 In July 1953 , the proposal was accepted and Avro was given the go @-@ ahead to start a full design study under the project name : " CF @-@ 105 " . In December , CA $ 27 million was provided to start flight modelling . At first , the project was limited in scope , but the introduction of the Soviet Myasishchev M @-@ 4 Bison jet bomber and the Soviet Union 's testing of a hydrogen bomb dramatically changed Cold War priorities . In March 1955 , the contract was upgraded to CA $ 260 million for five Arrow Mk.1 flight @-@ test aircraft , to be followed by 35 Arrow Mk . 2s with production engines and fire @-@ control systems . 
