DHC2 Beaver

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DHC2 Beaver

During the Second World War, de Havilland Canada had seen a need for a versatile and robust "bush plane" capable of tackling the millions of square miles of rugged Canadian northern wilderness and the isolated populations that lived there. Long and savage winters in the area led to some of the worst flying conditions in the world and a shortage of up to date airfields didn't help matters. However, with the demands of wartime production taking priority followed by the need for the DHC-1 Chipmunk trainer meant that the idea had to be put on hold. Once construction work on the Chipmunk was underway, attention turned again to the bush plane. Working in conjunction with the Ontario Department of Lands and Forests (who were looking to replace the aircraft they were using), a poll was taken amongst potential operators and pilots asking for their thoughts on the ideal aircraft. As a result, design work on the second local offering from de Havilland Canada began late in 1946. Given (logically) the designation DHC-2, the new aircraft continued de Havilland Canada's idea of being named after local wildlife and was soon given the name Beaver. On August 16, 1947, the company's chief test pilot (and Canada's top scoring night fighter ace) Russ Bannock made the first flight in the prototype (CF-FHB-X) with Canadian type certification following in March 1948.

Strength was a priority when designing the aircraft, as the conditions and manner in which it was to be used were none too gentle, many a tired and broken aircraft of earlier vintage and lesser character could attest to this. Essentially a flying "half ton truck", the Beaver was of all metal, stressed-skin construction. The front section of the fuselage, extending back to the cockpit, was a tubular steel structure carrying the four engine pickup points while the centre (cabin) section was strengthened to carry the high mounted, braced wings and wide landing gear. The load-bearing cabin floor was strengthened further by three cross beams and seating was provided for the pilot and three passengers with a rear hammock seat providing room for an additional three passengers. With the exception of the pilot's seat, all the seating was easily removed to carry up to half a ton of freight, removable doors and a rectangular fuselage cross section also helped in this respect. As previously mentioned, a large number of the more remote settlements that the aircraft would have to operate into and out of had no conventional airfields available and even when airstrips were available, many were rudimentary and spent a good amount of the year covered in snow. However, many of these settlements were built next to lakes and rivers so in addition to wheels, floats (including amphibious versions) or skis could be fitted as standard to the undercarriage. Another challenge faced by the designers was that the Beaver had to be able to land and take off fully loaded in areas not much bigger than the proverbial postage stamp. To achieve this, the wings featured wide-span slotted flaps and drooping ailerons which, when combined with a high aspect ratio (wide wing span and narrow chord, the latter being the distance between the leading and trailing edges), resulted in exceptional short take off and landing (STOL) capabilities. The extra horsepower provided by the use of a 450 hp Pratt and Whitney R-985-AN-1 Wasp Junior engine, instead of the more modest 295-330 hp de Havilland Gipsy Queen 50 originally planned, also helped to improve the Beaver's STOL performance.

The first four production models, the DHC-2 Beaver Mk.1, were delivered to the Ontario Department of Lands and Forests in April 1948 with a further 40 being delivered in subsequent years. Despite being designed with the civilian market in mind, over half of the 1,657 Beaver Mk.1s built were to end up in United States military service. In 1951, the US Air Force and US Army jointly sponsored a design competition for a new utility and liaison aircraft. This led to six Beavers being purchased by the two services for evaluation purposes and receiving the designation YL-20. The type was successful and, following special legislation from Congress to bypass the "buy American" policy, large scale acquisition commenced with 968 Beavers eventually being delivered as the L-20A (until 1962 when they became the U-6A). A further six aircraft featuring equipment and detail changes were delivered as the L-6B. This was the first peacetime purchase of a non-American built aircraft with the majority going to the US Army although over 200 ended up in the USAF. They saw service in both the Korean and Vietnam wars where, as well as their primary role of the aerial evacuation of wounded troops, they were used for tasks as varied as rescue, aerial photography, cargo and personnel transport and courier services.

The US military were not the only ones to recognise the virtues of the Beaver; approximately 15 other countries also ordered the aircraft for military use including the Royal New Zealand Air Force who purchased one in July 1956 for the Commonwealth Trans-Antarctic Expedition. Originally given the serial number NZ6001, it was changed to NZ6010 in 1959 when it was discovered that the RNZAF's sole Gloster Meteor had already been allocated NZ6001. In December 1956, the aircraft went to Antarctica and operated without any problems throughout the Antarctic winter before returning to New Zealand in early 1958 and being put into storage. It went back to Antarctica for the 1959 - 1960 summer season but crashed on Beardmore Glacier during whiteout conditions and was written off. In August 1960, a DHC-3 Otter (NZ6081) was purchased to replace the Beaver but never ended up going to Antarctica.

As well as the Beaver Mk.1, a single Beaver Mk.2 with a 520 hp Alvis Leonides 502/4 radial engine, increased wingspan and revised tail surfaces and 34 Beaver Mk.3s powered by a 580 shp Pratt and Whitney (Canada) PT6A turboprop engine were built before production ended in February 1967. Including those used by the military, the aircraft saw use in over 60 countries including New Zealand where (at the time of writing) there are still three on the civil register and another one undergoing restoration. Even today, well over half a century after the type first entered production, approximately two thirds of the total Beavers constructed are still in use around the world. Given its longevity, strength, versatility and popularity, it comes as no surprise that in 1987 the Beaver was named one of Canada's ten most important engineering achievements of the 20th century.

New Zealand Warbirds Beaver, ZK-CKH (c/n 25), was the first Beaver to be exported from Canada going first to South Africa and then, in 1951, to England. It was then flown in Libya and several other North African countries where it was allegedly involved in gun running activities before being imported into New Zealand in 1965 for agricultural work. Following a downturn in the New Zealand top dressing market in the mid 1980s, the aircraft was purchased by an Ardmore based warbirds syndicated and restored as NZ6001.

Text © 2002 Stuart Russell.

 

Specs. 

Power Plant: One 335.3kW (450hp) Pratt & Whitney R-985 Wasp Junior 

Wingspan: 14.64m (48ft) 

Length: 9.24m (30ft 4in) 

Max T-O weight: 2,313kg (5,100lb) 

Max Level speed: 225km/h (140mph) 

Range: 1,252km (778miles)

 

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