Canadair CL-44

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Canadair CL-44
Demonstration of the loading of the CL-44-D4 with automobiles. Canadair photo.
Type Military transport aircraft
Cargo aircraft
Manufacturer Canadair
Maiden flight 15 November 1959
Retired 1971 (RCAF)
Status Retired
Primary users Royal Canadian Air Force
Various airlines
Number built 39
Developed from Bristol Britannia
Variants Conroy Skymonster

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 and for commercial operators worldwide.

Contents

[edit] Design and development

In the 1950s, Canadair had acquired a licence to build the Bristol Britannia airliner, and in a similar fashion to the development of the CL-28 Argus, the company utilized the same basic Britannia design to create a new aircraft. With a RCAF requirement for a replacement for its C-54GM North Star 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 Britannia-based airliner 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 cancelled 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 2.400m at 9.000m (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.

[edit] Operational service

Three different versions of the CL-44 were built:

  • Initially, the CL-44-6 was produced for the Royal Canadian Air Force as the CC-106 Yukon. Once initial problems were resolved, in RCAF service the Yukon performed well and in December 1961, a Yukon set a world record for its class when it flew 6,7500 mi (10,860 km) from Tokyo to Trenton, Ontario, in 17 hours, three minutes at an average speed of 400 mph (640 km/h). Later a Yukon even set a new record staying airborne for 23 hours and 51 minutes. These records stayed untouched until broken by the new Boeing 747SP in 1975. Eleven Yukons flew for 437 Transport Squadron, two flew as VIP transports for 412 Squadron. By the time of their retirement, Yukons had flown 65 million miles, 1.5 billion passenger miles and 360 million ton-miles. The CL-44-6 was briefly considered for purchase by the USAF in the 1960s but the project was never culminated due to a political backlash in both Canada and the United States.[1]
  • The second version was the CL-44D4 intended as a civil, commercial cargo aircraft. In order to cater for large items and fast loading, the entire tail section was hinged, and could be opened using hydraulic actuators. Cargo, close in size to the full internal diameter of the fuselage, could then be loaded. An inflatable seal at the hinge-break enabled cabin pressure to be maintained, and eight hydraulic-operated locks assured structural integrity. The tail could be opened from controls within the tail in 90 seconds. The flying controls at the joint were maintained by a system of push pads.

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

  • The third version was the CL-44J, with four existing CL-44D4 aircraft, stretched by Canadair on request of Loftleidir Icelandic Airlines, with a section, 10 ft 1 in (3.07 m) forward of the wing, and another section of 5 ft 1 in (1.55 m) aft of the wing. This enabled the installation of 29 extra seats, bringing the capacity to 189 passengers. The maximum take-off weight stayed the same since the extra weight was compensated by removing the center wing tanks. Therefore it can be said that the stretch was a trade of capacity for range.

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 lead 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.

[edit] Survivors

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 needed an aircraft, which could operate as an in-flight refuelling tanker, and secondly, the chronic shortage of spares. The latter problems resulted from the fact that the CL-44 had never gone into large-scale production consequently, spare parts tended to be in short supply and relatively expensive. All Yukons were sold to South American and African operators since it 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 of a Boeing 707. After 40 years, out of the 39 built, 18 either crashed or were destroyed in operation, 13 aircraft have been cut up, two aircraft, 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.

[edit] Military operators

[edit] Specifications CL-44D-4

General characteristics

  • Crew: 3 (4 including loadmaster)
  • Capacity: 160 passengers
  • Length: 136 ft 11 in (41.73 m)
  • Wingspan: 142 ft 4 in (43.37 m)
  • Height: 36 ft 8 in (11.18 m)
  • Wing area: 2,075 ft² (192.7 m²)
  • Empty weight: 88,952 lb (40,348 kg)
  • Useful load: 66,048 lb (29,959 kg)
  • Max takeoff weight: 210,000 lb (95,000 kg)
  • Powerplant: 4× Rolls-Royce Tyne 515/50 turboprops, 5,730 shp (4,270 kW) each
  • Propellers: Four-blade variable pitch propellers

Performance

[edit] References

  1. ^ The CL-44. [1] Access date: 3 March 2007. Note: The USAF purchase of the CL-44 was complicated by two factors. It came in the aftermath of the cancellation of the Avro CF-105 Arrow and involved a "swap deal" wherein 100 F-101 Voodoo fighters were obtained in return for a contract for 232 CL-44-D4 transports for the Military Air Transport Service (MATS). The political controversy that resulted led to problems for both a Quebec-based company receiving a contract so soon after an Ontario-based company had lost a major contract; as well, the USAF also quickly found that buying a foreign aircraft was not easy when American companies wanted the business and relinquished the contract to Canadair, awarding a transport order to Boeing for the KC-135.
  • Milberry, Larry. The Canadair North Star. Toronto: CANAV Books, 1982. ISBN 0-07-549965-7.
  • Pickler, Ron and Milberry, Larry. Canadair: The First 50 Years. Toronto: CANAV Books, 1995. ISBN 0-921022-07-7.

[edit] External links

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