A short history of the Martin Mars flying boats

by | Jul 16, 2020 | Historic Aircraft | 0 comments

The story of the Martin Mars flying boats started in 1938, when the United States Navy placed an order to the Martin Aircraft Company for a large maritime patrol bomber. The prototype first flew on July 3, 1942. The Navy was pleased with the prototype, and decided to order twenty production models, designated JRM‑1. However, there was no longer a need for a large patrol bomber in the Atlantic and Pacific theaters, and so these twenty Mars flying boats were to be made in a cargo configuration.

Martin JRM-1 Hawaii Mars II - BuNo 76823

Martin JRM-1 Hawaii Mars II (BuNo 76823) moored at Sproat Lake, Port Alberni, BC, Canada.

The first JRM‑1 was delivered on July 27, 1945, dubbed Hawaii Mars. However, with the war in the Pacific ending only two months later, the Navy downsized their order from twenty aircraft to only five more. These followed the Pacific island naming convention, and were christened the Philippine Mars, Marianas Mars, Marshall Mars, Hawaii Mars II (the first Hawaii Mars had sunk in Chesapeake Bay and was then scrapped), and Caroline Mars, which was designated JRM-2, with more powerful engines and larger propellers.

Martin JRM-1 Hawaii Mars II - BuNo 76823

Martin JRM-1 Hawaii Mars II (BuNo 76823) moored at Sproat Lake, Port Alberni, BC, Canada.

The Marses were then used to ferry cargo from the mainland US to Hawaii and other Pacific islands. With their 200 foot wingspan, these were the largest flying boats of the time, capable of carrying up to 133 passengers, eighty-four stretchers and twenty-five passengers, or 32,000 thousand pounds of cargo. Throughout their service lifespan, the three oldest Marses logged between 18,000 and 20,000 flight hours each, carrying a total of a quarter of a million passengers and many tons of freight over the Pacific. One Mars set a record of 68,327 pounds of cargo carried. Stationed at NAS Alameda, they eventually just ferried cargo between San Francisco and Honolulu until their retirement in 1956. During this time, Marshall Mars had burnt down and sunk off of Diamond Head, Honolulu due to an engine malfunction. The four remaining aircraft were beached at NAS Alameda and awaited scrapping.

Martin JRM-1 Philippine Mars - BuNo 76820

Martin JRM-1 Philippine Mars (BuNo 76820) Coulson Flying Tankers, Port Alberni, BC, Canada.

In the 1950s, four logging companies in British Columbia (BC), Canada formed Forest Industries Flying Tankers (FIFT) and purchased the four surviving Mars airframes before they were scrapped for a total of $100,000, as well as thirty-five extra engines and crates of new spare parts for $21,410. These were then stripped of all unnecessary weight and converted into waterbombers. Operating out of a new base on Sproat Lake near Port Alberni, BC, they served aerial firefighting duties for the four member companies of FIFT. Marianas Mars was lost in 1961 when it crashed on a firefighting run and Caroline Mars was damaged beyond repair in 1962 due to a storm.

Wright R-3350 Duplex-Cyclone engine

Wright R-3350 Duplex-Cyclone engine, Coulson Flying Tankers, Port Alberni, BC, Canada.

The Marses proved to be true workhorses of aerial firefighting, capable of dropping 7,200 (US) gallons of water over up to four acres of land. The tankers are also capable of dropping firefighting foam, which is mixed from concentrate stored inside the aircraft while it scoops up water from the two underbelly-mounted probes. These probes are capable of taking in almost a ton of water per second as the Mars skims a lake at exactly seventy knots, filling the tanks in approximately twenty-five seconds. With a crew of four, firefighting operations in the Mars were perfectly coordinated operations.

Martin JRM-1 Hawaii Mars II - BuNo 76823

Martin JRM-1 Hawaii Mars II (BuNo 76823) moored at Sproat Lake, Port Alberni, BC, Canada.

The Captain carried out a normal water landing and kept the aircraft at seventy knots exactly, and then passed engine power to the flight engineer while engaging the water scoops. As the aircraft takes on more water, the flight engineer must gradually increase power to keep the aircraft at seventy knots to account for the increased weight. With fully loaded tanks, the flight engineer adds extra power to the engines and the aircraft takes off. The foam concentrate can then be mixed in, if needed. The concentrate stays in the water until the tanks are emptied, where the churning of the water causes the foam to be created during the drop. If a large enough water source is nearby, this whole process could have been carried out around every fifteen minutes by the crew. 

Nose section of the 8th uncompleted Martin Mars airframe

Nose section of the 8th uncompleted Martin Mars airframe, Coulson Flying Tankers, Port Alberni, BC, Canada.

In 2007, Coulson Group acquired the two surviving aircraft, Phillipine Mars and Hawaii Mars II and continued to operate them from Sproat Lake, flying missions in BC and Alberta Canada, as well as in Washington, Oregon and California. 2009 was the first year in their 49 consecutive years of firefighting service that the Marses were not used. As smaller flying tankers prove to be more versatile and efficient while being less costly than the Marses, they have been gradually phased out of service. In 2015, the Hawaii Mars II was briefly used to train Chinese pilots through the International Test Pilot School for the Chinese-made AVIC AG-600 Kunlong flying boat. The Phillipine Mars has been repainted in the original US Navy livery as it was intended to be delivered to the National Naval Aviation Museum at NAS Pensacola, Florida in 2016. However, the plan was put on hold, supposedly due to the coincidental election year in the US and a possible policy change, and has not occurred since.

(MK)

Martin JRM-1 Hawaii Mars II - BuNo 76823

Martin JRM-1 Hawaii Mars II (BuNo 76823) moored at Sproat Lake, Port Alberni, BC, Canada.

About The Author

Igor K.

I am the founder and editor-in-chief of the AirMuseumGuide.com blog. Together with my son - hopefully a future aerospace engineer - we are trying to visit as many aviation and aerospace museums in the US as possible with the ultimate goal of visiting them all. We have been able to visit approximately 60 so far. We are hoping this site will help preserve aviation history and inspire young people to pursue a career in aerospace.

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