Steel Airscrew Blades
Manufacture and Repair of Curtiss Hollow Types
This article first appeared in the Volume 4, Number 45 (July, 1942) issue of Aircraft Production magazine, and is presented here through the kind permission of Flight International. Thanks also to Bruce Vander Mark for furnishing volumes of Aircraft Production for scanning.
Blade repair is an important branch of the airscrew industry and as a result of methods which have been developed for both light alloy and wooden blades, a great majority are returned to service and constitute a valuable supplement to new production. Steel airscrew blades are an American introduction and for some time were not thought to be repairable. A technique has, however, now been developed and is being very successfully applied. Its need and importance are increased by the fact that blades of this type are fitted to a number of the aircraft supplied by the United States for the Royal Air Force.
In the United States the use of steel airscrew blades has gained considerable ground, the main advantages being their greater durability and resistance to erosion, which under the normal conditions of civil airline operation would extend their life indefinitely. In addition to being stronger, they are actually lighter in weight than aluminium alloy blades, an advantage which becomes more pronounced as the size of the blade increases.
This form of construction is sponsored by Curtiss-Wright, and production is carried on by the Curtiss Propeller Division of that Corporation. These blades are fitted to a number of aircraft, including the Kittyhawk, Mustang, and the Airacobra, now being supplied to this country by the United States.
|Fig. 1. Roller-milling one of the flat plates from which the blade sections are subsequently formed.||Fig. 2. Welding the two sections of the blade together. The atomic-hydrogen process is used.|
|Fig. 3. Upsetting the shank of a blade in a National forging machine. The three lower die apertures are used.||Fig. 4. Heat-treatment of the blade is done in vertical furnaces sunk in the floor.|
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