The Curtiss Twin JN (retrospectively called the Model 1B and also known as the JN-5) was an experimental aircraft built by the Curtiss Aeroplane and Motor Company for the United States Army Air Service. It was a biplane, designed for observation missions.
Based on the successful Curtiss JN-4, the Twin JN used the same wing structure, but the wingspan was extended by enlarging the center section. Lateral control was achieved with the tail of a Curtiss R-4. The Twin JN was powered by a pair of 90 hp (67 kW) Curtiss OXX-2 engines located between the wings.
One aircraft was evaluated by the United States Navy as a twin-float seaplane.