European Transonic Windtunnel

European Transonic Windtunnel (ETW) is an international aerospace research organisation in Cologne, operated as a non-profit company by France, Germany, the United Kingdom and the Netherlands. Since 1995 it has operated a high-Reynolds-number cryogenic transonic wind tunnel for aircraft manufacturers and research institutions worldwide, providing flight-representative test data for aircraft performance and flight-envelope limits. Its 2.0 m × 2.4 m × 9.0 m test section has 90 optical windows and supports Mach-number control from 0.7 to 1.0. ETW provides model preparation, rigging, testing and data-analysis services for clients, with controlled access and confidentiality measures; confirm arrangements before travelling because this is a working test centre rather than a general walk-in visitor attraction.