Red Queen British intelligence learned of the FuG 25 quite early-on and had published a report on the topic in 1943. At the time, there were only six units known to have been completed.
Rennie Whitehead, who led the design of the British
IFF Mark III, read the report and asked if there were circuit diagrams available. Instead, he was handed one of the units. A short time later, he was presented with a second unit. It was revealed that this unit had come from an operational German aircraft. In a fit of bravado, the pilot decided to show off by flying aerobatics just off the English coast. This ended when he crashed his aircraft into the coastline, which led to the FuG being ejected from the aircraft and landing in a bush unharmed. That same year, the
Luftwaffe began a low-intensity bombing effort against England. These raids sent up about sixty aircraft, but it was obvious from the start they were being led by a much smaller number of
pathfinder aircraft dropping flares. At one of
A.P. Rowe's "Sunday Soviets", Whitehead suggested that they might be using the FuG as a navigation tool, which would explain why no
radio beam could be detected. While jamming such a signal would be easy by sending out pulses on the known frequency, Whitehead suggested instead that they modify their
ground controlled interception radars to trigger the unit, which would make the pathfinder aircraft immediate stand out on the
radar display. A small force of
night fighters would also be equipped with an IFF Mark III modified to the same frequencies, so they would also be easy to identify. This plan, which was christened "Red Queen", took two weeks to bring to fruition. The first operations were not highly effective, but as everyone became more familiar with the system, the effectiveness shot up. Because the radar now filtered out returns from any of the other bombers, as well as other British aircraft in the area, it became a trivial matter for the operators to guide the specially selected Mosquitos directly at the German pathfinders, quickly shooting down half of them. This resulted in the raids being thrown into disarray, and replacement pathfinders were shot down as soon as they arrived. The entire effort was called off after six ineffectual weeks.
Perfectos The failure of the 1943 bombing raids meant that the FuG was once again being used primarily over Germany. In the summer of 1944, the first
British Mosquito aircraft were equipped with the "Perfectos", a device that activated the FuG 25a and triggered the response in synchronicity with their own radar signal transmissions. This produced an additional
blip on the radar display, which allowed the operators to immediately pick out the German night fighters. When night fighter losses suddenly shot up, the Germans quickly realized that the FuG 25a had been compromised. The crews were told to leave the system turned off until they approached their bases, where local anti-aircraft batteries would have no problems shooting them down while they flew slowly at low altitude. Of course, tired crews landing at night often forgot to turn the system back on, and a number of German night fighters were shot down by German flak forces. == Technical specifications ==