The Avro Canada CF-105 Arrow was an interceptor aircraft designed and built by Avro Canada. The CF-105 held the promise of Mach 2 speeds at altitudes exceeding and was intended to serve as the Royal Canadian Air Force's (RCAF) primary interceptor into the 1960s and beyond.Page et al. 2004, p. 159.
The Arrow was the culmination of a series of design studies begun in 1953 that examined improved versions of the Avro Canada CF-100 Canuck. After considerable study, the RCAF selected a dramatically more powerful delta-winged design, and serious development began in March 1955. The aircraft was intended to be built directly from the production line, skipping the traditional hand-built prototype phase. The first Arrow Mk. 1, RL-201, was rolled out to the public on 4 October 1957, the same day as the launch of Sputnik I.
Flight testing began with RL-201 on 25 March 1958, and the design quickly demonstrated excellent handling and overall performance, reaching Mach 1.9 in level flight. Powered by the Pratt & Whitney J75, another four Mk. 1s were completed, RL-202, RL-203, RL-204 and RL-205. The lighter and more powerful Orenda Iroquois engine was soon ready for testing, and the first Mk 2 with the Iroquois, RL-206, was ready for taxi testing in preparation for flight and acceptance tests by RCAF pilots by early 1959. Canada tried to sell the Arrow to the US and Britain, but no agreements were concluded.Peden 1978, p. 72.
On 20 February 1959, Prime Minister John Diefenbaker abruptly halted the development of both the Arrow and its Iroquois engines before the scheduled project review to evaluate the program could be held.Dow 1979, p. 127 Two months later the assembly line, tooling, plans, existing airframes, and engines were ordered to be destroyed. The cancellation was the topic of considerable political controversy at the time, and the subsequent destruction of the aircraft in production remains a topic for debate among historians and industry pundits. "This action effectively put Avro out of business and its highly skilled engineering and production personnel scattered".Payne 2006, p. 213.
Design and development
Background
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.Dow 1979, p. 67. 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.Dow 1979, p. 60. To counter this threat, Western countries developed interceptors that could engage and destroy these bombers before they reached their targets.Gunston 1981, p. 18.Dow 1979, pp. 84–85.
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.Dow 1979, pp. 61–62. The Canuck underwent a lengthy and troubled prototype stage before entering service seven years later in 1953.Dow 1979, p. 70. 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.Dow 1979, p. 83. In March 1952, the RCAF's Final Report of the All-Weather Interceptor Requirements Team was submitted to Avro Canada.
Higher speeds Avro engineering had been considering supersonic issues already at this point. Supersonic flight works in a very different fashion and presents a number of new problems. One of the most critical, and surprising, was the sudden onset of a new form of drag, known as wave drag. The effects of wave drag were so strong that engines of the era could not provide enough power to overcome it, leading to the concept of a "sound barrier".Anderson 2008. pp. 683, 695.
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.Whitcomb 2002, pp. 89–90.
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.
Almost every fighter project in the postwar era immediately applied the concept, which started appearing on production fighters in the late 1940s. Avro engineers explored swept-wing and tail modifications to the CF-100 known as the CF-103, which had proceeded to wooden mock-up stage. The CF-103 offered improved transonic performance with supersonic abilities in a dive. The basic CF-100 continued to improve through this period, and the advantages were continually eroded.Milberry 1984, p. 317. When a CF-100 broke the sound barrier on 18 December 1952, interest in the CF-103 waned.Zuk 2004, p. 184.
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.Stimson, Thomas E. Jr. "Era of the Flying Triangles". Popular Mechanics, 106 (3). September 1956, pp. 89–94.
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.
Further proposals based on the delta wing resulted in two versions of the design known as C104: the single engine C104/4 and twin-engined C104/2.Dow 1979, p. 84. 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.Campagna 1998, pp. 68–69. The proposals were submitted to the RCAF in June 1952.Page et al. 2004, p. 11.
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 .Dow 1979, p. 89. 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.Dow 1979, p. 25.
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.Peden 2003, p. 26.
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.Dow 1979, p. 85.
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.Dow 1979, p. 86. 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.Campagna 1998, pp. 66–67.
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".Page et al. 2004, p. 12. 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.Peden 2003, p. 45. 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.Shaw 1979, p. 58.
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.Whitcomb 2002, p. 86.Pigott 1997, p. 55. 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."