Delphin I was a single-engine all-metal high-wing monoplane. The two-step hull with its blunt bow was divided into several bulkheads and equipped with the Dornier sponsons. The all-metal wing consisted of two halves, each mounted to the lateral wall of the hull and braced with the sponsons by means of two struts. The power plant consisted of a BMW IIIa engine with a face-type radiator between the two-blade wooden propeller and the engine. The open flight deck equipped with a cover for test purposes, was located immediately aft of the engine. The cabin for 4-5 passengers and a baggage hold were located in the hull. The aircraft had a standard cross-shaped empennage.
First flight took place on November 24, 1920. During the test, the blunt bow of the hull was very unfavorable during the take-off phase. Therefore, the bow was extended. Four aircraft were built, two of them in the new Marina di Pisa/Italy plant. One Delphin I was taken over for testing of all-metal aircraft construction by the U.S. Navy. One Delphin I was delivered to the Japanese licensee, Kawasaki Dockyard Co. of Kobe.
