Starting in 1943 the Dornier company was working on an improved version of
the Do-24 to get it better suited for rescue and reconnaissance work. This
resulted in a study for the Do-318. The Do-318 had a lengthened front part of
the fuselage, a fuselage wich was highed, the Stummeln were bigger and the
overal weight was much higher. For use in rescue missions the take-off weight
would be 18.000 kg and for reconnaissance missions it would be 20.000 kg.
The building process followed the excact lines of the Do-24, for instance, the wing was made in three parts. The aircraft was to be equipped with three BMW-Bramo 323TA engines, each capable of 1200 hp. The fuselage consisted of 50 frames which together with the aluminum skin gave the aircraft a solid and tough frame. The bottom of the fuselage hollow chambers to prevent the aircraft from sinking by countering any ruptures in the skin.
The fuel was to be placed in selfsealing tanks in the wings and close-riveted tanks in the Stummeln. In the reconnaissance version the front cargo hold housed two further protected fueltanks, each capable of 700 liters.
Weser Flugzeugbau started with a project that was to be included in the Do-318, the so-called Grenzschitabsaugung. This was a process with which air was sucked into the wing and blown out over the flaps to give more lift for an even shorter take-off and landing. One example was indead equipped with the Walther agregat that supplied the power. The wings were placed on the fuselage, but there is no proof that the aircraft ever flew.