Avro Canada CF-105 Arrow Picture

Avro Canada CF-105 Arrow was a delta-wing interceptor aircraft, designed and built by Avro Aircraft Limited (Canada) in Malton, Ontario, Canada, as the culmination of a design study that began in 1953. Considered to be both an advanced technical and aerodynamic achievement for the Canadian aviation industry, the CF-105 held the promise of Mach 2 speeds at 50,000 ft+ altitude, and was intended to serve as the Royal Canadian Air Force's interceptor for the 1960s and beyond.

Following the start of its flight test program in 1958, the Arrow, and its accompanying Orenda Iroquois jet engine program, were abruptly cancelled in 1959,[1][2] sparking a long and bitter political debate. The Arrow is still the subject of controversy, almost 50 years after it was cancelled.

Origins

In the post-Second World War period, the Soviet Union began developing a fleet of long-range bombers capable of delivering nuclear weapons to North America and Europe. To counter this threat, Western countries developed interceptor aircraft that could engage and destroy these bombers before they reached their targets.[3]

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 Malton, Ontario Airport (today known as Pearson International Airport, Toronto's main airport). The next year the company began the design of Canada's first jet fighter for the Royal Canadian Air Force, the Avro CF-100 Canuck all-weather interceptor. The Canuck underwent a lengthy prototype period before entering service seven years later in 1953. It would nevertheless go on to become one of the most enduring aircraft of its class, serving into the 1980s in a variety of roles.

Recognizing that the delays that impacted the development and deployment of the CF-100 could also impact its successor, and the fact that the Soviets were working on newer jet-powered bombers, the RCAF began looking for a supersonic, missile-armed replacement 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.

[edit] Design and development

Avro engineering had been considering supersonic developments for some time at this point. German research during the Second World War had identified a number of solutions to the problems associated with supersonic flight. It was known that the onset of wave drag was greatly reduced by using thinner airfoils with much longer chord, but these airfoils were impractical because they left little internal room in the wing for armament or fuel.

Instead, aerodynamicists employed a swept-wing design to "trick" the airflow into behaving as though it was flowing over a long, thin wing. Almost every fighter project in the postwar era immediately applied the concept, which started appearing on production fighters in the late 1940s. Avro engineers had previously explored swept-wing and tail modification to the CF-100 known as the CF-103, which had proceeded to wooden mock-up stage. Although the design theoretically provided transonic speeds, the small performance gain over the CF-100 was not considered worth the extra development costs.

Instead, the engineers turned to the delta-wing design, which had many of the advantages of the swept wing in terms of transonic performance, but offered much more internal room and overall area. This had the advantage of providing more internal room for fuel, an important consideration given the thirsty engines of the era, and the large wing area provided lift at high altitudes. The disadvantages of the design were increased drag at lower speeds and altitudes, a cause for some debate in the industry at the time. For the interceptor role this was a minor concern, as the aircraft would be spending most of its time at high altitudes and speeds, mitigating these disadvantages.

In the words of designer James C. Floyd,

"At the time we laid down the design of the CF-105, there was a somewhat emotional controversy going on in the United States on the relative merits of the delta plan form versus the straight wing for supersonic aircraft… our choice of a tailless delta was based mainly on the compromise of attempting to achieve structural and aeroelastic efficiency, with a very thin wing, and yet, at the same time, achieving the large internal fuel capacity required for the specified range".[4]

Further proposals resulted in two versions of the design known as C104: the single engine C104/1, and twin-engined C104/2. The designs were otherwise similar, using a low-mounted delta-wing and powered by the new Orenda TR.9 engines. Armament featured a battery of Velvet Glove missiles, (a Canadair Aircraft product based on CARDE design work), stored in an internal bay. It would be crewed by a single pilot guided by a completely automatic weapons control system to track and attack the target, similar to the system utilized in the F-86D. The primary advantages of the twin-engine C104/2 version was that it was larger overall, with a much larger weapons bay, and that it provided twin-engine reliability. The proposals were submitted to the RCAF in June 1952.

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:

* Crew of two (It was considered unlikely even a fully automated system would reduce workload enough to allow a lone crewman).
* Twin engines (no single engine then available could lift the fuel load needed for the long-range missions the RCAF demanded).
* Range of 300 nautical miles (556 km) for a normal low-speed mission, and 200 nautical miles (370 km) for a high-speed interception mission.
* Operation from a 6,000 foot (1830m) runway.
* Mach 1.5 cruise at an altitude of 50,000 feet (15,000 m).
* Maneuverability (2 g turns with no loss of speed or altitude at Mach 1.5 and 50,000 feet).
* The time from a signal to start the engines to the aircraft's reaching 50,000 feet and Mach 1.5 to be less than five minutes.
* Turn-around time on the ground was to be less than ten minutes.

An RCAF team led by Ray Footit visited U.S. aircraft producers and surveyed British and French manufacturers before concluding that no existing or planned aircraft could fulfill these requirements.

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 plane'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 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, from 1,000 to 1,400 square feet (93 to 130 m²
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