The venturi compensator supplies a speed-dependent negative pressure, so that the pressure reduces as speed increases, compensating for the increased static pressure due to sink. According to Helmut Reichmann, "...the least sensitive venturi mounting point would appear to be on the upper quarter of the vertical fin, some 60 cm (2 feet) forward of the leading edge." Venturi compensator types include the Irving Venturi (1948), the Althaus Venturi, the Hüttner Venturi, the Brunswick Tube, the Nicks Venturi, and the Double-Slotted Tube, developed by Bardowicks of Akaflieg Hannover, also known as the Braunschweig Tube.[1][2][16][17]