The events of World War 2 proved beyond any doubt that the strategic bombing campaign greatly contributed to the Allies’ ultimate victory over Nazi Germany.
British night bombing raids and daylight carpet bombing missions flown by the USAAF crews rained destruction on German cities killing thousands of civilians in the process. Amidst this massive loss of civilian life the destruction of German industrial targets seemed almost like a side note. The arms race that kicked off even before the war began produced military aircraft capable of reaching ever higher operational ceilings. At first thin air at high altitudes was the domain of reconnaissance machines, but before long fighter and bomber aircraft began to venture there as well. In those early days high-altitude flight was a challenging business: it required the use of pressurized cockpits and boosted powerplants capable of delivering adequate power at altitude.
The two most common piston-powered fighter types operated by the Luftwaffe during the war were Messerschmitt Bf 109 and Focke-Wulf Fw 190. The latter, thanks to its sturdy design, proved to be easier to adapt to a variety of roles. It was used as a pure fighter, bomber destroyer, ground attack platform, reconnaissance aircraft and a fighter-bomber. The Fw 190’s excellent flight characteristics and a huge development potential inherent to the aircraft’s design led to the development of a new high-altitude fighter capable of holding its own against the USAAF escort fighters and heavy bombers.
Powered by a fourteen-cylinder BMW 801 radial engine the standard Focke-Wulf Fw 190 A went into action in mid 1941 and quickly demonstrated its superiority over the RAF’s Supermarine Spitfire Mk. V. However, it became clear just as quickly that the BMW 801’s stellar performance was limited to altitudes of about 6 000 meters. Aware of his aircraft shortcomings, prof. Kurt Tank, the Fw 190’s chief designer, began to look for feasible ways of turning the machine into a true high-altitude fighter. His first step was to take a closer look at the liquid-cooled Daimler-Benz DB 603 A in-line engine. However, the use of the powerplant by Focke-Wulf had to be authorized by the RLM and than there was a daunting task of adapting the Fw 190 airframe to the new engine.
Until those issues could be resolved the Focke-Wulf design team focused on improving high-altitude characteristics of the existing Fw 190 design equipped with the original BMW 801 powerplant. The work had to be done quickly and efficiently since the competition was already busy at work developing their own high-altitude fighter design – the Messerschmitt Bf 109 H.
In mid 1942 the United States entered the war and soon the skies over Europe saw high-flying USAAF heavy bombers. While Bf 109s, equipped with their liquid-cooled Daimler-Benz DB 601 engines, had little trouble operating above 6 000 meters, the Fw 190 was unable to fight at such heights. An interim solution was to be the introduction of light-weight Fw 190 variants: A-4/U5, A-4/U6 and A-4/U7. The Fw 190 A-4/U5’s engine was supposed to be moved forward, while most of the aircraft’s armor was to be removed. Only the pilot’s seat and the area around frame 5 would retain their original armor plating. All armor protection around the oil cooler and fuel tanks was stripped. The A-4/U6 variant was even more radical: the only armor left was light protection behind the pilot’s seat. The position of the engine mount remained unchanged. The A-4/U7 version was do be identical to the U6 variant with the exception of armor plates protecting the aircraft’s oil cooler and fuel tanks. Initially three prototypes of each variant were to be built, but the project was abandoned just a month later in favor of a new design – the Fw 190 A-3/U7. The aircraft was essentially an Fw 190 A-3 airframe partially stripped of armor plating and fuel tank protection, which reduced the fighter’s empty weight from 3 850 kg to 3 660 kg. Cockpit armor (including the pilot’s seat side and back protection) was removed, but the 48 kg engine armor and the 16 kg bullet-proof windshield remained in place. To further reduce the fighter’s weight the design team opted to remove the pair of fuselage-mounted MG 17s, which reduced offensive armament to two wing-mounted MG 151 20 mm cannons. Two air scoops added on each side of the engine bay were designed to improve the BMW 801’s high-altitude performance. Further modifications included the replacement of the FuG VII radio with the FuG 16 unit. The FuG 25 set was also removed. The revamped fighter’s operational ceiling increased to 12 000 m (previously 11 800 m), while its turn radius at 10 000 m dropped from 1 450 m to 1 250 m.