QinetiQ (Farnborough, Hampshire, U.K.) announced on Oct. 22 that it and Vestas Wind Systems A/S (Randers, Denmark) have successfully trialed a unique radar mitigation technology for wind turbines. Using a jointly designed 44m/144-ft prototype turbine blade manufactured by Vestas, the technology was demonstrated at full scale for the first time at a wind farm in Norfolk, U.K., as part of a program partially funded by the U.K. Government Department for Business Innovation and Skills (BIS).
The five-year project has developed Stealth Turbine technology that is said to significantly reduce the size of the radar signature made by individual turbines to the point where they can be effectively factored out of air traffic control and air defense systems. With 9 GW of potential sites currently blocked by objections from radar operators, this technology could have a revolutionary impact on wind farm planning in both the U.K. and the rest of the world.
The Stealth Turbine solution uses a portfolio of radar absorbing materials (RAM) that are integrated into the current manufacturing processes for turbine components – blades, nacelle and tower – and which can be designed to operate at aviation and maritime frequencies. These include modified composites for nacelle and blades, and sprayable RAM coatings that can be applied directly onto the tower and other static surfaces. The nature of the RAM and how they are integrated into the composite wind blade manufacturing process was not revealed by QinetiQ, but the company did note that one of the preset conditions Vestas placed on QinetiQ was that the solution "must not alter our current manufacturing processes," which are proprietary to Vestas.
The trial in Norfolk involved the fitting of the prototype stealth blade onto a Vestas V90 turbine. Radar cross section (RCS) measurements were taken using the QinetiQ multiband pulsed radar (MPR) system, with results showing significant RCS reductions in line with expectations based on analysis and blade material measurements.
A prototype of QinetiQ’s stealth blade is fitted onto a Vestas V90 turbine at Swaffham Wind Park in Norfolk. By addressing the effects of radar interference in the design of the blade, this new stealth technology could have a major impact on wind farm planning in the U.K.