The engine was a Daimler-Benz DB 605B driving a three-blade propeller and armament was to consist of two 13 mm MG 131 machine guns and two 20 mm MG 151/20 cannons. The tricycle landing gear from the Me 309 was retained, which worked better on the 509 due to the lower weight on the nosewheel - the Me 309's front landing gear had collapsed during trials. Visibility was also better with the smaller nose. The project was cancelled along with the Me 309, but the Japanese made a similar aircraft, the Yokosuka R2Y Keiun, which suffered from engine overheating.