How do twin rotor helicopters, like those of the Chinook at Dartmouth, avoid their blades clashing each other?
Despite the different heights of the blades, they would still hit if they weren’t synchronized. The blades do flap and it also has something called cyclic trim in which the heads tilt fore and aft for flight at different airspeeds to maintain a level fuselage attitude in flight. During ground taxi, the forward head also tilts forward, to pull the aircraft along. The synchronization is accomplished by a shaft that runs between the forward and aft transmissions. Both heads rotate together at the same speed and stay meshed due to this synch shaft. Failure of this shaft is most likely catastrophic to the rotor blades as they get out of synch.
