JRM-1 Mars

The JRM-1 Mars was a massive seaplane developed by the Glenn L. Martin Company in the early 1940s for the United States Navy. Conceived as a long‑range transport and patrol platform, the aircraft first flew on 30 July 1942 and entered service in 1944. Its most striking feature was the six‑engine, four‑engine (actually four Wright R-3350 Duplex‑Cyclone radial engines) configuration, driving four massive propellers arranged in a tandem push‑pull layout, which gave the Mars a distinctive silhouette and the ability to lift up to 30,000 lb of cargo or 70 troops. The hull measured 436 ft in length with a 115‑ft wingspan, making it the largest flying boat in the world at the time. The JRM‑1’s robust construction allowed water‑borne takeoffs in rough seas and a range of over 4,000 miles, supporting trans‑Pacific supply missions during World II and later serving as a testbed for experimental radar and rescue equipment. Though only a handful were built, the Mars demonstrated the feasibility of ultra‑large amphibious aircraft, influencing post‑war designs such as the Martin P5M Marlin and paving the way for modern heavy‑lift seaplanes.

Glenn L. Martin Company

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Design & Classification