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Aviation History
1920
1920 - 0127.PDF
JANUARY 29, 1920 the crankshaft, and the air compressor pump is driven off the water pump by means of reduction gears. The crankshaft is carried in five intermediate bronze bearings lined with white metal, and a very heavy ball- bearing at each end. Tubular connecting-rods are used with articulated ends. The pistons are light aluminium- alloy type with cast-iron rings. There are two magnetos mounted centrally with their distributors facing outwards, and placed midway between the two carburettors on each side. The carburettors are four in number, being one for each set of three cylinders. They are of cast aluminium, and are automatic at all engine speeds. With this arrange- ment the carburettors, the magnetos and the spark-plugs are perfectly accessible by removing one side of the engine- housing. These are parts of the engine which need most frequent attention and adjustment, and which have, there- fore, been made most readily accessible. The propeller is a geared-down type, with a ratio of 1 to 1-51. The reducing gears are herring-bone type, and the propeller shaft is of very big diameter, and is mounted on heavy radial and thrust ball-bearings. This shaft was originally in- tended for a machine gun to be fired through it, and is bored to 58 mm. internal diameter. The propeller, which may be either pusher or puller type, is locked on the shaft with a mechanism very similar to that of Rudge-Whitworth wire wheels. Cylinder bore is 120 mm., with a piston stroke of 150 mm. The engine develops 400 h.p. at 2,300 revolutions, and gives its maximum of 425 h.p. at 2,500 revolutions. Being geared down, the maximum propeller speed is 1,500 revolutions. Weight of the engine empty is 800 lbs., and weight with water and radiator 903 lbs. Weight per horse-power empty is exactly 2 lbs., and weight complete with water and radiator 2 • 3 lbs. per horse-power. THE A-18 300 H.P. 9-CYL. RADIAL The Fiat Co., having specialised during the War on vertical and V-type water-cooled aviation engines, the appearance of a nine-cylindered water-cooled star type comes somewhat as a surprise. The first sample of this series was exhibited at the Paris Aviation Salon, where it attracted considerable attention. The nine cylinders are steel forgings with welded-on water- jackets, and are mounted around a circular aluminium crankcase. The intake pipes are inside the water-jackets, and consequently are heated by the water-circulation system. There are four valves per cylinder mounted in the head and operated from a single-plate cam and push rods. The crank- shaft, which has a single throw, and is carried in ball-bearings, receives the master connecting-rod and the eight auxiliary rods, all of which are mounted in ball-bearings. Ignition is assured by two high-tension magnetos mounted on a platform on the rear face of the crank-chamber. Each magneto fires nine plugs, which are mounted horizontally in the cylinders below the valves ; thus either magneto is capable of running the engine. On the same face of the crank-chamber is the double piston-type oil pump, and immediately below it is the water pump. The single car- burettor, with adjustment for high altitude flying, is also on this side of the engine. The mixture is taken through gas passages in the base-chamber to the pipes inside the water-jackets, and from there to the valves in the head. This engine, designated Type A-18, develops 300 h.p. at 1,080 revolutions, and 320 h.p. at 2,000 revolutions. Its total weight empty is 500 lbs., and with water 546 lbs. The weight per horse-power is thus 1 -6 lbs. without water, and 1 -9 lbs. with cooling water. The Editor does not hold htmself responsible far 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.] COL. HOLT ON PARACHUTES ] My attention has just been drawn to a letter under the above heading by Mr. Calthrop in your issue of the 15th inst. No one can fail to admire Mr. Calthrop's great ingenuity and the fine design and admirable qualities of his Guardian Angel parachute, unsurpassed for certain specific purposes— and it is perhaps a pity that he should have imported a personal tone into his letter. Under the circumstances I will not trespass on your valuable space with more than a few brief comments. Mr. Calthrop lectures me severely for my use of the term " positive." Apparently he has " earmarked " this word and appropriated it to connote a certain definite thing—in effect " A parachute stowed on the Calthrop principle." Seemingly he would convert the term into a mere label for his special method of packing. I entirely demur to this definition, more especially as I have in mind an " Anti-suction " parachute without any bulky container or open mouth, to which this definition would be quite inapplicable, or if applied meaningless. After all it is a mere side issue, of no importance provided each party makes clear the sense in which he applies the word. Mr. Calthrop makes a number of very sweeping assertions and generalisations. I will refer to one only. He claims that his parachute, not only the Guardian Angel, but apparently every modification, is infallible. This is a strong word, more usually associated with popes or patent medicines. I have been told (Mr. Calthrop will no doubt correct me if I am in error) that not long ago there was a bad disaster in the United States owing to the parachute rope becoming entangled in the aeroplane's " bloater," and this though the machine was flying normally under control and the parachute itself was in charge of the Calthrop Co.'s own trained experts. This only shows that you cannot have ropes dangling in proximity to the machine without attendant risks. Mr. Calthrop apparently must himself at some time have begun to have misgivings as to whether his standard type Guardian Angel would be really effectual in the actual conditions that were likley to arise in the case of a sudden aeroplane collapse. For he seems subsequently to have patented various different types specially designed, as he himself says, to meet some particular emergency or to suit some particular type of machine. A few only of these figure in the Calthrop Co.'s price list, and it would be inter- esting to know whether any of the others ha\e been tested by or submitted to the Parachute Section since Maj. Orde Lees left it last spring. I am glad to be able to assure Mr. Calthrop that I have perused a few of his specifications—some with interest and pleasure, and some, if I may say so, with a little amusement. And now to " clear the air," if I may use his own words. This varied array of patents on which he appears to set so much store—soaring, dropping, drag, aileron, etc., etc.—what are they, and what do they represent ?—just so many desperate efforts to circumvent the natural limitations of his own parachute system. Having devised them, having brought them to the working stage, what then ? Does he propose to list dozens of different " marks " to suit different types of accidents, different types of machines, and different methods of stowing on the machine ? Of course not, that's not prac- tical. And further, does he propose to instal two or three different types of parachutes on one machine, each designed for a particular type of accident, furnished possibly with a sort of switchboard in the cockpit, enabling the airman to " switch on " the particular type of parachute suited to the emergency with which he is confronted ? Of course not ; that's nonsense. Further still ; in the larger machines, would he equip each passenger with two or three different parachutes, till it resembles nothing so much as a ladies' hatpin stand ? Of course not ; that's burlesque. What is the alternative ? one all-round parachute system, which can be used from any- where, on any machine, without modification. Not neces- sarily a " joy-riding " parachute ; a parachute is essentially, and will be always, the instrument of an emergency ; but a parachute that promises a satisfactory chance of escape in almost any conceivable circumstance. This is the goal, and it looks as if it could be attained only by the " non- positive " type. And that's just the whole of my case. H. S. HOLT Travellers' Club, January 21
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