The magnificent Martin JRM Mars
By Aad van der Voet1 March 2019
The Martin Mars has fought its last fire. The largest flying boat ever flown, if we don't count the 30-second hop by Howard Hughes' "Spruce Goose", the type gave valuable service as a military transport aircraft. Then, literally rescued from the scrapyard, it embarked upon a remarkable second career as an outsize airtanker. But after half a century this has now come to the inevitable end.
On 23 August 1938, the United States Navy placed an order with the Glenn L. Martin Aircraft Company for one XPB2M‑1 patrol bomber. This prototype, BuNo1520, was launched into Dark Head Creek at Martin's factory in Middle River, near Baltimore, Maryland, on 5 November 1941. The huge plane had a wingspan of 61 metres (200 ft) – larger than that of the Boeing 747-300 – and four 18-cylinder, 2,200‑hp Wright R‑3350 Duplex-Cyclone engines driving three-blade propellers. The most striking difference between this prototype and the later production versions of the Mars is that it had twin vertical tails.
One month later, during taxi trials on 5 December 1941, the propeller of the #3 engine threw a blade, which severely damaged the fuselage and caused a fire in engine #3. The fire destroyed the engine, the engine mount and part of the starboard wing. Two days later, America was at war. The repairs, as well as further tests and improvements, caused considerable delay in the programme, however, and the prototype did not make its first flight until 3 July 1942.
Testing was concluded in November 1942, but by that time the war situation in the Atlantic and the Pacific had changed considerably. There was no more need for a slow patrol bomber flying boat, and the US Navy decided to have the Mars prototype converted to a transport aircraft. This meant the removal of its gun turrets, fuselage and wing bomb bays, armored plating, and other combat provisions. Instead, the aircraft received additional cargo hatches and cargo loading equipment, existing hatches were enlarged and the decking was reinforced. It was now redesignated as the XPB2M‑1R, the R signifying the transport role.
The giant transport aircraft was officially delivered to the US Navy on 27 November 1943. It first flew with a newly formed unit, VR‑8 at Patuxent River, Maryland for crew training, and was later transferred to VR‑2 at NAS Alameda, near San Francisco in California. It was mainly used on the routes from California to Hawaii, establishing an impressive service record.
Satisfied with its performance as a transport aircraft, the Navy ordered twenty production machines. The production version, designated the JRM‑1, differed from the prototype in having a single vertical tail, a longer hull with fewer bulkheads, and a larger maximum take-off weight. It also got equipment for overhead cargo handling, and Wright R‑3350‑24WA Cyclones driving four-blade props.
By the time the first JRM‑1 Mars, BuNo 76819 Hawaii Mars, was delivered on 27 July 1945, World War II was almost over, and the Navy cut its order from 20 to only six aircraft. The last of these was delivered as a JRM‑2, equipped with more powerful Pratt & Whitney R‑4360 Wasp Major engines, which allowed it to carry even more weight on the flights between California and Hawaii. The Navy was very pleased with its performance, and decided to have the four remaining JRM‑1s (one had been destroyed in a landing accident) re-engined with Wasp Majors. These four aircraft were then redesignated to JRM‑3. The twin-finned prototype, named Old Lady, had meanwhile been withdrawn from service.
The US Navy lost a second Mars in 1950, but continued to operate its remaining JRM‑2 and three JRM‑3s until 1956. Their last Mars flight took place on 22 August 1956, and all four aircraft were then beached at NAS Alameda.
During the mid and late 1950s, a number of large forest fires plagued western Canada and destroyed thousands of acres of forest. In an effort to combat such fires, even in remote areas, several of Canada's major lumber corporations, among them MacMillan Bloedel Ltd., TimberWest Forest Corp. and Pacific Forest Product Ltd., decided to join forces and formed Forest Industries Flying Tankers (FIFT).
Regular airtankers obviously need a runway of some sort to reload after each drop runs. British Columbia province didn't have too many airfields. It does have lots of lakes and a long coastline with many bays and inlets. This makes it ideal territory for a large flying boat airtanker. Equipped to scoop up water, all it needs is a strip of open water of a few kilometers long. Therefore Dan McIvor, a Canadian airtanker pioneer and senior pilot with MacMillan Bloedel, suggested the use of large flying boats turned into water bombers. The purpose-designed Canadair CL‑215 amphibian was not yet around at this time, and anyway, was not the big whopper McIvor had in mind.
In 1959, the US Navy put the four Martin Mars flying boats up for auction. McIvor was informed too late and found the auction had already closed. The winning bid was from Hugo Forrester, trading as the Mars Metals Company, who bought all four aircraft for scrapping, for a total sum of only $23,650. McIvor contacted Forrester, whom he found willing to sell the four aircraft for $25,000 each. With some effort, McIvor was able to convince his superiors of the airtanker potential of these large flying boats, and the deal was made. FIFT now owned four Martin Mars. Established as the new home for the aircraft was the Port Alberni/Sproat Lake Tanker Base on Vancouver Island, off the Canadian west coast.
McIvor had the foresight to immediately start a hunt for spare parts. He bought six spare engines for $135 each, later followed by 29 R‑3350 Cyclones from a scrap dealer for $600 each. He also discovered the US Navy still had many crates of factory-new spare parts, which he was able to buy for only $3,200. These purchases enabled FIFT and its successor companies, Flying Tankers Inc., TimberWest and Coulson, to operate the Mars flying boats well into the 21st century.
Included in McIvor's shopping was even a complete nose section. It belonged to the unfinished seventh JRM (the eighth Mars, including the prototype), construction of which was already under way at Middle River when the war ended and the US Navy cut its order from 20 to only six aircraft. Not knowing what to expect in the future, Dan McIvor also acquired this nose section. But it was never put to use and lingered in the brushwood close to the Sproat Lake base for some 45 years.
McIvor remained the driving force behind the entire operation of getting the aircraft into service with FIFT and developing the correct and most efficient operating procedures. They were converted to airtankers during the early 1960s by Fairey Aviation of Canada at Victoria International Airport (Patricia Bay), Sidney, British Columbia. This involved the removal of all unnecessary military and cargo-loading gear, the re-installation of refurbished Cyclone engines, and the installation of large water tanks and a sophisticated retractable scooping system.
In the early years of the operation, two of the four aircraft were lost, one in a crash in 1961 which took the lives of all four crew members, and another which was damaged beyond repair during a storm in 1962. Although these were very serious setbacks, they did not deter the people of FIFT. They pressed on with the other two aircraft, the last of which was converted in 1964. No other serious accident has occurred since that time.
There were a few noteworthy differences between these last two aircraft. Philippine Mars' water tanks had been installed inside the main fuselage, where the cargo used to be stowed. Hawaii Mars (it was, in fact, Hawaii Mars II – see production list) had them installed in the bottom of the fuselage, where the fuel tanks used to be. This also mandated a difference in the dropping mechanisms: Philippine Mars dropped its load from two outlets on either side of the fuselage, whilst Hawaii Mars dropped like most airtankers, from the belly.
The removal of fuel tanks from Hawaii Mars meant that it was able to take on far less fuel than Philippine Mars: only take 24,550 litres (6,485 gallons), compared to 49,962 litres (13,200 gallons) of fuel for Philippine Mars. This made little difference in firefighting operations, however. Both aircraft could carry the same amount of water: 27,276 litres (7,200 gallons). This water could optionally be mixed with foam concentrate from a tank with a capacity of 2,270 litres (600 gallons), which increased the effectiveness of a water drop by about 30 percent.
The aircraft were always flown by a crew of four: a captain, a first officer, and two flight engineers who were closely involved in the loading and dropping operations. To refill the water tanks, a normal landing procedure was executed. Once on the water, the captain allowed the speed to drop to about 130 km/h (70 knots), while keeping the aircraft 'on the step' (the ledge on the lower fuselage, used to break the water suction). One of the flight engineers then took control of the engine power, and the two scoops were lowered into the water. These scoops were essentially two forward-facing pipes with a diameter of 18 cm (7 inches).
The aircraft would then take on water at a rate of more than 1,000 litres (264 gallons) per second, and it took only about 25 seconds to completely fill the tanks. During this time, the increasing weight of the aircraft requires the flight engineer to slowly increase engine power to maintain the speed at around 120 km/h (65 knots). With the tanks filled up, the scoops were raised and the captain performed a normal loaded take-off.
Obviously the Mars could reload much faster than a land-based plane. On a good day, when operating with a suitable lake or bay nearby, it could on average drop a full load on the fire every 15 minutes, and it could make 20 consecutive 7,200 gallon runs before the foam concentrate tanks were empty. No other tanker could even come close.
Times of change
In 2001, FIFT was renamed Flying Tankers Inc. The company was by then a wholly-owned subsidiary of TimberWest Forest Corp., the other participating firms having dropped out of FIFT years earlier. Not much initially changed but on 10 November 2006, TimberWest offered both aircraft for sale, and the flying career of the giant water bombers seemed to be coming to an end.
A serious candidate to buy one Mars was the Glenn L. Martin Maryland Aviation Museum, located right at the birthplace of the flying boats, at Middle River in Maryland. A fund-raising campaign was started, and the museum reached an agreement with the British Columbia Aviation Council (BCAC) to work together to acquire both Mars from TimberWest. BCAC had plans for a new Daniel McIvor Martin Mars Museum to be established at the Port Alberni, and this new museum would receive one of the two aircraft, with the other Mars going to the Glenn L. Martin Maryland Aviation Museum.
Surprisingly, however, on 13 April 2007 it was announced that TimberWest had reached an agreement to sell both Martin Mars flying boats to another Vancouver Island-based lumber corporation, the Coulson Group of Companies. The group's aerial division, Coulson Aircrane Ltd. is a helicopter operator, specializing in aerial firefighting and heli-logging, and is based at Port Alberni Airport, only 3 km away from the home base of the Mars. The sale included engines and other spare parts, specialized equipment and the Sproat Lake base itself. Part of the purchase agreement was that upon eventual retirement of the aircraft, one Martin Mars should be made available to the Port Alberni community for preservation.
It seemed at this time that retirement was still a long way off, with the new Coulson Flying Tankers division proudly applying its titles to the aircraft, and optimistically initiating upgrades to the Mars' avionics and communications systems. But in fact the British Columbia provincial government, which used to contract the aircraft each summer season, was increasingly reluctant to do so. Despite widespread popular support for the Mars, the province argued they were much more expensive than more modern airtankers, less suitable for operations in mountainous terrain or in the vicinity of other firefighting assets, dwindling in reliability, and allegedly able to use only 113 large enough bodies of water in the province for scooping up water, meaning they were not often called upon.
In fact, Philippine Mars had fought its last fire in the summer of 2006, and in August 2012, Coulson announced that the idle aircraft would be retired and flown to the US Naval Aviation Museum at NAS Pensacola, Florida. It was duly repainted in its original US Navy midnight blue and markings, but the flight to Florida was delayed several times, with Canadian officialdom apparently wanting to declare the plane 'cultural property' of Canada, and the Pensacola museum reportedly awaiting fresh political backing pending the 2016 US presidential election. Meanwhile the relatively small Glenn L. Martin Maryland Aviation Museum started another fundraising campaign to bring the same aircraft home.
In May 2013, the British Columbia government announced that Hawaii Mars, too, would no longer be contracted after that season, not having been used to fight any fires in the province for two years. In July 2015, during a particularly bad fire season, it was back in service after public outcry, the BC government awarding a 30-day contract which cost $15,000 a day plus some $11,000 per flying hour, according to the wildlife service.
Hawaii Mars bowed out for the aviation enthousiasts community with flight displays at EAA AirVenture Oshkosh in July 2016, 'in hopes of finding another business or home for it,' as Coulson president Wayne Coulson commented. The aircraft was quickly patched up after striking some shallow rocks in Lake Winnebago, but it has not taken to the air again since recovering to Sprout Lake.
As of early 2019, both Mars were still sitting at Port Alberni. There's no doubt about the Coulson family's best intentions. When they took over the airtanker operation in 2007, they quickly took care of the neglected Martin Mars nose section which Dan McIvor had bought. It was still out in the brushwood near the Sproat Lake base, with weeds and small trees growing all around it. The Coulsons recovered and restored it, painted it in the same red and white colours as the two remaning Mars, and placed it on display at a newly established visitors centre at the Sproat Lake base. Disappointly low public attendance has forced the closure of this visitors centre, however, making Wayne Coulson sceptical about the viability of the proposed Daniel McIvor Martin Mars Museum which would preserve Hawaii Mars at Port Alberni.
Specifications Martin JRM-3 Mars (firefighting)
- Capacity: crew of four
- Length: 35.74 m (117 ft 3 in
- Height: 11.71 m (38 ft 5 in) afloat; 15 m (48 ft) ashore
- Span: 60.96 m (200 ft 0 in)
- Wing aera: 342.4 m² (3,686 ft²)
- Powerplant: four Wright R‑3350 Duplex-Cyclone, 2,500 hp (1,900 kW) each
- Empty weight: 34,279 kg (75,573 lb)
- Normal take-off weight: 40,823 kg (90,000 lb)
- Maximum take-off weight: 74,843 kg (165,000 lb)
- Payload: 27,276 litres (7,200 US gal) of water, plus 2,270 litres (600 US gal) of foam concentrate
- Maximum speed: 356 km/h (221 mph)
- Cruise speed: 306 km/h (190 mph)
- Drop speed: 222 km/h (138 mph)
- Range: 7,964 km (4,948 miles)
Full production list
Please click here for a full production list of the Martin JRM Mars.