Martin JRM Mars

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 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 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 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 crew members 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 a 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 was repainted to its original U.S. Navy colors and is expected to be delivered to the museum in July 2013 with the Hawaii Mars to remain on contract for regular use.^[9]

On 10 May 2013, the B.C. provincial government announced that the Hawaii Mars would no longer be on contract after the 2013 season, due to having not fought any B.C. fires for two years and increased operation of newer and more versatile aircraft for the Coulson group including a Lockheed C-130 Hercules converted to firefighting use. Although Coulson stated that the Hawaii Mars has been under numerous recent upgrades to make it safer and more reliable, the future of the aircraft after 2013 remains uncertain.^[10]

In Popular Culture

The Sproat Lake water bombers are referenced in Canadian singer Bruce Cockburn's song Wondering Where the Lions Are, with the lyric in the fifth verse, "Huge orange flying boat rises off the lake",^[11] although the Martin Mars are, in fact, red.

In the Movie The A-Team, the A-Team fly out of Germany with a Martin Mars with the red-white Coulson Flying Tankers livery.

Variants

XPB2M-1

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

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.

JRM-1

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.

JRM-2

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.^[12]

JRM-3

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.

Aircraft

JRM-3 Marshall Mars burning near Honolulu, Hawaii

JRM-2 Caroline Mars in the St. Johns River at NAS Jacksonville, Florida in 1949

• The Old Lady - Bureau Number (BuNo) 1520. Ordered on 23 August 1938 and completed as the prototype long-range patrol XPB2M-1, it was first flown on 3 July 1942 and converted in December 1943 to transport variant and designated XPB2M-1R. Assigned initially to VR-8 at NAS Patuxent River, Maryland for crew training, it was later transferred to VR-2 at NAS Alameda, California and scrapped in 1945.
• Hawaii Mars I - JRM-1 BuNo 76819 first flown on 21 July 1945 and delivered to the United States Navy. It sank on 5 August 1945 in the Chesapeake Bay and was disposed as scrap.
• Philippine Mars - JRM-1 BuNo 76820, delivered to the USN on 26 June 1946 and assigned to VR-2 at NAS Alameda, California. Converted and re-designated JRM-3. Withdrawn from service on 22 August 1956 and sold in 1959, it was converted to forest fire fighting aircraft and registered CF-LYK (later C-FLYK). The aircraft continued to fly with Coulson Group at Sproat Lake, British Columbia, Canada until its retirement in 2012. Has been repainted to original U.S. Navy markings and is being prepared to be a museum display at the National Naval Aviation Museum at NAS Pensacola, Florida.
• Marianas Mars - JRM-1 BuNo 76821, delivered to the USN on 26 February 1946 and assigned to VR-2 at NAS Alameda. Converted and re-designated JRM-3, it was withdrawn from service on 22 August 1956 and sold in 1959. Converted to forest fire fighting aircraft and registered CF-LYJ, the aircraft crashed into Mount Moriarty near Nanaimo, Vancouver Island, on 23 June 1961, when the water drop mechanism failed, leaving the aircraft unable to climb quickly enough to clear a mountain. In the ensuing crash, the crew of four were killed.
• Marshall Mars - JRM-1 BuNo 76822, delivered to the USN, converted and re-designated JRM-3. It was destroyed by an engine fire and sank on 5 April 1950 off Diamond Head, Oahu, Hawaii.^[13][14]
• Hawaii Mars II - JRM-1 BuNo 76823, delivered to the USN on 23 April 1946 and assigned to VR-2 at NAS Alameda. Converted and redesignated JRM-3, it was withdrawn from service on 22 August 1956 and sold in 1959. Converted to forest fire fighting aircraft and registered CF-LYL (later C-FLYL), it remains the only aircraft of this type in service and is still flying with Coulson Group at Sproat Lake, British Columbia, Canada.
• Caroline Mars - * JRM-2 BuNo 76824, delivered to the USN on 10 May 1948 and assigned to VR-2 at NAS Alameda. It was sold in 1959 and converted to forest fire fighting aircraft by Forest Industry Flying Tankers. Registered CF-LYM. the aircraft was destroyed during Typhoon Freda at Victoria, Canada on 12 October 1962.^[12]

Specifications (JRM-3 Mars)

Bow of JRM-3 Marshall Mars

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

General characteristics

• Crew: four (with accommodations for a second relief crew)
• Capacity: 133 troops, or 84 litter patients and 25 attendants
• Payload: 32,000 lb (15,000 kg) of cargo, including up to seven jeeps
• Length: 117 ft 3 in (35.74 m)
• Wingspan: 200 ft 0 in (60.96 m)
• Height: 38 ft 5 in (11.71 m)
• Wing area: 3,686 ft² (342.4 m²)
• Empty weight: 75,573 lb (34,279 kg)
• Loaded weight: 90,000 lb (40,820 kg)
• Max. takeoff weight: 165,000 lb (74,800 kg)
• Powerplant: 4 × Wright R-3350-24WA Duplex Cyclone 18-cylinder radial engines, 2,500 hp (1,900 kW) each

Performance

• Maximum speed: 192 knots (221 mph, 356 km/h)
• Cruise speed: 165 knots (190 mph, 305 km/h)
• Range: 4,300 nautical miles (5,000 mi, 8,000 km)
• Service ceiling: 14,600 ft (4,450 m)

See also

Related development

• Martin PBM Mariner

Aircraft of comparable role, configuration and era

• Blohm & Voss BV 222
• Blohm & Voss BV 238
• Kawanishi H8K
• Saunders-Roe Princess
• Short Shetland

Related lists

• List of aircraft of World War II
• List of seaplanes and amphibious aircraft

References

Notes

Bibliography

External links

Wikimedia Commons has media related to Martin Mars.

• "The Mars Makes Good", Popular Science, April 1944 article
• "Life Line Of The Fleet," Popular Mechanics, June 1944, pp. 69,70 photos
• Flying Tankers, Inc.
• Martin Mars Page of the Glenn L. Martin Maryland Aviation Museum
• Museum-Canadian Mars Alliance Created
• Martin Mars Page including a detailed production list of all seven aircraft built
• "Memo To: Overocean Airlines RE: the Martin Mars", a 1945 Flight advertisement for the Mars
• Life photos by George Strock of the prototype Mars rollout 1941; Marauders in background
• Martin Mars photos old and recent on the Nanaimo site

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