On 31 October, 1945, an agreement was reached between the Canadian Government and the still unformed company represented by Sir Roy Dobson and F.T. Smye. It was agreed that the new company would design, build and develop two 'Single Seater Jet-Type Fighter Airframes' in accordance with DND specification AIR 7-1, issue 1. Early in 1946 J.H. Millie, fighter project engineer, laid out three proposals for single-seat fighters under the direction of Stuart Davies of Avro in Manchester who was then visiting Malton. The three schemes were submitted for consideration by the RCAF. After rethinking its requirements the RCAF decided what was really needed for the defense of Canada was an all-weather, twin-engined, two-seat fighter.
Avro Canada then developed three new proposals to suit the new requirements and these were submitted to the RCAF in October 1946. The RCAF accepted one of these which was felt, with certain changes, to be suitable. These changes were introduced but work on the aircraft was slow in starting until the arrival of its project designer, John C.M. Frost, in May 1947.
The original design had been laid out by James A. Chamberlin but Frost did not like it. However he was unable to produce a better one so he accepted it. He then objected to the long nacelles and wanted short ones. Chamberlin protested that this would increase the drag and, more than that, under some conditions short nacelles could be lethal. Chief Engineer Atkin could not resolve the difference of opinion and it was agreed to make wind-tunnel tests of both nacelles. The long nacelles were tested first and the results were so good that the short ones were not tested. One change in the CF-100's design did take place in this early period but it and its consequences will be discussed later.
The aircraft had a circular-section fuselage mounted on a symmetrical NACA aerofoil of 10 per cent thickness, and the pressurized cockpit housed a crew of two provided with Martin-Baker ejection seats. The two engines were placed close to the fuselage in almost circular nacelles which were faired to the fuselage by an aerofoil section following the latest German research. Rolls-Royce Avon engines were installed in the two prototypes to get them flying while the Orenda engine intended for the production machines was still under development.
The wing was of NACA 0010 section and had plain split flaps inboard of the ailerons. Ahead of the flaps, the prototypes had dive-brakes consisting of an interconnected flat surface on the top and bottom surfaces of the wing. These normally laid flush with the wing surface and were raised when deployed. Chamberlin did not approve of them and forbade their use. New serrated dive-brakes were installed on the Mk.2 and subsequent machines and Mk.2 wings were fitted to both Mk.1s early in 1951. Tip tanks each with 350.68 gal (1,327 l) capacity increased the ferry range.
Structurally, the CF-100 was of quite conventional stressed-skin construction. The wing had a single spar located at the 40 per cent chord line. The flying controls were manually operated with Fairey boosters.
The CF-100 prototype, RCAF 18101, was first flown at Malton on January 19, 1950, by William 'Bill' A. Waterton, a Canadian serving as Gloster Aircraft's Chief Test Pilot in England and who had been sent out for the preliminary test flying. The prototype was tested at the Central Proving Establishment at Ottawa and in November 1950 at Wright Field. Although Waterton had pronounced the aircraft as pleasant and safe to fly and ready for operational use, it was found that its longitudinal stability was not acceptable and its lateral control needed improvement.
These deficiencies were, of course, brought out in the tests but nevertheless the CF-100 received many favorable comments during its Wright Field trials. In particular, its short take off, good rate of climb, and maneuverability at altitude, as well as other points, were most favorably regarded. It was also regarded as a 'pilot's aircraft' and Lt-Col L.C. Moon, Chief Test Engineer at Wright Field, was quoted as saying 'This is the first aircraft I have flown for some time that I wouldn't mind going to war in'. The stability and control deficiencies noted were investigated and quickly corrected by Avro Canada.
The CF-100 was then developed through four more basic mark numbers along with several secondary versions, and these along with proposed versions were as shown below.
The armament and proposed armament of the CF-100 was changed several times during the development of the type. Originally it was to have four 1.18 in (30 mm) Aden guns, production designation EM-1. The Aden gun was being developed in Britain from the German Mauser Mk 213/30 and was felt to be a promising weapon, with a rate of fire of 1,200 rpm. Avro Canada did considerable work on the Aden installation including firing trials with Canadian Arsenals Ltd at Long Branch, Ontario, but the formidable problem of feeding the large shells at the required high rate was still not solved when the scheme was stopped in November 1949.
Then the installation of eight 0.50 in (12.7 mm) M-3 guns was specified. A gun pack housing these weapons and 200 rounds per gun was developed. It could be quickly hoisted into the fuselage gun bay, insuring a rapid re-arming of aircraft in service. The first missile considered for CF-100 installation was the Velvet Glove, an air-to-air missile being developed by the Canadian Armament Research & Development Establishment (CARD E) at Valcartier, Quebec. At least two CF-100s, a Mk.3A, RCAF 18117, and a Mk.3B, RCAF 18322, were fitted to carry four Velvet Glove missiles during development trials by the National Aeronautical Establishment. The Velvet Glove missile never entered production and the CF-100 program for its installation was cancelled in February 1956.
The CF-100 Mk.4 was originally intended to be armed with rockets only and to have both wingtip pods and a fuselage rocket pack. The tip pods each held twenty-nine 2.75 in (70 mm) folding-fin aircraft rockets (FFAR) and were fitted with frangible nose cones. These pods were used on both the Mk.4 and the Mk.5. A training pod holding seven rockets was also supplied. A rocket firing inter-valometer was developed to accommodate both the tip pods and the fuselage pack. A preselected rocket sequence was fired by the intervalometer upon receipt of a signal from the fire-control system.
The fuselage rocket pack never went into production although it was developed. The pack, holding 48 rockets and weighing over 1,000 lb (454 kg), upon receipt of the firing signal had to be quickly extended outside the fuselage and at the same time a trim compensating signal put into the control system to counteract the drag of the pack. Upon firing the preselected rockets, it then had to be ensured that no rocket had a hang-fire before the pack was retracted. The pack was developed and air tested in the MK.4, RCAF 18112, with Jan Zurakowski piloting. It was then decided that the threat to Canada would come from high altitude and the rocket pack development was stopped in favor of a high-altitude version (HAV) of the CF-100 which appeared as the Mk.5.
Versions of both the Mk.4 and Mk.5 were considered which mounted Bristol Orpheus engines at the wingtips in addition to the Orenda 11s.
The Sparrow 2 missile (used on the CF-105) was to have been used on the Mk.6. Seven Mk.5s were modified to mount four Sparrows and had the MG-2C fire-control system installed. Two Mk.5Ms, RCAF 18138 and, probably, 18139, participated in the Sparrow development program at NAS Point Mugu in California. Development of the Sparrow 2 was stopped as was the Mk.6. In addition studies were done on the fitting of infra-red guided Falcon GAR-2A missiles and the installation of 2 in (50.76 mm) and 5 in (126.9 mm) rockets but neither of these studies was pursued extensively.
Early in the CF-100's career the type received a substantial setback. On October 17, 1951, the RCAF officially accepted its first CF-100, a Mk.2, RCAF 18104, during a ceremony at Malton. On November 19 it was returned with a cracked centre-section spar web. Waclaw Czerwinski was asked to investigate the problem and find a cure. His cure was (a) to pin joint the nacelle structure to the spar which eliminated some difficult-to-handle loads, (b) to increase the skin thickness of the centre portion of the nacelle and (c) to add local reinforcing to the spar. An emergency program was started to incorporate the necessary changes, and there was no further problem. Some CF-100s were still flying 25 years later.
The background of this serious problem was as follows. Originally the engines were mounted above the wing spar which ran through the centre section unaffected. While Project Designer Frost was on a trip to Britain Chief Aerodynamicist Chamberlin found a stability problem which required lowering the engines. This was done and the top spar boom had to be kinked downward to clear the engines. On his return Frost protested at this solution but Chief Engineer (later Technical Director) E. H. Atkin agreed that the engines had to be lowered which left the aircraft with a poor structural feature. A stress report was issued showing the wing was under strength but no action was taken. W. Czerwinski, during a weight saving investigation, had found the wing under strength and reported it informally. In early flight trials a local spar cracking was experienced along with buckling of the wing-to-nacelle fairing. The spar was strengthened locally and a gap was left at the fillet which permitted the wing to flex without wrinkling the fillet.
Jan Zurakowski, who had joined Avro Canada as Chief Development Pilot in April 1952, soon became convinced that it would be possible for the CF-100 to exceed Mach 1 although earlier tests showed a normal limit of Mach 0.88. Building up speed gradually in a series of dives, he exceeded Mach 1 in a dive on December 18, 1952, while flying the Mk.4, RCAF 18112. This CF-100 then became the first straight wing aircraft to exceed the speed of sound without rocket power.
Several CF-100s were lost during flight testing at Malton. The second Mk.1, RCAF 18102, dived nearly vertically into a small swamp near London, Ontario, on April 5, 1951, killing its pilot, Flt Lt Bruce Warren, and engineering observer, Robert Ostrander, possibly caused by the pilot's lack of oxygen. Glendon J. Lyons, flying alone near Malton, entered a spin at low altitude on October 20, 1955, and ejected but was too low for his parachute to function. During a fuselage rocket pack test flight in RCAF 18112 on August 23, 1954, Zurakowski had an explosion on board and then a second one; he ejected safely but his engineering observer, Jack Hiebert, was killed. (Read the News Report) Zurakowski concluded that a fuel leak, caused by buffeting during the rocket pack test, created fumes which were ignited electrically.
The RCAF named the CF-100, the Canuck, after the sobriquet of the Curtiss JN-4(Canadian) of WW I. The name was hardly appropriate for a fighter and was never generally accepted, and its crews, in its later years, dubbed the aircraft the Clunk. The RCAF had once considered naming the Mk.4 the Jaeger.
In RCAF service the type was first assigned to squadrons on the northern defense of Canada and stationed at North Bay, Ontario; Bagotville, Quebec; Comox, British Columbia: and Uplands (Ottawa). In 1956 four squadrons of CF-100s replaced four Sabre squadrons in the No.1 Air Division serving in France and West Germany. CF-100s served with all of the following squadrons, 409, 410, 413, 414, 416, 419, 423, 428, 432,433, 440, 441 and 445.
Though not quite as fast as some of the smaller contemporary fighters, the CF-100's good climb, excellent radar and fire-control system, twin-engine reliability and all-weather capability, made the type most suitable for the defense of northern Canada, and in Europe their reliability and all-weather capability made them much appreciated in the fog and murk of West Germany. There was only one other contemporary fighter in its class and that was the Northrop F-89 Scorpion. It was significant that when Belgium was selecting an all-weather fighter, the CF-100 was chosen in competition with the F-89, and fifty-three CF-100 Mk.5s were supplied to Belgium, paid for 25 per cent by Canada and the balance by the USA.
After being replaced in its fighter role, a number of CF-100s were fitted with electronic counter measure (ECM) equipment, and some were fitted as target tugs, in which capacity some still serve.
Prototype and development aircraft. Two 5,700 lb (2,585 kg) s.t Rolls-Royce Avon RA.2 engines. No armament or radar. First flight January 19, 1950. Pilot William A. Waterton. Two aircraft.
Preproduction aircraft. Two 6,000 lb (2,724 kg) s.t Avro Canada Orenda 1 engines. New dive-brakes. No armament or radar. First flight June 20, 1951. Pilot Donald H. Rogers. Three aircraft.
As Mk.2 but with dual controls. Two aircraft.
Proposed photographic conversion. Not built.
Similar to Mk.3B. Two 6,000 lb (2,724 kg) s.t Orenda 8 engines. Three aircraft.
Production fighter. Two 6,000 lb (2,724 kg) s.t Orenda 2 engines. Eight-gun pack. APG-33 radar and E-1 fire control system. 21 aircraft.
Production fighter. As Mk.3A except Orenda 8 engines. 45 aircraft.
Trainer version. Conversion of Mk.3A to dual control. Earlier designation Mk.3CT. One aircraft.
Trainer version. Similar to Mk.2T but with Orenda 2 engines. First flight (first Mk.3) June 22, 1952. Pilot Janusz Zurakowski. Four aircraft.
Preproduction gun and rocket fighter. Two 7,300 lb (3,314 kg) s.t Orenda 11 engines. New nacelle lines. Free blown, one piece, canopy. Electrical de-icing on wing and tail. APG-40 radar and MG-2 fire control system. Hinged and interchangeable radar nose. Eight-gun pack and two 29-rocket tip pods. First flight October 11, 1952. Pilot Janusz Zurakowski. One aircraft.
Production gun and rocket fighter. As Mk.4 but with two 6,300 lb (2,860 kg) s.t Orenda 9 engines. 137 aircraft.
Production gun and rocket fighter. As Mk.4A but with Orenda 11 engines. 141 aircraft.
Proposed version of Mk.4B with 8% thickness/chord wing and afterburners. Submitted to RCAF July 1952.
High-altitude rocket fighter. Orenda 11 engines. Two 29-rocket tip pods. APG-40 radar and MG-2 fire control system. First flight of production aircraft October 24, 1955. Pilot Janusz Zurakowski. 332 aircraft.
High-altitude missile fighter. Modified Mk.5. Four Sparrow 2 missiles. MG-2C fire control system. Seven aircraft modified.
Proposed high-altitude missile fighter. Orenda 11R engines. Four Sparrow 2 missiles. MG-2D fire control system. Improved cockpit heating. Combat ceiling 50,000 ft (15,239 m). Cancelled July 1953.
Proposed high-altitude fighter. E-9A fire control system. The Mk.7 was cancelled and some features were transferred to the Mk.6, but this, too, was cancelled.
Proposed high-altitude fighter. Armstrong Siddeley Sapphire 7 engines. Two 29-rocket tip pods. Maximum speed 603 mph (970 kmh) at 35,000ft (10,667m). Project cancelled.