Drawn Full Scale
     As soon as the envelope of the aircraft was defined, full scale layouts of these master lines were drawn on glass cloth: These master lines were reproduced on to glass cloth for the purpose of filling in the actual structural details in the area concerned. This is called the assembly glass cloth. In addition to the master lines and the assembly glass cloth, dimensional geometry drawings for interchangeability hard points were also supplied by Engineering.
     In order to provide a basic source of control for the accurate manufacture of details that are in contact with the air frame envelope, master models were built.
     To construct the master model of a component, the master lines glass cloths were contact printed on to light alloy sheets cut to profile, and mounted on a suitable frame. After splining in to ensure accuracy of profile, the spaces between the templates were plastered in to present the finished model. This model is now the tooling master which establishes the shape of the component and the shape and size of the various skin panels.

All detail parts adjacent to the outside contour of the structure, and therefore control the aircraft shape, must have their tooling related directly to this model.
     Through this process the Production Engineering Department derived a direct contact relationship between the Engineering information and the tools and parts.
     To ensure accuracy and to eliminate hand finishing, in the forming of metal parts from heavier materials, a great deal more pressure was required far rubber forming technique. This resulted in the procurement of the 15,000 tons Siempel Kamp Rubber Forming Press, the largest of its kind in North America. The installation of this huge hydraulic Press started in March, 1955 and operations commenced to meet Arrow production requirements in months later. Operation of the press is controlled electronically.
     Early in the design stage of the Arrow it was determined that integrally-stiffened skins and completely-machined structural members were necessary to meet design requirements which specified one-piece wing panels for integral fuel storage tanks. Because of this specialized equipment such as the electronically-controlled Skin Mill was procured to machine these parts from solid billets of specially-alloyed rolled plate material. The stationary working surface of this complex machine is 28 feet long and the whole thing weighs 100 tons.

Travelling Cutter
      Raw material is held in place by vacuum pressure. The cutter head moves over the material remotely guided by a tracer which follows a template and mills finished skins have integral siffeners.
     Together with the large Skin mill other smaller mills were required, including special variable angle contour cutting mills. These are used to machine spars and other structural members from solid pieces of material. A special saw was designed and built by Avro in order to meet cutting capacity for materials up to three inches thick and 20 feet long. In addition special ultra sonic test equipment was needed to properly inspect large pieces of material to locate any imperfections before machining operations started.
     A new hot air heat treat furnace was installed which provided adequate space
(Continued on page 12, Col. 3)