Editing Avro Canada CF-105 Arrow (section)

==Design and development==

===Background===
[[File:Avro Arrow Replica CanadianAirAndSpaceMuseum Toronto.jpg|thumb|Full size replica of the CF-105 Arrow at the [[Canadian Air and Space Museum]], 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.<ref name = 'dow67'>Dow 1979, p.&nbsp;67.</ref> 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.<ref name = 'dow60'>Dow 1979, p.&nbsp;60.</ref> To counter this threat, Western countries developed [[interceptor aircraft|interceptors]] that could engage and destroy these bombers before they reached their targets.<ref name= "Gunston p. 18">Gunston 1981, p.&nbsp;18.</ref><ref name = 'dow84-5'>Dow 1979, pp.&nbsp;84–85.</ref>

[[Avro Canada|A.&nbsp;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.<ref name = 'dow61-2'>Dow 1979, pp.&nbsp;61–62.</ref> The Canuck underwent a lengthy and troubled prototype stage before entering service seven years later in 1953.<ref name = 'dow70'>Dow 1979, p.&nbsp;70.</ref> Nevertheless, it went on to become one of the most enduring aircraft of its class, serving in a variety of roles until 1981.<ref name="Frontiers">Lombardi, Mike and Larry Merritt. [http://www.boeing.com/news/frontiers/archive/2005/june/i_history.html "Toronto's Long History of Aerospace Achievement"]. ''Boeing Frontiers'' (online), Volume 4, Issue 2, June 2005. Retrieved: 26 September 2010.</ref>

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.<ref>Dow 1979, p.&nbsp;83.</ref> In March 1952, the RCAF's ''Final Report of the All-Weather Interceptor Requirements Team'' was submitted to Avro Canada.<ref name = 'dow84'/>

===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 (physics)|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]]".<ref>Anderson 2008. pp.&nbsp;683, 695.</ref>

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 (aircraft)|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.<ref name="Whitcomb 2002, pp. 89–90">Whitcomb 2002, pp.&nbsp;89–90.</ref>

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.<ref name="Whitcomb 2002, pp. 89–90"/>

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 [[Avro Canada CF-103|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.<ref>Milberry 1984, p.&nbsp;317.</ref> When a CF-100 broke the sound barrier on 18 December 1952, interest in the CF-103 waned.

===Delta wings===
{{quote box|align=right|width=33%|quote=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&nbsp;... our choice of a tailless delta was based mainly on the compromise of attempting to achieve structural and aero elastic efficiency, with a very thin wing, and yet, at the same time, achieving the large internal fuel capacity required for the specified range.|source= —Designer [[James C. Floyd]]<ref name=Floyd>Floyd, James. "The Canadian Approach to All-Weather Interceptor Development. The Fourteenth British Commonwealth Lecture." ''Journal of the Royal Aeronautical Society'', December 1958</ref>}}

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.<ref name = 'stimsonpm'>Stimson, Thomas E. Jr. [https://books.google.com/books?id=peEDAAAAMBAJ "Era of the Flying Triangles"]. ''Popular Mechanics'', 106 (3). September 1956, pp.&nbsp;89–94.</ref>

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.<ref name = 'stimsonpm'/>

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.<ref name = 'dow84'>Dow 1979, p.&nbsp;84.</ref> 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.<ref name = 'campagna68-69'>Campagna 1998, pp.&nbsp;68–69.</ref> The proposals were submitted to the RCAF in June 1952.<ref>Page et al. 2004, p.&nbsp;11.</ref>

===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 {{nowrap|300 nautical miles (556 km}}) for a normal low-speed mission, and {{nowrap|200 nmi (370 km)}} for a high-speed interception mission. It also specified operation from a {{nowrap|6,000 ft (1,830 m)}} runway; a Mach&nbsp;1.5 cruising speed at an altitude of {{nowrap|70,000 ft (21,000 m)}}; and manoeuvrability for 2&nbsp;[[g-force|''g'']] turns with no loss of speed or altitude at Mach&nbsp;1.5 and {{nowrap|50,000 ft}}. The specification required five minutes from starting the aircraft's engines to reaching {{nowrap|50,000 ft}} altitude and Mach&nbsp;1.5. It was also to have turn-around time on the ground of less than {{nowrap|10 minutes}}.<ref name = 'dow89'>Dow 1979, p.&nbsp;89.</ref> An RCAF team led by Ray Foottit visited US aircraft producers and surveyed British and French manufacturers before concluding that no existing or planned aircraft could fulfill these requirements.<ref name = 'dow25'>Dow 1979, p.&nbsp;25.</ref>

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&nbsp;1.9 at 50,000&nbsp;ft, Combat speed of Mach&nbsp;1.5 at 50,000&nbsp;feet and 1.84&nbsp;g without bleeding energy, time to 50,000&nbsp;ft of 4.1&nbsp;minutes, 500-foot per minute climb ceiling of 62,000&nbsp;feet, 400&nbsp;nmi radius on a high-speeds mission, 630&nbsp;nmi radius on a low-speed mission, Ferry range is not given, but estimated at 1,500&nbsp;nmi."<ref>{{cite book|page =162 |title= Avro Aircraft & Cold War Aviation |first= R.L |last= Whitcomb}}</ref>

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 {{nowrap|1,000 ft<sup>2</sup> and 1,400 ft<sup>2</sup> (93 m<sup>2</sup> to 130 m<sup>2</sup>)}}; the {{nowrap|1,200 ft<sup>2</sup> (111 m<sup>2</sup>)}} sized version was eventually selected.<ref name = 'peden26'>Peden 2003, p.&nbsp;26.</ref>

The primary engine selection was the [[Rolls-Royce RB.106]], an advanced two-spool design offering around {{convert|21000|lbf|kN}}. Backup designs were the [[Bristol Olympus|Bristol Olympus OL-3]], the US-built [[Curtiss-Wright J67]] version of the OL-3, or the [[Orenda Engines|Orenda TR.9]] engines.<ref name = 'dow85'>Dow 1979, p.&nbsp;85.</ref>

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 [[Hughes Falcon]] guided missile, the [[CARDE]] [[Velvet Glove]] air-to-air missile, or four general-purpose 1,000&nbsp;lb bombs.<ref name = 'dow86'>Dow 1979, p.&nbsp;86.</ref> 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.<ref name = 'campagna66-67'>Campagna 1998, pp.&nbsp;66–67.</ref>

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".<ref>Page et al. 2004, p.&nbsp;12.</ref> 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 [[Joe 4|testing of a hydrogen bomb the next month]] dramatically changed [[Cold War]] priorities.<ref name = 'peden45'>Peden 2003, p.&nbsp;45.</ref> In March 1955, the contract was upgraded to CA$260&nbsp;million for five Arrow Mk.1 flight-test aircraft, to be followed by 35 Arrow Mk. 2s with production engines and [[fire-control system]]s.<ref>Shaw 1979, p.&nbsp;58.</ref>

===Production===

[[File:Cf-105 Arrow002.jpg|thumb|RL-204, late 1958]]
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.<ref>Whitcomb 2002, p.&nbsp;86.</ref><ref name = 'pigott55'>Pigott 1997, p.&nbsp;55.</ref> 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&nbsp;... 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."<ref name=Floyd/>

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 using sophisticated computer programs.<ref name = 'peden38'>Peden 2003, p.&nbsp;38.</ref> In a related program, nine instrumented free-flight models were mounted on solid fuel [[Project Nike|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&nbsp;1.7+ before intentionally crashing into the water.<ref>Page et al. 2004, p.&nbsp;15.</ref><ref>Belleau, Naomi. [http://www.navy.forces.gc.ca/cms/4/4-a_eng.asp?category=12&id=193 "Domestic Operations: Trinity's "Fiona" takes the plunge in search of Avro Arrow"] ({{webarchive|url=https://web.archive.org/web/20110613033931/http://www.navy.forces.gc.ca/cms/4/4-a_eng.asp?category=12&id=193|date=13 June 2011 }}) ''Canadian Navy''. Retrieved: 11 September 2010.</ref>

Experiments showed the need for only a small number of design changes, mainly involving the wing profile and positioning. To improve [[angle of attack|high-alpha]] performance, the leading edge of the wing was drooped, especially on outer sections, a [[Dogtooth extension|dog-tooth]] was introduced at about half-span to control spanwise flow,<ref>Whitcomb 2002, pp.&nbsp;89–91.</ref> and the entire wing given a slight negative [[Camber (aerodynamics)|camber]] which helped control trim drag and pitch-up.<ref name = 'campagna37'>Campagna 1998, p.&nbsp;37.</ref> 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.<ref name=Floyd/>

The construction of the airframe was fairly conventional, with a semi-[[monocoque]] frame and multi-spar wing. 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.<ref>Whitcomb 2002, pp.&nbsp;109–110.</ref>

The Arrow's thin wing required aviation's first {{cvt|4000|psi|MPa}} hydraulic system to supply enough force to the control surfaces,{{fact|date=December 2019}} 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.<ref name = 'campagna73-74'>Campagna 1998, pp.&nbsp;73–74.</ref>

In 1954, the [[Rolls-Royce RB106|RB.106]] program was cancelled, necessitating the use of the backup [[Wright J67#Curtiss-Wright Derivatives|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.<ref name = 'pigott56'>Pigott 1997, p.&nbsp;56.</ref>

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]] [[AIM-7 Sparrow#Sparrow II|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 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".<ref name = 'peden46-47'>Peden 2003, pp.&nbsp;46–47.</ref> 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 and the move added yet more expense.<ref name = 'campagna68'>Campagna 1998, p.&nbsp;68.</ref>

===Rollout and flight testing===

[[File:Unveiling of CF-105 Dévoilement de l’aéronef CF-105 (49553834541).jpg|thumb|right|Unveiling of CF-105 on October 4, 1957. Pilots Ron Hodge (left), Ed Wright (right).]]
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 {{nowrap|13,000}} guests to the occasion.<ref>Gainor 2001, p.&nbsp;15.</ref> Unfortunately for Avro, the media and public attention for the Arrow rollout was dwarfed by the launch of [[Sputnik]] the same day.<ref name= "Gunston p. 18"/><ref>{{cite magazine |archive-date=17 May 2014 |url=http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%201472.html |title=The Arrow Unveiled |magazine=[[Flight International]] |archive-url=https://web.archive.org/web/20140517120058/http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%201472.html |date=11 October 1957 |pages=562–563 |access-date=24 May 2023}}</ref>

The J75 engine was slightly heavier than the [[Orenda Iroquois|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.<ref>Page et al. 2004, p.&nbsp;161.</ref>

{{quote box|align=left|width=25%|quote=The aircraft, at supersonic speeds, was pleasant and easy to fly. During approach and landing, the handling characteristics were considered good&nbsp;... On my second flight&nbsp;... the general handling characteristics of the Arrow Mark 1 were much improved&nbsp;... On my sixth and last flight&nbsp;... the erratic control in the rolling plane, encountered on the last flight, [was] no longer there&nbsp;... Excellent progress was being made in the development&nbsp;... from where I sat the Arrow was performing as predicted and was meeting all guarantees.|source= —Jack Woodman, the only RCAF pilot to fly the Arrow<ref name = 'campagna86-87'>Campagna 1998, pp.&nbsp;86–87.</ref>}}

RL-201 first flew on 25 March 1958 with Chief Development Test Pilot S/L [[Janusz Żurakowski]] at the controls.<ref name = 'pigott57'>Pigott 1997, p.&nbsp;57.</ref> 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.<ref name = 'campagna84'>Campagna 1998, p.&nbsp;84.</ref><ref>[https://books.google.com/books?id=MQTGAAAAIAAJ "Air & Space Smithsonian, Volume 13"]. Smithsonian Institution. 1998, p.&nbsp;37.</ref> 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]].<ref name = 'campagna85'/> The aircraft went supersonic on its third flight and,<ref name = 'pigott57'/> on the seventh, broke {{nowrap|1,000 mph (1,600 km/h)}} at {{nowrap|50,000 ft (15,000 m)}} while climbing. A top speed of Mach&nbsp;1.98 was achieved, and this was not at the limits of its performance.<ref name = 'campagna87'/> An Avro report made public in 2015 clarifies that during the highest speed flight, the Arrow reached Mach&nbsp;1.90 in steady level flight, and an indicated Mach number of 1.95 was recorded in a dive.<ref name = 'Waechter15'>Waechter 2015, pp. 113–18.</ref> Estimates up to Mach&nbsp;1.98 likely originated from an attempt to compensate for [[Pitot-static system#Lag errors|lag error]], which was expected in diving flight.<ref name = 'Waechter15a'>Waechter 2015, p. 73.</ref>

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{{#tag:ref|The CF-105 used tandem main undercarriage units with two wheels and tires: one in front of and one behind the gear leg.|group=Note}} being very narrow, in order to fit into the wings; the leg shortened in length and rotated as it was stowed.<ref name = 'campagna70'>Campagna 1998, p.&nbsp;70.</ref> 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<ref>{{cite book |last1=Martin |first1=P |title=Report on accident to AVRO Arrow I 25201 on 11 June 1958 at Malton |date=1958 |url=https://nrc-digital-repository.canada.ca/eng/view/ft/?id=f586fd5a-affc-4260-849b-dc94680af18f}}</ref>.<ref name = 'campagna87'/> In a second incident with Arrow 202 on 11 November 1958, the flight control system commanded [[elevon]]s 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.<ref name = 'campagna86'>Campagna 1998, p.&nbsp;86.</ref> A photograph taken of the incident proved that inadvertent flight control activation had caused the accident.<ref>[https://web.archive.org/web/20070927201035/http://www.avromuseum.ca/index.php?q=node%2F45 "Avro Museum"]. Avro Museum of Canada via ''web.archive.org''. Retrieved: 4 September 2010.</ref> 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.<ref>Page et al. 2004, p.&nbsp;115.</ref>

The stability augmentation system also required much fine-tuning.<ref name = 'campagna87'>Campagna 1998, p.&nbsp;87.</ref> Although the CF-105 was not the first aircraft to use such a system,{{#tag:ref| The CF-105 Arrow used the stability augmentation system for all three axes; other aircraft in the 1950s, were experimenting with these systems, but had only reached the stage of incorporating simple, one-axis or two-axes stability augmentation.<ref>Abzug and Larrabee, 2002, p.&nbsp;316.</ref>|group=Note}} it was one of 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.<ref name="Page et al. 2004, p.&nbsp;117">Page et al. 2004, p.&nbsp;117.</ref>

===Political issues===
From 1953, some senior Canadian military officials at the chiefs of staffs began to question the program.<ref>Story, Donald C. and Russel Isinger. "The origins of the cancellation of Canada's Avro CF-105 arrow fighter program: A failure of strategy". ''Journal of Strategic Studies'', 30(6), December 2007.</ref> 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 Lester Campbell|Hugh Campbell]], RCAF Chief of Staff, backed it right up until its cancellation.<ref>Stewart 1988, p.&nbsp;235.</ref> In June 1957, when the governing [[Liberal Party of Canada|Liberals]] lost the federal election and a [[Progressive Conservative Party of Canada|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.&nbsp;V. Roe Canada banner.<ref>Stewart, 1988, p.&nbsp;238.</ref>

In September 1957,<ref>{{Cite web |title=North American Aerospace Defense Command > About NORAD > NORAD Agreement |url=https://www.norad.mil/About-NORAD/NORAD-Agreement/#:~:text=as%20a%20bi-national%20command,that%20established%20NORAD%20was%20formalized. |archive-url=http://web.archive.org/web/20250407195725/https://www.norad.mil/About-NORAD/NORAD-Agreement/ |archive-date=2025-04-07 |access-date=2025-05-01 |website=www.norad.mil |language=en-US}}</ref> the Diefenbaker government signed the [[NORAD]] (North American Air Defense)<ref>[https://fas.org/nuke/guide/usa/airdef/norad-overview.htm "NORAD at 40 Historical Overview"]. ''fas.org''. Retrieved: 4 September 2010.</ref> 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 [[Semi Automatic Ground Environment|SAGE]] project, and offered Canada the opportunity to share this sensitive information for the air defence of North America.<ref>[https://web.archive.org/web/20110615013937/http://www.cda-cdai.ca/cdai/uploads/cdai/2009/04/rodzinyak02.pdf "Good Neighbours Make Good Fences: Canadian Continental Defence Planning and the 1954 Decision to fund the Mid-Canada Early Warning Line"]. Conference of Defence Associates Institute, April 2009.</ref> 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&nbsp;million, while SAGE would absorb another C$107&nbsp;million, not counting the cost of improvements to radar; in all, it was projected to raise Canada's defence spending by "as much as 25 to 30%", according to [[George Pearkes]], the minister of national defence.<ref>Campagna 1998</ref>

Defence against ballistic missiles was also becoming a priority. The existence of ''Sputnik'' had also raised the possibility of attacks from space, and, as the year progressed, word of a "[[missile gap]]" began spreading. 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.<ref>"Canada-U.S. Defence Problems, File: DDE Trip to Canada, Memcons, 8–11 July 1958." ''Eisenhower Library''.</ref> It is also said Canada could afford the Arrow or Bomarc/SAGE, but not both.<ref>Campagna 1998, p.&nbsp;88.</ref>

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.<ref name = 'campagna108'>Campagna 1998, p.&nbsp;108.</ref> 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".<ref>"File 79/469 Folder 19." ''Directorate of History, Department of National Defence''</ref>