- Avro Canada CF-100 Mk4B Canuck at Duxford in 1975. | Photo: Steve Fitzgerald

Flightline: 158 - Avro Canada CF-100 Canuck

Developed after WWII, the Canuck holds the distinction of the only domestically-developed fighter to enter production for Canada.

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In the closing years of World War Two, the Royal Canadian Air Force sought to acquire a jet-powered all-weather interceptor to patrol the vast Canadian wilderness. Having judged that no existing aircraft or program then in development met their needs, the RCAF contracted on 13 October 1946 with Avro Canada to design a prototype for the new fighter.

Orthograph of the CF-100. | Illustration: aviastar

Orthograph of the CF-100. | Illustration: aviastar

The result, designated the CF-100, was a two seat, twin-engined plane with low-mounted, straight wings. The CF-100 incorporated an advanced radar and fire control system and was armed with eight .50 machine guns. The CF-100 was fitted with Rolls-Royce Avon engines, while the pre-production and production aircraft were to be fitted with Avro TR5 Orenda turbojets, developed in Canada.

*CLUNK*

The first CF-100 Mk.1 prototype had it's maiden flight on 19 January 1950, while the second flew in July. On 5 April 1951 the second prototype crashed, the victim of a flaw in the design of the Canuck. The accident led to the dismissal of several members of the design team, while a special group was established to find a solution to the problem. The fix turned out to be a minor change, retrofitted to the prototype and pre-production aircraft and incorporated into the forthcoming production CF-100s. The five pre-production Mk. 2 aircraft were completed during 1951, though production was slow due to the delayed development of the Orenda engine.

Avro CF-100 prototype #18102 in flight. | Photo: Adirector

Avro CF-100 prototype #18102 in flight. | Photo: Adirector

Testing of the Mk.2s (two of which were fitted with dual controls and were designated the Mk.2T trainer/conversion aircraft) continued through 1951 and 1952, with a few minor issues cropping up and being addressed. The Orenda engine in particular was said to perform more smoothly than contemporary British or American engines. Testing of the Mk.1 and Mk.2 allowed the refinement of the production aircraft, designated the Mk.3, which took flight for the first time on 11 October 1952. In addition to changes in the airframe and control systems, the Mk.3s also incorporated an APG-33 radar and eight .50 cal M3 Browning machine guns grouped in a ventral pack for easy maintenance and reloading.

Technicians attaching a gun pack to a CF-100. | Photo: RCAF

Technicians attaching a gun pack to a CF-100. | Photo: RCAF

The CF-100 Mk.3 was accepted by the RCAF in 1953, with 70 aircraft produced. Two sub types, the Mk.3A and 3B, were also produced, with the main difference being upgraded Orenda 2 and Orenda 8 engines respectively. One Mk.3 was also converted to a dual-control trainer, designated the Mk.3CT. The aircraft were well liked by pilots, who called the plane "Clunk", after the sound made by the retraction of the nose gear. The Clunks were soon flying patrols of the vast Canadian wilderness as part of NORAD, maintaining watch for Soviet bombers attempting to penetrate Canada's airspace.

A formation of Mk.3 Clunks flying in formation. CF-100s in RCAF service flew in unpainted metal for much of their service life. | Photo: RCAF

A formation of Mk.3 Clunks flying in formation. CF-100s in RCAF service flew in unpainted metal for much of their service life. | Photo: RCAF

One Mk.3 was modified to serve as the prototype of the next version, the Mk.4, which would supplement the machine guns with wingtip pods of Mighty Mouse FFARs. The nose of the Mk.4 was also enlarged to accommodate the upgraded APG-40 radar. On 18 December 1952, the prototype broke the speed of sound in a dive, making it the first straight winged aircraft to break Mach 1. The Mk.4 first flew on11 October 1952, and at the end of its test series the RCAF canceled the last 54 Mk.3s on order and replaced them with orders for 137 Mk.4As, which in addition the changes in fire control and weapons were powered by Orenda 9 engines. The Mk.4A was followed by 141 Mk.4Bs, which was fitted with Orenda 11 engines. In March 1956, four CF-100s were flown to Eglin AFB in Florida as part of Project BANANA BELT, a series of comparative armament trials flown by USAF crews.

A Mk.4B of the 440 Squadron at Prestwick Airport, Scotland, in 1960. | Photo: RuthAS

A Mk.4B of the 440 Squadron at Prestwick Airport, Scotland, in 1960. | Photo: RuthAS

Two RCAF Mk.4Bs from 423 Squadron in 1962. The aircraft were training at the Air Weapons Unit in Sardinia while attached to RCAF Station Grostenquin, France. | Photo: Canadian Department of National Defence

Two RCAF Mk.4Bs from 423 Squadron in 1962. The aircraft were training at the Air Weapons Unit in Sardinia while attached to RCAF Station Grostenquin, France. | Photo: Canadian Department of National Defence

The final version of the Canuck was the Mk.5, which was optimized for higher altitude flight. The wingtips were lengthened by 1.06 meters, as wells as an enlarged empennage. The Browning machine guns were removed, with the type relying solely on the rocket pods. The Mk.5s were also fitted with Orenda 11 or 14 turbojets. Production of the Mk.5 totaled 332 aircraft, with an additional 53 produced for the Belgian Air Force, the sole foreign operator of the Clunk. Under the NIMBLE BAT program, four squadrons of CF-100s were deployed to Europe to replace Canadair Sabre squadrons. These forward deployed Clunks were painted in an RAF-style camo of mottled gray and green over light gray. Later in their service life, a small number of Mk.5s were modified into Electronic Counter Measures/Electronic Warfare (ECM/EW) Mk.5Ds, while several others were converted to Mk.5Ms, able to carry and fire AIM-7 Sparrow radar-guided missiles.

A CF-100 Mk.5M, armed with 4 AIM-7 Sparrows, banks away from the camera plane. | Photo: RCAF

A CF-100 Mk.5M, armed with 4 AIM-7 Sparrows, banks away from the camera plane. | Photo: RCAF

A Mk.5M fires a Sparrow during a test exercise. | Photo: RCAF

A Mk.5M fires a Sparrow during a test exercise. | Photo: RCAF

CF-100 Mk.5Ds of 414 Sqn. at North Bay/Jack Garland Airport in 1979. | Photo: RCAF

CF-100 Mk.5Ds of 414 Sqn. at North Bay/Jack Garland Airport in 1979. | Photo: RCAF

Advances and replacements

A Mk.6 variant, to act as an "interim" fighter between the Clunk and the forthcoming CF-105 Arrow was proposed. The Mk.6 would have been powered by afterburning Orenda 11R engines and would have been equipped with Sparrow missiles, but development was not pursued.

Simplified schematic of the Mk.6 showing the extended wingtips, reshaped tail, and AIM-7s. | Illustration: airvectors.com

Simplified schematic of the Mk.6 showing the extended wingtips, reshaped tail, and AIM-7s. | Illustration: airvectors.com

A more advanced derivative of the Clunk was in the works even as the type was being prototyped. The CF-103 would keep the basic fuselage of the CF-100, but would utilize a swept wing a tail along with uprated afterburning Orenda 17 engines. The CF-103 would offer only modest performance improvements over the Canuck, but was seen as a hedge against the possibility of contacts for the Clunk not materializing. Initial progress was slow, and Avro's concentration on the CF-100 saw work on the CF-103 grind to a halt in 1951. A mockup was completed, but was scrapped in 1952.

Orthograph of the CF-103. | Illustration: Bzuk

Orthograph of the CF-103. | Illustration: Bzuk

Mockup of the CF-103 in 1951. | Photo: Avro

Mockup of the CF-103 in 1951. | Photo: Avro

The CF-105 Arrow was intended to be the eventual replacement to the Canuck, but that program was canceled with much controversy. With the Arrow dead, two batches of USAF F-101 Voodoo were sold to the RCAF as CF-101s to replace the Clunk, although the CF-100s were actually maintained in RCAF service until 1981 when they were eventually replaced by the CF-188 Hornet.

A number of CF-100s, in various configurations, are preserved around Canada, as well as several in Belgium, the US and the UK

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