New "stealth" wind blade helps reduce radar signatures

The Stealth Turbine solution uses a portfolio of radar-absorbing materials that are integrated into the current manufacturing processes for turbine components – blades, nacelle and tower.

QinetiQ (Farnborough, Hampshire, U.K.) and Vestas Wind Systems A/S (Randers, Denmark) capped their joint five-year Stealth Turbine technology project Oct. 22 with the announcement of a successful trial for 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 trial involved the fitting of a prototype stealth blade onto a Vestas V90 turbine. Radar cross-section (RCS) measurements were taken using QinetiQ’s multiband pulsed radar (MPR) system. Test results demonstrated significant RCS reductions, an outcome in line with QinetiQ and Vestas expectations, based on their design analysis and blade material measurements.

The Stealth Turbine strategy is expected 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. Because development of 9 gigawatts (GW) of potential wind farm sites is currently blocked by objections from radar operators, QinetiQ and Vestas contend that this technology could have a revolutionary impact on wind farm planning, not only in the U.K. but worldwide.

The Stealth Turbine solution takes advantage of radar absorbing materials (RAM) that are integrated into the current manufacturing processes for turbine blades, nacelles and towers. The materials, which can be tailored to operate most effectively at aviation or maritime radar frequencies, include modified composites for nacelle and blades, and sprayable RAM coatings that can be applied directly to the tower and other static surfaces. Although QinetiQ, thus far, has revealed little about RAM composition or how RAM are integrated into the composite manufacturing process, the company notes that Vestas stipulated that the solution “must not alter our current manufacturing processes.”