Martin 2-O-2 and 4-O-4
The cancellation of military aircraft production contracts at the end of World War II led Martin, like a number of other American airframe manufacturers, to look to the re-emerging market for civilian airliners. The resulting 2-O-2 attracted considerable early interest, with the initial orders for 55 aircraft being placed in November 1945 by Pennsylvania Central Airlines and Colonial Airlines. By the time of the 2-O-2’s first flight, Martin had taken orders for some 200 aircraft but, with contract terms permitting airlines to cancel without financial penalty, many of the early customers melted away in the face of production delays. A fatal crash in August 1948, traced to metal fatigue in the main wing spar, resulted in the type being grounded while Martin re-designed the wing. A retrofit of the 2-O-2s already built was carried out, and a new batch of 12 aircraft featuring the new wing was assembled from surplus parts for Trans World Airlines.
Martin decided in March 1950 to launch a pressurised version of the 2-O-2A under the designation 4-O-4. The company teamed up with Trans World Airlines and Eastern Air Lines to produce bespoke versions for each carrier, these being known in service as the Skyliner and Silver Falcon respectively. The 4-O-4 saw service with these airlines until the early-1960s, when most were sold for operation by smaller, regional carriers. The biggest of these was Southern Airways, which operated a fleet of some 25 4-O-4s until the late-1970s. Another of the final operators was Provincetown-Boston Airlines, which was operating feeder services for Eastern and still had a small number of 4-O-4s in its 113-strong fleet when it was grounded by the Federal Aviation Administration in November 1984.
One 2-O-2 and a small number of 4-O-4s remain in the custody of museums and enthusiast groups.
First flight: 22 Nov 46 (c/n 9122, NX93001)
Production: 47, at Baltimore, MD
First delivery: 13 Nov 47, to Línea Aérea Nacional de Chile (c/n 9125, CC-CLR-0299)
Last delivery: 29 Sep 50, to Trans World Airlines (c/n 14082, N93212)
Variants: 2-O-2 - unpressurised airliner with seating for up to 43 passengers, powered by 2 Pratt & Whitney R-2800 Double Wasp radials (34 built); 2-O-2A - re-engineered version with new wing, uprated engines and additional fuel capacity (12 built); 3-O-3 - pressurised version of 2-O-2 (1 built).
First flight: 21 Oct 50 (c/n 14101, N40401)
Production: 105, at Baltimore, MD
First delivery: 21 Oct 51, to Eastern Air Lines (c/n 14109, N440A)
Last delivery: 19 Feb 53, to Eastern Air Lines (c;n 14247, N499A)
Variants: 4-O-4 - pressurised airliner with seating for up to 40 passengers, powered by Pratt & Whitney R-2800-CB16 Double Wasp radials (103 built); RM-1G - designation applied to standard production 4-O-4 delivered to US Coast Guard as a staff transport (2 built, re-designated RM-1Z then in 1962 VC-3A).