October 1960: High speed wind tunnels

With computing ability advancing rapidly, the 1960s saw some key advances in the application of wind tunnel testing.  And in October 1960, The Engineer reported on the opening of two new high speed wind tunnels at the Warton Aerodrome, near Preston.

The facility, which was owned and operated by English Electric, was already home to four other wind tunnels but the two new tunnels introduced a valuable new capability for aircraft and weapons development.

With a speed range from Mach 0·4 to 4·0 and a working section 4ft square, the larger of the two tunnels – M4 - was intended mainly for aircraft development.  The smaller tunnel – which had have a speed range of Mach 1·5 to 6·0, and a working section 18in square was  described as a guided weapons tunnel.

Because of its wide working speed range, the design of the control system for the larger tunnel proved particularly challenging wrote The Engineer. ’The characteristics of the control valve ….called for a two-stage device in which the first stage opened to an extent inversely proportional to the upstream pressure the  constant of proportionality being varied with the desired density and the second stage  responded to errors in the selected pressure drop along the tunnel.  The article explained that the smaller tunnel had separate shut-off  and control valves developed by US firm Compudyne Corporation.