OL-4

The Loening Aeronautical Engineering Corporation’s OL‑4 was introduced in the early 1930s as a refined evolution of the company’s earlier amphibious designs, building on the success of the pioneering Loening monoplane series. Conceived by Grover Loening, the OL‑4 combined a sturdy welded‑steel tube fuselage with a wooden wing structure, employing a high‑wing cantilever configuration that afforded excellent visibility and stability during water operations. Powered by a reliable 450‑horsepower Wright R‑1820 radial engine, the aircraft featured a pusher propeller mounted behind the cockpit, a layout that reduced spray ingestion and enhanced aerodynamic cleanliness. Its retractable main landing gear and a hull‑shaped fuselage allowed seamless transition between land and sea, making the OL‑4 a versatile platform for coastal patrol, mail transport, and executive travel.

Although only a modest production run of 15 units was completed before the company’s merger with Consolidated Aircraft, the OL‑4 demonstrated the practicality of twin‑role amphibians and contributed valuable data on hull shaping and structural integrity under mixed‑environment stresses. Its design innovations influenced later amphibious transports, cementing the OL‑4’s place as a noteworthy stepping stone in the development of modern seaplanes and multi‑mission aircraft.