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23rd of June, 1942

The Martin JRM Mars made its first flight on this day in 1942.

In 1938 the US Navy contracted the Glen L Martin Company to develop the XPB2M-1 Mars as long-range patrol aircraft, this would become the Martin JRM Mars. Only 7 aircraft were ever produced (20 were originally ordered by the US Navy) and 4 were modified as fire fighting aircraft later in their life. At this time only 2 airframes remain, although not in airworthy condition, in British Columbia (Canada). The Martin JRM Mars entered service with the US Navy on the 23rd of January 1944. A total of 5 aircraft were taken into service with the US Navy. The last aircraft designated as a JRM-2 as it was powered by the P&W R-4360 Radial engines (3000 hp), had a higher MTOW and some other improvements. It was this aircraft, named Caroline Mars, that set a world record on the 4th of March 1949 by carrying 260 passengers between San Diego and Alameda in California (USA).

.One aircraft was lost due to a fire, Marshall Mars after the crew safely evacuated the aircraft in 1950. The remaining aircraft remained in service flying cargo between mainland USA and Hawaii until they were withdrawn from military service in 1959. Intentionally the aircraft were to be sold for scrap but were bought by a Canadian Aerial Fire Fighting company. Late in 1959, all the aircraft were ferried to Canada for conversion into waterbombers. A 7200 US Gal (27.000 litres) plywood tank was installed, with retractable scoops which could fill the tank in approximately 22 seconds. Later in their fire fighting career, the water capacity was increased and also a 600 Gallon foam tank was added. One aircraft, the Hawaii Mars was modified with an EFIS Cockpit and modern avionics allowing flight-tracking, performance analysis. The 7 airframes build, had 5 different "specifications


  • 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.

  • 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, Single-tail design, and having a longer hull with fewer bulkheads and a larger maximum take-off weight. It 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.

  • 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.

Some specifications of the latest version, the JRM-3as a fire fighting aircraft

  • Crew: four (with accommodations for a second relief crew)

  • Capacity: JRM Mars - 133 troops, or 84 litter patients and 25 attendants or 32,000 lb (15,000 kg) payload, including up to seven Willys MB jeeps

  • Water/foam load: Mars waterbomber - 60,000 lb (27,000 kg)

  • Length: 117 ft 3 in (35.74 m)

  • Wingspan: 200 ft 0 in (60.96 m)

  • Width: 13 ft 6 in (4.11 m) Hull beam

  • Height: 38 ft 5 in (11.71 m) afloat, 48 ft (15 m) beached

  • Hull draught: 5 ft 6 in (1.68 m)

  • Wing area: 3,686 sq ft (342.4 m2)

  • Empty weight: 75,573 lb (34,279 kg)

  • Gross weight: 90,000 lb (40,823 kg)

  • Max takeoff weight: 165,000 lb (74,843 kg)

  • Fuel capacity: Hawaii Mars: 6,485 US gal (24,550 l; 5,400 imp gal) Philippine Mars: 13,200 US gal (50,000 l; 11,000 imp gal)

  • Powerplant: 4 × Wright R-3350 Duplex-Cyclone 18-cylinder radial engines, 2,500 hp (1,900 kW) each

  • Propellers: 4-bladed Curtiss Electric, 15 ft 2 in (4.62 m) diameter variable-pitch propellers

  • Maximum speed: 221 mph (356 km/h, 192 kn)

  • Cruise speed: 190 mph (310 km/h, 170 kn)

  • Range: 4,900 mi (8,000 km, 4,300 nmi)

  • Service ceiling: 14,600 ft (4,500 m)

  • Drop speed: 138 mph (120 kn; 222 km/h)

  • Landing approach speed: 115 mph (100 kn; 185 km/h)

  • Touchdown speed: 92 mph (80 kn; 148 km/h)

  • Fuel consumption (cruise): 420 US gal (1,600 l; 350 imp gal) per hour

  • Fuel consumption (operations): 780 US gal (3,000 l; 650 imp gal) per hour

  • Operations duration (normal): 5 1/2 hours

  • Area covered, single drop: 3 to 4 acres (1.2 to 1.6 ha)

  • Drop height: 150 to 200 ft (46 to 61 m)

  • Full water tank load: 7,200 US gal (27,000 l; 6,000 imp gal)




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