The Avro Arrow

An engineering marvel ahead of its time

The arrow in flight.
The arrow in flight.

On October 4th 1957, the Avro Arrow made its official roll-out from the Avro Airplane Hangar in Malton, Ontario. The same day, the Russians launched Sputnik and the world entered into the space age. Sputnik was seen by many as the beginning of the end of aerial combat, and would be one of the reasons the Arrow project was suddenly cancelled less than two years later.

With the threat of the Cold War in the 1950's, North America needed to strengthen defence at the area most vulnerable to Russian attack, the open North. The vast area to be covered, coupled with the frigid, desolate environment made technologies of the day insufficient to do the job. In response, the Canadian Department of National Defence called for a "state of the art, supersonic, all-weather interceptor aircraft, far in advance of anything contemplated at the time." The Royal Canadian Air force immediately consulted A.V. Roe Ltd. (later named Avro), who already had a strong reputation in the aerospace industry with a number of successes including the Silver Dart, the first aircraft to fly in Canada. Avro had also built fighter planes; the Avro Lancaster and the Avro CF-100 interceptor played key roles in North American and British defence during World War II.

Chief engineer Charles Grinyer called the Arrow "a considerable challenge in aerodynamics, thermodynamic, and mechanical design as well as manufacturing technology." It had to be, since its performance requirements were ahead of its time. The Arrow was to have a maximum speed of mach 2.5 or 2800km/h at a ceiling of 50,000 feet (mach 1 is the speed of sound, about 1100km/h). By comparison, the F-16a fighter jet, built almost 20 years later, cannot reach mach 2. In addition the plane was to have a thrust to weight ration of 5:1 (see inset), the best ratio achieved at the time had been 3.5:1. The plane’s 'airborne-from-readiness' (pilot in cockpit but engines not running) needed to be less than 60 seconds.

The Arrow also made ambitious use of then primitive computers. At a time when computers were built of large vacuum tubes and were less powerful than our calculators, Avro engineers took great advances in electronics and gave the Arrow the ability to fly itself. This included making automatic adjustments for changes in wind or air pressure, flying to a predetermined destination, automated landing, and even the ability to engage in aerial combat. It was not until 1971 when Cornell University led a research group to create the X-15 that similar capabilities were displayed.

Although the Arrow could literally fly itself, the pilot was of course necessary. Computers were unable to make decisions outside of the set of pre-programmed variables. However, 'fly by wire' was necessary for the Arrow, as human reaction is hindered at supersonic speeds. As well, the accuracy required to make corrections under complicated flying conditions were best handled by computers.

On February 20th, 1959, John Diefenbaker's Conservative government terminated the Avro Arrow project, leading to one of the largest Canadian mass-layoffs ever. An initial 14,000 Canadians were laid off at Avro, and another 25,000 employees of Canadian contractors were to follow. Indeed, the demise of the Arrow popularly marks the beginning of what is commonly known as "Canada's Brain Drain." Many of Avro's top engineers were immediately hired by companies outside Canada. These people played key roles in such projects as NASA's space program and the development of France's Concorde.

With the launching of Sputnik, many thought they were seeing the end of aerial combat. But, even today we see the progression and advancement in the area (for example, stealth technology has allowed planes to become virtually undetectable by conventional radar).

Many attribute American influence to the end of the Arrow. But, when Canada officially announced the end of the Arrow, bids to buy the project came from General Motors and other U.S. companies, as well as from France, Britain and Germany. The Canadian government officially refused to sell anything. Instead, the government subsequently spent money and military energy to scrap the Arrows and anything related to the project: design blue prints, test beds, pictures, and records.

At the time of the Arrow project, the eyes of the technological world were placed on Canada. Now, the only surviving memory of the Arrow is the front end of Arrow #206, along with a section of landing gear, two outer wing panels and various cockpit controls, all on display at the National Aviation Museum in Ottawa.

Anthony Cutrona spent his summer making a full scale model of the Avro Arrow at the Toronto Aerospace Museum.

Thrust to weight ratio

The thrust to weight ratio of an aircraft is an efficiency factor for total propulsion or flying ability. There are basically four forces that act on an aircraft in flight: lift, weight, thrust, and drag. The motion of the aircraft through the air depends on the magnitude of the various forces.

Thrust is determined by the size and type of propulsion system used on the airplane (type of engine, number of engines) and on the throttle setting selected by the pilot.

Weight is directly proportional to mass and depends on the size of the aircraft, the materials used to build it, and the size of its payload.

Lift and drag are aerodynamic forces that depend mainly on the shape and size of the aircraft and the speed at which the aircraft is travelling.

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