Success with the DHC-2 Beaver persuaded de Havilland Canada, in the late 1940s, that there was room in the STOL utility market for a larger version of the Beaver, with cabin space for some 14 passengers or a freight load of up to 2,240 lbs. The company therefore developed the DHC-3 Otter, (which was initially known as the King Beaver). The prototype first flew on December 12, 1951, and the first deliveries of the airplane were made in 1952. The choice of a single engine for an aircraft designed to operate in Canada's harsh climate and sparsely populated hinterland regions may seem lacking in forethought, however, successful operations by the Beaver and other single-engined airplanes had confirmed that the well-proven radials of Pratt & Whitney design were more than adequate for the task; they were universally familiar and, more importantly, were extremely reliable. Like the Beaver, the Otter could operate on wheel, ski, float, or amphibious float landing gears.
There were 223 of these built under the designation U-1A for the U. S. Army. When production ceased in 1968, some 460 airplanes had been built. The DHC-3 Otter was powered by one 600-hp Pratt & Whitney R-1340-S1H1-G Wasp radial piston engine, giving the airplane a maximum speed at sea level of 153 mph, maximum cruising speed of 132 mph, economical cruising speed of 121 mph, service ceiling of 18,000 feet, and a range with 2,100-lb. payload and reserves of 875 miles.
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