Avro CF-105 Arrow

Higher speeds

Avro engineering had been considering supersonic issues for some time 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 [Vous devez être inscrit et connecté pour voir ce lien], known in the West as [Vous devez être inscrit et connecté pour voir ce lien].

Wave drag was so powerful, engines of the era could not provide enough power to overcome it, leading to the concept of a "[Vous devez être inscrit et connecté pour voir ce lien]".
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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 slowly as possible.

This suggested the use of thinner airfoils with much longer [Vous devez être inscrit et connecté pour voir ce lien] than what designers would have used on subsonic aircraft.

These designs were impractical because they left little internal room in the wing for armament or fuel.

However, they 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 [Vous devez être inscrit et connecté pour voir ce lien].

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.
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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 modifications to the CF-100 known as the [Vous devez être inscrit et connecté pour voir ce lien], which had proceeded to wooden mock-up stage, and offered improved transonic performance with supersonic abilities in a dive.

However, the basic CF-100 continued to improve through this period, and the advantages were eroded.

Delta wings

An innovative aspect of the design was the [Vous devez être inscrit et connecté pour voir ce lien] design.

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 enabled slower landings than swept wings in certain conditions.
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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.
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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.

The designs were otherwise similar, using a low-mounted delta-wing; the primary advantages of the C104/2 were a larger overall size which offered a much larger internal weapons bay, at the time a cutting-edge feature in a fighter, and gave twin-engine reliability.

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 crew of two, twin engines, with a range of 300 [Vous devez être inscrit et connecté pour voir ce lien] (556 km) for a normal low-speed mission, and 200 nmi (370 km) for a high-speed interception mission.

It also specified operation from a 6,000 ft (1,830 m) runway; a Mach 1.5 cruising speed at an altitude of 70,000 ft (21,000 m); and manoeuvrability for 2 [Vous devez être inscrit et connecté pour voir ce lien] turns with no loss of speed or altitude at Mach 1.5 and 50,000 ft.

The specification required five minutes from starting the aircraft's engines to reaching 50,000 ft altitude and Mach 1.5.

It was also to have turn-around time on the ground of less than 10 minutes.

An RCAF team led by Ray Foottit visited U.S. aircraft producers and surveyed British and French manufacturers before concluding that no existing or planned aircraft could fulfill these requirements.
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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 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 1,000 ft² and 1,400 ft² (93 m² to 130 m²); the 1,200 ft² (111 m²) sized version was eventually selected.

The engines considered for the aircraft were the [Vous devez être inscrit et connecté pour voir ce lien], the [Vous devez être inscrit et connecté pour voir ce lien] or the [Vous devez être inscrit et connecté pour voir ce lien] engines.

Armament was stored in a large internal bay located in a "belly" position, taking up over one third of the aircraft fuselage.

A wide variety of weapons could be deployed from this bay, such as the [Vous devez être inscrit et connecté pour voir ce lien] guided missile, the [Vous devez être inscrit et connecté pour voir ce lien] air to air missile, or four general-purpose 1,000 lb bombs.

The [Vous devez être inscrit et connecté pour voir ce lien] radar-guided missile had been under development with the RCAF for some time, but was proven 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 [Vous devez être inscrit et connecté pour voir ce lien] Bison jet [Vous devez être inscrit et connecté pour voir ce lien] and the Soviet Union's testing of a [Vous devez être inscrit et connecté pour voir ce lien] dramatically changed [Vous devez être inscrit et connecté pour voir ce lien] 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 [Vous devez être inscrit et connecté pour voir ce lien].^{[Vous devez être inscrit et connecté pour voir ce lien]}

Production


In order to meet the timetable set by the RCAF, Avro decided that Arrow program would adopt the [Vous devez être inscrit et connecté pour voir ce lien]; effectively eliminating the prototype phase, the first test airframes were constructed on production jigs.^{[Vous devez être inscrit et connecté pour voir ce lien]
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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, however: "...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."
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In order to mitigate risks, a massive testing program was started.

By mid-1954, the first production drawings were issued and wind tunnel work began, along with extensive computer simulation studies carried out both in Canada and the United States utilizing sophisticated computer programs.

In a related program, nine instrumented free-flight models were mounted on solid fuel [Vous devez être inscrit et connecté pour voir ce lien] rocket boosters and launched from Point Petre over Lake Ontario while two additional models were launched from the NACA facility at [Vous devez être inscrit et connecté pour voir ce lien],
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.^{[Vous devez être inscrit et connecté pour voir ce lien]
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Experiments showed the need for only a small number of design changes, mainly involving the wing profile and positioning.

To improve [Vous devez être inscrit et connecté pour voir ce lien] performance, the leading edge of the wing was drooped, especially on outer sections, a [Vous devez être inscrit et connecté pour voir ce lien] was introduced to control spanwise flow, and the entire wing given a slight negative [Vous devez être inscrit et connecté pour voir ce lien] which helped control trim drag and pitch-up.


The [Vous devez être inscrit et connecté pour voir ce lien] 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.
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The aircraft used a measure of [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien] in the fuselage, the latter limited largely to the area around the
engines and to fasteners.

Titanium was still expensive and not widely used because it was difficult to machine.

The construction of the airframe itself was fairly conventional, however, with a semi-[Vous devez être inscrit et connecté pour voir ce lien] frame and multi-spar wing.

The Arrow's thin wing required aviation's first 4,000 [Vous devez être inscrit et connecté pour voir ce lien] (28 MPa) hydraulic system to supply enough force to the control surfaces, while using small actuators and piping.

A rudimentary [Vous devez être inscrit et connecté pour voir ce lien] system was employed, in which the pilot's input was detected by a series of pressure-sensitive transducers in the stick, and their signal was sent to an electronic control servo that operated the valves in the hydraulic system to move the various 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.
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In 1954, the RB.106 program was cancelled, necessitating the use of the backup J67 engine instead. In 1955, this engine was also cancelled, leaving the design with no engine.

At this point, the [Vous devez être inscrit et connecté pour voir ce lien] was selected for the initial test-flight models, while the new TR 13 engine was developed at [Vous devez être inscrit et connecté pour voir ce lien] for the production Mk 2s.
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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 [Vous devez être inscrit et connecté pour voir ce lien] in place of the MX-1179 and Falcon combination.

Avro vocally objected on the grounds that neither of these were even in testing at that point, whereas both the MX-1179 and Falcon were almost ready for production and would have been nearly as effective for "a very large saving in cost".The Astra proved to be problematic as the system ran into a lengthy period of delays, and when the USN cancelled the Sparrow II in 1956, [Vous devez être inscrit et connecté pour voir ce lien] 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 4 October 1957.

The company had planned to capitalize on the event, inviting more than 13,000 guests to the occasion.

Unfortunately for Avro, the media and public attention for the Arrow rollout was dwarfed by the launch of [Vous devez être inscrit et connecté pour voir ce lien] the same day.^{[Vous devez être inscrit et connecté pour voir ce lien]
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The J75 engine was slightly heavier than the PS-13, and therefore required ballast to be placed in the nose to return the [Vous devez être inscrit et connecté pour voir ce lien] 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 [Vous devez être inscrit et connecté pour voir ce lien] 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, a large part due to the natural qualities of the delta-wing, but responsibility can also be attributed to the Arrow's stability augmentation system.

The aircraft went supersonic on its third flight and, on the seventh, broke 1,000 [Vous devez être inscrit et connecté pour voir ce lien] (1,600 km/h) at 50,000 ft (15,000 m), while climbing and accelerating.

A top speed of Mach 1.98 was achieved, however this was not at the limits of its performance.
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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 former problem 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 the chain mechanism (used to shorten the gear) in the Mark 1 gear jammed, resulting in incomplete rotation.

In a second incident with Arrow 202 on 11 November 1958, the flight control system commanded [Vous devez être inscrit et connecté pour voir ce lien] full down at landing; the resulting reduction in weight on the gears reduced the effective tire friction, ultimately resulting in brake
lockup and subsequent gear collapse.^{[Vous devez être inscrit et connecté pour voir ce lien][Vous devez être inscrit et connecté pour voir ce lien]}

A photograph taken of the incident proved inadvertent flight control activation had caused the accident.

The only occasion when a test flight was diverted occurred on 2 February 1959, when a TCA Viscount crash-landed in Toronto, necessitating a landing at CFB Trenton.
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The stability augmentation system also required much fine-tuning.^{[Vous devez être inscrit et connecté pour voir ce lien][Vous devez être inscrit et connecté pour voir ce lien]}

Although the CF-105 was not the first aircraft to use such a system, it was one of the first of its kind, and was consequently 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 onwards, some senior Canadian military officials at the Chief of Staffs began to question the program.

It was not until June 1957, however, when the governing [Vous devez être inscrit et connecté pour voir ce lien] lost the federal election and a [Vous devez être inscrit et connecté pour voir ce lien] government under [Vous devez être inscrit et connecté pour voir ce lien] took power, that the aircraft's fate began to noticeably change.

Diefenbaker, from the Canadian west, had campaigned on a platform of reining in what the Conservatives claimed was "rampant Liberal spending."

The Arrow was not the only major industrial project targeted during the campaign, others such as the "million dollar monster" postal sorting computer from [Vous devez être inscrit et connecté pour voir ce lien] were singled out for additional political scorn.

A criticism that had been voiced in the 1950s in the media was that Avro Canada as a company had little interest in competing with its products on the market, and instead had come to rely solely upon the availability of government financing for its activities.

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.
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In August 1957, the Diefenbaker government signed the [Vous devez être inscrit et connecté pour voir ce lien] (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 defense system with the [Vous devez être inscrit et connecté pour voir ce lien] 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 [Vous devez être inscrit et connecté pour voir ce lien] nuclear-tipped anti-aircraft missile.

This led to studies on basing BOMARCs in Canada in order to push the line further north, however the deployment was evaluated as being extremely costly.

“	The introduction of SAGE in Canada will cost in the neighbourhood of $107 million. Further improvements are required in the radar... NORAD has also recommended the introduction of the BOMARC missile... will be a further commitment of $164 million... All these commitments coming at this particular time... will tend to increase our defence budget by as much as 25 to 30%.	”
—[Vous devez être inscrit et connecté pour voir ce lien], then Minister of National Defence, 1958[Vous devez être inscrit et connecté pour voir ce lien]

Defence against ballistic missiles was also becoming a priority.

The existence of Sputnik had also raised the spectre of attack from space, and, as the year progressed, word of a "missile gap" began spreading.

An American brief of the meeting with Pearkes reported Pearkes "stated that the problem of developing a defence against missiles while at the same time completing and rounding out defence measures against manned bombers posed a serious problem for Canada from the point of view of expense".

It is also said Canada could afford the Arrow or Bomarc/SAGE, but not both.
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By 11 August 1958, Pearkes requested cancellation of the Arrow, but the Cabinet Defence Committee (CDC) refused.

He 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 in 31 March 1959, however, the Sparrow/Astra system was cancelled in September 1958.

Efforts to continue the program through cost-sharing with other countries were then explored.

“	We did not cancel the CF-105 because there was no bomber threat, but because there was a lesser threat and we got the Bomarc in lieu of more airplanes to look after this.	”

Operational history

Foreign interest

Canada tried to sell the Arrow aircraft to the U.S. and Britain, but had no takers.

The aircraft industry in both countries was considered a national interest and the purchase of foreign designs was rare; and in this era the Arrow was far from the only heavy high-speed interceptor to end in cancellation.

From 1955 onwards, the UK had shown considerable interest in the Arrow; in April 1956, the UK's Air Council recommended a purchase of 144 Arrows for the [Vous devez être inscrit et connecté pour voir ce lien] to serve alongside the [Vous devez être inscrit et connecté pour voir ce lien] mixed power interceptor, instead of the "thin-wing" [Vous devez être inscrit et connecté pour voir ce lien] then under study.

The CF-105 would serve as a stopgap until the UK's [Vous devez être inscrit et connecté pour voir ce lien] project came to fruition; however with the F.155 due in 1963 and the Arrow not likely to reach the RAF before 1962, there was little point in proceeding.

The infamous [Vous devez être inscrit et connecté pour voir ce lien], described as "the biggest change in military policy ever made in normal times", led to the cancellation of almost all British manned fighter aircraft then in development, and completely curtailed any likelihood of a purchase.

In January 1959, the UK's final answer was no; and introduced an offer to sell Canada the [Vous devez être inscrit et connecté pour voir ce lien] instead.
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Acting on media speculation that the Iroquois engine program was also in jeopardy of being cancelled, the French government whose original intention was to place a major order for 300 Iroquois engines for the [Vous devez être inscrit et connecté pour voir ce lien] bomber, chose to end negotiations in October 1958 and opted for the indigenous [Vous devez être inscrit et connecté pour voir ce lien] engine.

The [Vous devez être inscrit et connecté pour voir ce lien] had already developed three aircraft with performance intended to be broadly similar to the Arrow, originally as part of their "[Vous devez être inscrit et connecté pour voir ce lien]" project—the [Vous devez être inscrit et connecté pour voir ce lien], [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien].

Additionally two more advanced interceptors, the [Vous devez être inscrit et connecté pour voir ce lien] and [Vous devez être inscrit et connecté pour voir ce lien], were under development, although both would ultimately be cancelled in the early design and mock-up phases.

The U.S. decision to cancel many of their own interceptors, along with a firm rejection of an offer to procure Arrows for their own use, added weight for the justification of cancelling the Arrow.

In 1958, Avro Aircraft Limited President and General Manager [Vous devez être inscrit et connecté pour voir ce lien] elicited a promise from the USAF to "supply, free, the fire control system and missiles and if they would allow the free use of their flight test centre at... Edwards AFB".