Appendix C: Stall Flag Patent
At ECN the stall flag was regarded to be a valuable new instrument and therefore it was
decided to apply for a patent. The procedure started with a Dutch patent no. OA 1003153
Ned., which was applied May 17, 1996 and granted November 11, 1997. It was also decided
to extend the application to Europe and the Unites States of America. The application in
Europe is still running, while that in the USA has just been granted. The latter is included
here.
135
Flow Separation on Wind Turbine Blades
136