De Havilland Canada DHC-5 Buffalo

The de Havilland Canada DHC-5 Buffalo is a short takeoff and landing (STOL) utility transport turboprop aircraft developed from the earlier piston-powered DHC-4 Caribou. The aircraft has extraordinary STOL performance and is able to take off in distances much shorter than even most light aircraft can manage.
Design and development.
The Buffalo arose from a 1962 United States Army requirement for a STOL transport capable of carrying the same payload as the CH-47A Chinook helicopter. De Havilland Canada based its design to meet the requirement on an enlarged version of its DHC-4 Caribou, already in large-scale service with the United States Army, to be powered by General Electric T64 turboprops rather than the Pratt & Whitney R-2000 piston engines of the Caribou. (It had already flown a T64-powered Caribou on 22 September 1961).
De Havilland's design, the DHC-5 Buffalo, was chosen as the winner of the United States Army competition in early 1963, with four DHC-5s, designated YAC-2 (later CV-7A and subsequently C-8A) ordered. The first of these aircraft made its maiden flight on 9 April 1964. All four aircraft were delivered in 1965, the Buffalo carrying nearly twice the payload as the Caribou while having better STOL performance. The prototype CV-7A was exhibited by the manufacturer at the 1965 Paris Air Show wearing US Army markings. No further US orders followed, however, as at the start of 1967 (See the Johnson-McConnell agreement of 1966), inter-service politics led to large fixed-wing transports being transferred to the United States Air Force, who considered themselves adequately equipped with the Fairchild C-123 Provider.
Company data claims a takeoff distance over a obstacle of at and a landing distance of over a obstacle of at for the DHC-5A model.
In the early 1980s, de Havilland Canada attempted to modify the Buffalo for civilian use. The aircraft was to be branded as the "Transporter." After loss of the demonstration aircraft (SN "103 C-GCTC") at the 1984 Farnborough Airshow, the project was abandoned.
A production DHC-5D Buffalo was used for breaking time-to-height records for the weight category on 16 February 1976, reaching in 2 min 12.75 sec, in 4 min 27.5 sec and in 8 min 3.5 sec.
New production.
On 24 February 2006, Viking Air of Victoria, British Columbia, a manufacturer of replacement parts for all out-of-production de Havilland Canada aircraft, purchased the type certificates from Bombardier Aerospace for all versions of the DHC-1 through DHC-7 series aircraft, giving Viking exclusive rights to manufacture and sell new aircraft of those types. In December 2008, Viking Air indicated their intention to put the Buffalo series back into production at their home factory in Victoria, British Columbia or in Calgary, Alberta. A potential new production Buffalo would have had Pratt & Whitney Canada PW150 turboprops, a glass cockpit, enhanced vision and night vision goggle capability. The aircraft was proposed as a replacement for the Royal Canadian Air Force fleet of existing DHC-5As but was not one of the three aircraft in the final assessment, in 2016, which selected the EADS CASA C-295. Several letters of intent for the DHC-5NG were received in 2014.
Operational history.
In late 1965, one of the prototype DHC-5s operated by the U.S. Army was deployed to Bien Hoa Air Base in South Vietnam for a three-month evaluation period, assigned to the 2nd Flight Platoon of the 92nd Aviation Company.
The Royal Canadian Air Force first acquired 15 DHC-5A designated as CC-115 for tactical transports. These were initially operated at CFB St Hubert, QC by No. 429 Squadron in a tactical aviation role as part of Mobile Command. In 1970, the Buffalo aircraft were transferred to a transport and rescue role with No. 442 Squadron, No. 413 Squadron and No. 424 Squadron as part of Transport Command. No. 426 Squadron also flew the aircraft for training. Some were leased back or loaned back to the factory for trials and eventually returned to military service.
Three of the aircraft were also deployed on UN missions to the Middle East with No. 116 Transport Unit until 1979. They had a white paint scheme which was retained while they were serving in domestic transport with 424 Sqn in between deployments. On 9 August 1974, Canadian Forces CC-115 Buffalo 115461 was shot down by a Syrian surface-to-air missile, killing all nine CF personnel on board. This represents the single biggest loss of Canadian lives on a UN mission as well as the most recent Canadian military aircraft to be shot down.
In 1975, the Buffalo dropped its tactical transport role and was converted to domestic search and rescue, except for a few that kept serving on UN missions. The initial paint scheme for the SAR converted aircraft were white and red while others still had the original drab paint. The previous drab paint and white paint were eventually replaced with the distinctive yellow and red scheme commonly seen today. The number of aircraft have been reduced to eight, with six on active service, one in storage (recently dismantled) and one used for battle damage training. The remaining operational Buffalos operate in the Search and Rescue role for No. 442 Squadron at CFB Comox. Air Command was renamed the "Royal Canadian Air Force" in 2011, meaning the CC-115 has served with the RCAF, Air Command and now the RCAF once again. The Buffalo was replaced by the CC-130 Hercules aircraft at search-and-rescue bases in CFB Greenwood and CFB Trenton. As early as 2002, Canada has tried to replace both the Buffalo fleet and the SAR Hercules fleet with a newer aircraft. For some time, the Alenia C-27J Spartan was seen as the likely replacement, with the government considering sole-sourcing the new aircraft. However, after changes in Canada's defense budget as well as accusations of bias from the aerospace industry, the Buffalo replacement program was relaunched as an open competition. After review from the National Research Council, the Department of Defense as well as consultation with the Canadian aerospace industry, a request for proposal was published in 2015. Bidders included Alenia offering the C-27J Spartan, Airbus Defense and Space with its C-295 and Embraer with its KC-390. In 2016, the Department of Defense awarded Airbus a contract for 16 C-295s with delivery scheduled to begin in 2019 and running through 2022.
Production of the DHC-5A ended in 1972 after sales to Brazil and Peru but restarted with the DHC-5D model in 1974. This variant sold to several overseas air forces beginning with Egypt. Production of the DHC-5D ended in December 1986.
Demonstrators for new technologies.
The Buffalo was a suitable airframe for converting to demonstrate some new technologies.
Augmented Wing Jet-flap STOL Research Aircraft.
A cooperative NASA/Canadian Government research program on augmentor wing concepts started in 1965 and culminated in the need for a proof-of-concept aircraft.
A NASA C-8A Buffalo (later named "Bisontennial" in 1976) was modified in 1972 for augmentor-wing jet STOL research. The modifications were done by Boeing, de Havilland Canada and Rolls-Royce of Canada Ltd. The wing had a reduced span to give a wing loading representative of future aircraft. It also had full-span leading edge slats, blown ailerons and double-surface flaps enclosing a venturi-shaped passage. The usual turboprop engines were replaced with Rolls Royce Spey 801 SF (Split Flow) bypass engines with a new bypass duct which separated the hot and cold flows to provide both propulsion and augmentor airflow to the powered lift system. 
 The hot flow was directed through Pegasus-engine swivelling nozzles to ensure it deflected with the flap downwash. The cold flow was directed into the flap venturi and entrained extra airflow. Beginning in 1972 with its first flight in this experimental configuration, this aircraft was used jointly by the NASA Ames Research Center and the Canadian Department of Industry, Trade and Commerce for STOL research.
Quiet Short-Haul Research Aircraft.
In the late 1970s and early 1980s, NASA used another C-8A Buffalo in the Quiet Short-Haul Research Aircraft program.
Boeing designed and installed an experimental swept, supercritical wing incorporating a boundary layer control system. Instead of the standard engines, this aircraft was powered by four prototype Avco Lycoming YF102 high-bypass turbofan engines (originally from the Northrop YA-9 program) mounted above the wing to take advantage of the Coandă effect. In 1980, this aircraft participated in carrier trials aboard USS "Kitty Hawk", demonstrating STOL performance without the use of catapults or arrestor gear. 
The aircraft is currently stored at NASA's Ames Research Center in Mountain View, California.
Air Cushion Landing System Aircraft.
After demonstrations by Bell aircraft using a Lake LA-4 light amphibian with Air Cushion Landing Gear the development of this type of gear was pursued in a joint effort between the USAF and the Canadian Government by retrofitting a similar system to a medium cargo transport, a Buffalo. The air supply to the cushion was provided by an air supply package consisting of a PT6F-70 and two-stage axial flow fan under each wing. The aircraft also had underwing combination floats/skids.
Accidents and incidents.
In total, 26 accidents involving hull losses have been recorded.