Thanks for the comments.
The furling is a fairly complicated thing to try and explain. Our turbines use the same broad furling principle that a lot of upwind turbines use (such as bergey) - but we have changed the way in which it operates.

It is difficult to see, but on the Mistral and Merlin turbines the yaw pivot is offset from the centreline of the turbine. Also, the tail booms are rigidly attached at an angle when looking from above. Finally, the pivoting tail-fin itself is mounted via teflon bearings on an incline. All of these things work together to create a gravity reset furling system. Without getting into the nitty gritty of it all, at high windspeeds the thrust from the rotor overcomes the yawing moment of the tail fin - making the turbine want to dry and go downwind. At the same time a lifting force is present on the tail-fin which pushes it upon against its inclined pivot. The result is that the rotor yaws to a 'glancing angle' to the oncoming wind. This reduces the exposed rotor area and also puts the rotor blades at incorrect angles of attack. This helps regulate rotor speed, but also reduces the overall forces exerted. When the gust has passed, gravity pulls the tail fin back to its normal position and the turbine reorientates back into the wind.

One of the main features of our design is that only the tail-fin pivots rather than the entire tail boom. This exponential reduces the stresses encountered along the tail boom /fin. It also helps prevent wear and tear as fin and boom are not free to articulate under normal running conditions.

A picture says a thousand words. I have attached a photo of the furling in operation.

Many Thanks,
Dave
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dave