A NEW PROCESS

Hauraki Plains Gazette, Volume 47, Issue 2670, 15 September 1937, Page 6

A NEW PROCESS

USE WITH AEROPLANES HARDENING WOOD PROPELLORS RECENT article appearing in the London Daily Telegraph and referring to the claims of a new type of wooden propeller is of general interest. It refers to a new German process which hardens the wood and preserves it from changes and deterioration due to atmospheric conditions. This process is of great value when applied to such wooden articles as aeroplane propellers and all wooden propellers supplied to the Royal Air Force are now required to be finished by it. Imperial Airways and numerous aeroplane manufacturers also use propellers treated in this manner. The importance of the process is all the greater in view of the large size of many of the propellors now in demand. With increased diameter the weight of the metal propellor becomes a disadvantage and the metal is, moreover, subject to fatigue. The new hardening process is a reinforcement of the leading edge of the blade by a narrow brass sheath sweated to a strip of specially manufactured phosphor bronze gauze. The propellor is then covered with sheet celluloid which is forced into the wood under enormous pressure in a sealed chamber. The surface is thus made so hard that it is impossible to stamp identification particulars in the usual way. They have to be stamped on a brass plate inserted flush with the covering.

The propellors, although made of light wood, are immensely strong. They are unaffected by a heavy hail which scarifies the edge of an ordinary wooden propellor and they may be left exposed to the weather when a machine is standing in the open.