Mach 2 1/ 72 Martin
PBM 3/5 Mariner
The origins of the Glenn L. Martin Aircraft Company go right to the beginnings of powered flight. Glenn L. Martin taught himself to fly in 1909. By 1912 the Glenn L. Martin Aircraft Co. was in business and producing aircraft he sold via his demonstrations and exhibitions. From the beginning Martin tended toward big military aircraft and for the next 40 years Martin meant bombers and flying boats.
The first of the big Martin flying boats actually was designed by Curtiss, then improved by the Naval Aircraft Factory and contracted out to Douglas, Martin, Keystone and Hall Aluminum for production. Martin built 30 of these PM-1s.
Next came another competitor’s design. This time Consolidated had won the competition for another large flying boat design, the XPY-2. As was the practice of the day, the Navy placed a development contract, and then they owned the rights to the design. They would request bids on the production contract and award it to the lowest bidder. Martin underbid Consolidated and got the production contract to build the design as the PM-2. Consolidated was not happy with this bidding process, and this apparent problem caused an ongoing poor relationship between the two companies that would later surface again.
The next big step in the evolution of the Martin Flying boats was the Model 130 China Clipper. As with most of the “Clippers”, Pan American was the instigator of the Martin Clippers. Pan American had placed orders for three each of the Sikorsky and Martin boats to be used on the future North and South Atlantic routes. The British chose to block access to bases in Newfoundland and Bermuda until their own boats became available. With the Atlantic routes closed, Pan Am used the three Martins to pioneer the Pacific routes later made famous by the forthcoming Boeing Clippers.
By 1937, Consolidated was firmly entrenched in the Navy Patrol Bomber business with the early versions of the PBY. The Catalina was slow, under-powered and under-gunned. The Navy was starting to see that perhaps it might not be able to bomb heavily defended targets. Both Sikorsky and Consolidated had new four engine designs in the works. But this was 1937. The nation was still in the depression, and the Navy did not have money for very expensive four engine aircraft.
Martin offered a somewhat radical concept in an attempt to land the new contract. They offered a very large, streamlined flying boat powered by just two of the new Wright R-2600 engine. Everything looked like a winner for the new Martin model 162 when the president of Consolidated, still unhappy with the loss of previous flying boat contracts to Martin, stormed into Washington DC. He disputed Martin’s projected performance figures and threatened “political action” if Consolidated lost the contract. He did manage to defer the production contract until the new XPBM-1 could be built and proven.
Martin, perhaps sensing the Consolidated Company rapidly running up their backside, was not willing to wait the year required to build and test the somewhat radical XPBM-1, hit upon a brilliant solution. They built a three-eighths sized flying model of the new design. This Martin model 162A was powered by a single Martin modified Chevrolet engine. The engine powered both props via belts. This test bird was ready in November 1937 and quickly proved that Martin had the numbers right. In December the Navy awarded a split contract. Consolidated got 4.5 million for 33 PBY-4s, and Martin got 5.3 million to turn out 21 new PBM-1s.
The Mariner was a far superior airplane to the Catalina. It had internal bomb bays in the engine nacelles, was 17 miles per hour faster and had 1/3 more range. Another intangible was the creature comforts the much bigger PBM provided. It had a full galley, a bunkroom, and two decks with real stand up and walk around space. The PBY, on the other hand, was a crawl around, over and through airplane. How much this might have influenced the Navy procurement people is unknown, but the crews on long patrols for sure much appreciated it.
It wasn’t long before the Mariner started performing a wide variety of missions, including Anti Submarine patrols in both the Atlantic and Pacific. Later, in 1943 they became Patrol bombers in the Pacific, protecting the fleet and fleet bases and anchorage from attack. As the Navy war in the Pacific and Atlantic shifted from defense to offence, the missions shifted to anti-shipping and night bombing missions. They operated alongside the now famous “Black Cat” Catalina missions. In the Mariner’s case, they were labeled “Nightmares”. By the war’s end they were actually dropping bombs on the Japanese main islands.
As one might expect from a seaplane in the Pacific, they also hauled cargo and personnel. They were also used in air-sea rescue. By the end of the war, four VH (hospital) squadrons had been formed and were active.
From the very beginning of the design the Wright 2600 engines provided problems and with the inevitable weight gains the power was inadequate. In 1941 the Navy ordered the PBM-4. It was to be powered by the then new Wright 3350. The difficulty of using this engine quickly became apparent. The Air Force had it all wrapped up for the much higher priority B-29 program. Martin quickly substituted the smaller Pratt & Whitney R-2800. It was a vast improvement over the 2600, and the design came off the assembly line as the PBM-5.
After the war, the Navies of the Netherlands, Argentina, and Uruguay operated the PBM-5 and a few found their way into South America as airliners. At least one Mariner hauled lobsters in New England.
Mariners continued to serve the U. S. Navy post war. They provided transport support for the Bikini atomic tests, mapped Antarctica with Admiral Byrd, and monitored various missile tests.
The 1368th and last Mariner rolled (yep, rolled, by this time Martin had build 36 PBM-5A amphibians) out of the Martin plant on March 9, 1949. But the fat old lady still had another war to fight. In 1950-51 Mariners again flew long over-water patrols off the coasts of Korea. Two Navy reserve squadrons were called up, and two new squadrons were formed to perform the mission once again.
By the mid 1950’s it was a very tired old lady that gave way to the next generation flying boat. It had a very strong family resemblance, but was really a whole new design. That was the Martin P5M Marlin.
The PBM never attracted the public’s eye like the Catalina, and eventually only about half as many were built, but in most respects the Mariner represented a far superior airplane. But the few years between the PBY design and the Mariner were pivotal years in aircraft design and engine development.