Avro Canada CF-105 Arrow MK1 Picture

The Avro Canada CF-105 Arrow was a delta-winged 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 altitudes exceeding 50,000 ft (15,000 m), and was intended to serve as the Royal Canadian Air Force's primary interceptor in the 1960s and beyond.

Not long after the 1958 start of its flight test program, the development of the Arrow (including its Orenda Iroquois jet engines) was abruptly and controversially halted,[1][2] sparking a long and bitter political debate.

Design and development

[edit] Background

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 until 1981 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 that would render the CF-100 ineffective, 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] Proposals

Avro engineering had been considering using 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 modifications to the CF-100 known as the C103, which had proceeded to wooden mock-up stage, and offered transonic performance with supersonic abilities in a dive. However, the basic CF-100 continued to improve through this period, and the advantages were eroded. When Janusz Żurakowski broke the sound barrier in a dive, interest in the C103 waned.[citation needed]

Another solution, picked up by the Avro engineers, was the delta-wing design. The delta-wing had many of the same advantages of the swept wing in terms of transonic performance, but offered much more internal room and overall area. This providing more 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, 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.

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 Sabre. 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 NM (556 km) for a normal low-speed mission, and 200 NM (370 km) for a high-speed interception mission.
* Operation from a 6 000 ft (1 830 m) runway.
* Mach 1.5 cruising speed at an altitude of 50 000 ft (15 000 m).
* Manoeuvrability (2 g turns with no loss of speed or altitude at Mach 1.5 and 50 000 ft).
* The time from a signal to start the engines to the aircraft's reaching 50 000 ft and Mach 1.5 to be less than 5 min.
* Turn-around time on the ground was to be less than 10 min.

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.

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, ranging between 1 000 ft2 and 1 400 ft2 (93 m2 to 130 m2). The 1 200 ft2 (111 m2) version was eventually selected. Three engines were considered as well: the Rolls-Royce RB106, the Bristol B.0L.4 Olympus, and the Curtiss-Wright J67 (a license-built version of the Olympus). The RB106 was selected, with the J67 as backup.

The weapons bay design was larger than the original C104/2 design, situated in a large thin box on the bottom fuselage, running from a point adjacent to the front of the wing to the middle of the fuselage. The weapon system originally selected was the Hughes MX-1179, which was a pairing of the existing MA-1 fire-control system with the AIM-4 Falcon missile of both radar-guided and heat-seeking variants. This system was already under development for proposed use in the USAF's WS-201 1954 interceptor (dating from 1949, which would lead to the F-102 Delta Dagger). The Velvet Glove radar-guided missile had been under development with the RCAF for some time, but was considered unsuitable for supersonic launch, and further work on that project was eventually cancelled in 1956.

In July 1953, the proposal was accepted and Avro was given the go-ahead to start a full design study. In December, CA$27 million was provided to start flight modeling. 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 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.

[edit] Production

Most aircraft designs start with the construction of a small number of hand-built prototypes that are test flown and modified, if required, before being committed to a set of jigs for production. This requires extra time to move from testing to manufacturing. The Arrow program instead adopted the Cook-Craigie plan. Developed in the 1940s, Cook-Craigie eliminated the prototype phase, with the first test airframes constructed on production jigs. 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, but together with the RCAF, "...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."[4]

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. In a related program, nine instrumented free-flight models were mounted on solid fuel Nike rocket boosters and launched over Lake Ontario while two additional models were launched from Wallops Island, USA, 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. Ongoing efforts have been made to search for the models in Lake Ontario; as of 2009[update], two have been found,[citation needed] along with one Nike booster and another for a Velvet Glove.

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 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.[4]

The aircraft used a measure of magnesium and titanium 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-monocoque frame and multi-spar wing.

The Arrow's thin wing required aviation's first 4 000 lb/in2 (28 MPa) 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, 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. An advanced stability augmentation system was added as well, recognizing that long, "thin" aircraft have a number of coupling modes that can lead to departure from controlled flight if not damped out quickly. Since the center of lift moved aft with speed, the flight control system also assisted stability and manoeuvre.

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 Pratt & Whitney J75 was selected for the initial test-flight models, while the new TR 13 (soon PS-13 Iroquois) engine was developed at Orenda for the production Mk 2s. Ultimately, only the rejected Bristol Olympus engine would actually go into production.

In 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 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. RCAF planners felt the greatly improved performance of the Sparrow was worth the gamble.

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, Canadair was quickly brought in to continue the Sparrow program in Canada, although they expressed grave concerns about the project as well.

[edit] Operational history

[edit] Political issues

In June 1957, the governing Liberals lost the federal election, and a Progressive Conservative government under John Diefenbaker took power. Diefenbaker, from the Canadian west, had campaigned on a platform of reining in what they claimed was "rampant Liberal spending." The debate was politically presented as an east versus west divide, with the Conservatives campaigning on a platform of eastern Canada using money from across the country to fund their "industrial welfare" projects. The Arrow was not the only major industrial project targeted during the campaign, others such as the "million dollar monster" postal sorting computer from Ferranti Canada were singled out for additional political scorn.

In August 1957, the Diefenbaker government signed the NORAD (North American Air Defense[5]) Agreement with the United States, which required the subordination of the RCAF Air Defence Command to American command and control[citation needed]. The USAF was in the process of completely automating their air defense system with the SAGE project, and insisted that the RCAF had to use it as well. One aspect of the SAGE system was the BOMARC nuclear-tipped anti-aircraft missile, which when intercepting bombers over Ontario and Quebec would be exploding over major Canadian cities. This led to studies on basing BOMARCs in Canada in order to push the line further north, away from the cities.

Storms of Controversy revealed a top secret brief prepared for George Pearkes, then Minister of National Defence, for his July 1958 meeting with U.S. officials. The brief states,

"The introduction of SAGE in Canada will cost in the neighborhood 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%…"

Pearkes was also concerned about funding defence against ballistic missiles. 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…"[6] In a document written after the cancellation, Pearkes noted, "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"[7] It is also said Canada could afford the Arrow or Bomarc/SAGE, but not both.[8].

In a later interview in the 1990s, Pearkes discussed these problems and revealed he was advised by an American official, while en route to Colorado, Canada did not need to build aircraft because the US had plenty and could make them available at any time. Pearkes states this is when he made his decision to cancel the Arrow. His dilemma was how to fill in the defence gap from cancellation of the Arrow to the time when Bomarc bases would be operational. He revealed he struck a deal to allow American training in Goose Bay (Labrador) and Cold Lake (Alberta) in exchange for protection.

By 11 August 1958, Pearkes requested cancellation of the Arrow, but the Cabinet Defence Committee 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, to better examine world conditions. They did, however, cancel the Sparrow/Astra system in September 1958. Efforts to continue the program through cost-sharing with other countries were then explored.

Worldwide, the Arrow was not the only heavy high-speed interceptor design cancelled at that time; the Republic Aircraft XF-103 and the North American Aviation XF-108 Rapier, designed to have higher performance specifications than the Arrow, were cancelled in the mock-up stage of development at approximately the same time.[9][10] Even the Convair F-106 Delta Dart was very nearly terminated. In the UK, the ramifications of the 1957 Defence White Paper led to the cancellation of almost all manned fighter aircraft development.

[edit] 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.[11]

From 1955 onwards, the UK had shown considerable interest in the Arrow; in April 1956, the UK's Air Council[12] recommended a purchase of 144 Arrows for the RAF to serve alongside the Saunders-Roe SR.177 mixed power interceptor, instead of the "thin-wing" Gloster Javelin then under study. The CF-105 would serve as a stopgap until the UK's F.155 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, even if the costs of acquisition had not been so high. The infamous 1957 Defence White Paper, prompted by a general lack of funds, foretold an end to manned fighters and completely curtailed any likelihood of a purchase. In January 1959, the UK's final answer was no—with an offer to sell Canada the English Electric P.1 (the aircraft that would become the English Electric Lightning) instead. The French government was prepared to buy some 200 Iroquois engines, but cancelled their order in 1958, being advised by persons unknown that the Arrow was going to be cancelled.[citation needed]

The US Air Force had already developed three aircraft with performance intended to be broadly similar to the Arrow, originally as part of their "1954 Interceptor" project—the McDonnell F-101B Voodoo, Convair F-102 Delta Dagger and Convair F-102B (later Convair F-106 Delta Dart). Additionally, two more advanced interceptors (the Republic XF-103 and North American XF-108) were under development, although both would ultimately be cancelled in the early design and mock-up phases.[13] Nevertheless it appears the USAF was concerned about the effect the cancellation would have on Canada's defence industry. In 1958, Avro Aircraft Limited President and General Manager Fred Smye 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 center at Muroc Lake in California (now known as Edwards AFB)".[14]

[edit] Cancellation

The cancellation on 20 February 1959 known as "Black Friday"[15] immediately put 14,528 Avro employees [16] out of work as well as nearly 15,000 other employees in the Avro "supply chain" of outside suppliers.[17][18] Declassified records show Avro management was caught unprepared by the suddenness of the announcement by the government. While executives were aware that the program was in jeopardy, they expected it to continue at least until the March review. It was widely believed that during this lead-up to the review, the first Arrow Mk 2, RL-206, would be prepared for an attempt at both world speed and altitude records.

An attempt was made to provide the completed Arrows to the National Research Council of Canada as high-speed test aircraft. The NRC refused, noting that without sufficient spare parts and maintenance, as well as qualified pilots, the NRC could make no use of them. A similar project initiated by the Royal Aircraft Establishment (Boscombe Down) had resulted in Avro Vice-President (Engineering) Jim Floyd, preparing a transatlantic ferry operation. This proposal, like others from the United States, was never realized.
Avro CF-105 Arrow nose section on display at the Canada Aviation Museum
Avro CF-105 Arrow nose section on display at the Canada Aviation Museum showing torch cut marks where the nose was severed.

[edit] Aftermath

Within two months of the project cancellation, all aircraft, engines, production tooling and technical data were ordered scrapped. Officially, the reason given for the destruction order from Cabinet and the Chiefs of Staff was to destroy classified and "secret" materials utilized in the Arrow/Iroquois programs.[19]The action has been attributed to Royal Canadian Mounted Police fears that a Soviet "mole" had infiltrated Avro, later confirmed to some degree in the Mitrokhin archives[20].

Along with the five flying test models and production aircraft, blueprints and other materials were destroyed, leading to the creation of a piece of Canadian mythology. The rushed destruction incited a number of conspiracy theories alleging American culpability for the Arrow's demise. There remains an enduring but fanciful legend that one of the prototypes was spirited away after the cancellation and remains intact somewhere.[21]

Following the Canadian government's cancellation of the Avro Arrow project in 1959, CF-105 Chief Aerodynamicist Jim Chamberlin led a team of 25 engineers to NASA's Space Task Group to become lead engineers, program managers, and heads of engineering in NASA's manned space programs—
Avro Canada CF-105 Arrow MK1