First of all I have a question. On a blade that does not have active blade twist there a built in twist to the blade. In other words if the blade has a 7-degree twist then with the blades in a static position with no collective pitch the root would be at 7-degrees and the tip at 0-degrees.
Does an active twist blade have this built in twist or, is all twist commanded to meet specific aerodynamic loading? It has been stated that the ideal active twist blade would have 0-degrees AOA to the relative wind. If there is no built in twist then with full collective pitch the root would measure for instance 18-degrees and the tip would measure 0-degrees which means that the active pitch range would be in excess of 18-degrees which seems to be excessive. If the blade has a built in twist and the twist can be altered then this same blade would have a root measurement of 18-degrees plus the built in setting of 7-degrees giving a total of 25-degrees of twist in order to maintain a 0-degree AOA at the tip. Hopefully I got the numbers correct.
