Martin 4-0-4 / RM-1

The prototype of an improved Martin 3-0-3 had been flown on 20 June 1947, but with it was decided instead to develop a new Martin 4-0-4. This incorporated the wing structural revisions and introduced a pressurised and slightly lengthened fuselage, accommodating as standard a crew of three or four and 40 passengers.

The airliner was unveiled in 1949 and immediately ordered by a variety of air carriers, gaining 101 orders from TWA and Eastern. The subsequent 4-0-4 was introduced in 1950 with a fuselage 39 inches longer, slightly more powerful engines than the 202, and pressurization.

The onset of the Korean War suddenly made airplane materials significantly more expensive, and Martin found itself filling orders at a loss and stopped production. 

Two or these 40-passenger transports were in service with the U.S. Coast Guard in 1955 as the RM-1, similar to the civil Martin 4-0-4 airliner.

Martin RM-1

A total of 148 of the 2-0-2, 3-0-3, and 4-0-4 types were built until 1952. Examples served well into the 1980s with commuter airlines.

RM-1
Engines: two 2,400 h.p. Pratt & Whitney R2800-34W
Span: 93 ft. 3 in.
Weight: 44,900 lb.
Max. Speed: 312 m.p.h.

4-0-4
Engines: 2 x 2400hp Pratt Whitney R-2800 CB-16
Max take-off weight: 20366 kg / 44900 lb
Empty weight: 13211 kg / 29125 lb
Wingspan: 28.42 m / 93 ft 3 in
Length: 22.73 m / 74 ft 7 in
Height: 8.66 m / 28 ft 5 in
Wing area: 80.27 sq.m / 864.02 sq ft
Cruise speed: 502 km/h / 312 mph
Ceiling: 8840 m / 29000 ft
Range: 3058 km / 1900 miles
Seats: 52

Martin 4-0-4