Fw 190A-4 “brown 10” of the II/JG 2
The Fw 190A-4 series built upon the experiences gained from the A-3 and was produced from July 1942 to January 1943 at various facilities, including Focke-Wulf, Arado, AGO, and Fieseler. The most notable external change was the shift of the formerly horizontal radio antenna mast on the tailfin to a vertical position. While there were hopes to enhance the engine’s performance, the BMW 801D-2 remained largely unchanged, though some high-altitude performance was attempted to be compensated for with new systems.
MW 50 Injection System: The Fw 190A-4 introduced the MW 50 water-methanol injection system, which provided a temporary power boost. This system injected a mixture of 50% methanol, 49.5% water, and a small amount of oil into the engine’s boost air, cooling it and increasing the engine’s output temporarily. This was particularly useful at lower altitudes for brief bursts of extra power, such as during takeoff or combat. Initially, the BMW 801 engines were sensitive to this system, leading to reliability issues that restricted its use to very short periods. However, over time, improvements allowed for more reliable operation, providing 10 to 20 minutes of enhanced performance.
GM 1 Injection System: Additionally, the Fw 190A-4 was evaluated with the GM 1 system, which used liquid nitrous oxide to boost high-altitude performance by injecting it into the engine to improve fuel combustion and reduce knocking. However, the GM 1 system faced practical challenges, including increased fuel consumption, added weight, and complexity, which limited its widespread use.
Armament and Equipment: The A-4 retained the armament configuration from the A-3, including two MG 17 machine guns and two MG FF or MG 151 cannons. It also featured the improved FuG 16Z VHF communication and homing system, enhancing coordination and navigation. Some specific variants of the A-4 included the A-4/U1 and A-4/U3 ground attack versions, with the latter having reduced side armor for weight savings. The A-4/U3 series also featured “formation destroyer” kits, which consisted of WGr.42 rocket launchers to disrupt enemy bomber formations from a safe distance.
Operational Impact: The Fw 190A-4 was notably involved in defending against large-scale Allied bombing raids. In October 1943, units equipped with the Fw 190A-4/R6, fitted with rocket launchers, participated in a significant engagement against 228 American bombers targeting Schweinfurt. The attack resulted in the downing of 62 bombers over Germany, with additional losses and damages on both sides. However, such tactics became less effective as Allied forces adapted, including the use of long-range escort fighters, which provided protection to the bombers and reduced the effectiveness of these heavy fighter attacks.
Overall, the Fw 190A-4 was a critical step in the evolution of the Fw 190 series, combining various experimental systems and upgrades in an attempt to maintain air superiority amidst increasing Allied advances in technology and tactics.