de Havilland Canada DHC-6 Twin Otter

https://en.wikipedia.org/wiki/De_Hav...C-6_Twin_Otter

The de Havilland Canada DHC-6 Twin Otter, currently marketed as the Viking Air
DHC-6 Twin Otter, is a Canadian 19-passenger STOL (Short Takeoff and Landing)
utility aircraft developed by de Havilland Canada and currently produced by
Viking Air. The aircraft's fixed tricycle undercarriage, STOL capabilities, twin
turboprop engines and high rate of climb have made it a successful commuter
passenger airliner as well as a cargo and Medevac aircraft. In addition, the
Twin Otter has been popular with commercial skydiving operations, and is used by
the United States Army Parachute Team and the United States Air Force's 98th
Flying Training Squadron.

Development of the aircraft began in 1964, with the first flight on May 20,
1965. A twin-engine replacement for the single-engine DHC-3 Otter retaining
DHC's renowned STOL qualities, its design features included double-slotted
trailing-edge flaps and ailerons that work in unison with the flaps to boost
STOL performance. The availability of the 550 shp (410 kW) Pratt & Whitney
Canada PT6A-20 turboprop in the early 1960s made the concept of a twin more
feasible. To bush operators, the improved reliability of turboprop power and the
improved performance of a twin-engine configuration made it an immediately
popular alternative to the piston-powered Otter which had been flying since
1951.

The first six aircraft produced were designated Series 1, indicating that they
were prototype aircraft. The initial production run consisted of Series 100
aircraft, serial numbers seven to 115 inclusive. In 1968, Series 200 production
began with serial number 116. Changes made at the beginning of Series 200
production included improving the STOL performance, adding a longer nose that
was equipped with a larger baggage compartment (except for aircraft fitted with
floats), and fitting a larger door to the rear baggage compartment. All Series
1, 100, and 200 aircraft and their variants (110, 210) were fitted with the
550-shaft-horsepower PT6A-20 engines.

In 1969, the Series 300 was introduced, beginning with serial number 231. Both
aircraft performance and payload were improved by fitting more powerful PT6A-27
engines. This was a 680 hp (510 kW) engine that was flat-rated to 620 hp (460
kW) for use in the Series 300 Twin Otter. The Series 300 proved to be the most
successful variant by far, with 614 Series 300 aircraft and their subvariants
(Series 310 for United Kingdom operators, Series 320 for Australian operators,
etc.) sold before production in Toronto by de Havilland Canada ended in 1988.


Role
Utility aircraft

Manufacturer
de Havilland Canada
Viking Air

First flight
20 May 1965

Introduction
1966

Status
In production

Produced
1965–1988 (Series 100-300)


Number built
900+

Unit cost

US$6.5 million (2017)

Developed from
de Havilland Canada DHC-3 Otter

Developed into
de Havilland Canada Dash 7

Twin Otters could be delivered directly from the factory with floats, skis, or
tricycle landing gear fittings, making them adaptable bush planes for remote and
northern areas. Areas including Canada and the United States, (specifically
Alaska) had much of the demand. Many Twin Otters still serve in the far north,
but they can also be found in Africa, Australia, Asia, Antarctica, and other
regions where bush planes are the optimum means of travel. Their versatility and
maneuverability have made them popular in areas with difficult flying
environments such as Papua New Guinea. In Norway, the Twin Otter paved the way
for the network of short-field airports, connecting rural areas with larger
towns. The Twin Otter showed outstanding reliability, and remained in service
until 2000 on certain routes. Widerøe of Norway was, at one time, the world's
largest operator of Twin Otters. During one period of its tenure in Norway, the
Twin Otter fleet achieved over 96,000 cycles (take-off, flight, and landing) per
year.

As of August 2006, a total of 584 Twin Otter aircraft (all variants) remain in
service worldwide. Major operators include: Libyan Arab Airlines , Maldivian Air
Taxi , Trans Maldivian Airways , Kenn Borek Air and Scenic Airlines. Some 115
airlines operate smaller numbers of the aircraft including Yeti Airlines in
Nepal, Malaysia Airlines (which uses the Twin Otter exclusively for passenger
and freight transportation to the Kelabit Highlands region in Sarawak), and in
the United Kingdom, the FlyBe franchise operator Loganair which uses the
aircraft to service the island of Barra in the Hebrides islands.

The Twin Otter has been popular with commercial skydiving operations. It can
carry up to 22 skydivers to over 17,000 ft (a large load compared to most other
aircraft in the industry); presently, the Twin Otter is used in skydiving
operations in many countries. The United States Air Force operates three Twin
Otters for the United States Air Force Academy's skydiving team.

Specifications

Source:

DHC-6 Series 100

Flight deck crew
1–2

Seating
19

Length
51 ft 9 in (15.77 m)

Wingspan
65 ft 0 in (19.8 m)

Wing area
420 sq ft (39 m2)

Empty weight
5,850l lb (2,653 kg)

Height
19 ft 4 in (5.9 m)

Maximum takeoff weight
11,566 lb (5,246 kg)

Maximum landing weight
11,566 lb (5,246 kg)

Maximum speed
160 knots (297 km/h at cruise altitude) 170 knots (314 km/h at cruise altitude)

Cruise speed
150 knots (278 km/h at cruise altitude)

Stall speed
58 knots (107 km/h at cruise altitude) (landing configuration)

Range (Max fuel, no payload)
771 nmi (1,427 km)

Maximum fuel capacity
382 US gal (1,447 L)

Service ceiling
25,000 ft (7,620 m)

Powerplants (×2)
Pratt & Whitney PT6A-20 550 shp each Pratt & Whitney PT6A-27

Rate of climb
1,600 ft/min (8.1 m/s)

Power/mass
0.12 hp/lb (0.20 kW/kg) or 8.33 lb/hp (5 kg/kW) reciprocal value




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