AIRCRAF T ENGINEERING December, 1934 A French Addition to Airscrew Workshop Equipment Designed on Novel Lines H E problem of the machine finishing of perfectly balanced airscrews is claimed t o have been solved in France with the appearance of a machine developed for the purpose after several years of experiment by th e Société L'Helice Equilibré. A Ne w Principle The machine, which is based on an entirely new principle, can turn out an indefinite numbe r of airscrews, or airscrew blades, of a given type, completely finished and polished, an d with an accuracy of ±1/10 deg. Details of Design The characteristics of the machine are given as follows for the type of machine producing two-bladed airscrews: Movement of the working table .. .. .. 8 ft. 2⅓ in Length of slide supporting table .. .. .. 14 ft. 9 in. Width between cheeks .. .. .. .. 4 ft. 3¼ in. Free height between distance piece and working table 4 ft. 1¼ in. Number of speeds of movement of the working on to the aeroplane by any mechanic in case table for the profiling Identical Products 3 (19·69 in., 39·38 in. and 59·07 in. per minute) of damag e to a blade without its being necessary The technical advantages of the machine Number of speeds of movement of the working to take any special precautions as to balance. over the usual process of machine roughing table for milling .. .. .. .. .. .. 4 The necessary prototype is obtained by out and hand finishing airscrews are many. Power of the motor for moving table .. .. .. 6 h.p. making a single blade by hand. This is then In the first place, all the airscrews are identical Number of speeds of the chuck while turning duplicated on the machine either as separate airscrew blade .. .. .. 4 (4, 5, 6·5 and 8 r.p.m.) in length, width, thickness at any given point, blades or as complete airscrews. Power of the motor turning the chuck .. .. 1½ h.p. and weight. The curves are necessarily equal Speed of rotary tool .. .. .. .. 800 r.p.m. also. Single-piece airscrews are symmetrical. Unskilled Labour A Workshop Tool The vibrations which the airscrew sets up, From a commercial point of view, the advan arising from slight differences in the curve of The construction of the machine is very tages are a considerable saving of time, and the blades of hand-finished airscrews, are of simple and strong, so tha t it is not a laboratory th e possibility of using unskilled mechanics for course eliminated, as the curves are perfectly device, but a solid workshop machine, which the manufacture. To complete a two-bladed identical. The airscrew turned on this machine can work automatically, or be run by any 650-h.p. airscrew on this new machine requires has, therefore, greater efficiency than the hand- mechanic, or even by a semi-skilled workman. only five hours, and specialised workmen who finished article, as well as reducing the wear The speed of the various movements is tak e years to train, and are difficult to keep, on the engine. very slow. This considerably reduces the are no longer needed. The result is that the wear, but as an extra precaution wherever it cost is considerably reduced. Interchangeabl e Blades is considered necessary the bearings are The machine is at present produced for the arranged so that the play can be taken up, Another important advantage is that, all making of either two-bladed or three-bladed and the machine can thus keep its accuracy the blades being alike, they are interchangeable. airscrews, as well as for the production of single without constant adjustments. It is possible to stock blades which can be put blades.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Dec 1, 1934