Monday, April 2, 2012
"In September of 1959, JPL held a press conference to celebrate the opening of its new hypersonic wind tunnel, the third wind tunnel built at JPL from 1947 to 1959. A JPL engineer is shown positioning a scale model of a missile in the tunnel's 21 x 21 inch test section. The two horizontal stainless steel plates were flexible and could be moved by a system of hydraulic jacks seen above and below, to change the speed of the airflowand other variables. Testing time was to be used equally by Army Ordnance contractors, Air Force contractors, and the JPL Aerodynamic Research Section. This NASA wind tunnel is especially noteworthy, as JPL has mostly concentrated on astronautical research as opposed to aeronautical. This is aunique wind tunnel in that not only is it at JPL, but as Donald Baals and William Corliss state in Wind Tunnels of NASA (NASASP-440), "the hypersonic facility was a particularly significant addition to the existing NACA spectrum of tunnels. Covering the range from Mach 4 to Mach 11, with continuous-flow capability, it operated at pressures up to 715 psi and temperatures to 1350 F."
This image shows a very unique wind tunnel. Not only is it shaped like the bell of a convergent-divergent nozzle (and that makes sense considering it is used to test hypersonic airflow) but it is also flexible and can be shaped at will. It looks as if there are small tubes all around the wind tunnel wall, I suspect they may be for cooling purposes. Perhaps water cooling?