to be maximized at this outer edge. This was normally accomplished by leaving the majority of the front face of the engine open to the air, causing considerable drag. During the late 1920s, NACA led development of a dramatic improvement by placing an airfoil-shaped ring around the outside of the cylinder heads (the NACA cowling). The shaping accelerated the air as it entered the front of the cowl, increasing the total airflow, and allowing the opening in front of the engine to be made smaller.
Tank introduced a further refinement to this basic concept. He suggested placing most of the airflow components on the propeller, in the form of a oversized propeller spinner whose outside diameter was the same as the engine. The cowl around the engine proper was greatly simplified, essentially a basic cylinder. Air entered through a small hole at the centre of the spinner, and was directed through ductwork in the spinner so it was blowing rearward along the cylinder heads. To provide enough airflow, an internal cone was placed in the centre of the hole, over the propeller hub, which was intended to compress the airflow and allow a smaller opening to be used. In theory, the tight-fitting cowling also provided some thrust due to the compression and heating of air as it flowed through the cowling.
As to the rest of the design philosophy, Tank wanted something more than an aircraft built only for speed. Tank outlined the reasoning:
The Messerschmitt 109 [sic] and the British Spitfire, the two fastest fighters in world at the time we began work on the Fw 190, could both be summed up as a very large engine on the front of the smallest possible airframe; in each case armament had been added almost as an afterthought. These designs, both of which admittedly proved successful, could be likened to racehorses: given the right amount of pampering and easy course, they could outrun anything. But the moment the going became tough they were liable to falter. During World War I, I served in the cavalry and in the infantry. I had seen the harsh conditions under which military equipment had to work in wartime. I felt sure that a quite different breed of fighter would also have a place in any future conflict: one that could operate from ill-prepared front-line airfields; one that could be flown and maintained by men who had received only short training; and one that could absorb a reasonable amount of battle damage and still get back. This was the background thinking behind the Focke-Wulf 190; it was not to be a racehorse but a Dienstpferd, a cavalry horse.
An Fw 190F's tailfin, showing the triangular hinged panel for access to the tailwheel retraction mechanics inside of it.