Background , Toronto In the post-Second World War period, the
Soviet Union began developing a capable fleet of long-range
bombers with the ability to deliver
nuclear weapons across North America and Europe. The main threat was principally from high-speed, high-altitude bombing runs launched from the Soviet Union travelling over the
Arctic against military bases and built-up industrial centres in Canada and the United States. To counter this threat, Western countries developed
interceptors that could engage and destroy these bombers before they reached their targets.
A. V. Roe Canada Limited had been set up as a subsidiary of the
Hawker Siddeley Group in 1945, initially handling repair and maintenance work for aircraft at the
Malton, Ontario, Airport, today known as
Toronto Pearson International Airport. The next year the company began the design of Canada's first jet fighter for the Royal Canadian Air Force (RCAF), the
Avro CF-100 Canuck all-weather interceptor. The Canuck underwent a lengthy and troubled prototype stage before entering service seven years later in 1953. Nevertheless, it went on to become one of the most enduring aircraft of its class, serving in a variety of roles until 1981. Recognizing that the delays that affected the development and deployment of the CF-100 could also affect its successor, and that the Soviets were working on newer jet-powered bombers that would render the CF-100 ineffective, the RCAF began looking for a supersonic, missile-armed successor for the Canuck even before it had entered service. In March 1952, the RCAF's
Final Report of the All-Weather Interceptor Requirements Team was submitted to Avro Canada. German research during the Second World War had shown the onset of wave drag was greatly reduced by using airfoils that varied in curvature as gradually as possible. This suggested the use of thinner airfoils with much longer
chord than designers would have used on subsonic aircraft. These designs were impractical because they left little internal room in the wing for armament or fuel. The Germans also discovered it was possible to "trick" the airflow into the same behaviour if a conventional thicker airfoil was used swept rearward at a sharp angle, creating a
swept wing. This provided many of the advantages of a thinner airfoil while also retaining the internal space needed for strength and fuel storage. Another advantage was that the wings were clear of the supersonic shock wave generated by the nose of the aircraft. When a CF-100 broke the sound barrier on 18 December 1952, interest in the CF-103 waned.
Delta wings Another solution to the high-speed problem is the
delta wing. The delta wing had many of the same advantages of the swept wing in terms of transonic and supersonic performance, but offered much more internal room and overall surface area. This provided more room for fuel, an important consideration given the inefficient early jet engines of the era, and the large wing area provided ample lift at high altitudes. The delta wing also enabled slower landings than swept wings in certain conditions. The disadvantages of the design were increased drag at lower speeds and altitudes, and especially higher drag while maneuvering. For the interceptor role these were minor concerns, as the aircraft would be spending most of its time flying in straight lines at high altitudes and speeds, mitigating these disadvantages. The designs were otherwise similar, using a low-mounted delta-wing and sharply raked vertical stabilizer. The primary advantages of the C104/2 were its twin-engine reliability and a larger overall size, which offered a much larger internal weapons bay. The proposals were submitted to the RCAF in June 1952.
AIR 7-3 and C105 Intensive discussions between Avro and the RCAF examined a wide range of alternative sizes and configurations for a supersonic interceptor, culminating in RCAF Specification AIR 7-3 in April 1953. AIR 7-3 called specifically for a two crew, twin engine, aircraft with a range of ) for a normal low-speed mission, and for a high-speed interception mission. It also specified operation from a runway; a Mach 1.5 cruising speed at an altitude of ; and manoeuvrability for 2
g turns with no loss of speed or altitude at Mach 1.5 and . The specification required five minutes from starting the aircraft's engines to reaching altitude and Mach 1.5. It was also to have turn-around time on the ground of less than . An RCAF team led by Ray Foottit visited US aircraft producers and surveyed British and French manufacturers, concluding that no existing or planned aircraft satisfied these requirements. In 1955 Avro estimated the performance of the Arrow Mk 2 (with Iroquois) as follows, from the January 1955 British evaluation titled Evaluation of the CF.105 as an All Weather Fighter for the RAF: "Max speed Mach 1.9 at 50,000 ft, Combat speed of Mach 1.5 at 50,000 feet and 1.84 g without bleeding energy, time to 50,000 ft of 4.1 minutes, 500-foot per minute climb ceiling of 62,000 feet, 400 nmi radius on a high-speeds mission, 630 nmi radius on a low-speed mission, Ferry range is not given, but estimated at 1,500 nmi." Avro submitted their modified C105 design in May 1953, essentially a two-man version of the C104/2. A change to a "shoulder-mounted" wing allowed rapid access to the aircraft's internals, weapons bay, and engines. The new design also allowed the wing to be built as a single structure sitting on the upper fuselage, simplifying construction and improving strength. The wing design and positioning required a long main landing gear that still had to fit within the thin delta wing, presenting an engineering challenge. Five different wing sizes were outlined in the report, ranging between ; the sized version was eventually selected. The primary engine selection was the
Rolls-Royce RB.106, an advanced two-spool design offering around . Backup designs were the
Bristol Olympus OL-3, the US-built
Curtiss-Wright J67 version of the OL-3, or the
Orenda TR.9 engines. Armament was stored in a large internal bay located in a "belly" position, taking up over one third of the fuselage. A wide variety of weapons could be deployed from this bay, such as the
Hughes Falcon guided missile, the
CARDE Velvet Glove air-to-air missile, or four general-purpose 1,000 lb bombs. The Velvet Glove radar-guided missile had been under development with the RCAF for some time, but was believed unsuitable for supersonic speeds and lacked development potential. Consequently, further work on that project was cancelled in 1956. In July 1953, the proposal was accepted and Avro was given the go-ahead to start a full design study under the project name "CF-105". In December, CA$27 million was provided to start flight modelling. At first, the project was limited in scope, but the introduction of the Soviet
Myasishchev M-4 Bison jet
bomber and the Soviet Union's
testing of a hydrogen bomb the next month dramatically changed
Cold War priorities. In March 1955, the contract was upgraded to CA$260 million for five Arrow Mk.1 flight-test aircraft, to be followed by 35 Arrow Mk. 2s with production engines and
fire-control systems.
Production To meet the timetable set by the RCAF, Avro decided that the Arrow program would adopt the
Cook-Craigie plan. Normally a small number of prototypes of an aircraft were hand-built and flown to find problems, and when solutions were found these changes would be worked into the design. When satisfied with the results, the production line would be set up. In a Cook-Craigie system, the production line was set up first and a small number of aircraft were built as production models. Any changes would be incorporated into the jigs while testing continued, with full production starting when the test program was complete. As Jim Floyd noted at the time, this was a risky approach: "it was decided to take the technical risks involved to save time on the programme ... I will not pretend that this philosophy of production type build from the outset did not cause us a lot of problems in Engineering. However, it did achieve its objective." In a related program, nine instrumented free-flight models were mounted on solid fuel
Nike rocket boosters and launched from Point Petre over Lake Ontario while two additional models were launched from the NASA facility at
Wallops Island, Virginia, over the Atlantic Ocean. These models were for aerodynamic drag and stability testing, flown to a maximum speed of Mach 1.7+ before intentionally crashing into the water. Experiments showed the need for only a small number of design changes, mainly involving the wing profile and positioning. To improve
high-alpha performance, the leading edge of the wing was drooped, especially on outer sections, a
dog-tooth was introduced at about half-span to control spanwise flow, and the entire wing given a slight negative
camber which helped control trim drag and pitch-up. The
area rule principle, made public in 1952, was also applied to the design. This resulted in several changes including the addition of a tailcone, sharpening the radar nose profile, thinning the intake lips, and reducing the cross-sectional area of the fuselage below the canopy. The Arrow's thin wing required aviation's first hydraulic system to supply enough force to the control surfaces, while using small actuators and piping. A rudimentary
fly-by-wire system was employed, in which the pilot's input was detected by a series of pressure-sensitive transducers in the stick, their signal sent to an electronic control servo operating valves in the hydraulic system to move the flight controls. This resulted in a lack of control feel; because the control stick input was not mechanically connected to the hydraulic system, the variations in back-pressure from the flight control surfaces that would normally be felt by the pilot could no longer be transmitted back into the stick. To re-create a sense of feel, the same electronic control box rapidly responded to the hydraulic back-pressure fluctuations and triggered actuators in the stick, making it move slightly; this system, called "artificial feel", was also a first. In 1954, the
RB.106 program was cancelled, necessitating the use of the backup
Wright J67 engine instead. In 1955, this engine was also cancelled, leaving the design with no engine. At this point, the
Pratt & Whitney J75 was selected for the initial test-flight models, while the new TR 13 engine was developed at Orenda for the production Mk. 2s. After evaluating the engineering mock-ups and the full-scale wooden mock-up in February 1956, the RCAF demanded additional changes, selecting the advanced RCA-Victor
Astra fire-control system firing the equally advanced
United States Navy Sparrow II in place of the MX-1179 and Falcon combination. Avro vocally objected on the grounds that neither of these were even in testing, whereas both the MX-1179 and Falcon were almost production-ready and would have been nearly as effective for "a very large saving in cost". The Astra proved problematic as the system ran into a lengthy period of delays, and when the USN cancelled the Sparrow II in 1956,
Canadair was quickly brought in to continue the Sparrow program in Canada, although they expressed grave concerns about the project as well and the move added yet more expense.
Rollout and flight testing Go-ahead on the production was given in 1955. The rollout of the first CF-105, marked as RL-201, took place on 4 October 1957. The company had planned to capitalize on the event, inviting more than guests to the occasion. Unfortunately for Avro, the media and public attention for the Arrow rollout was dwarfed by the launch of
Sputnik the same day. The J75 engine was slightly heavier than the
PS-13, and therefore required ballast to be placed in the nose to return the
centre of gravity to the correct position. In addition, the Astra fire-control system was not ready, and it too, was replaced by ballast. The otherwise unused weapons bay was loaded with test equipment. RL-201 first flew on 25 March 1958 with Chief Development Test Pilot S/L
Janusz Żurakowski at the controls. Four more J75-powered Mk 1s were delivered in the next 18 months. The test flights, limited to "proof-of-concept" and assessing flight characteristics, revealed no serious design faults. The CF-105 demonstrated excellent handling throughout the flight envelope, in large part due to the natural qualities of the delta-wing, but responsibility can also be attributed to the Arrow's
Stability Augmentation System. Estimates up to Mach 1.98 likely originated from an attempt to compensate for
lag error, which was expected in diving flight. Although no major problems were encountered during the initial testing phase, some minor issues with the landing gear and flight control system had to be rectified. The first was partly due to the tandem main landing gear being very narrow, in order to fit into the wings; the leg shortened in length and rotated as it was stowed. During one landing incident on 11 June 1958, the chain mechanism (used to shorten the gear) in the Mark 1 gear jammed, resulting in the Arrow 201 experiencing a
runway excursion and gear collapse. A photograph taken of the incident proved that inadvertent flight control activation had caused the accident. The only occasion when a test flight was diverted occurred on 2 February 1959, when a
Trans-Canada Airlines Vickers Viscount crash-landed in Toronto, necessitating a landing at RCAF Trenton. The stability augmentation system also required much fine-tuning. Although other aircraft had used such systems before, the CF-105 was among the first of its kind, and was problematic. By February 1959, the five aircraft had completed the majority of the company test program and were progressing to the RCAF acceptance trials.
Political issues From 1953, some senior Canadian military officials at the chiefs of staffs began to question the program. The chiefs of staff of the army and navy were both strongly opposed to the Arrow, since "substantial funds were being diverted to the air force", while Air Marshal
Hugh Campbell, RCAF Chief of Staff, backed it right up until its cancellation. In June 1957, when the governing
Liberals lost the federal election and a
Progressive Conservative government under
John Diefenbaker took power, the aircraft's prospects began to noticeably change. Diefenbaker had campaigned on a platform of reining in what the Conservatives described as "rampant Liberal spending". Nonetheless, by 1958, the parent company had become Canada's third largest business enterprise and had primary interests in rolling stock, steel and coal, electronics, and aviation with 39 different companies under the A. V. Roe Canada banner. In September 1957, the Diefenbaker government signed the
NORAD (North American Air Defense) Agreement with the United States, making Canada a partner with American command and control. The USAF was in the process of completely automating their air defence system with the
SAGE project, and offered Canada the opportunity to share this sensitive information for the air defence of North America. One aspect of the SAGE system was the
Bomarc nuclear-tipped anti-aircraft missile. This led to studies on basing Bomarcs in Canada in order to push the defensive line further north, even though the deployment was found to be extremely costly. Deploying the missiles alone was expected to cost C$164 million, while SAGE would absorb another C$107 million, not counting the cost of improvements to radar. Minister of national defence
George Pearkes projected these initiatives would raise Canada's defence spending by "as much as 25 to 30%". Defence against ballistic missiles was increasingly prioritized. The existence of
Sputnik raised the possibility of attacks from space, and, as the year progressed, word of a "
missile gap" spread. An American brief of the meeting with Pearkes records his concern that Canada could not afford defensive systems against both ballistic missiles and manned bombers. It is also stated Canada could afford the Arrow or Bomarc/SAGE, but not both. By 11 August 1958, Pearkes requested cancellation of the Arrow, but the Cabinet Defence Committee (CDC) refused. Pearkes tabled it again in September and recommended installation of the Bomarc missile system. The latter was accepted, but again the CDC refused to cancel the entire Arrow program. The CDC wanted to wait until a major review on 31 March 1959. They cancelled the Sparrow/Astra system in September 1958. Efforts to continue the program through cost-sharing with other countries were then explored. In 1959, Pearkes would say the ballistic missile was the greater threat, and Canada purchased Bomarc "in lieu of more airplanes". ==Foreign interest==