Martin JRM Mars: Rare aircraft

• the Hawaii Mars was contracted for a specialized training program aimed at Chinese pilots
• The Martin Mars aircraft are equipped with the capacity to carry an impressive 7,200 US gallons of water
• The operational history of the Mars aircraft, however, was not without sorrow.

The Martin JRM Mars is recognized as a remarkable feat of engineering within the realm of aviation history. This substantial, four-engined cargo transport flying boat was meticulously designed and constructed by the Martin Company specifically for the United States Navy during the critical years of World War II. Distinguished as the largest Allied flying boat to enter production, it is noteworthy that only seven units were built.

The United States Navy contracted the development of the XPB2M-1 Mars in 1938, envisioning it as a long-range ocean patrol aircraft; this initiative later culminated in the production of the JRM Mars, which was primarily designated for long-range transportation missions across the vast Pacific theatre. Of the original seven aircraft, four have survived into the present day and have been successfully converted for civilian purposes as firefighting water bombers. Among these, the "Hawaii Mars" operated until 2016 before its retirement, while the "Philippine Mars," now the sole remaining airworthy unit, is making a significant transition to be housed at the Pima Air & Space Museum located in Tucson, Arizona.

The Philippine Mars has not only captured the attention of aviation enthusiasts but has also developed a resolute community of supporters who have meticulously tracked its journey. Recently, a sizable gathering convened near the shores of Vancouver to observe the historic moment of the aircraft being towed from the water. This event marks a transformative period in the aircraft's legacy. Upon arriving at its destination, the Philippine Mars is scheduled for partial disassembly, a process that reflects the careful diligence required for preserving such an iconic structure.

Originally engineered without traditional landing gear—although the design included provisions for attaching wheels for transport—the Mars served diversified functions throughout its operational life, including maritime patrol and aerial firefighting. Its distinctive design features, which include four powerful engines mounted on the wings and a spacious bomb bay, facilitated its varied applications. The Martin JRM Mars stands as a striking subject for both academic inquiry and professional exploration, offering insights into the intersection of military aviation and civilian applications.

The Philippine Mars is poised to take its place in the Pima Air & Space Museum, where it will be preserved as a testament to aviation innovation and history. This transition ensures that future generations will have the opportunity to study and appreciate the significance of this extraordinary flying boat within the broader narrative of aviation development.

Design

The Martin Mars aircraft epitomizes a remarkable achievement in aviation engineering, distinguished by a formidable wingspan of two hundred feet and a length surpassing 117 feet. As one of the largest flying boats ever constructed, it is notable for its extraordinary maximum take-off weight of 165,000 pounds, achieved in its ultimate configuration. This impressive aircraft is powered by four Wright R-3350 Duplex-Cyclone radial engines, each contributing a robust 2,500 horsepower, enabling optimal performance for both transport and firefighting operations.

The design and development of the Martin Mars were initiated by the Glenn L. Martin Company, which scaled up their existing PBM Mariner patrol bomber to create the prototype XPB2M-1 Mars. This prototype was officially announced on 8 November 1941, coinciding with an era of heightened military innovation during World War II. Initial test flights were delayed due to an engine fire that occurred during ground runs, yet the aircraft took to the skies on 23 June 1942, demonstrating its capabilities after comprehensive evaluations conducted between 1942 and 1943.

Upon completion of flight tests, the XPB2M was transferred to the United States Navy, which had begun to recognize the obsolescence of traditional patrol bombers in favour of more versatile aircraft. Consequently, the XPB2M was converted into a transport variant designated XPB2M-1R, thereby enhancing its operational utility.

The Navy was sufficiently impressed with the performance of the modified Mars design and subsequently issued an order for twenty JRM-1 Mars aircraft. The first of these units, christened Hawaii Mars, was delivered in June 1945, marking a significant milestone in the aircraft's operational history. However, the conclusion of World War II led the Navy to reevaluate its needs, resulting in a scaled-back order for only five aircraft that were already in production. Tragically, the original Hawaii Mars was lost in an accident shortly after its inaugural flight over the Chesapeake Bay. Nonetheless, the remaining five aircraft were successfully completed, with the last unit being delivered in 1947, thus concluding the production of this iconic flying boat.

History

The Martin Mars flying boats represent a significant milestone in aviation history, with seven aircraft produced between 1942 and 1947. Originally engineered for the United States Navy as maritime patrol bombers, these innovative aircraft were subsequently adapted for a variety of critical missions. During World War II, they transported essential cargo across vast stretches of the Pacific Ocean, ensuring logistical support for military operations. Following the conclusion of the war, they were repurposed to conduct medical evacuation flights during the Korean War, facilitating the timely transfer of injured personnel between Hawaii and California.

In 1958, the surviving fleet of four Martin Mars aircraft was sold to a consortium of timber companies in British Columbia, Canada. These aircraft underwent significant modifications to become the world's largest water bombers, with the capacity to carry 7,200 U.S. gallons of water per drop. Over their extensive operational lifespan, spanning more than five decades, these aircraft collectively discharged over fifty million gallons of water on various wildfires, thereby achieving a record as the most effective firefighting aircraft in history.

However, by the mid-2010s, the financial burden associated with the maintenance and operation of the aging Martin Mars fleet had become increasingly untenable. Despite being actively marketed for sale, the aircraft remained without buyers as potential operators were deterred by the excessive costs involved. Both the Hawaii Mars and Philippine Mars were retired from active service.

Recently, the Hawaii Mars was successfully relocated to the British Columbia Aviation Museum, where it will be preserved as a historical artifact. Concurrently, the Philippine Mars has journeyed to Arizona, marking its new resting place. This transition signifies the end of an iconic era for these remarkable flying boats, which have made substantial contributions to military planning and firefighting operations over the course of more than half a century, leaving behind a legacy of innovation and service in challenging environments.

Operational

The Martin JRM Mars aircraft were a significant asset to the United States Navy, with the first units entering operational service on January 23, 1944. These aircraft were initially deployed to facilitate the transportation of vital cargo to Hawaii and various strategic Pacific Islands, enhancing logistical capabilities during World War II. Among the various models, the final production variant, designated the Caroline Mars (JRM-2), achieved notoriety for setting a remarkable world record for passenger load on March 4, 1949, highlighting its immense capacity and engineering prowess. 

Tragically, on April 5, 1950, the Marshall Mars experienced a catastrophic engine fire shortly after the crew was evacuated near Hawaii, resulting in the complete loss of the aircraft. The remaining operational aircraft, collectively known as the "Big Four," continued to serve on the San Francisco-Honolulu route until their eventual retirement in 1956, marking the end of their initial military phase.

In 1959, the fate of the last Mars aircraft seemed bleak as they were scheduled for scrapping. However, a Canadian consortium called Forest Industries Flying Tankers (FIFT) recognized their potential and acquired both the aircraft and a significant inventory of spare parts. This strategic acquisition allowed for a transformative conversion of the aircraft into water bombers, incorporating a specialized 27,000-liter plywood tank equipped with retractable pick-up scoops. This innovative modification enabled the aircraft to collect water while taxiing, significantly enhancing their efficiency in firefighting operations. Remarkably, they could load approximately twenty-seven tonnes of water within a rapid time of just 22 seconds.

The operational history of the Mars aircraft, however, was not without sorrow. The Marianas Mars tragically encountered an accident on June 23, 1961, during firefighting operations, resulting in the loss of all four crew members aboard. In a subsequent misfortune, on October 12, 1962, the Caroline Mars was deemed irreparable after sustaining extensive damage from Typhoon Freda while grounded. Despite these setbacks, the Hawaii Mars and Philippine Mars successfully underwent modifications, entering service in 1963 as highly effective water bombers, and became a popular fixture at local airshows, highlighting their impressive aerial firefighting capabilities.

On November 10, 2006, TimberWest Forest Ltd. made headlines by announcing their intention to sell the Mars aircraft. The stipulation attached to this sale required that one aircraft be donated back to Port Alberni, where it would serve as a historical attraction. Following this announcement, both surviving Mars aircraft were sold to Coulson Forest Products in April 2007, where they continued their operational duties until their retirement, planned for 2024. The Hawaii Mars played an active role shortly thereafter in firefighting efforts during the California wildfires of October 2007, while the Philippine Mars underwent significant maintenance that was anticipated to restore it to service by 2010.

The Martin Mars aircraft are equipped with the capacity to carry an impressive 7,200 US gallons of water, allowing them to effectively cover an area of up to four acres per deployment. In addition to water, they have the capability to transport 600 US gallons of foam concentrate, which is crucial for creating gelled water loads to enhance firefighting effectiveness. Their operational focus primarily centred on combating wildfires along the British Columbia coast, with the flexibility to extend their reach into inland regions as required.

On August 23, 2012, the Coulson Group announced the impending retirement of the Philippine Mars after five years of inactivity, with plans underway to transfer the aircraft to the National Naval Aviation Museum in Pensacola, Florida. However, this proposed transfer has faced delays, as the Navy required further evaluations. The Hawaii Mars was subsequently removed from fire contracts after the conclusion of the 2013 season, a decision driven by decreased operational utilization and the advent of newer, more efficient firefighting aircraft.

In May 2015, the Hawaii Mars was contracted for a specialized training program aimed at Chinese pilots, evaluating its operational standards in preparation for a forthcoming aircraft acquisition. The following year, it successfully re-entered service under a contract with the British Columbia Government amid a challenging fire season. Highlighting its historical significance, in 2016, the aircraft was highlighted at EAA AirVenture Oshkosh, generating interest for potential sales or leasing opportunities. As of January 2022, the Hawaii Mars was officially listed for sale at a price exceeding $5 million, with ongoing active discussions regarding its future transfer to the British Columbia Aviation Museum as of June 2023, preserving its legacy in aviation history.

Specifications (JRM-3 Mars)

General characteristics

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

    Capacity: JRM Mars - 133 troops, or eighty-four litter patients and twenty-five 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 take-off 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

Performance

    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 (one hundred 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)