A hybrid power drive system for an aircraft comprises a rotor that receives power and a first power drive sub-system including at least one engine in connection with the rotor is configured to provide a first power to the rotor. Further, the hybrid power drive system also includes a second power drive sub-system connected in parallel to the first power drive sub-system. The second power drive sub-system is configured to provide a second power to the rotor a second power drive sub-system connected in parallel to the first power drive sub-system and configured to provide a second power to the rotor when the first power provided by the first power drive sub-system is less than a power demand of the rotor.