Aviation History: The Avro CF-100 Canuck – Clunking Up for 30 Years

There were many tragedies that came from World War Two, but one of the positives was aviation technology moved forward in leaps and bounds over that relatively short period of time.  It was during the war that the first combat jet aircraft, the German Messerschmitt Me 262, saw service.  The Allied forces weren’t too far behind with the British Gloster Meteor and the American Lockheed P-80 Shooting Star, both of which were released as the war was ending.  Even after the war ended this momentum in aviation technology didn’t slow down.  It was really just the beginning, as it was the dawn of the jet age.

Avro CF-105 Arrow

Although much smaller in population than the USA, Germany, and Britain, Canada also got swept up in this jet age and developed a significant local aviation industry.  It was during this era that Canada made a number of advanced aircraft designs; however, many would never go beyond the development stages.  Most Canadians are well versed in the story of the Avro CF-105 Arrow.  It was to be a revolutionary, world class jet interceptor.  But the Arrow never went beyond the prototype stage and was cancelled by the Canadian Government.  The Arrow’s predecessor was the CF-100 Canuck.  It was a successful all-weather interceptor designed entirely in Canada.  Despite an excellent service record, the CF-100 is overshadowed by the loss of the Arrow.

To examine the history of the CF-100, let’s step back to the time before World War Two.  In 1938 a new Aircraft plant was opened in Malton, Ontario as a Division of National Steel Car Corporation.  By 1939, this factory produced Westland Lysanders under license and later produced the Handley-Page Hampton bombers.  Once World War Two started, the plant was converted to build other aircraft that suited the needs of the RCAF.  This included aircraft such as the Hawker Hurricane and the Anson Trainer, but most famously the Avro Lancaster bomber.  Shortly after the decision was made to produce the Lancaster, the Canadian government decided to purchase the aircraft plant to take over the operations.  The company was renamed the Victory Aircraft Company.

The Victory Aircraft Company produced many Lancasters during WWII

Victory Aircraft proved to be an excellent manufacturer, producing 430 Lancasters, 3197 Avro Ansons and a handful of a few other large Avro aircraft.  Nevertheless, after World War Two ended, the Canadian Government had no further interest in being in the aircraft industry.  As a result, the Victory Aircraft Company was sold the Hawker-Siddeley Group in 1945.  The company was renamed A.V. Roe Canada LTD, more commonly called Avro Canada, and it was officially the Canadian branch of the UK based A.V. Roe and Company.

At this time, the Canadian Government owned another Crown Corporation called Turbo Research Limited.  This company had been working on the development of jet engines and in fact had a jet engine in the design stage.  In 1946 the Canadian Government sold Turbo Research to Hawker-Siddeley to become part of A.V. Roe Canada and it was renamed Orenda Engines.

With the end of the war, there was little work for newly formed Avro Canada with no immediate need to produce aircraft.  The company had some aircraft maintenance contracts but this wasn’t enough to sustain the business.  So they stayed afloat by producing a variety of products including truck fenders, oil furnaces, and tractors.

Northrop’s F-89 Scorpion didn’t meet the specifications set out by the RCAF for an all-weather interceptor

At the same time, during 1946 the RCAF had developed a list of requirements for a new long range all–weather interceptor aircraft.  A team was formed to evaluate aircraft from the USA and Europe.  The search proved futile, as no aircraft met the specifications.  The RCAF presented their request to Avro Canada and a contract was formalized in October of 1946.  It specified two prototypes to be produced and the aircraft was designated the XC-100.

These are early mock-ups of the XC-100, which show the engines in the original location.

By June of 1947, the design was well underway and nearly at the mock-up stage.  It has also been re-designated the CF-100.  This was when John Frost joined the team and became the new Project Design Engineer.  Formerly of deHavilland Aircraft in England, he brought great experience to the table as the lead designer of the deHavilland DH108 Swallow.  The CF-100 design was a straight wing aircraft, but Frost preferred a swept wing.  At this point it was too far along to implement a major change to the design, but he did make some other significant changes to refine the aircraft design.  One change implemented was the relocation of the engines.  They were moved more forward and lower into the wing.  This revision required the main wing spar to be notched to clear the engine, which would later lead to significant structural problems.

A swept wing variant was to be called the CF-103 never went beyond the mock-up stage. It proved to offer little aerodynamic advantage.

The prototype CF-100s, designated Mark 1s, were to be powered by Rolls Royce Avon engines, as it was a proven engine used in the Gloster Meteor.  It was deemed that the unproven aircraft should at least use a proven engine.  That said, the RCAF set out its specifications for the Mark 2 during 1949 and it was to be powered by the Canadian designed and built Orenda 2 engine.

The first prototype, number 18101

After a lengthy gestation period, in December 1949 the first prototype CF-100 Mark 1 was completed.  Canadian born Bill Waterton who was working for Hawker Siddeley in England would be the test pilot.  The chief test pilot for Avro Canada, Don Rogers, was tied up with the C102 Jetliner project and he lacked experimental flight experience.  Waterton on the other hand had hundreds of hours flying jet aircraft and was familiar with the Rolls Royce Avon engine.

18101 with RCAF and Government officials.

On January 19th 1950 the CF-100 took flight for the first time, in front of a group of RCAF and Canadian Government officials.  The aircraft was in the air for 40 minutes, reaching a maximum altitude of 5000 feet and a maximum speed of 215 mph.  However, it had one significant problem, the landing gear wouldn’t retract, which is why the speed was limited.

The second prototype, 18102, prior to being fitted with wing tip tanks.  This particular F-86 was used as a test-bed for the Orenda engine.  The Sabre was used by the RCAF as its daytime interceptor.  Sabre pilots tended to call the CF-100’s “Leadsleds” due to their weight.

By January 25th 1950 the landing gear was repaired and the aircraft made its second flight.  With the gear retracted Waterton put the CF-100 through its paces and reached a speed of nearly 500 mph.  Upon landing it was noted that the wing root fairings had twisted and torn.  This was discovered to be due the main spar being weakened when the engines were relocated.  The CF-100 was speed restricted while the engineers fixed the problem.  However, even after the fix, this problem would persist for some time.

The second prototype, 18102, fitted with wing tip tanks with the stabilizing fins (in red)

A second prototype was built and first flew in July of 1950.  The second prototype was fitted with wing tip tanks to help increase range.  However, once fitted, it caused instability due to the excessive torsional loads during some maneuvers.  The solution was to add a stabilizing fin to the rear of the tank, which actually resulted in the aircraft being more stable than without tanks.  The first prototype CF-100 had a long life, and was later updated and put into military service where it served until 1965.  Conversely, the second prototype had a short life.  It crashed without warning on June 23rd 1951, killing both crew members, while practicing long range flying at high altitude.  There was no fault found with the aircraft and the cause of the crash was believed to be due to oxygen failure, as no attempt was made for the crew to bail out.  Nevertheless, the prototype aircraft proved to meet the specifications set out by the RCAF and the CF-100 deemed a capable performer.  It had an excellent climb rate, being able to reach 40,000 feet in 2/3s the time of a Gloster Meteor, and it set an intercity speed record between Toronto and Montreal.

In early 1950 the conflict in Korea was becoming more serious, so the RCAF increased the order of CF-100s from 12 to 124 aircraft.  This order ended up being the final nail in the coffin for the C-102 Avro Jetliner, as the Government requested that Avro concentrate on the CF-100 and Orenda engine production.

Orenda was tasked to develop a jet engine with 6500 lbs of thrust for the CF-100 Mark 2.  In 1949, the Orenda 1 engine had been developed.  It had a 10 stage axial compressor with 6 combustion chambers and a single stage turbine and produced 6,250 lbs of thrust.  The first three prototype engines proved very durable.  The first prototype engine, however, failed after 1000 hours.  This was due to lab technician’s coat being sucked into the engine.  It was repaired and the three engines lasted nearly 2000 hrs.  This was double the hours many other engines of the era would achieve.

This Avro Lancaster was used as a test bed for the Orenda jet engines.  It was said to have been able to out run the P-47s flown by the US National Guard.

The Orenda team faced some development challenges, like failing compressor blades, but the engineers fixed this with strengthened the rotor blades.  Once the lab tests were completed, the Orenda jet engine was installed in two very different aircraft for testing; an Avro Lancaster and a North American F-86 Sabre.  The Lancaster had its two outboard Merlins replaced with Orenda jet engines.  It first flew on July 10th 1950 and logged over 500 hours before it was destroyed in a hangar fire.

The first F-86 Sabre powered by an Orenda engine flew in California in July of 1950.  The Orenda turbojet engine provided the Sabre with more power, improving its already excellent performance.  The F-86 was produced under license in Canada by Canadair and Canadair decided it would switch from the J47 engine to the Orenda engines.  Combined with the impending CF-100 demand, this resulted in Orenda having to increase production capacity with a new plant.

This was the Mark 2 prototype, and the only Mark 2 that was not dual control.  All other Mark 2 CF-100s were converted to dual control trainers.

After a successful test period, a CF-100 Mark 2 prototype was built and fitted with the production engine, called the Orenda 2.  The Mark 2 took first flight on June 20th 1951.  The Mark 2 aircraft was still a preproduction plane and the RCAF planned to conduct its own tests.  In October 1951, the RCAF’s Central Experimental and Proving Establishment received a CF-100 Mark 2 for evaluation.  After a relatively short testing period, the structural problems at the wing and engines nacelle returned.  The RCAF was not impressed and production of the CF-100 was halted until the structural issues were resolved.

CF-100 Canucks could be fitted with four hard points which could each carry a 1000 lb bomb.  However, it was never developed to be a fighter-bomber.

The engineers worked at strengthening the joint where the wing met the nacelle, but found making it stronger only caused it to fail in a shorter number of cycles.  Ultimately the engineers found a permanent solution.  Rather than a single rigid joint, a pin joint was used.  This was combined with strengthening the aircraft’s center section where the wing joined to the fuselage.  This prevented the stresses from the wing to cause the nacelle skin to distort.  The ordeal caused an 8 month delay in production.

A Mark 2T was tested with JATO.

The RCAF realized it would need to train its pilots to fly the CF-100 and ordered all remaining Mark 2s to be converted to dual control trainer units.  These dual control Mark 2s went on strength with the RCAF on May 6th 1952 and served until July of 1958.  There were still some teething problems with the aircraft though.  The control column was offset, which meant if the pilot centered the stick between his legs on takeoff, the aircraft would slowly roll into the ground.  Furthermore, once the canopy was jettisoned, the navigator/radar operator in the second seat had difficulty ejecting due to the windblast.  Later, a secondary windshield was added to prevent this problem.

CF-100 Mark 3 was the first to see operational use.

After a short Mark 2 production run, Mark 3 production was able to commence with improvements learned from the Mark 2.  The Mark 3 was the interceptor the designer had originally envisioned and was the first operational variant.  Improvements included a larger fairing at the wing and nacelle junction, to improve high speed performance and reduce high altitude buffeting.  The Mark 3 also used an improved Orenda engine, called the Orenda 8.  The Mark 3 first flew on October 11th 1952 and went on strength with the RCAF in April 1953.  It was given the name “Canuck,” which didn’t really stick well with the pilots.  It was more commonly called the “Clunk” due to the clunking sound of the landing gear when it retracted, or “Leadsled” due to its heavy weight and controls.

The drop out ventral gun pack allow for quick rearmament 

There were several variants of the Mark 3, including trainer versions.  Unlike the Mark 2s, the Mark 3 trainers were not conversions; rather they were originally manufactured as dual control aircraft.  It was also the first armed version of the CF-100.  It used eight 50 caliber machine guns mounted in a ventral pack under the fuselage.  The removable pack allowed for ground crews to drop the entire unit out of the fuselage and replace it with a new freshly loaded gun pack.  This made for far quicker rearmaments.  The Mark 3 used the Hughes E-1 fire control system with an AN/ADG-33 radar mounted in the nose.  This system allowed the CF-100 to track and destroy its target in all weather conditions and was same system use on the F-89A Scorpion, the US counterpart to the CF-100.

Mark 3s taking off, or “clunking up”

As the first Canuck to see operational status, pilots complained about the poor heating.  It was learned that many pilots were not wearing proper footwear, so the design office attributed the complaints to be unfounded.  One test pilot decided to prove that the heating system was poor, and took a technical observer from the design office for a flight.  The pilot wore two pairs of socks and underwear, and two sweaters to stay warm.  After the one hour flight, the observer was so cold and stiff that he had to be lifted out of the cockpit.  Shortly afterwards the design team agreed to improve the heating system.

The prototype CF-100 Mark 4 in a vertical climb, in formation with another CF-100 performing a loop maneuver.

The design for the Mark 4 started in 1950 and the prototype first flew on October 11th 1952, the same date as the Mark 3 prototype.  However, Mark 4 production didn’t start until September 1953.  The Mark 4 prototype was the last CF-100 to use one of the original preproduction airframes as its basis.  It was also a quite extraordinary performing aircraft.  On December 18th 1952, Avro test pilot Jan Zurakowski used the Mark 4 prototype to break the sound barrier in a full power dive.  Many believed that the CF-100 would become uncontrollable above Mach 0.85, and Zurakowski knew that a pilot could possibly exceed that number in a combat situation.  So he set out to test the aircraft at near supersonic speed.  He conducted a full power dive and hit Mach 1.08, never losing control of the aircraft.  This stunt made the CF-100 the first straight wing aircraft to break the sound barrier without rocket assistance, but it also resulted in a few broken windows at the Avro design office.

Mark 4s in flight.  Note the rocket pods in place of the wing tip tanks.

The Mark 4 had a number of significant design improvements and was considered the first truly satisfactory version of the CF-100.  Updates included a clear one piece blown canopy and the fuselage fuel tanks were revised to be two longitudinal tanks rather than a fore and aft tank.  This allowed for less trim changes as the fuel was consumed.  Mark 4s also used newer, more powerful Orenda engines, starting with the Orenda 9 with later Mark 4s using the Orenda 11 which had 7,275 lbs of thrust.

The most obvious change was the larger, blunter nose cone.  This nose cone enclosed the newer but larger Hughes MG-2 fire control system and APG-40 radar.  In addition to the eight 50 caliber machine guns, the Mark 4’s used wing tip mounted rocket pods.  These pods contained fifty-eight 70 mm (2.74 in) diameter unguided folding-fin aerial rockets (FFARs), also known Mighty Mouse rockets.  These rockets proved to be significantly more potent at destroying a large bomber, but were also known to be inaccurate and unpredictable at times.

A Mark 4 firing its FFARs.

This diagram shows how a CF-100 was intended to attack a bomber.  Its weapons system would allow for this type of attack in zero visibility conditions.

The original design of the CF-100 was to have a ventral rocket mounted in the fuselage behind the machine gun pack.  The rocket pack would lower down out of the fuselage so it could fire.  This setup was tested with the Mark 4.  However, it was abandoned after trial flights showed the rocket pack caused buffeting when it was lowered into the airstream.  It also caused the aircraft to nose up and resulted in structural cracks.

A CF-100 Mark 5 with its US counterpart, a F-89 Scorpion, performing exercising in July 1957 out of St. Hubert, Quebec.

The proposal for the Mark 5 was created in January 1952.  Initially Avro proposed significant changes for the Mark 5, with redesigned wings and afterburning engines.  Ultimately the RCAF wanted a cheaper alternative.  As a result The Mark 5 became a refinement of the Mark 4, but it was arguably the best version of the CF-100.  The biggest difference for the Mark 5 was the addition of the 3’8” wing tip extensions to improve high altitude performance.  The longer wings increased the ceiling from about 45,000 feet to about 54,000 feet.  Additional efforts were also made to improve performance by reducing weight.  Over 3,500 lbs of weight was removed.  Part of this weight saving program was the removal of the 8 fuselage mounted guns, leaving the FFAR rockets as the sole weaponry.

This photo clearly shows the wing tip extensions added on the Mark 5

The Mark 5 prototype was a converted CF-100 Mark 4B, and it first flew in September 1954.  The Mark 5 showed improved high altitude performance, but low altitude performance was compromised by the longer wings.  The Mark 5 entered service in 1955.  Avro ended up selling 53 to the Belgian Air Force, who chose the CF-100 over the competing Gloster Javelin, the Sud Avation Vautour IIN, the North American F86K Sabre and the Northrop F89D Scorpion.

The Queen inspecting a squadron of CF-100s from a 1957 Cadillac Eldorado

More advance armament was tested on the CF-100, but none would go beyond the testing stage.  This included the Canadian led Velvet Glove air to air guided missile program, but it was abandoned in 1956.  This program was replaced by the Sparrow 2 program, and several CF-100s were modified for testing.  However, the US Navy cancelled the program which ended the program in Canada as well.

There were several CF-100 retrofitted with the Sparrow 2 missiles, but they were never operational

Avro proposed Mark 6 and Mark 7 variants of the CF-100, which would have included the thinner wings and more powerful engines.  However, the RCAF had no further interest in investing in the old Canuck when the CF-105 Arrow program well underway.  The CF-100 stayed in production until December of 1958, with a total of 693 produced.  Shortly afterwards on February 20th 1959, the Avro Arrow program was cancelled, which ultimately led to the eventual demise of Avro Canada.

CF-100s that served in Europe used camouflage livery like this Mark 4.

The CF-100 often intercepted friendly aircraft, like this B-36 Peacemaker

Nevertheless, the CF-100 continued in front line service for Canada and NATO.  It served in nine RCAF Squadrons, four of which were in Europe during the 1950s.  For its time, it was arguably the best all-weather fighter, and for a time it was the only all-weather fighter used by NATO forces in Europe.  It remained on the front lines until 1963, when it was supplanted by the American McDonnell CF-101 Voodoo, a supersonic all-weather fighter.  By this time CF-100 didn’t have the speed to properly intercept new supersonic bombers, such as Russia’s TU-22.

The replacement of the CF-100 with the Voodoo meant there was a surplus of CF-100s and many were scrapped.  However, the CF-100 continued to serve for some time after it was removed from the front lines.  It was used in Electronic Counter Measures and training roles.  The airframes proved to be quite durable, having double or triple the lifespans than what was originally believed.  Tests showed that the airframes could last up to 20,000 hours before complete destruction.

A CF-100 Mark 5 on static display in North Bay, Ontario.  CFB North Bay was the last air base to station the CF-100 before it was removed from service at the end of 1981.

After almost three decades of service for the RCAF, the CF-100 was removed from service in December 1981.  The final aircraft served in the 414 Black Night Squadron out of North Bay, Ontario.  Today, many CF-100s are on static display across Canada.

The CF-100 Canuck with a F-102 Delta Dagger.  These two aircraft did many interceptions during the 1950s and early 1960s and helped to keep North American air space safe.

While many Canadians lament that the CF-105 Arrow and the Avro Jetliner never came to fruition, the CF-100 is often ignored.  It was hardly a cutting edge aircraft, but it was a highly respected all-weather fighter.  While it never had to fire its weapons in anger at an intruder, it certainly played a big role in protecting both the North American and European airspaces.  Despite that fact that it wasn’t the sleekest or most likable aircraft, the old Clunk served for nearly three decades and did its job well.  For these reasons, the CF-100 should be remembered as an important part of aviation and Canadian history.