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Aviation History
1910
1910 - 0811.PDF
OCTOBER I, 191 O. [/OGHT] menting till I could get leaps up to about 50 t., which I think is pretty fair for a machine of that weight. I am at present occupied building another machine, 35 ft. span, 27 ft. length, which will weigh about 320 lbs. without engine. I am building it of Oregon pine, and intend fitting a 40-h.p. engine. When I have had trials with it I will give full particulars and photos. I might state that there is not a machine in New Zealand that has flown with motive power to my knowledge, and very few people take an interest in aviation over here. Otago, New Zealand. W. A. F. POTTER. CENTRE OF PRESSURE. [777] Your correspondent, Mr. V. K. Vyvyan (No. 652), refers to Mr. Sellers' article on the centre of pressure, published in the May 14th issue of your esteemed paper. I am of opinion that however excellent the research may be on this subject the results are only of theoretical assistance. What a pilot really wants is an indicator showing him the approximate position of the c. of p. relative to the c. of g. during flight. On thinking this over I invented the apparatus which I hope will overcome the difficulty, and for which I have obtained protection. Maybe the following short description will interest your readers :— Working on the fact that fabrics such as are used for covering planes have a certain amount of elasticity, the air-pressure on a plane in flight will cause the fabric to assume a curve where it is not sup ported by ribs. This curve I call a natural curve. As the centre of pressure alters its position during flight this natural curve will also alter its position. Now if anything of suitable character is placed on the fabric between the ribs, i.e., on the convex side of the lower surface, it will be lifted according to its position relative to this natural curve. By having a series of special design levers arranged at right angles o the ribs, the movement of the centre of pressure with the natural curve can be electrically indicated to the pilot by means of a cali brated dial placed in front of him. Denmark Hill. CLANE. fitted with shock-absorbers, diverts most of the downward force to the horizontal line of travel in landing, giving time to disperse the balance force before the aeroplane is brought to a standstill. Leicester. T. F. C. THREE-BLADED PROPELLERS. [778] I should be very much obliged if you would tell me what there is against using a three-bladed propeller for an aeroplane. I cannot find any mention of one, and yet it seems to me that it would have its advantages. Possibly, however, its disadvantages outweigh its advantages, though the only disadvantage I can think of is that it might cause vibration, though whether this is the case I don't know. I am bound to say I don't know very much about the subject as yet, though it is one in which I am very interested. Ford, Salop. R- A. BOWLES. [A three-bladed propeller would be more expensive to make than a two-bladed propeller, and that has in all probability been the chief reason why it has not been used. It should be better balanced than a two-bladed propeller if equally well made.—ED.] FLYING IN 1909. [779] Would you kindly answer the following question : Did any machine leave the aerodrome and fly past the Tower at the Blackpool meeting last year (1909)? H. BENSON. [We were present during the entire duration of the official pro ceedings at Blackpool last year, and have no recollection of any machine flying outside the boundaries of the aerodrome except when Latham in his magnificent flight was blown somewhat out of his course and over the heads of some of the spectators.—ED.] TECHNICALITIES FROM THE BOURNEMOUTH MEETING. [780] I am greatly interested in the remarks concerning landing equipment which your article deals with in the issue of July 23rd, and having had the pleasure of working for a client at a patent landing arrangement, now being manufactured for several owners, I thought the device might be of interest to others. This patent (26,924, 1908) adds very little weight to a machine, and touches the writer's remarks concerning small wheels. It has large free rims and endless rolling skids, which will span hollows and mount obstacles that would " scotch" small wheels. I believe most of the minor mishaps at least are due to the grip of the tyres on the turf at the moment of contact, and although pneumatic tyres are used on this arrangement they cannot grip the turf as they are encircled by the endless rims. With small landing wheels, no known mechanical shock-absorber could effectively absorb the shock of a chance landing, but this landing device, while AEROPLANE ENGINES. [781] Replying to letter 584, 1 enclose a sketch of an engine that I have constructed, which relates to the question at issue. Air is drawn in through the hollow crank by the fan, G, driven over a carburettor not shown at I. Entering the cylinders at the ports shown when the pistons uncover them from above, the cranks of the four cylinders are at 90° therefore giving four impulses per revolution, as it works on the two-stroke principle. --The fly-wheel is a steel ring mounted concentrically between two steel discs which are a close running fit in the casing, Q, and also between these discs are blades. The pressure when the piston gets down to the line, T, repre sents 95 lbs. to the sq. in., which is put on to the fly-wheel blades four times per revolution ; when the pressure in the casing drops below atmospheric pressure il then acts as a scavenger for burnt gases, the ingoing air keeping the turbine cool. This engine without any valves whatsoever when running at 2,000 revolutions gives 16,000 impulses on the crank-shaft per minute. Bournemouth. W. L. ADAMS. McNElLL'S BIPLANE. [782] As there seems to be a great similarity about biplanes I am sending you a diagram of my machine which, as will be seen, is a distinct departure from the usual run of biplanes. The diagram represents only that portion of my machine which I consider original. The propellers have been placed in position to show the direction of transit through the air. The advantages claimed, and which have been proved, are as follows :— 1. Will lean at coned angle when turning. 2. Less liability to damage wings when landing on unsuitable ground. 3. Less chance of diving in any direction. Will occupy less room when taken to pieces. 5. Has advantages of a form of dihedral angle without disad vantage of letting air escape too freely. Bayswater. H. M. MCNEILL. 809
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