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B-47 Stratojet

Boeing · Strategic bomber/reconnaissance · United States · Early Jet (1946–1969)

The Canadair CL-52 was a Canadian engine testbed built from a single Boeing B-47B Stratojet airframe to flight-qualify the Orenda PS-13 (Iroquois) turbojet intended for the CF-105 Arrow interceptor. Canadair — then the Montreal-based General Dynamics subsidiary — accepted USAF B-47B serial 50-085 on 8 March 1956, completed the conversion across 1956-1957, and first flew the aircraft in 1957. The lone CL-52 served as Canadair's engine testbed until 1959, when it was handed back to the USAF and scrapped following cancellation of the CF-105 Arrow programme.

Five of the B-47B's six J47 turbojets were retained, with the PS-13 mounted in a streamlined nacelle on the right rear fuselage, just forward of the tail. Top speed was Mach 0.84, range around 4,000 km in the Iroquois testbed configuration, service ceiling 12,200 m, and MTOW 102,000 kg. Hanging one heavy engine on the right with nothing to balance it to port produced asymmetric handling, but the deviation was judged acceptable within the limited test envelope. The PS-13 itself was Canada's most ambitious 1950s powerplant: a 26,000 lbf afterburning turbojet designed specifically for the Arrow.

Flight testing ran from Canadair Cartierville (Montreal) between 1957 and 1959, gathering enough data to clear the PS-13 for installation in CF-105 production prototypes. That step never came. Prime Minister John Diefenbaker cancelled the Arrow on 20 February 1959 — 'Black Friday' in Canadian aviation memory. Six CF-105 prototypes were broken up, and the PS-13 engine programme was killed alongside them. The CL-52 returned to the USAF and was scrapped the same year. The combined termination of the CL-52, CF-105 Arrow and Iroquois engine is still studied as a defining moment in Canadian industrial history and a case study in high-stakes defence-programme politics.

For Kids — a shorter, friendlier version

The Canadair CL-52 was a special Canadian airplane built in the 1950s. It was made to test a powerful new jet engine called the Orenda PS-13. This engine was designed for a fast Canadian fighter jet called the CF-105 Arrow.

Canadair took a big American bomber called the B-47 and changed it. They kept five of its six original engines. Then they added the new PS-13 engine on the right side of the tail. This made the plane look and fly a little differently on each side.

The PS-13 engine was the most powerful jet engine Canada had ever built. It could push with a force of 26,000 pounds. That is heavier than four full-grown elephants pushing at once.

The CL-52 flew tests from 1957 to 1959. It helped engineers learn how the new engine worked in real flight. Sadly, the Arrow jet was cancelled in 1959 on a day called Black Friday.

After the Arrow was cancelled, the CL-52 was sent back and scrapped. Only one CL-52 was ever built. It was a short but important part of Canadian aviation history.

Fun Facts

The CL-52 was a regular bomber that Canadair turned into a flying engine lab.
It had six engines total — five old ones and one brand-new test engine on the right side.
The new PS-13 engine could produce 26,000 pounds of pushing force — more than most engines of its time.
Because the new engine was only on the right side, the plane handled differently left and right.
The CL-52 could reach a top speed close to the speed of sound.
It could fly as high as 12,200 meters — that is higher than most weather clouds.
The plane was heavier than a large truck, with a max weight of 102,000 kilograms.
Only one CL-52 was ever made, and it was scrapped in 1959 after just two years of test flights.

Kids’ Questions

What was the CL-52 used for?

The CL-52 was used to test a brand-new Canadian jet engine called the PS-13. Engineers needed to fly the engine to see how well it worked. It was being built for a fast Canadian jet called the CF-105 Arrow.

Why did the CL-52 have an extra engine on one side?

Canadair added the new PS-13 test engine to the right side of the plane near the tail. There was no matching engine on the left side. This made the plane fly a little unevenly, but it still worked well enough for testing.

What happened to the CL-52?

The CL-52 was scrapped in 1959. This happened because the CF-105 Arrow jet was cancelled on a day called Black Friday. With no Arrow to fly, there was no need to keep testing the engine.

Was the CL-52 a fast plane?

The CL-52 could fly close to the speed of sound, reaching about Mach 0.84. That is very fast, but it was built for testing engines, not for speed. Its job was to gather data, not to race.

Variants

CL-52 (1957-1959): Single B-47B modified as Iroquois engine testbed.

Notable Operators

Canadair (1957-1959): Engine flight test.

Frequently Asked Questions

Why was the CF-105 Arrow cancelled?

The Avro Canada CF-105 Arrow was a Canadian twin-engine high-altitude supersonic interceptor that, at its March 1958 first flight, ranked among the most ambitious fighter designs anywhere. Prime Minister John Diefenbaker cancelled it on 20 February 1959 for four cited reasons: cost — the programme estimate had grown from CA$200 million to CA$1.5 billion, a huge figure for 1959 Canada; the absence of any committed export customer; the US Bomarc surface-to-air missile being offered as a cheaper air-defence alternative; and a shifting threat environment in which the rise of ICBMs undercut the manned-interceptor doctrine. The 'Black Friday' decision destroyed six prototypes, ended the PS-13 programme, and triggered 14,000 layoffs at Avro Canada. Many of Canada's best aerospace engineers emigrated to the United States — to NASA, Lockheed and Boeing — a brain drain often credited with feeding later US aerospace successes. The Arrow cancellation remains a flashpoint in Canadian industrial-policy debate.

Sources

Wikipedia — Canadair CL-52