de Havilland Canada DHC-3 Otter
Another in de Havilland Canada's successful line of rugged and useful STOL utility transports, the Otter was conceived to be capable of performing the same roles as the earlier and highly successful Beaver, but was bigger, the veritable "one-ton truck".
Using the same overall configuration of the earlier and highly successful DHC2 Beaver, the Otter is much larger overall. The Otter began life as the King Beaver, but compared to the Beaver is longer, has greater span wings, and is much heavier. Seating in the main cabin is for 10 or 11, whereas the Beaver could seat six. Power is supplied by a 450-kW (600-hp) Pratt & Whitney R1340 Wasp radial. Like the Beaver, the Otter can be fitted with skis and floats. The amphibious floatplane Otter features a unique four-unit retractable undercarriage, with the wheels retracting into the floats.
Design work at de Havilland Canada began on the DHC3 Otter in January 1951, the company's design efforts culminating in the type's first flight on 12 December 1951. Canadian certification was awarded in November 1952.
After de Havilland Canada demonstrated the Otter to the US Army, subsequently that service went on to become the largest DHC3 operator (as the U1). Other military users included Australia, Canada, and India.
Small numbers of Otters were converted to turbine power by Cox Air Services of Alberta, Canada. Changes included a Pratt & Whitney Canada PT6A turboprop, a lower empty weight of 1692 kg (3705 lb) and a higher maximum speed of 267 km/h (144 kt). It was called the Cox Turbo Single Otter. A number of other aftermarket PT6 conversions have also been offered.
The Otter found a significant niche as a bush aircraft and today it remains highly sought after.