A Method and a Blade Lifting Yoke for Lifting a Wind Turbine Rotor Blade

A method for lifting a wind turbine rotor blade, comprising:

• using a blade lifting yoke, the blade lifting yoke comprising:
• at least one crane attachment section for attachment to a crane;
• a base section;
• at least one holding device;
• a first upper and lower clamping element;
• a second upper and lower clamping element;
• and
• a support element attached to the at least one holding device comprising an extended member, wherein the extended member extends away from the nearest lower clamping element such that the support element is capable of supporting a lower surface of the wind turbine rotor blade in a predetermined distance from the first or second lower clamping elements;
• wherein each of the first and second upper clamping elements are arranged above the respective first and second lower clamping elements, which are arranged in each respective first and second distances substantially perpendicular to a longitudinal direction of the rotor blade above the respective first and second lower clamping elements;
• and
• wherein the first and second upper clamping elements configured for pressing the rotor blade against the respective first and second lower clamping elements;
• determining:
• a first and a second clamping position for the first upper and lower clamping elements and the second upper and lower clamping elements;
• a support position of the support element relative to a selected rotor blade when arranged in the blade lifting yoke;
• and
• a clamping pressure between the first and second upper clamping elements and the respective first and second lower clamping elements;
• arranging the selected rotor blade relative to the at least one holding device, such that said first and second upper clamping elements are arranged adjacent to a first surface of said selected rotor blade at the predetermined clamping positions of the respective first and second upper clamping elements, and said first and second lower clamping elements are arranged adjacent to a second surface of said selected rotor blade relative to the predetermined clamping position of the first and second lower clamping elements;
• arranging said support element adjacent to the second surface in a predetermined distance from the first and/or second lower clamping element, wherein the support element is arranged in a predetermined support position between a center of gravity and a trailing edge of the wind turbine rotor blade;
• adjusting said clamping pressure between said first and second upper clamping elements and said respective first and second lower clamping elements using a clamping mechanism, keeping the center of gravity of a wind turbine rotor blade substantially in or near of a rotor blade's clamping area, wherein the clamping area is defined by the first and a second clamping positions of the first and second upper clamping elements and the first and second lower clamping elements;
• wherein during a hoisting operation, the first and second upper clamping elements, the first and second lower clamping elements and the support element provide static stability of the wind turbine rotor blade relative to the blade lifting yoke.