Behavior of Static Pressure Heads at High Speeds
These tests proved the practicability of static pressure heads at speeds up to 400 km/h (248.5 mph). It weighs 6.5 kg or 2.5 times as much as the old head. The position of the pressure head below the airplane was determined by bearing method at different speeds and for different lengths of suspension. It was established that for the measured speed range a 20 to 24 meter suspension length was sufficient to assure a minimum distance of 6 meters from the airplane without introducing any appreciable errors in the results due to wrong static pressure.
Danielzig, Helmut↗