The Canadair CL-44 was a Canadian turboprop airliner and cargo aircraft based on the Bristol Britannia that was developed and produced by Canadair in the late 1950s and early 1960s. Although innovative, only a small number of the aircraft were constructed for the Royal Canadian Air Force (as the CC-106 Yukon), and for commercial operators worldwide.
Design and development
In the 1950s, Canadair had acquired a licence to build the Bristol Britannia airliner. Their first use of the licence was to built the heavily modified Canadair CL-28 Argus patrol aircraft, that combined the Britannia's wings and tail sections with a new fuselage and engines. The resulting aircraft had lower speed and altitude, but had two bomb bays and greatly extended loiter times.
With an RCAF requirement for a replacement for its C-54GM North Star (modified C-54 Skymaster with Merlin engines) fleets, Canadair began work on a long range transport primarily intended to provide personnel and logistics support for Canadian Forces in Europe. In January 1957 Canadair received a contract for eight aircraft, later increased to 12. The RCAF designation for the new design was the CC-106 Yukon, while the company's civilian variant was known as the CL-44-6. In company parlance the CL-44 was simply "the Forty-Four."
The RCAF had specified the CL-44 to be equipped with Bristol Orion engines. When the British Ministry of Supply canceled the Orion program, the RCAF revised the specifications to substitute the Rolls-Royce Tyne 11. The CL-44 fuselage was lengthened by 12 ft 4 in (3.75 m) to be almost identical to the Britannia 300 with two large cargo doors added on the port side while the cabin was pressurised to maintain a cabin altitude of 2,400 m at 9,000 m (30,000 ft). The design used modified CL-28 wings and controls. The Yukon could accommodate 134 passengers and a crew of nine. In the casualty evacuation role it could take 80 patients and a crew of 11.
The rollout of the Yukon was a near-disaster when the prototype could not be pushed out of the hangar since the tail was unable to clear the hangar doors. The first flight took place 15 November 1959 at Cartierville Airport. During test flights many problems were encountered from complete electrical failure to engines shaking loose and almost falling off. Rolls-Royce had problems delivering engines resulting in the sarcastically named "Yukon gliders" being parked outside Canadair as late as 1961.
Three different versions of the CL-44 were built:
The CL-44D4 was the first large aircraft to be able to 'swing' its tail, although some small naval aircraft had this feature to ease storage. These, however, required rigging before flight. There were only four original customers who bought and operated the CL-44D4: Seaboard World Airlines, The Flying Tiger Line, Slick Airways, Icelandic Airlines Loftleiðir
Loftleiðir was the only passenger operator of the CL-44J, which was the largest passenger aircraft flying over the Atlantic ocean at that time. Loftleidir marketed the CL-44J under the name "Rolls-Royce 400 PropJet". This led to the confusion that the CL-44J is sometimes referred to as the Canadair-400. Loftleiðir Icelandic Airlines merged with Flugfelag Islands in 1973 and became today's Flugleiðir being the Icelandic name and Icelandair in English.
One CL-44D4 was converted by Conroy Aircraft, who removed the fuselage shell above the floorline, and rebuilt an enlarged fuselage to make it into a Guppy-type aircraft. It was designated the CL-44-O, and was intended to transport Rolls-Royce RB-211 engine pods to the United States for Lockheed's L-1011 Tristar. This aircraft became known as the Skymonster or CL-44 Guppy.
The CC-106 Yukons retired in March 1971 and were replaced by the Boeing 707 (RCAF CC-137). The Yukons might have served longer with the RCAF but for two factors: the RCAF's need for an aircraft which could operate as an in-flight refueling tanker, and the chronic shortage and high cost of spares, the latter resulting because the CL-44 had never gone into large-scale production. All Yukons were sold to South American and African operators as they could not be registered in Northern America or Europe since the Britannia windshields did not meet new security standards.
In commercial operations, the CL-44 proved to be an extremely profitable aircraft to run with a fuel burn half that of a Boeing 707. After 40 years, out of the 39 aircraft built, 18 either crashed or were destroyed in operation, 13 have been cut up, and two (including the Guppy) remain more or less operational. The remaining eight aircraft are parked around the world or have already been scrapped. Not a single CL-44 has been conserved or been prepared for a museum although the Ecuadorian Air Force salvaged #13 for eventual display at a new aviation museum in Guayaquil, Ecuador.
Published - July 2009
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