OTTER & TWIN OTTER - THE UNIVERSAL AIRPLANES

This Series 300 version of the Twin Otter and its floatplane sister are the final developments of a remarkable run of highly successful aircraft which were originally conceived for the particularly tough requirements of Canadian backwoods operations.

This Series 300 version of the Twin Otter and its floatplane sister are the final developments of a remarkable run of highly successful aircraft which were originally conceived for the particularly tough requirements of Canadian backwoods operations. In time they have been put to work all over the world wherever there has been a need for a relatively large bush aeroplane with exceptional short take off and landing capabilities. The first Series 300 took to the air in 1965 a third of a century ago and most of the 844 built are still at work today.

The Twin Otter was the logical development of the Otter, a single piston engined aircraft with seats for up to fourteen passengers; it first flew in 1951. The Otter was in turn the big brother of the highly successful DHC 2 Beaver, which seated up to seven passengers and is probably still unsurpassed in its role as a small STOL bush aircraft. Indeed, the Otter was originally going to be sold as the 'King Beaver', but acquired its own distinctive name before its first flight.

The design philosophy of the Otter was to supply a one ton truck to the Beaver's half ton. The cabin volume of the Otter was therefore 21Ž2 times that of the Beaver, but the increase in power was no more than one third. The 450 hp Pratt & Whitney R 985 AN 1 Wasp Junior radial fitted to the Beaver gave way to the 600 hp of the Wasp R 1340. De Havilland Canada believed that the proven reliability of the Wasp 18,000 of them fitted to Harvard trainers, for example, made up for its relatively low power when compared with other possibilities.

To improve the engine's efficiency they geared the propeller to swing a large diameter three blader, and strove for lightness and low drag wherever they could. The belly fuel tank so easily refuelled in the field, the high lift wing with double slotted flaps, and the large fuselage cut outs to facilitate cargo handling were all copied from the Beaver. The result was a remarkably efficient machine. Admittedly, once airborne the rate of climb when fully laden could be worrying as the trees at the far end of the clearing loomed up, but nonetheless the Otter was another success, selling 466 aircraft over the years to customers who included the U.S. Army and the United Nations.

This is a beautifully produced book with any excellent period photographs. The whole volume has an air of quality about it, and I note that the support of the Canada Council for the Arts is acknowledged. The book offers a study in depth of the aircraft type in all its variants, including some interesting concepts which never made it to production. There are also some interesting sidelights on the chequered history of de Havilland Canada now Bombardier. I found the text slightly hard to follow at times because chronology has been abandoned in places for spurious literary effect, but for anyone wanting to know almost all there is to know about these rugged and efficient aeroplanes the book will be a joy. Nigel Everett.

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