# Furling of a Horizontal Axis Wind Turbine **URL:** \ **Category:** Computer-Aided Engineering Software Tools\ **Created:** [February 6, 2012, 6:41am UTC](https://forums.nlr.gov/t/furling-of-a-horizontal-axis-wind-turbine/445 "2012-02-06T06:41:49Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Abdur.Rahman](https://avatars.discourse-cdn.com/v4/letter/a/ccd318/32.png) [@Abdur.Rahman](https://forums.nlr.gov/u/Abdur.Rahman)\ **Post date:** [February 6, 2012, 6:41am UTC](https://forums.nlr.gov/t/furling-of-a-horizontal-axis-wind-turbine/445/1 "2012-02-06T06:41:49Z")
I am looking to design a Furling mechanism for a Horizontal Axis Wind Turbine. I am required to calculate: 1. horizontal offset of turbine axis from the vertical yaw axis 2. tail surface area 3. The length of the boom 4. The weight of the tail is there any software which would be helpful for designing of a furling system? ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [February 6, 2012, 1:39pm UTC](https://forums.nlr.gov/t/furling-of-a-horizontal-axis-wind-turbine/445/2 "2012-02-06T13:39:23Z")
Dear Abdur, Our FAST aero-elastic tool can simulate a wind turbine of a given design with the various furling features you’ve specified, but it may not be easy to identify the appropriate values for optimal furling performance. I haven’t designed a furling wind turbine myself, but my understanding is that is common for those who do to compare many designs by sweeping through different values of the various furling features (a large parameter sweep) until the desired performance is achieved. I hope that helps. Best regards, ---
**Author:** ![Abdur.Rahman](https://avatars.discourse-cdn.com/v4/letter/a/ccd318/32.png) [@Abdur.Rahman](https://forums.nlr.gov/u/Abdur.Rahman)\ **Post date:** [February 7, 2012, 10:38am UTC](https://forums.nlr.gov/t/furling-of-a-horizontal-axis-wind-turbine/445/3 "2012-02-07T10:38:17Z")
I am working on the designing of a furling mechanism for a horizontal axis wind turbine. Turbine diameter is 5.6 m. I did following calculation: Turbine thrust is 1.628 kN (using WT\_perf) at 20 m/s wind speed (speed at which furling should start) Offset between generator and tower axes is 0.28 (5% of Turbine diameter) Turbine Moment is 0.4558 (kN-m) (Turbine Thrust x offset) Boom length is 2.8 m (Turbine radius) Fin Area is 1.23 m^2 (Turbine swept area x offset = 2 x Boom Length x Fin Area) Angle of Fin bracket from vertical is 20 degree Angle of Fin bracket from the plane of the blades 45 Fin mass is calculated from following relations: Turbine Moment = Fin Moment Fin Moment = Furl Resistance x Boom Length Furl Resistance = Furl Mass (kg) x 9.8 x sin20 x sin45 From above three equations we can write that: Furl Mass = Turbine Moment / Boom Length / sin20 / sin45 / 9.8 Furl Mass = 0.4558 x 1000 / 2.8 / sin20 / sin45 / 9.8 So, Furl Mass = 68.7 kg Its look too much. I go through from data available for different HAWT furling system, and found that they use around 30 kg furl mass for 5 to 6 m diameter HAWT. Is this Furl mass OK (68.7 kg for 5.6 m diameter HAWT)? Or can you identify the mistake. Thanks