FIRST flight of the de Havilland Canada DHC-5 Buffalo took place from Downsview Airport, Toronto, on May 9. It lasted more than an hour, and Bob Fowler, chief test pilot of The de Havilland Aircraft of Canada Ltd, later described the handling qualities and flight characteristics of the new aircraft as "excellent." The accompanying illustrations show the family resemblance the Buffalo bears to its predecessor, the DHC-4 Caribou. In fact, the DHC-5 was originally known as the Caribou 2, but it is much more than just a Caribou with new engines.

        Powerplant of the Caribou is the Pratt & Whitney R-2000 Twin Wasp-the special size of 14-cylinder Wasp developed for the DC-4. Rated at 1,450 h.p., this engine was adequate for the performance demanded of the Caribou, and its acceptability to customers is shown by the fact that over 200 of these STOL machines have been sold outside Canada. The Caribou continues in production, and may be the last piston-engined aeroplane of its size still being built.

        But for many years the design engineers at Downsview have been well aware of the magnitude of the benefits to be reaped from a switch to turbine propulsion. The company decided to wait until a suitable American powerplant became available, and the General Electric T64 --subject of a recent licence-agreement with Bristol Siddeley Engines, as reported in our April 30 issue -- fits the bill admirably. Rated at an initial 2,850 e.h.p., and already yielding well over 3,000,e.h.p. and capable of development to more than 4,000, the T64-10 turboprop version weighs appreciably less than the Caribou engine but is more than twice as powerful.

        Flight development of the T64 actually began using a converted Caribou as the test bed, and this aircraft logged 222 engine flight hours in its first programme starting in September 1961. In the test bed the powerplants were YT64-4 models, with the propeller gearbox below the engine axis, and the air intake above the spinner. Optimizing the size of propeller, thrust-line and length of landing gear led to the choice of the T64-10 as the engine for the DHC-5, with the propeller mounted high and the intake located below the spinner.

        The rest of the DHC-5 is a logical improvement on the DHC-4. The wing is basically the same size, but incorporates refinements to increase CL max (the slightly kinked leading edge may be noted) and is stressed to operate at much increased weights. It also provides room for a larger quantity of fuel: 13,550 lb. of kerosine, compared with 5,030 lb. of petrol. The body is slightly wider, and the lighter engines have enabled the wing to be moved aft and some 5 ft. added to the fuselage behind the wing. This increases the usable internal volume from approximately 1,000 cu. ft. in the Caribou to 1,580 cu. ft. in the Buffalo, and the maximum seating (44 civil passengers) is in the Herald/F-27/748 class. The tail is completely new, and stems from the extensive full-scale rig and free-flight testing on STOL configurations carried out at Downsview since 1958 (see this journal for July 15, 1960, and January 17, 1963).