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Aviation History
1910
1910 - 0723.PDF
SEPTEMBER 3, 1910. ROTARY ENGINES. [725] We have seen in your paper FLIGHT a photograph and description of a so-called new rotary engine, constructed by Mr. C. A. Fletcher, which he states "seems to have in its con struction and working, all the claims of the ' Dreadnought' engine, advertised in your paper this week." This engine, although differing in many points, as to the method of separating the petrol gas mixture from the lubricating oil, compared with that used with the " Dreadnought" rotary engine, at the same time, in all probability, goes sufficiently near to infringe the " Dreadnought" rotary engine patents, and thus unless Mr. Fletcher holds a patent of a prior date, thereby permitting him legally to em ploy this patent principle, it would seem that he is butting his head against a stone wall—or against the " Dreadnought " rotary engine patents, and thus any profits arising from his engine must necessarily accrue to the " Dreadnought " Rotary Engine Syndicate, as owners of the original patents. The Syndicate, however, desires to encourage all inventors of aerial engines (even though they unfortunately should have parallel ideas to theirs), and if this engine gives anything like the results the in ventor claims, a manufacturing "entente" and Royalty basis could doubtless be arranged, on amicable terms, between both parties. From the photograph published, we fear that the inventor's sanguine anticipations may not be realised, as rotary engines need to be built on certain practical lines—the chief of which is compactness—for the sake of safety. This engine, from the photograph, seems to be about 4 ft. 6 ins. in diameter, and it would appear to us that such diameter is absurd and that cylinders of that particular form would be very difficult to construct, and to turn on a lathe, so that a proper balance and fly wheel effect would be most hard to obtain, whereby uneven running is to be feared, as well as other dangers to which large diameter rotary engines are liable. The inventor will also find, we think, that auxiliary exhausts in the cylinder walls are unsuited for rotary engines. In brief, we may say, to compare this rotary engine with the compact " Dreadnought " rotary engine is absurd. On one point however doubtless this photograph of the new engine has done good, namely, in proving to your readers that a rotary engine in which the petrol gas and the lubricating oil can be separated is a possibility. In thisxespect, by one letter, our competitor has done more than we have, by our many pages of advertisements, and for that reason we are prepared to try to help him to perfect his engine, which as it stands at present, we iear, is not a commercial proposition. THE " DREADNOUGHT " ROTARY ENGINE SYNDICATE. SPEED ALARMS AND THE WIND. [726] Having read with great interest the specifications of the three devices for measuring the speed of an aeroplane, it seems to me that all three have one great drawback, viz., that not one of them registers the true speed of the machine. Assuming that the devices have been "tuned up" to give sounds relative to certain true speeds while the machine is in still air, let us now consider two cases :— 1. Speed of wind, nil. Speed of aeroplane in still air 40 m.p.h. " Whistle " will register note corresponding to 40 m.p.h. 2. Speed of wind, 20 m.p.h., opposing aeroplane. Speed of aeroplane in still air = 40 m.p.h., .'. true speed of aeroplane = 40-20 m.p.h. = 20 m.p.h. But relative speed of aeroplane and wind = 40 m.p.h., . \ "whistle" will still register 40 m.p.h., when speed is only 20 m.p.h. Therefore, it seems to me that unless the aviator can by some means find out the speed of the wind, and also the angle between direction of wind and direction of aeroplane, the devices are of very little practical value. As anemometers are not to be found at every i mile across country, how is our aviator to gauge wind speed ? Crewe. A. W. BRUCE-JOY. [Flight is relative to the wind in every respect, save that of accomplishing a journey between two points on earth, and questions of safety are essentially related to the relative wind and have nothing to do with the speed over the earth. It is the speed through the wind that these alarms are intended to indicate.—ED.] AN 120-150-H.P. ENGINE WANTED. [727] I notice in your correspondence column (letter No. 710) an inquiry by Mr. W. F. C. Steuart-Seton for a reliable British aerial engine, to weigh under 400 lbs., and to develop at least 160-h.p. ^ He also asks whether the " mysterious ' Dreadnought people are sufficiently enterprising to produce such an engine for him. I may say that this has already been done, and that the Dread nought" Rotary Engine Syndicate are prepared to put on the [/OGHT] market shortly an iS-cyl. rotary engine weighing 360 lbs.', and developing a guaranteed 160-h.p. at under 1,000 revs. • - This is undoubtedly the lightest and most powerful aerial engine that has ever been p>oduced. »»»•*• . • This 18-cyl. "Dreadnought" engine will be listed at.^1,200, and may be obtained on the hire-purchase system. JAMES BETT (Proprietor of the "Dreadnought" Rotary Engine Syndicate). SUGGESTIONS FOR PRIZES. [728] Your correspondent, H. H. (653, FLIGHT, NO. 83), suggests a prize for flights by aeroplanes using the smallest engine- power. Perhaps it will interest some of your readers to know that one identical to the above was suggested by the well-known aviator, A. V. Roe (and flight pioneer, with his 9-h.p. motor), as far back as June, 1909, in your correspondence columns. He also suggested, amongst others, prizes for the undermentioned, if I may repeat them :—Lightest aeroplane, smallest span, fastest aeroplane, slowest aeroplane, most portable, aeroplane with greatest range of speed, fast or slow. Lowestoft. LEWIS E. RICHARDS. DUPLICATE ENGINES AND SCREWS FOR AEROPLANES. [729] The application of duplicate engines and propellers to aeroplanes seems to be of vital importance, as so many accidents have occurred owing to failure of motor power. I enclose a rough sketch of what I think the best solution of the problem. k, -~ A right- and a left-hand screw are mounted on concentric shafts, each driven by a separate motor through a chain-and-ratchet drive. The ratchet is necessary, as in case of failure of one motor its pro peller will revolve freely, and thus not interfere with the steering of the aeroplane. With one engine only working the aviator would be able to make for the nearest safe land. The pitch of the back propeller would, of course, be coarser than the front one, and, being driven by an independent engine, would be equally efficient. With the propellers thus arranged, the thrust with either one or both engines working would always be in the same line. Oxford. T. J. BENNETT. THE GNOME ENGINE. [73°] 1° your aD'e article on the technicalities of the Bourne mouth meeting, appearing in your issue of July 23rd, you make a proposal to brighten the cylinders of the Gnome engine so that colour changes may afford an indication of the temperature within. You, however, mentioned that this engine is apt to get hot, particu larly so when not quite clean. As polished surfaces radfate heat more slowly than those left dull, it is possible that the writer's proposal might lead to trouble. A «£J5 ** • Farnborough. V. H. P. DAMAN. t [Our correspondent puts forward a very logical argument in favour of leaving radiating surfaces dull, and we agree that where two cylinders are known to be equally clean, that which is dull on the outside will probably keep cooler than that which is bright. We happen to know of a case in which the Gnome engine is kept in the manner that we describe, however, and we believe that it has given entire satisfaction. Our object in making the reference, however, was not so much to advocate brightness per se as to emphasise the desirability of extreme cleanliness, even to the extent of brightness outside as well as in. A mechanic in charge of an engine would not easily be able to justify the presence of dirt of any sort if his instructions were that the cylinders were to be bright. We do not think that the margin of cooling in the Gnome engine is likely to be so fine cut as to depend for its adequacy on a dull surface, otherwise we imagine that the manufacturers would have provided for a permanently dull surface in the first instance.—ED.]
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