Avro Canada Orenda

The Orenda design started in the summer of 1946 when the Royal Canadian Air Force (RCAF) placed an order with Avro Canada for a new night/all-weather fighter. To power the design, Avro decided to build their own engines. Avro had recently purchased Turbo Research, a former crown corporation set up in Leaside, Toronto, to develop jet engines.

Turbo Research was in the midst of designing their first engine, the 3,000 lbf (13 kN) TR.4 Chinook, which could easily be scaled up for the new fighter design. It was decided to continue working on the Chinook to gain experience even though they had no intention of producing it.

As work on the Chinook continued, Avro's newly christened Gas Turbine Division started work on the larger 6,000 lbf (27 kN) thrust design needed for the RCAF contract. Winnett Boyd started detailed design in autumn 1946, and a formal contract was received in April 1947. The only major change was the addition of a tenth compressor stage of stainless steel, and changing the third stage from aluminum to steel as well. The design work was completed on 15 January 1948, just prior to the first run of the Chinook on 17 March 1948. During the design Joseph Lucas of the UK was contracted to help with the combustion design, which led to a slight delay as they recommended using a longer combustion chamber than originally designed. The resulting TR-5 was named "Orenda", an Iroquois word meaning "Tribal Soul on the Right Path".

Given the experience of the Chinook, and the fact that the two designs were similar in many ways, progress on the Orenda was rapid. Parts started arriving in 1948, and the first engine was completed and run for the first time on 8 February 1949. Avro was so confident of the design that they invited high-ranking officials from the RCAF and Canadian government to witness this very first test, which went off without a hitch after fixing a minor electrical problem. Within two months the engine had already passed 100 hours of running time, and on 10 May had reached its design thrust of 6,000 lbf (27 kN). At the time, it was the most powerful jet engine in the world, although it held this record only briefly until the Rolls-Royce Avon RA.3 was introduced the next year.

By 1 July it had passed 500 hours, and had run for 477 of these before requiring a rebuild. In September it was on its way to 1,000 hours when a technician's lab coat was sucked into the engine, complete with a set of razor blades in his pocket. From then on testing was carried out with a set of metal rings in the intake to avoid ingesting foreign objects. After repairing the damage the engine returned to testing, now joined by two further examples of the Orenda 1. Together they passed a total of 2,000 hours by 10 February 1950. By this point a problem with fatigue cracks in the seventh and eighth stages had become apparent, which required them to be redesigned and made much thicker. This solved the problem, and by July they had passed 3,000 hours.

Flight testing started with a converted Avro Lancaster, FM209, one of the many Mk.10's built at the Victory Aircraft (now Avro) plants during the war. The two outboard Merlin engines were replaced with the Orendas, and the new aircraft took to the sky on 10 July. Avro test pilots had much fun flying the aircraft across Lake Ontario to the Buffalo, New York area, where they were able to easily outperform the P-47 Thunderbolts of the Air National Guard that were sent to investigate.[1] In one incident at an airshow, all four engines were turned off by mistake, but the Orenda's quick start time allowed them to save the day.[1] The aircraft ran up 500 hours by July 1954, when this portion of flight testing ended; it was destroyed in a hangar fire on 24 July 1956.

The Orenda was fairly conventional in layout, built in three main parts; compressor, combustion area, and turbine/exhaust.

At the front was the compressor section, containing the ten-stage compressor housed in a tapering magnesium alloy shell. The shell was machined with grooves that held the stators. At the front of the compressor was an intake fairing with a prominent "nose cone" containing the front main bearing. Four guide vanes held the cone in place, with two power takeoff shafts running inside two of them to power the top- and bottom-mounted accessories section (fuel pumps, oil pumps). The nose cone also held the electric starter motor, which acted as a generator once the engine was up and running. The engines used on the CF-100 also contained a uniquely Canadian invention, two prominent winglets at the very front that sprayed alcohol into the intake as a de-icing system. The CF-100 versions also mounted the debris cage, mentioned earlier.

The compressor had ten axial stages of mixed steel and aluminum construction. In the original Orenda 8, 9 and 10's this operated at a 5.5:1 compression ratio, compared to about 3.5 for wartime designs. The hub consisted of three aluminum disks carrying the first nine stages, and a steel disk bolted onto the end carrying the tenth. The central casing held the power shaft and was made from magnesium alloy. Around it were the six flame cans. The turbine was made of solid Inconel blades attached to an austenitic steel hub. The blades were air cooled by bleeding off compressed air from the fifth compressor stage and piping it to the turbine face, the six pipes lying between the flame cans. The exhaust section consisted of welded steel sheeting.

Orenda 14

Data from:Aircraft engines of the World 1959/60,[3] Aircraft engines of the World 1953 [4]

Orenda 1

original prototype models, 6,000 lbf (27 kN)

Orenda 2

first production model

Orenda 3

An Orenda 1 modified for installation in a North American F-86A Sabre, becoming the first Orenda to fly under its own power.[5]

Orenda 8

improved reliability, 6,000 lbf (27 kN)

Orenda 9

improved thrust, 6,500 lbf (29 kN), required some changes to the nacelles

Orenda 10

Orenda 9 adapted for the Sabre

Orenda 11

main production version for the CF-100, 7,400 lbf (33 kN)

Orenda 11R

with afterburner

Orenda 14

similar to the 7,500 lbf (33 kN) Orenda 11, used on both the CF-100 and Sabre

Orenda 17

combined the compressor from the 9 with the turbine of the 11, along with an afterburner 8,490 lbf (37.8 kN) wet

Data from Aircraft engines of the World 1959/60[3]

Comparable engines

• General Electric J47
• Rolls-Royce Avon

Related lists

• List of aircraft engines

• Kay, Anthony L. (2007). Turbojet: History and development 1930-1960. Ramsbury, Wilts: Crowood Press. pp. 215–216. ISBN 978-1-86126-939-3.

Wikimedia Commons has media related to Avro Canada Orenda.

• Orenda, Avroland
• Lancaster FM-209, images of the Orenda installations
• Orenda-8
• "Avro Orenda" a 1949 Flight article
• The Avro CF-100 Canuck, Greg Goebel
• The Canadian Built Avro Lancasters, FM209