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A Look Back: THE DE HAVILLAND DASH 7

In a recent edition of A Look Back, we looked at the Fox Moth, the half brother of the successful Tiger Moth.


May 18, 2010
By Raymond Canon

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In a recent edition of A Look Back, we looked at the Fox Moth, the half brother of the successful Tiger Moth. Both aircraft were built by de Havilland, both were designed in Great Britain, and both were produced and flown there and in Canada. Although the number of Fox aircraft produced was only a small fraction of the Tiger, the Fox was not considered a failure. It experienced a successful career on both sides of the ocean; so much so that in Canada, an example of the aircraft (donated by Max Ward) can be found in the National Air Museum in Ottawa.

dash7  
22 years after the last Dash 7 was rolled out, over half of them are still in operation.
PHOTO: brian mcnair


 

The de Havilland DHC-7, popularly known as the Dash 7, has a similar story. It followed in the wake of a successful series of the company’s STOL aircraft such as the Beaver, Otter and especially the Twin Otter, but unlike these aircraft, the Dash 7 met with limited success.

Unlike these aircraft, the Dash 7 had four of the reliable Pratt & Whitney (Canada) PT6A turbo-prop engines. For those whose memories stretch back to the Second World War, the Dash 7 design incorporated a version of the Fowler flap, made famous by the Lockheed Hudson twin-engined patrol plane. (The Dash 7, however, employed a considerably more complex flap system that ran the entire length of the high-mounted wing). This wing, together with the four engines, provided satisfactory lift even down to very low speeds; if thrust reversal was selected on landing, the same layout decreased lift and thus increased the effectiveness of the brakes. It is no small wonder that it was able to approach and land using glide slopes that would be impossible with other similar types of aircraft.

The Dash 7 was a product of the 1970s and enjoyed the financial backing of the Canadian government. Dash 7 development started in 1972 and first flight followed three years later. Production, strangely enough, took place in two phases with the first from 1975 to 1984, with initial delivery to Rocky Mountain Airways in 1978. There was a slight hiatus in 1984 to concentrate on the Dash 8. Production of the Dash 7 restarted later that year when a further 14 were built, resulting in a total production of 114. The line was finally shut down in 1988 when the parent company, de Havilland Canada, was purchased by Boeing and was later sold to Bombardier. Bombardier sold the aircraft design (type certificate) to Viking Air in 2006.

There are, however, explanations for why the Dash 7 met with limited commercial success. Perhaps one of the main reasons was turboprop operators used them as feederliners into large airports, where STOL performance was generally not considered essential. Airports that called for a high performance STOL aircraft were generally small and were well served by the Twin Otter. Also, the use of four engines instead of two drove up maintenance costs considerably.

To be sure, however, there was a fit for the Dash 7. The most notable example came with the opening of the London City Airport in England in 1987; the Dash 7, right from the beginning, proved to be one of the few aircraft capable of landing and taking off at the airport. It was also found eminently suitable for use on the postage-stamp-sized airports in Greenland and elsewhere.

There were also military uses. Two Dash 7s were a familiar sight for years at Canada’s NATO base near Lahr, Germany, while the United States armed forces still use a number of these aircraft as surveillance vehicles. Transport Canada operates a single Dash 7 to conduct maritime surveillance, pollution and ice patrols as part of the Transport Canada National Aerial Surveillance Program (N.A.S.P.).

Perhaps the most telling statistic is that 22 years after the last Dash 7 was rolled out, over half of them are still in operation, a tribute to yet another of the fine stable of de Havilland aircraft created since the Second World War.

Quick facts… about the Dash 7

Role: Regional STOL airliner
Manufacturer: de Havilland
First Flight: March 27, 1975
Introduced: Feb. 3, 1978
Status: Many still active
Primary Users: U.S./Canada military, various airlines
Number Built: 114
Maximum Speed: 235 knots (271 mph)
Range: 700 nautical miles
Capacity: 102(3) passengers
Crew: 2
Wingspan: 28.35 m (93 ft.)
Length: 24.58 m (80 ft. 7 3/4 in.)
Height: 7.98 m (26 ft. 2 in.)
Service Ceiling: 21,000 ft.


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