Our task was to design and optimize the drive system and battery support frame structures of a low- wing, two-seat, closed cockpit, single-engine electric or hybrid-powered aircraft. The most important aspect of the design for both the electric and hybrid drive systems was to keep the weight as low as possible, thus increasing the range of the aircraft. Accordingly, the material of the aircraft's structure is composite, however, the parts of the drive system and the battery pack are fixed in a high-strength steel frame. The hybrid drivetrain consists of a battery-powered electric motor and a three-cylinder diesel engine. The excess energy stored in the battery is used for take-offs and landings, while the purpose of the diesel engine is to charge the batteries during flight.