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Aviation History
1920
1920 - 0057.PDF
JANUARY 8, 1920 •S,, CORRESPONDENCE [The Editor does not hold himself responsible for opinions expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters intended for insertion in these columns.'] PROFESSOR ARNOLD'S NEW HIGH-SPEED STEEL [1987] The claim put forward by Dr. Arnold of havingdiscovered a new high-speed steel in which no tungsten is used and the resulting discussion in the press has createdwidespread interest in metallurgical and engineering circles. As we have been manufacturing tungstenless molybdenumhigh-speed steels for some considerable time, and have given very great attention to the theory and practice of alloy- steels generally, perhaps you will permit us to give the public some important facts relating to the matter which have notbeen brought to light. We may say at the outset that we fully endorse Dr. Arnold'sview that molybdenum in high-speed steel produces far better results than tungsten. We must, however, disputehis claim that his formula is new, and also that vanadium has proved an efficient stabiliser of molybdenum when usedwith it. As a matter of fact, not long after the introduction of tungsten high-speed steel molybdenum high - speedsteel both with and without vanadium was made in the United Kingdom, France, Germany, Luxembourg, Austriaand the United States, similar to the formula which Dr. Arnold has now made public. The occasional startling results ofsuch molybdenum mixtures, superior to the very best tungsten high-speed steel, induced many firms to plunge into schemesfor producing molybdenum steels on an extensive scale, but all had to be abandoned because the resulting productlacked uniformity. Much of it was of excellent quality, but on the other hand batches of tools failed entirely whensubjected to workshop tests, although they showed the correct analysis. In the cases where vanadium was added it failed to be uniform in bulk manufacture, just the same as themolybdenum steel without vanadium, consequently the makers fell back upon tungsten.We attribute Dr. Arnold's erroneous faith in vanadium as a stabiliser to molybdenum steel to the circumstancethat he experimented merely on small quantities. Howerer, only bulk production can disclose the presence or otherwiseof a real stabilising element. Mr. P. R. Kuehnrich, of Sheffield, who has the reputationof having carried out more tool-steel alloying experiments than any living man, made the discovery that cobalt actedas a definite stabiliser to molybdenum, and he patented a formula to this effect.As the licensees under that patent, we have made a»d distributed hundreds of tons of the Como brand molybdenumsuper high-speed steel, and completely proved that cobalt is de facto a stabiliser." Como " steel is now largely used in many parts of the world, and is thoroughly justifying the warranty advertisedin the technical press guaranteeing it to produce superior results to tungsten high-speed steel.The molybdenum high-speed steel is more costly to produce than tungsten steel Users, however, are only too willing topay the higher price, as the greater service the material renders makes it intrinsically the cheaper material. ' " • DARWIN AND MILNER, LTD., SYBRY SEARLS AND CO., LTD., - SPARTAN STEEL CO., LTD., Manufacturers, Licensees and Distributors of Como (Molybdenum Super High-Speed SUtl). THE CURTISS "EAGLE THE following brief particulars are to hand of the Curtiss" Eagle " eight-seater aerial limousine, which was recently put through its first public demonstration by Roland Rohlfs,at Roosevelt Field, L.I., U.S.A. Six passengers were taken up on each trip, and on one occasion an altitude of 20,000 ft.was attained. The " Eagle " is intended for passenger or cargo work,and is a. fuselage biplane fitted with three 150 h.p. Curtiss K-6 engines. One of these engines is placed in the nose of thefuselage and drives a tractor screw, whilst the other two engines are disposed one on each side of the fuselage, in astreamlined nacelle, and also drive tractor screws. Aft of the central engine the fuselage is formed into a cabin, which isluxuriously fitted up. There are eight upholstered wicker chairs, arranged in two rows with a wide aisle in between*the two front seats being for the pilots. In the front of the cabin, and at the sides at each seat, are large Triplex windows.At the rear is a compartment for luggage. If used as a cargo machine, a useful load of one ton can be carried. The enginesare provided with electric starters, and dual control of the Deperdussin type is provided.The overall span of the " Eagle " is 61 ft. 4 ins., chord 6 ft. 9 ins., and wing area 770 sq. ft. The gross weight ofthe machine is 7,450 lbs. It has a speed range of 54-107 m.p.h., and climbs to 4,000 ft. in ten minutes. At full power therange is 350 miles, or at cruising speed 475 miles. The machine will fly on any two motors, and with light load, onone engine. The Curtiss "Eagle "—in full make-up—which is fitted with three 150 h.p. Curtiss K-6 engines, onein the nose, or " beak," of the fuselage, and one, in a nacelle, on each side of the fuselage. • 55 ' •7S:-^:.t...*:Jt.- "r
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