JRM Mars
JRM-2 Mars "Caroline Mars" in US Navy service
Role Flying boat
National origin United States
Manufacturer Glenn L. Martin Company
First flight 23 June 1942
Introduction 30 November 1943
Retired 1956 (USN)
Status Inactive
Primary users United States Navy (historical)
  • Forest Industries Flying Tankers (FIFT) (historical)
  • Coulson Flying Tankers (historical)
Produced 1945–1948
Number built 7
Developed into Martin 193

The Martin JRM Mars is a large, four-engined cargo transport flying boat designed and built by the Martin Company for the United States Navy during World War II. 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.

Four of the surviving aircraft were later converted for civilian use to firefighting water bombers. Two of the aircraft still remain based at Sproat Lake just outside of Port Alberni, British Columbia, although neither is operational. On March 28, 2024, the British Columbia Aviation Museum announced it will be acquiring the Hawaii Mars from Coulson Aviation. It will fly in the Fall of 2024 to Victoria and be part of a permanent display. [1] On April 25, 2024, it was announced that Philippine Mars will be acquired by the Pima Air and Space Museum in Tucson, Arizona to be put in permanent display there.[2]

Design and development

The prototype XPB2M-1 Mars, 1942

The Glenn L. Martin Company scaled up their PBM Mariner patrol bomber design to produce the prototype XPB2M-1 Mars.[3] The XPB2M-1 was announced on 8 November 1941. Delayed 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.[3] 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.[4] Though the original Hawaii Mars was lost in an accident on the 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

JRM-1 BuNo 76820, Philippine Mars taking off from San Francisco Bay, 1946

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 on 23 January 1944.[5] 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 San Francisco, CA.[6] 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.[3]

Civilian use

Moored on Sproat Lake, Vancouver Island. October 2006
Undergoing winter maintenance in 2008 with Philippine Mars in the background
Martin JRM Mars C-FLYL, Hawaii Mars

In 1959, the remaining Mars aircraft 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 inventory. The company represented a consortium of British Columbia forest companies, and the bid was accepted and the sale completed in December 1959. The four aircraft were flown to Fairey Aviation at Victoria, British Columbia, for conversion into water bombers. The conversion involved the installation of a 6,000 imp gal (27,000 L; 7,200 US gal) plywood tank in the cargo bay with 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.[7]

The Marianas Mars crashed near Northwest Bay, British Columbia, on 23 June 1961 during firefighting operations; all four crew members were lost. Just over a year later, on 12 October 1962 while parked onshore at the Victoria airport, the Caroline Mars was damaged beyond repair by Typhoon Freda when she was blown 200 yards, breaking her back.[8] The Hawaii Mars and Philippine Mars had their conversion into water bombers advanced and entered service in 1963.[3] They appeared at local airshows, demonstrating their water-dropping ability. Flying Tankers Inc. flew the water bombers to hot spots around the province when a need developed, such as in August 2003, when a large forest fire threatened the outskirts of Kelowna, British Columbia.

On 10 November 2006, TimberWest Forest Ltd. announced they were looking for buyers of the Mars. A condition of sale was that the purchaser would have to donate one plane back to Port Alberni when they were retired, as a historic attraction.[9] The Glenn L. Martin Maryland Aviation Museum and British Columbia Aviation Council initiated a joint effort to preserve the aircraft, one for display in Maryland and the other at the current location in Canada.[10] 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 presently 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 firefighting efforts at the California wildfires of October 2007. Meanwhile, the Philippine Mars had been undergoing "extensive maintenance and renovation" and was expected to be ready to fly again by 2010.[11] As of 13 August 2009, the Hawaii Mars was in service fighting the La Brea Fire east of Santa Maria in Southern California.

The interior of Philippine Mars, August 2008. The large tanks hold Fire retardant, which is mixed with the water load

The aircraft can carry 7,200 U.S. gallons (27,276 litres) of water and each deployment 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.[12] They are mainly 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.[13]

On 23 August 2012, the Coulson Group announced that the Philippine Mars, due to its lack of use for five years, would be retired and flown to the National Naval Aviation Museum at Naval Air Station Pensacola, Florida to become a static exhibit. The aircraft was repainted to its original U.S. Navy colors and was to have been delivered to the museum in November 2012.[14] After many delays, the trade deal of transferring the aircraft to the museum was put on hold by the Navy in June 2016, pending the outcome of the 2016 US Presidential election.[15]

Hawaii Mars and Philippine Mars at Sproat Lake, 2014

On 10 May 2013, the B.C. provincial government announced that the Hawaii Mars would no longer be placed on contract after the 2013 season, due to not having been used to fight any B.C. fires for two years and the operation of newer and more versatile aircraft by the Coulson group including a Lockheed C-130 Hercules converted to firefighting use. Although Coulson has stated that the Hawaii Mars has been under numerous recent upgrades to make it safer and more reliable,[16] no buyers have come forward to purchase the aircraft. Coulson also cautioned against any plans to open the aircraft as a tourist attraction, citing the 2013 closure of the Flying Tankers Bomber Base Museum from poor attendance.[17]

In May 2015, the Hawaii Mars received a small contract to be used briefly for training Chinese pilots. This was done using the Martin Mars to evaluate against civil certification regulations by the International Test Pilots School on how to handle such a large amphibious aircraft. The pilots would be involved with the Chinese state-owned Aviation Industry Corporation of China as they got ready to launch their forthcoming AVIC AG600 airplane.[18] Subsequently, in July 2015, the airplane was put back in service after public outcry, being awarded a 30-day contract from the BC Government to help with a particularly bad fire season.[19]

In 2016, the Hawaii Mars made its first appearance at EAA AirVenture Oshkosh in hopes of being sold or leased to a new home or business.[20] One of the pilots on the way to Oshkosh was well-known Kermit Weeks.

In January 2022, the Hawaii Mars was the subject of multiple news articles when it was placed on sale by the company Platinum Fighter Sales for over $5 million.[21][22] In June 2023, plans were being finalized for the transfer of the Hawaii Mars to the British Columbia Aviation Museum.[23]


Model 170 prototype long-range patrol flying boat powered by four Wright R-3350-8 piston engines, one built, converted to XPB2M-1R.
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 lb.[24]
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, 5 April 1950
The nose of Marshall Mars, photographed by a joint NOAA, University of Hawaii, National Park Service survey in 2004.[25]
JRM-2 Caroline Mars in the St. Johns River at NAS Jacksonville, Florida in 1949

Specifications (JRM-3 Mars)

3-view line drawing of the Martin JRM-1 Mars
3-view line drawing of the Martin JRM-1 Mars

Data from Jane’s Fighting Aircraft of World War II[4][33]

General characteristics


See also

Related development

Aircraft of comparable role, configuration, and era

Related lists



  1. ^ "Historic B.C. Martin Mars water bomber will fly one last time". Alberni Valley News. 2024-03-28. Retrieved 2024-04-02.
  2. ^ "Coulson Aviation's Philippine Mars Waterbomber to land permanently at Arizona museum". CHEK. 2024-04-25. Retrieved 2024-04-25.
  3. ^ a b c d Goebel, Greg. "The Martin Mariner, Mars, & Marlin Flying Boats." Air Vectors, 6 May 2006. Retrieved: 13 November 2010.
  4. ^ a b Bridgman 1946, pp. 244–245.
  5. ^ Associated Press, "Aerial Box Car Sent To Nimitz", The Spokesman- Review, Spokane, Washington, Monday 24 January 1944, Volume 61, Number 255, page 1.
  6. ^ Boyne, Walter J. (July 2007). Beyond the Wild Blue (2nd edition): A History of the U.S. Air Force, 1947-2007. St. Martin's' Press. p. 465. ISBN 978-0-312-35811-2..
  7. ^ McEuen, Judy (1984). "The Flying Fire Extinguisher". Proceedings. 110 (11). United States Naval Institute: 187–189.
  8. ^ Septer, Dirk (June 2002). "Martin Mars, "God of Rain"" (PDF). British Columbia Forest History Newsletter (66): 6. Retrieved 14 March 2023.
  9. ^ "TimberWest Seeks Buyers For Martin Mars Water Bombers." TimberWest Forest Ltd., 12 November 2006.
  10. ^ "Canadian Aviation Organization and U.S. Museum Create Alliance." Archived 2007-09-28 at the Wayback Machine Maryland Aviation Museum, 12 November 2006.
  11. ^ Hansen, Darah. "Fires fought without super-soakers." Archived 2009-08-11 at the Wayback Machine Vancouver Sun, 6 August 2009. Retrieved: 6 August 2009.
  12. ^ "Aircraft Fleet." Flying Tankers Inc., 6 May 2006.
  13. ^ "Kamloops fire."[permanent dead link] bclocalnews.com. Retrieved: 13 November 2010.
  14. ^ McCulloch, Sandra. "Water bomber retires to US." Archived 2012-11-06 at the Wayback Machine Alberni Valley Times, 23 August 2012. Retrieved: 27 August 2012.
  15. ^ a b "Philippine Mars museum deal grounded". Alberni Valley News. June 23, 2016. Archived from the original on June 27, 2016. Retrieved July 19, 2016.
  16. ^ McCulloch, Sandra. "Last summer for Port Alberni Mars water bomber as province cuts contract." Times Colonist, 10 May 2013. Retrieved: 12 May 2013.
  17. ^ "Mars bomber future now up in air". Alberni Valley Times. April 14, 2014. Archived from the original on 19 May 2014. Retrieved 18 May 2014.
  18. ^ Slepian, Katya. "Test pilot school a success for Martin Mars - Alberni Valley News". Alberni Valley News. Archived from the original on 2016-03-04. Retrieved 2016-02-27.
  19. ^ Bell, Jeff (27 August 2015). "Martin Mars' firefighting season likely over". Times Colonist. Retrieved 2016-02-27.
  20. ^ "Owner looking for new home for Martin Mars water bomber". Times Colonist. May 10, 2016. Retrieved July 19, 2016.
  21. ^ Fabled water bomber once used to fight B.C. wildfires on sale for $5M, Sun., January 16, 2022, CBC via Yahoo News website.
  22. ^ Iconic Hawaii Mars, world’s largest flying water bomber, listed for sale for $5M, By Simon Little Global News, Posted January 15, 2022.
  23. ^ "Famed Martin Mars water bomber could be headed to museum". 14 June 2023.
  24. ^ a b "JRM-2 76824." Gauthier Memorial Collection. Retrieved: 13 November 2010.
  25. ^ "MARS IS FOUND IN SEAFLOOR SURVEY AROUND JAPANESE MINI-SUBMARINE NOAA and Partners Survey "Flying Boat" Crash Sites". NOAA Magazine. December 14, 2004. Retrieved 31 May 2016.
  26. ^ "Philippine bomber in WWII colours - Alberni Valley Times". Alberni Valley Times. Archived from the original on 2016-03-05. Retrieved 2016-02-27.
  27. ^ "Pima Air and Space Museum Acquires Iconic Philippine Mars". Vintage Aviation News. 25 Apr 2024. Retrieved 27 April 2024.
  28. ^ "Naval Aviation and Deep Water Discoveries: Pearl Harbor 2004." National Marine Sanctuaries. Retrieved: 28 December 2010.
  29. ^ 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.
  30. ^ "Fleet".
  31. ^ Patterson, Thom (July 2016). "Tour the Cockpit of the Hawaii Mars". YouTube. Archived from the original on 2021-12-22. Retrieved 25 June 2020.
  32. ^ "Hawaii Martin Mars Announcement: Short film of the origin rescue story". YouTube. 29 March 2024. Retrieved 2 April 2024.
  33. ^ "Specifications" (PDF). www.martinmars.com. Coulson Flying Tankers. Archived from the original (PDF) on 4 March 2016. Retrieved 7 August 2014.