Guided by a philosophy of excellence, ETW has grown into one of the world’s most important aerodynamics research and development facilities for the aviation industry. Since 1995, the organization has helped aircraft manufacturers from all over the world to optimize their aircraft designs. The wind tunnel provides realistic flight conditions to analyze the aerodynamic properties of scaled-down aircraft models. The models are equipped with pressure and temperature sensors, as well as additional flow sensors, and then mounted in a test section, where a 50-megawatt compressor generates nitrogen flow at supersonic speeds of up to 1.3 mach. To allow simulation of realistic flight and flow conditions on a small scale, the temperature in the wind tunnel is lowered to approximately negative 160 degrees Celsius and air pressure is increased to 4.5 bar. Such conditions can be created only by using extremely cold nitrogen combined with a sophisticated system of airlocks to keep moisture out.
The airlock system, the transport of the model, and the wind tunnel’s settings were controlled by half a dozen VAX systems. Six more VAXes collected real-time measurement data. All the systems ran on OpenVMS. “OpenVMS is still one of the world’s best operating systems,” explained Wolfgang Strudthoff, group leader of the computer systems department at ETW. “It’s very reliable. We’ve had only a few outages over the past 20 years.” But workstations capable of running OpenVMS were growing rare. In the mid-1990s, Digital Equipment Corporation replaced 32-bit CISC VAX systems with 64-bit RISC-based Alpha AXP systems. Despite several attempts, Digital was never able to ensure that all applications could be transferred to the new RISC platform without modification. In the case of ETW, that meant that their custom-built applications could not be moved to AlphaServers, and therefore the old VAX systems had to be carefully maintained. “Our initial investment in software development was huge,” explained Strudthoff. But after almost 30 years of continuous use, the hardware was reaching the end of its life.