The Focke-Wulf Fw 190B was one of three attempts to improve the high altitude performance of the aircraft, in this case by giving it a longer wing, GM-1 engine boost and a pressurized cabin.
When the Fw 190 entered combat in 1941 it gave the Germans a clear advantage over their British opponents, but although the aircraft was excellent at low and medium altitudes, its performance fell away at higher altitudes. By the spring of 1942 the German Air Ministry was aware that the British were aiming to produce high altitude aircraft (the Spitfire IX outperformed the normal Fw 190A at altitude), and in May 1942 they held a meeting with Messerschmitt and Focke-Wulf to ask for high altitude fighters.
Kurt Tank decided to try three different approaches to improving the Fw 190, each using a different engine. The Fw 190B evolved from attempts to improve the performance of the BMW 801, the Fw 190C was to use the Daimler-Benz DB 603 and the Fw 190D the Junkers Jumo 213.
The first attempt to improve the high altitude performance of the basic Fw 190 was the Fw 190A-3/U7. This had a standard BMW 801 D-2 engine, but with its normal automatic engine management system removed to give the pilot more control of the engine at high altitude. The U7 was also given large air intake tubes on either side of the engine cowling, which were meant to direct more air to the rear row of the engine. All but the MG 151 cannon in the wing roots were removed to save weight.
Three examples of the A-3/U7 were produced, and the first made its maiden flight on 16 August 1942. Results of the test flights were disappointing, and the A-3/U7 was only 5-6mph faster than the standard A-3 at altitude.
Tank’s second attempt to improve the performance of the BMW 801 powered aircraft involved giving the aircraft longer wings, a pressurised cabin and GM-1 nitrous injection for a power boost. This version of the aircraft was given the Fw 180B designation.
Work originally began on giving Fw 190 V-12 new longer wings, with a 40ft 8.25in span. This was soon abandoned, and four of the pre-production A-0s were used as prototypes instead.
The first of the Fw 190B-0s was built in the second half of 1942. At first it kept the normal wing, but gained the pressurized cabin. The first version failed because the glazing was too thin – 4.4mm to 5.3mm instead of 6mm, leading to dramatic failures at fairly lower pressure. The first aircraft didn’t make its maiden flight until 9 January 1943. Once it was in the air it was discovered that the canopy glazing allowed the cold in, so a double-glazed version was produced, using heat from the engine to keep it warm. The longer 40ft 8.25in span was then installed, and flight tests continued until June 1943. In October the standard length wing was installed.
The second of the B-0s was built with the double glazed canopy and was armed with two MG 151 cannon in the wing roots and two 7.92mm MG 17s in the nose. It entered the test programme in March 1943, and problems were soon discovered with condensation in the double glazed canopy.
The third B-0 made its maiden flight on 6 April 1943. It was carrying the 20mm MG FF cannon in the outer wings, had the double glazed canopy and a new heater to keep the cockpit from icing up.
The fourth B-0 was given the GM-1 nitrous oxide boost equipment and a 115 litre tank of nitrous.
In January 1943 a series of six Fw 190B-1 production aircraft was ordered, but by the summer of 1943 this had been cancelled after the design failed to live up to expectations. One Fw 190B-1 was completed, and made its maiden flight on 21 January 1944, by which time work had moved onto the excellent Fw 190D, with the Junkers Jumo engine.