The Amazing Flying Machines of DHC
This pair of DHC-6 Twin Otters waits for the call outside the Aklak Air hanger at Inuvik.
With the rollout of the first new-build 400-series Twin Otter approaching I thought it would be appropriate to look back at the series of aircraft built by deHavilland Canada that so perfectly filled the tiny niche market of short-field high-performance bush planes.
Originally a division of the British deHavilland Aircraft Company, after WWII deHavilland Canada started production of it own designs focusing on the unique requirements of the Canadian wilderness. Despite changing owners several times in the last 25 years (being owned by the Canadian Government, Boeing, and now Bombardier Aerospace) the company has produced many innovative and commercially successful aircraft over the last 50 years.
Their first offering (not counting the DHC-1 Chipmunk trainer that was designed during the war) was the venerable DHC-2 Beaver. Developed in 1947, the Beaver literally redefined what a "bush plane" was supposed to be. Its STOL capabilities and 2000lb. payload were so impressive that during the 20 year production run deHavilland sold over a thousand aircraft to various militaries around the world (mostly the US Army). Of the 1700 built a large number are stilll flying today, many with a conversion to turbine power. I recall flying in one many years ago on a trip out to the middle of nowhere on the Arctic Ocean for an ice monitoring project.
The follow on to the Beaver was the DHC-3 Otter, a larger version of the Beaver with a new high-lift wing able to carry twice as much payload. First flown in 1951, the Otter was a huge leap forward in capability. Almost 500 were built and it again caught the attention of the US Army which purchased the bulk of the production as the U-1A Otter.
With its attention now focused on the military market, the next in the series was the DHC-4 Caribou. Built primarily to meet a US Army specification for a twin engine tactical transporter, the Caribou first flew in 1958 and most saw extensive service in Vietnam although many were built for other militaries (including Canada) and a few civilian operators. Very few Caribou's are still flying today but there are some and even a handful of conversions to turbine power.
Canadian Forces DHC-5 Buffalo 452 on the ramp in Inuvik after a local SAR mission.
Designed as an improved Caribou, the DHC-5 Buffalo was again aimed at the military market however just prior to full production the main customer (again the US Army) was mandated out of fixed wing aircraft operations. In the end, by 1982 only 122 examples had been built (all military) after 20 years of extremely low-rate production. An attempt at a civilian version designated the DHC-5D 'Transporter' was cancelled after a dramatic crash of the demonstrator at the Farnborough Air Show in 1984. Most existing military operators have or are planning to retire the Buffalo very soon so more airframes will likely be showing up on the civilian market.
A 100-series Twin Otter on wheel-skis spools up for a trip north to Banks Island.
With the availability of the first Pratt and Whitney Canada PT6 turboprop engines in 1963, deHavilland immediately began work on an upgraded version of the Otter utilizing the new powerplant. With a 'minimum change, maximum gain' design philosophy, the new DHC-6-100 Twin Otter carried over most of the original Otter design focusing chiefly on the replacement of the large radial engine with a pair of the new turbines. As a result, the new aircraft ended up being overly heavy and not particularly efficient. The 200-series version was introduced in the late sixties with incremental improvements in performance and an enhanced STOL performance 300-series version was offered in 1970.
Over the 22-year production run 844 Twin Otters were built however their relative inefficiency prevented them from selling in anything other than the very small bush plane market where the aircraft excelled at getting in and out of remote areas and operating in extreme weather conditions. In addition, because they were extremely rugged they tended to last a long time. The result was that production eventually ended because everyone that needed a Twin Otter already had one and they didn't need to be replaced for a long time. Fast forward another 20 years to today. No one has designed a successful aircraft for the same market as the DHC-6, the oldest 'Twotters' are now ready to be replaced and attrition has finally created a demand for new airframes. To meet this new demand, Viking Air (a manufacturer of replacement parts for all the DHC aircraft) purchased the type certificate for the Twin Otter in 2006 and began offering a new-build 400-series model. To date they have over 40 aircraft on order and are forecasting a possible market of as many as 400 airframes.
Environment Canada operates this custom-built DHC-7 'Dash 7' for ocean ice reconnaisance, seen here at Inuvik last summer.
In the early seventies, deHavilland foresaw a market for a 50 passenger regional aircraft that would be able to operate in and out of smaller city-centre airports. Often with very short (3000ft.) runways and restrictive noise-limitations, these smaller airports were normally the domain of general aviation aircraft but their proximity to downtown areas would make them much more attractive to business travellers. To meet this forecast, they began development of the DHC-7. Based on a scaled-up version of the Twin Otter wing with a new fuselage and four uprated PT6 engines, this new aircraft (known simply as the Dash 7) entered service in 1978.
Air Tindi's Dash 7 arriving in Inuvik last summer after filling in for Canadian North on the Yellowknife-Norman Wells-Inuvik run.
Even with the unrivalled STOL performance and noise levels of the Dash-7, only 113 were built and production ceased in 1988. Despite its intended inner-city market, most operators that purchased the Dash 7 were using it as a regional airliner operating between smaller centers and major hub airports. At the time, the Dash 7 was the only modern airliner of this size that was available however its unused STOL capabilities, short range and four engines made it inefficient for what it was being used for. Realizing its error in reading the market, deHavilland quickly redesigned the Dash 7 into a purpose-built regional commuter aircraft, the Dash 8. With a simpler, more efficient wing design, two larger (rather than four smaller) engines, and advanced avionics (which had just become available) the Dash 8 was deHavilland's first big success since the Twin Otter.
This Arctic Sunwest Charters Dash 8-100 loads up in Inuvik after a trip from Yellowknife.
(apologies for the crappy camera phone picture).
In continuous production since 1983 with over eight hundred sold, the Dash 8 has been stretched and improved over the years, culminating with the latest 80 passenger version, the Q400.
