Martin JRM Mars

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JRM Mars
The "Caroline Mars" JRM-2 Mars in Navy service.
RoleFlying boat
National originUnited States
ManufacturerGlenn L. Martin Company
First flight23 June 1942
Introduction30 November 1943
Retired1956 (USN)
Primary usersUnited States Navy
Flying Tankers
Produced1945 - 1948
Number built7
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JRM Mars
The "Caroline Mars" JRM-2 Mars in Navy service.
RoleFlying boat
National originUnited States
ManufacturerGlenn L. Martin Company
First flight23 June 1942
Introduction30 November 1943
Retired1956 (USN)
Primary usersUnited States Navy
Flying Tankers
Produced1945 - 1948
Number built7

The Martin JRM Mars is a large, four-engined cargo transport seaplane originally designed and built in limited numbers for the U.S. Navy during the World War II era. It was the largest Allied flying boat to enter production, although only seven were built. The United States Navy contracted the development of the XPB2M-1 Mars in 1938 as a long range ocean patrol flying boat, which later entered production as the JRM Mars long range transport.

The surviving aircraft were later converted for civilian use to firefighting water bombers. One example of the aircraft still remains in active service.

Design and development

The Glenn L. Martin Company scaled up their PBM Mariner patrol bomber design to produce the prototype XPB2M-1 Mars.[1] The XPB2M-1 was launched on 8 November 1941. After a delay caused by an engine fire during ground runs, the aircraft first flew on 23 June 1942. After flight tests with the XPB2M between 1942 and 1943, she was passed on to the Navy. The original patrol bomber concept was considered obsolete by this time, and the Mars was converted into a transport aircraft designated the XPB2M-1R. The Navy was satisfied with the performance, and ordered 20 of the modified JRM-1 Mars.[1] The first, named Hawaii Mars, was delivered in June 1945, but with the end of World War II the Navy scaled back their order, buying only the five aircraft which were then on the production line.[2] Though the original Hawaii Mars was lost in an accident on Chesapeake Bay a few weeks after it first flew, the other five Mars were completed, and the last delivered in 1947.

Operational history

U.S. Navy service

The prototype XPB2M-1 Mars

Named the Marianas Mars, Philippine Mars, Marshall Mars, Caroline Mars, and a second Hawaii Mars, the five production Mars aircraft entered service ferrying cargo to Hawaii and the Pacific Islands. The last production airplane (the Caroline Mars) was designated JRM-2, powered by 3,000 hp (2,200 kW) Pratt & Whitney R-4360 engines, and featured a higher maximum weight and other improvements. On 4 March 1949, the Caroline Mars, set a new world passenger load record by carrying 269 people from San Diego to Alameda, CA.[3] On 5 April 1950, the Marshall Mars was lost near Hawaii when an engine fire consumed the airplane after her crew had evacuated. The remaining "Big Four" flew record amounts of Naval cargo on the San Francisco-Honolulu route efficiently until 1956, when they were beached at NAS Alameda.[1]

Civilian use

Hawaii Mars ("Redtail")

In 1959, the remaining Mars were to be sold for scrap but a Canadian company, Forest Industries Flying Tankers (FIFT), was formed and bid for the four aircraft and a large spares holding. The company represented a consortium of British Columbia forest companies and the bid was accepted and the sale was completed in December 1959. The four aircraft were flown to Fairey Aviation at Victoria, British Columbia for conversion as water bombers. The conversion involved the installation of a tank in in the cargo bay and retractable pick-up scoops to allow uploading of water while the aircraft was taxiing. The scoops allowed 30 tons of water to be taken on board in 22 seconds. Later some of the hull fuel tanks were replaced with water tanks.

The Marianas Mars crashed near Northwest Bay, British Columbia on 23 June 1961 during firefighting operations; all four crewmembers were lost. Just over a year later, on 12 October 1962, the Caroline Mars was destroyed by Typhoon Freda while parked onshore. The Hawaii Mars and Philippine Mars had their conversions to water bombers accelerated and entered service in 1963.[1] They appeared at local airshows, demonstrating their water-dropping ability. Flying Tankers Inc. also flew the water bombers to other hot spots around the province when a need developed, such as in August 2003, when a large forest fire threatened the city of Kelowna, British Columbia.

Hawaii Mars undergoing winter maintenance at Sproat Lake in 2008 with Philippine Mars in the background

On 10 November 2006, TimberWest Forest Ltd. announced that they were looking for buyers of the Mars. A condition of this sale was that the purchasers would have to donate one back to Port Alberni when they are retired, as an historic attraction.[4] The Maryland Aviation Museum and British Columbia Aviation Council have initiated a joint effort to preserve the aircraft, one in Maryland and the other at their current location in Canada.[5] On 13 April 2007, TimberWest announced the sale of both aircraft to Coulson Forest Products, a local forestry company in Port Alberni, British Columbia. The two surviving tankers are operated by Coulson Flying Tankers and are based and maintained at Sproat Lake near Port Alberni. On 25 October 2007, the Hawaii Mars ("Redtail") arrived at Lake Elsinore in southern California, on a private contract, to assist with the firefighting efforts containing the California wildfires of October 2007. The Philippine Mars had been undergoing "extensive maintenance and renovation" and was expected to be ready to fly again in 2010.[6] As of 13 August 2009 (2009-08-13), the Hawaii Mars was in service fighting the La Brea fire east of Santa Maria in Southern California.

The aircraft can carry 7,200 U.S. gallons (27,276 litres) of water and each drop can cover an area of up to 4 acres (1.6 hectares). The aircraft can also carry up to 600 U.S. gallons (2,270 litres) of foam concentrate for gelling the load drop.[7] They are used to fight fires along the coast of British Columbia and sometimes in the interior. As of July 29, 2010, the Martin Mars was being used to fight the Mason Lake/Bonaparte Lake fire north of Kamloops.[8]

On 23 August 2012, the Coulson Group of Port Alberni, British Columbia announced that the Philippine Mars, due to its lack of use for five years, will be retired and flown to the National Naval Aviation Museum at Naval Air Station Pensacola, Florida to become a static exhibit. The aircraft has been repainted to its original U.S. Navy colors and is expected to be delivered to the museum in November 2012. The Hawaii Mars will remain on contract for regular use.[9]


Model 170 prototype long-range patrol flying boat powered by four Wright R-3350-8 piston engines, one built, converted to XPB2M-1R.
JRM-1 BuNo 76820
Philippine Mars
Prototype converted in December 1943 as a prototype transport version, armament removed, installation of additional cargo hatches and cargo loading equipment, existing hatches were enlarged and the decking was reinforced.
Model 170A, production long range transport variant, originally 20 aircraft ordered later reduced to six. Single-tail design, and having a longer hull with fewer bulkheads and a larger maximum take-off weight. It had also been fitted with equipment for overhead cargo handling and was powered by four Wright R-3350-24WA Cyclone engines with 4-bladed propellers, five built, surviving four converted to JRM-3.
The last JRM-1 on order was completed as the JRM-2 with the engines changed to 3,000 hp Pratt & Whitney R4360-4T engines with 4-blade, 16 ft, 8 in diameter Curtiss Electric propellers. Gross weight increased by 20,000 lbs.[10]
Model 170B, conversion of the remaining four JRM-1s re-engined with 2,400 hp Wright R3350-24WA engines turning 16 ft, 8 in Curtiss-Electric props, of which the inboard two engines were fitted with reversible-pitch devices.


JRM-1 Marshall Mars burning near Honolulu, Hawaii
JRM-2 Caroline Mars in the St. Johns River at NAS Jacksonville, Florida in 1949

Specifications (JRM-3 Mars)

JRM-1 Marshall Mars

Data from Jane’s Fighting Aircraft of World War II[2]

General characteristics


See also

Related development
Aircraft of comparable role, configuration and era
Related lists



  1. ^ a b c d Goebel, Greg. "The Martin Mariner, Mars, & Marlin Flying Boats." Air Vectors, 6 May 2006. Retrieved: 13 November 2010.
  2. ^ a b Bridgeman 1946, pp. 244–245.
  3. ^ Hills, Warring. "Caroline Mars Sets World Record 1949.", 25 February 2011.
  4. ^ "TimberWest Seeks Buyers For Martin Mars Water Bombers." TimberWest Forest Ltd., 12 November 2006.
  5. ^ "Canadian Aviation Organization and U.S. Museum Create Alliance." Maryland Aviation Museum, 12 November 2006.
  6. ^ Hansen, Darah. "Fires fought without super-soakers." Vancouver Sun, 6 August 2009. Retrieved: 6 August 2009.
  7. ^ "Aircraft Fleet." Flying Tankers Inc., 6 May 2006.
  8. ^ "Kamloops fire." Retrieved: 13 November 2010.
  9. ^ McCulloch, Sandra. "Water bomber retires to US." Alberni Valley Times, 23 August 2012. Retrieved: 27 August 2012.
  10. ^ a b "JRM-2 76824." Gauthier Memorial Collection. Retrieved: 13 November 2010.
  11. ^ "Naval Aviation and Deep Water Discoveries: Pearl Harbor 2004." National Marine Sanctuaries. Retrieved: 28 December 2010.
  12. ^ Gorell, Fred. "Mars is found in seafloor survey around Japanese mini-submarine. NOAA and Partners Survey "Flying Boat" Crash Sites." National Oceanic and Atmospheric Administration, US Department of Commerce via NOAA Magazine. Retrieved: 28 December 2010.


  • Bridgeman, Leonard. “The Martin Model 170 Mars.” Jane's Fighting Aircraft of World War II. London: Studio, 1946. ISBN 1-85170-493-0.
  • Coulson, Wayne and Steve Ginter. The Mighty Martin Mars: From 1945 US Navy Transport to 21st century initial attack firefighting. Port Alberni, BC, Canada: Half Moon Bay Publications, 2009. ISBN 978-0-9812987-0-2
  • Ginter, Steve. Martin Mars XPB2M-1R & JRM Flying Boats (Naval Fighters 29). Simi Valley, California, USA: Ginter Books, 1995. ISBN 0-942612-29-9.

External links