Itoh Emi 31
| Industry | Aviation |
|---|---|
| Founded | 1922 |
| Founder | Sun-ichi Bando, Yukichi Goto |
| Products | Civil flying boats |
The Itoh Emi 31 was a unique Japanese civil flying boat that took to the skies for the first time in 1922. It served an airline on a scheduled route for two years and briefly operated for a newspaper, accommodating up to three passengers.
Design and development
The project commenced in 1922 when the Japan Air Transport Research Society acquired a Curtiss Seagull flying boat as their initial passenger aircraft for service between Tokyo and Yokohama Bay. Following significant damage to this plane, founders Sun-ichi Bando and Yukichi Goto—previous owners of the Emi 16 racing aircraft—commissioned Itoh to create a replacement. Tomotari Inagaki designed the Itoh Emi 28, which drew inspiration from the Seagull and was intended to be powered by a Hispano-Suiza engine; however, this model never reached production. Meanwhile, Choichi Inoue’s Japanese Air Transport Research Association (JATRA), which operated Japan's inaugural regular floatplane route between Sakai and Takamatsu, required a more capable passenger flying boat, leading to the development of the Emi 31.
Constructed with a wooden frame, the Emi 31 was a fabric-covered biplane featuring unequal-span wings arranged in a pusher configuration. The biplane had two bays supported by parallel interplane struts. Its lower wing, shorter in span, was mounted directly atop the hull, while the upper center section was held by struts supporting the pusher engine. Ailerons were installed exclusively on the upper wings.
The aircraft was powered by a water-cooled Hispano-Suiza 8B V-8 engine mounted on a pylon beneath the upper wing. Two upright rectangular radiators were positioned edgewise just ahead of the wing’s leading edge. The hull, covered with plywood, closely followed the single-step design seen on the Seagull. Stability during water operations was provided by small floats with pronounced upward angles located beneath the outer interplane struts. The cockpit arrangement consisted of two open tandem cockpits placed side-by-side; initially, the pilot and flight engineer occupied the forward cockpit, with seating for two passengers behind them. However, during service, it became common to substitute the engineer with an additional passenger.
The tail assembly was fabric-covered and bore resemblance to that of the Curtiss design. It featured a tailplane and elevator mounted high on a shortened fin. The large rudder had a distinctive comma shape and operated within a deep cutout in the elevator, incorporating a forward balance area that projected over the tailplane.
Operational history
The Emi 31 was finalized around mid-1922. After undergoing test flights at Itoh's facility in Tsudanuma, it commenced operations from JATRA’s Sakai base along its intended route. The aircraft also served The Asahi Shimbun newspaper during army manoeuvre coverage, attracting notable attention from the Prince Regent. Over several months in service, it experienced multiple modifications before remaining active with JATRA until 1924. Subsequently, it was retired and repurposed as a water taxi and sightseeing vessel.