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Aviation History
1957
1957 - 1560.PDF
6o • R ^T 4-r B o v B B £ K 59 ,62 ARROW In all its essentials this is the project which has now materializedas the Arrow. It took only a month for the R.C.A.F. and Depart- ment of Defence Produaion to agree that the C105 was dose tothe optimum, and in July Avro were asked to prepare a full design study. This work occupied the rest of the summer, one of themajor tasks being the adapting of the original project to take a pair of Rolls-Royce R.B.106 engines—big and powerful turbo-jets which have yet to be officially mentioned in this country. These engines were then "in an advanced stage of development." By September the first tunnel-model had begun to yield read-ings, and since that time several thousand tunnel hours have been logged on C105 configurations at all speeds up to more thanMach 2 (just how much more we may not say). The total num- ber of tunnel models constructed was 17, ranging in scale from1/80 to 1/6, and these were tested chiefly at the N.A.E., at the Langley Aeronautical Laboratory of the N.A.C.A. and at theCornell Aeronautical Laboratory. Nevertheless, even the excel- lent faculties thus made available could not fully explore the wholeflight envelope of the C105 without introducing complications and possible inaccuracies. To fill in the gaps Avro established aprogramme of free-flight model testing, using ballistic air-dropped models and large-scale models with solid-propellant boost motors.Nine of the latter were fired at the range of the Canadian Arma- ment Research and Development Establishment at Port Petrie,Ontario, and two more were tested at the N.A.C.A. Pilotless Aircraft Research Station at Wallops Island, Virginia, the workoccupying from December 1954 to January of this year. During 1954, when the preliminary design was complete, theR.C.A.F. adopted the CF-105 designation, and the whole project moved into the detail stage. Configuration was fixed in a formwhich has only altered in minor details since, and the complete CF-105 weapon system was planned, with Avro acting as theprime contractor for all of it (thus breaking new ground in Canada). But progress was soon retarded by the prospect ofunavailability of the R.B.106 engine, and Avro turned back to the Wright J67—only to learn from the U.S.A.F., early in 1955, thatthe J67 would also not be ready to meet the CF-105 schedule. It was finally decided that the CF-105 would have to be developedin two versions. The Mk 1 was planned as an intermediate development machine, powered by a pair of Pratt and WhitneyJ75s. The Mk 2 was foreseen as the definitive operational machine, with two of the more powerful Orenda PS. 13 engines(since named Iroquois). During 1955 an engineering mock-up was built, and almost atonce it was changed to accommodate the Pratt and Whitney engines. This mock-up was evaluated by the R.C.A.F. inFebruary 1956 and on the same occasion a mock-up of the armament pack then envisaged was assessed. By 1956 the mock-up was again being worked upon, first in order to fit it for the Iroquois engine and later in order to convert it completely tothe configuration of the Mk 2 aircraft. This had to be done relatively early in order to permit all necessary modifications tobe incorporated in the Mk 2 engineering-release. Illustrated in a diagram on page 650 is the remarkablyrapid progress of the CF-105, and it particularly emphasizes the
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