Probably, but you'd need a tailrotor or tip props on the blade tips for countertorque. There was an unsuccessful HPH design with one tip-driven rotor. The negat

Probably, but you'd need a tailrotor or tip props on the blade tips for countertorque. There was an unsuccessful HPH design with one tip-driven rotor. The negative is that you're generating aerodynamic force that is non-lifting, and thus wasting power. Four rotors were probably chosen for this design (and many past others) for stability; a helicopter in hover is about as stable as an air hockey puck, it needs constant control input to stay in one spot. Directional control is much easier with a vehicle resting on four legs than on one.