Douglas
DC-5/C-110/R3D

The Douglas DC-5 (Douglas Commercial Model 5) was a 16-to-22-seat, twin-engine propeller aircraft intended for shorter routes than the Douglas DC-3 or Douglas DC-4. By the time it entered commercial service in 1940, many airlines were canceling orders for aircraft. Consequently, only five civilian DC-5s were built. With the Douglas Aircraft Company already converting to World War II military production, the DC-5 was soon overtaken by world events, although a limited number of military variants were produced.

The fuselage was about two feet above the ground, so loading of passengers and cargo was easier than aircraft with the then-standard conventional landing gear. A very early design change was the addition of a 15-degree dihedral to the horizontal tail group to negate a hint of an aeroelasticity problem. The dorsal strake, introduced in minimal form and expanded to full growth on the Boeing 307, is also well developed on the DC-5. Another significant modification was adding exhaust stacks to the engine nacelles, which was retroactively incorporated after the series entered production. An unusual optical trick was applied to the prototype. The top of the vertical stabilizer and the outline of the engine nacelles were painted a darker color following the aircraft's contour, making the tail and engines appear somewhat smaller and the aircraft sleeker.