Abstract

In the late 1950’s laminar flow flying surfaces were being considered to reduce drag on transport aircraft using suction control. It was believed at that time that wind tunnels were too turbulent for testing such wings and so flight research was planned on a swept suction wing designed by the Handley Page Company. The test wing was mounted vertically on the fuselage of a Lancaster bomber based at Cranfield where the flight experiments were made. These experiments were terminated by the Ministry of Aviation in 1965 because the US research using the X21 laminar flow aircraft made by Northrop was cancelled when the military decided not to pursue their program further I will give an account of our work involving turbulent contamination along the attachment line and ways of controlling this. Sometime later, 1985, when Airbus were planning some flight suction experiments on an A320 fin I proposed a research programme on a new leading edge device for preventing contamination. The project was assigned to Onera who designed a new version of the ‘Bump’. The ‘Bleeding Slot’ was eventually demonstrated in the Airbus wind tunnel and shown to prevent contamination. I believed that some small drag reduction could be achieved by using this device on conventional wings to maintain laminar leading edges. This was recently demonstrated in the Airbus tunnel.