Wind is another source of rotor blade loading. They are a measure of rotor blade tip Mach number. The structures are tall with a rotor blade diameter of . Two ramjets, one at the tip of each rotor blade, power the helicopter. One reportedly flew home after losing of main rotor blade to a tree. Vertical motion is controlled with conventional rotor blade blade pitch. The transfer of energy occurs only across the rotor blade row. Experiments have also used jet nozzles at the rotor blade tips. Other turbines use an electric servomotor for every rotor blade. To obtain this condition the rotor blade angles must be equal. A new wide-chord rotor blade was featured. A rotor blade produces more lift in the advancing half. One modification for the S-61 is the Carson Composite Main Rotor Blade. At the same time, a rotor blade in the retreating half produces less lift.