The Avro CF-100 Canuck

Canada and the US collaborated closely on the defense of North America during the Cold War. While the US was clearly the bigger partner in the defense relationship, the Canadians carried their weight, and provided their own distinctive contributions to the partnership. One of the more memorable was the "Avro CF-100 Canuck" interceptor. This straightforward and effective machine served as one of the mainstays of North American air defense through the 1950s. This document provides a history and description of the CF-100.

Avro CF-100 Canuck origins

The CF-100 grew out of a January 1945 Royal Canadian Air Force (RCAF) requirement for a twin-jet, radar-equipped all-weather interceptor. Avro Canada, which had been established by the British Hawker Siddeley group in July 1945 through purchase of the Victory Aircraft plant, got the formal contract to develop the new aircraft under AIR Spec 7-1 in October 1946. The contract specified construction of two flight prototypes and a static test airframe, all with the designation of "XC-100". Development was performed by a team led by the company's chief engineer, John Frost.

The two prototypes were to be powered by twin British Rolls Royce Avon axial-flow turbojets, but that was strictly an interim engine fit. The Gas Turbine Engine branch of Avro Canada had developed their own axial-flow engine, the "TR4 Chinook", which they then scaled up to the excellent "TR5 Orenda" for the CF-100. Initial test runs of the Orenda were performed in 1949, with results meeting or exceeding expectations.

The initial "CF-100 Mark 1" prototype, as the XC-100 had been redesignated, performed its initial flight on 19 January 1950, with the aircraft given an overall black color scheme detailed with white lighting bolts running down the sides. Since Avro Canada's test pilots didn't have fast jet experience at the time, first flight honors were performed by Bill Waterton, a Canadian who was the chief test pilot of the British Gloster firm, which was part of the Hawker Siddeley group. The Mark 1 was powered by two Avon RA.3 turbojets with 28.9 kN (2,950 kgp / 6,500 lbf) thrust each. Performance and handling were up to spec, but the wings flexed too much. This would be a serious issue in early development, with aircraft having a nasty tendency to come back down with cracked wing spars. The problem was a major threat to the program and wouldn't be finally resolved until 1952.

The second prototype performed its first flight in July 1950; it was effectively identical to the first prototype. Its trials included a session at the Wright-Patterson Air Force Base in Ohio, where US Air Force pilots got a chance to fly the machine and were impressed by it. One of the main roles of the second prototype was evaluation of wingtip fuel tanks, which imposed unacceptable stresses on the wings until a fin was attached on the outboard side of each tank, which somewhat surprisingly improved overall flight stability as well.

The CF-100 prototypes set the basic design for the series. The machine was of simple and elegant configuration. It had a low mounted straight wing and twin jet engines, each mounted in a nacelle next to the fuselage. The fuselage was loaded with fuel tanks and had tandem seating, with the pilot in front and a radar operator in back. Both sat on Martin-Baker ejection seats in a pressurized cockpit, under a canopy that slid back on rails to open.

The wing featured double slotted flaps, had airbrakes on both top and bottom, and pneumatic leading-edge deicing boots. All flight controls were hydraulically powered. The CF-100 had tricycle landing gear, with the nose gear retracting backward and the main gear hinged in the wings to retract inward to the fuselage. All the gear assemblies had twin wheels to handle the machine's relatively heavy takeoff weight.

The second prototype crashed near London, Ontario, on 5 April 1951, with both crew killed; the cause was believed to be a failure of the crew oxygen system that knocked out the pilot. The first prototype remained in trials service through the 1950s, to be finally scrapped in 1965.

Avro CF-100 Canuck Mark 2 through Mark 5

In July 1949, even before the first flight of the Mark 1, ten unarmed "CF-100 Mark 2" development machines had been ordered. The first, with twin Orenda 2 engines providing 26.7 kN (2,720 kgp / 6,000 lbf) thrust each, performed its initial flight on 20 June 1950. As it turned out, this machine would be the only real Mark 2 as such. The next four in the batch were built as trainers with dual controls and designated "Mark 2T". These five machines were used both for initial RCAF familiarization training and for trials. There was a scheme to build a photo-reconnaissance variant of the Mark 2, designated the "Mark 2P", using one of the Mark 2 evaluation airframes, but this program was cancelled.

The success of the flight-test program led to an initial production order in September 1950 for 124 "CF-100 Mark 3s". The initial Mark 3 performed its first flight in September 1952 and entered squadron service with the RCAF in April 1953, to be given the name "Canuck". The RCAF never actually liked the name much in practice, and pilots and crews would generally call it the "Clunk".

The Mark 3 was fitted with a US-built Hughes E-1 fire control system, organized around an AN/APG-33 radar mounted in the nose, the same radar as fitted to the CF-100's American counterpart, the Northrop F-89A Scorpion. Armament consisted of eight Browning 12.7 millimeter (0.50 caliber) machine guns in a belly tray that could be dropped out for fast servicing. Trials were conducted with a tray containing four 20 millimeter cannon, but technical problems led to the abandonment of this weapons fit. The Mark 3 featured a pitot tube on the left wing; earlier aircraft had been occasionally fitted with a nose pitot tube during trials. The Mark 3s generally flew in natural metal finish.

Two stores pylons could be fitted under each wing, for a total of four, for carriage of munitions, such as four 450 kilogram (1,000 pound) bombs. Although the test program included bombing trials, the CF-100 was never used in the attack role operationally. Trials also included tests of "rocket assisted take-off gear (RATOG)", but though the scheme worked well it was also not used operationally.

Another test fit evaluated by the Mark 3 was the "Velvet Glove" radar-guided air-to-air missile (AAM), with four missiles carried on the underwing pylons, or in some trials on pylons under the fuselage and engine intakes. Velvet Glove was a collaborative effort conducted by Canada, the US, and the UK; most of the missile was designed in Canada, with a solid-rocket motor provided by the US. The program was cancelled in 1956 and Velvet Glove never entered service.

Only 70 Mark 3s were actually built, not counting four preproduction machines that had actually started life as part of the batch of ten Mark 2 preproduction aircraft; these four aircraft were built as "Mark 3T" dual-control trainers. Of the 70 production Mark 3s, 9 were built as "Mark 3As", with Orenda 2 engines; 11 were built as "Mark 3CT" dual-control trainers, also with Orenda 2 engines; and 50 were built as "Mark 3Bs", with Orenda 8 engines, providing greater reliability than the Orenda 2 but the same level of thrust.

In service, the Mark 3 was promising, but it suffered from a number of of teething problems; the Mark 3s amounted in effect to training and evaluation machines. One problem was that the stick obscured the compass, a problem that was fixed in the field by modifying the stick. A second problem was a manual fuel control system that was too workload-intensive; the fuel system was also overly complicated and unreliable. Other annoyances were lack of nosewheel steering and unreliable landing gear.

When the Mark 3 was supplanted by improved versions of the Canuck, 4 Mark 3As and 43 Mark 3Bs were converted by Bristol Canada to "Mark 3D" dual control trainers, with the Mark 3As upgraded to Orenda 8 engines in the process. This exercise was followed by conversion of 9 Mark 3CTs to the Mark 3D standard, with these aircraft retaining Orenda 2 engines.

In the meantime, the RCAF decided to adopt the American practice of using clusters of unguided 70 millimeter (2.75 inch) "Mighty Mouse" folding fin rockets as an air to air weapon, instead of guns. One of the Mark 2Ts was used for initial trials of wingtip-mounted rocket pods.

The first operational variant to carry the rockets was the "CF-100 Mark 4", with the initial prototype, which had started life as the last of the ten preproduction Mark 2s, performing its first flight on 11 October 1952. It could outrun its Sabre chase plane, though it was nowhere near as agile as the Sabre, and even broke Mach 1 in a dive on 4 December of that year. It was used for evaluation of a belly rocket pack, mounted behind the gun pack, that could carry 48 FFARs. The belly pack caused severe buffeting when it was extended and was abandoned. The Mark 4 prototype was lost during trials with this weapons fit on 23 August 1954, the pilot ejecting successfully but the back-seater being killed.

The first production Mark 4 was rolled out in September 1953. The Mark 4 featured:

• A windscreen between the forward and rear halves of the cockpit to make it easier for the back-seater to punch out after the front-seater had ejected. A one-piece canopy was also introduced; some sources claim early Mark 4 production maintained the Mark 3's two-piece canopy, but it is difficult to find any photographic evidence to support this notion.
• Twin Orenda 9 engines with 28.9 kN (2,950 kgp / 6,500 lbf) thrust each, with the new engines requiring modified engine nacelles.
• A new Hughes MG-2 collision-course fire-control system, with AN/APG-40 radar accommodated in a bigger nose. This was the same system as used on the Northrop F-89D Scorpion; it not only permitted attacks on targets from a forward or right-angle ("collision course") flight path, but also provided a beacon mode for tracking and a ground-mapping mode for navigation.
• Wingtip pods with 29 Mighty Mouse rockets each, which could be swapped with wingtip tanks for ferry flights. Three-round and seven-round wingtip rocket pods were fitted for training.

Early production Mark 4s lacked an autopilot; it is unclear if they were refitted with one later. Most Mark 4 production had a tail bumper, but this item was deleted from late production aircraft.

The Mark 4 was the first really satisfactory CF-100 variant, and so the last the Mark 3 order was cut short, ending Mark 3 production as mentioned at 70 aircraft. 137 Mark 4s were built, and then the uprated Orenda 11 engine, with 32.4 kN (3,300 kgp / 7,275 lbf) thrust, was introduced as a production change; 193 of these souped-up Mark 4s were built and designated "Mark 4B", with the 70 Orenda 9 powered machines retroactively redesignated "Mark 4A". Two of the Mark 4As were converted to Mark 4B configuration.

The last CF-100 variant was the "Mark 5", which had a simple straight 1.06 meter (3 foot 6 inch) extension to each wingtip and wider tailplane to increase the type's effective operational ceiling. The Mark 5s were powered by Orenda 11s, or Orenda 14s with similar thrust. The Mark 5s were armed solely with wingtip rocket pods, with the gun pack and gunsight deleted. Wing leading-edge deicing boots and the unused fittings for RATOG were also deleted to reduce weight.

First flight of the Mark 5 prototype was in September 1954, with first flight of a production item on 12 October 1955.

281 Mark 5s were built as new production, and 49 Mark 4Bs were upgraded to the Mark 5 standard. A total of 693 Canucks were built in all. It was the only Canadian-designed jet fighter to ever reach production.

The CF-100 served with nine RCAF squadrons at its peak, in the mid-1950s. Four of these squadrons were deployed to Europe from late 1956 into 1962 under the NIMBLE BAT ferry program, replacing squadrons equipped with Canadair Sabre day-fighters to provide all-weather defense against Soviet intruders. Canucks flying at home retained natural metal finish, but those flying overseas were given a British-style disruptive camouflage scheme -- dark sea gray and green on top, light sea gray on the bottom.

Following the end of the CF-100's first-line service, a small number of Mark 5s were refitted as electronic countermeasures aircraft. The initial conversion was the "Mark 5C", featuring active radar jammers, fitted in the gun pack bay, and chaff dispensers on underwing pylons. The wingtip extensions were removed and wingtip tanks were carried as standard. These machines were followed by "Mark 5D" conversions, which added active communications jamming gear. They stayed in service until 1981 and were the last CF-100s to fly for the RCAF. For the farewell flight, at one was painted black with white lightning bolts up each side of fuselage, the same paint scheme used on the initial Mark 1 prototypes.

53 Mark 5s were also provided to the Belgian Air Force, all being filtered through the RCAF and with initial deliveries in late 1957. They flew using the same disruptive camouflage scheme applied to RCAF CF-100s in Europe. The Belgian Mark 5s were retired in the early 1960s and all were scrapped. Not one made its way to an air museum; in 1971 a Belgian air museum bought a Canadian CF-100 for the princely sum of a Canadian dollar. The Belgians displayed it with its original RCAF markings.

The following table provides a summary of CF-100 variants and production:

Avro CF-100 Special variants and modifications

There were a number of special variants and modifications of the Canuck:

• Two Mark 4s were converted to target tugs and given a gaudy all-red color scheme, with the machines nicknamed "Red Dragon" and "Pink Lady". They carried a tow target on each wingtip and a tow winch on a pylon under each wing. Most RCAF target-tug duties were actually performed by the CT-133 Silver Star, the Canadian-built version of the Lockheed T-33, which was cheaper to operate.
• In 1967, Pratt & Whitney Canada (PWC) requested loan of a Mark 5 from the Canadian government, with the aircraft to be used as a testbed for the company's JT15D small turbofan engine. The engine was fitted under the fuselage, where the gun pack had been carried on earlier Canuck variants, with the high landing gear of the CF-100 providing plenty of clearance; clamshell doors were installed on the engine intake to prevent damage from foreign object ingestion. This machine was finally removed from service in 1982, and is believed to have been the last flying CF-100.
• CF-100s were used during the 1960s in collaborative efforts with the US military to characterize the infrared emissions of missile and rocket launches, with instrument systems carried in modified wingtip tanks. A CF-100 was similarly used to evaluate an infrared sensor for the US Nimbus weather satellite, and in 1963 one CF-100 carried gear to observe an eclipse of the Sun.
• Following the cancellation of the Velvet Glove AAM, a few Mark 5s were used to fire Sparrow radar guided AAMs in tests and redesignated "Mark 5M". Four Sparrows were carried on the underwing pylons. There were similar trials with Canucks carrying four Hughes GAR-8 Falcon AAMs on underwing pylons, or carrying a single MB-1 Genie unguided, nuclear-armed AAM on each wingtip. Of course, no CF-100 ever carried these weapons in service.

There were several concepts for a "Mark 6", such as a machine with afterburning Orenda 11R ("reheat") engines and Sparrow armament. The "Mark 7" was to feature a thinner wing and Sparrow armament. The "Mark X" was a concept for a high-altitude machine that added a Bristol Orpheus turbojet to each wingtip; and the "CF-103" was a swept-wing version of the Canuck.

None of these machines were built. The CF-103 led, somewhat indirectly, to the development of the ultra-sophisticated Avro Canada CF-105 Arrow interceptor. The Arrow program effectively blocked development of improved Canuck variants, and unfortunately the CF-105 ended up being cancelled in 1959 in one of the great defense-procurement fiascos of all time.

Avro Canada then proposed a "CF-100 Mark 8" that would carry long-range missiles and feature improved radar and new engines, but the Canadian government had already selected the the US McDonnell F-101B Voodoo as their next-generation interceptor. The Voodoo wasn't an Arrow but it was certainly a generation ahead of the Canuck, and the F-101B would replace the Canuck in the RCAF for air defense in the early 1960s.

Author: Greg Goebel