The V-22 is the "tilt-rotor" hybrid helicopter-airplane. If in forward flight you get a slight imbalance in thrust, you still go forward, but in a tandem-rotor helicopter, like the Chinook if you get different lift, you get serious problems immediately. When you're transitioning from lift to forward flight like the V-22, it's deadly. Then again, there's LOTS that is deadly about the V-22, as has bee said.