This disclosure is directed to a single blade propeller and systems, devices, and techniques pertaining to assisting in critical stages of flight (e.g., takeoff, landing, emergency situations, etc.) in vertical takeoff and landing (VTOL) aircraft. The single blade propeller may be incorporated into fixed and rotary wing VTOL aircraft as part of a first propulsion system. The first propulsion system may include one or more single blade propellers driven by electric motors, combustion engines, and/or hybrid engines. Each of the single blade propellers may include a lift-producing blade and a counterweight opposite the lift-producing blade. As each of the single blade propellers spins, it may produce lift in a direction approximately perpendicular to the horizon to effect vertical flight.