Second of the huge trans-oceanic
flying boats used by Pan American Airways System between the wars, the
Martin Model 130 resulted from the same specification to which Sikorsky
had evolved the S-42. Unlike the Sikorsky design, however, the Martin
'China Clipper', as it was to become known, truly possessed the long
over water capability that the airline required.
Pan Am's planned trans-Pacific route to the Philippines was San Francisco
Honolulu-Midway Island-Wake Island-Guam-Manila, the five stage lengths
being, respectively, 2,410, 1,380 1,260 1,450 and 1,550 miles (3,880,
2,220, 2,030, 2,333 and 3,220 km). To accomplish this it required an
aircraft with a non-stop range Of 2,500 miles (4,025 km) carrying 12
passengers, which even by mid-1930S standards was hardly an economic
payload/weight ratio. While the routes were being surveyed in 1935 by
S-42B, Martin was building three M-130's, which in service were named
China Clipper (NC14716), Philippine Clipper and Hawaii Clipper.
Of all-metal construction, the M-130 had
a two-step hull, the upper portions of which were clad in corrugated
duralumin sheet, and sponsons (sometimes called 'sea wings') were fitted
to the hull sides at cabin floor level. These aerofoil-shaped surfaces
fulfilled a dual function: they helped to stabilize the aeroplane while
resting or manoeuvring on the water, and served also as storage areas for
nearly half of the flying boat's 3,800 US gallon (14,383 litre) fuel load.
Retractable platforms were built into the leading-edge of each wing on
either side of each engine nacelle, to provide access for servicing the
engines, two of which were completely changed every three trips.
The flight crew of five comprised
captain, first officer, radio officer, flight engineer and steward. Aft of
the flight deck, in order, were the forward passenger compartment, lounge
and two rear passenger compartments. Each passenger compartment could
accommodate 8 seats or 6 sleeping berths, and the lounge seated 12. Since
the long distance payload was only 12 passengers altogether, one can
appreciate the declaration by one American observer that passengers
'rattled around in the vast expanse of hull in a degree of comfort never
Proving flights were made in late 1935 and early 1936, China Clipper
making the first ever commercial double crossing of the Pacific between
November 22,1935 and December 6,1935. The full, regular trans-Pacific
M-130 service opened on October 21,1936, the flight spanning five days and
occupying a total of 60 hours actual flying. By 1940 (Hawaii Clipper
having been lost at sea) the surviving pair of M-130s had accumulated some
10,000 flying hours each equal to an average daily utilization of 5 1/2
hours and had flown 12,718,200 passenger miles (20,467,930 passenger-km)
in addition to express and mail flights.
In 1942 they were impressed for war
service as US Navy transports, though not given a Naval designation. China
Clipper was wrecked early in 1945, shortly after the tenth anniversary of
its first flight, when it struck an unlit boat during a night landing.
An even larger flying-boat than the M-130 was built by Martin in 1937.
This was the Model 156, whose design followed closely that of its
predecessor except for the provision of twin fins and rudders. Powered by
four 1,000 hp Wright Cyclone engines, it could accommodate 33-53 passengers
(compared with a maximum of 52 in the M-130) and had a gross weight of
63,000 lb (28,576 kg).