FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1921
1921 - 0095.PDF
"FEBRUARY IO, 1921 ignition, a certain amount of induction occurs—in the form of actual leakage from the cables—which, as uncontrolled eddies or waves, seriously interferes with directional wireless ; as a parallel case, so to say, with the presence of iron near a ship's compass, prior to the famous discovery of Lord Kelvin, which neutralised that falsifying influence. The neutralising method here seems, in its way, to be a discovery as simple as it is important. It is merely to collect those eddies or waves, and earth them by groups into the motor. This is done by sheathing the cables in a braided covering of electri- cally conductive material, and carrying the _ cables in aluminium brackets four inches apart, secured to the top of the crank- chamber. ; i. Still, the same high-tension current—but in lacunae of metal twice or thrice as great as a wiring-length—exists in the distributors, So these, too, are now earthed by means of brass shields, each with a short length of copper wire attached to an earthing terminal in the crank-chamber metal. So now, while the voltage for the "Lion's" twenty-four spark-plugs remains undiminished for ignition purposes, its surplus is so neutralised that it cannot interfere with either the directional or any other wireless pertaining to the aero- plane itself. 4 Another new detail again relates to the carburettors. This is a cock, located in the return water lead to the pump from their •water jackets. For, as it may well happen that in tropical climates water jacketing is euperfiuous, and might indeed lead to over- thinning of the mixture, turning this cock cuts out of circulation that part of the water system at least. It may be urged that a simple thermostat, acting, so to say, back- wards, might do the same thing automati- cally. But then it is very much a moot-point whether such a device would be appropriate to the working conditions, about half the time, even in the tropics. It is one of those points in which the Napier designing staff, with their preference for being merely effective, are clever enough to avoid the temptation of being merely clever without being sure. The toggle-action device for the engage- ment and disengagement of the starting - gear was fully described in these columns many months ago, actually before it was first exhibited at the Aero Show, so needs no recapitulation ; or, indeed, mention, except to say that, although a standardised fitment for hand-starting, the sub- stitution of an electric starting motor in no way affects its construction or general assembly. REAR VIEW OF THE NAPIER SIXTEEN-CYLINDEREDfcl,000 h.p. " CUB " AERO-ENGINE : Chiefly displaying the magneto mounting • and the horizontal relation of the water pump. THE 1,000 H.P. NAPIER "CUB First Photographs LAST week a brief reference was made in our columns to the new 1,000 h.p. Napier " Cub," from which great things are expected. Although no details may be divulged at present, we are able to place before our readers this week a set of photographs which show admirably the general lay-out of this our most powerful aero engine unit. As will be seen from the photographs, the cylinders are arranged in four banks of four each, the two upper rows being placed at a narrow angle, while the lower are at a wide angle. Apart from the advantages of this arrangement for relieving crankshaft stresses, it has one very great advantage from the aircraft designer's point of view. The engine housing may be kept relatively narrow at the top, thus hindering the pilot's view to a much smaller extent than would a wid-ir Vee. Also the large unencumbered space along each side of the engine facilitates the mounting in the machine. As will be seen from the illustrations, there are four over- head camshafts operating the four valves of each cylinder. The inlet valves, as usual, are on the inside of the cylinder banks, with the two duplex carburettors that supply them placed at the forward or airscrew end, and supplying the mixture through four induction pipes, as shown. The four magnetos are mounted on platforms on the rear end of the engine. A large reduction gear is provided, as one would expect for an engine of this power, and our propeller designers are now faced with the problem of producing an airscrew to absorb this power. That this will have to be of the four- bladed type is scarcely to be doubted. So much, and anything else which the reader may glean from an inspection of the photographs, may be said regarding the " Cub," and no more at the moment. We might add, however, that this monument to British aero engine engineer- ing was designed by Mr. J. Rowledge, mainly in the South of France, where Mr. Montagu Napier is residing for reasons connected with his health, and where, consequently, Mr. Rowledge went with a staff of draughtsmen. The engine, of which the first is ready for exhaustive tests while a second is coming along, was, of course, built in this country, and its performance will be watched with the keenest interest by all connected with aviation. Although designed primarily for Air Ministry purposes, there is little doubt that as a commercial proposition it will play an important part in connection, with the really large commercial machine of the near future. NOTICE TO AIRMEN ':..,- :t -" '*• .. *::' * . Aerodromes for Civil Use : Amendments NOTICE to Airmen No. 1 of 1921 (Aerodromes for Civil Use : Consolidated List) is amended as follows :— LIST C. Licensed Civil Aerodromes, (b) Civil aerodromes licensed as " suitable for Avro 504 K and similar types of aircraft only." Walsall should be deleted. (No. 14 of 1921.) 95I
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
