English: A researcher examines the Orenda Iroquois PS.13 turbojet in a Propulsion Systems Laboratory test chamber at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The Iroquois was being developed to power the CF-105 Arrow fighter designed by the Avro Canada Company. Avro began design work on the Arrow jet fighter in 1952. The company’s Orenda branch suggested building a titanium-based PS.13 Iroquois engine after development problems arose with the British engines that Avro had originally intended to use. The 10-stage, 20,000-pound-thrust Iroquois would prove to be more powerful than any contemporary US or British turbojet. It was also significantly lighter and more fuel efficient. An Iroquois was sent to Cleveland in April 1957 so that Lewis researchers could study the engine’s basic performance for the air force in the Propulsion Systems Laboratory. The tests were run over a wide range of speeds and altitudes with variations in exhaust-nozzle area. Initial studies determined the Iroquois’s windmilling and ignition characteristics at high altitude. After operating for 64 minutes, the engine was reignited at altitudes up to the 63,000-foot limit of the facility. Various modifications were attempted to reduce the occurrence of stall but did not totally eradicate the problem. The Arrow jet fighter made its initial flight in March 1958 powered by a substitute engine. In February 1959, however, both the engine and the aircraft programs were cancelled. The world’s superpowers had quickly transitioned from bombers to ballistic missiles which rendered the Avro Arrow prematurely obsolete.