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Aviation History
1931
1931 - 0101.PDF
JANUARY 30, 1931 THE AIRCRAFT ENGINEER SUPPLEMENT TO FLIGHT This latter practice makes the accessories more accessible, and particularly in the ease of the magnetos, avoids the difficulties experienced with a rear drive subject to the full amplitude of suing of the tail end of the crankshaft: but from the point of view of cleanliness and consequent reliability of operation the magneto is preferably placed at the rear of the engine where it is suitably protected. On the newer engines there should be mentioned the \rmstrontr-Siddeley seven-cylinder radial (ienet major of the same cylinder dimensions as the well-known five-cylinder Genet engine, and the two-row double Mongoose of ten cylinders The Clerget compression-ignition engine. (FLIGHT Photo.) Oaripd on the five-cylinder Mongoose of similar cylinder size. These two engines are of standard Armstrong-Siddeley 'i'"si#n, and further the policy of this firm of making a com- pii'tf range of horse-powers with a maximum of interchange- Itility of parts. Other new engines are the Gnome-Rhone five-cylinder ; "lial 240-h.p. Titan K, and the seven-cylinder 300-h.p. ' itiin Major. These have the same cylinder bore as the piter engines made by this firm, but the stroke is reduced 105 mm. The cylinder head is of cast aluminium and has11 valves each of 75 mm. diameter ; the compression ratio is •'••>• The valve gear is compensated for expansion, and the "i«li rods are operated by a three-lobed cam driven by a small1|: 'in of gears to obtain the required fpeed reduction. The ""ankshaft is split and held together by a pinch bolt only, and 'io floating bush is used on the big end although these are htted to the small ends of the connecting rods. The engine can bo fitted with geared fan or supercharger and can be ^upplied either with direct drive or Farman reduction gear, is stated that the seven-cylinder engine has given an out- put of 420 h.p. at its maximum speed of 2,200 r.p.m. Nine and fourteen-eylinder engines of similar tvpe are under consideration. Of the engines shown by the Lorraine Company, the one " most recent interest is the twelve-cylinder Vee water- •ooled 900-h.p. Eider. The design of this engine is compact result fajrly orthodox but im-fo-date lines, and the frontal pK an engine of low weight/power ratio and smallarea. The engine can be supplied geared and ungeared, ion should l b d f h l i i a. The engine can be supplied geare - ration should also be made of the AtlasV" °f 6°° h f 1 " °f 1'950engine, a nine-Theier,. '?mPany> whose products have a high reputation. r 's fitted erdimenSi°ns are 165 mm" by 18° mm' stroke'and tr"p =i 7^ a *wo"valve cylinder head which indicates a> i* «, A -e and consequent doubtful reliability. Other- •'* the design is normal. Compression ignition engines using heavy fuel oil were shown by Hispano-Suiza, Panhard and Levassor, Lorraine and Peugeot Aviation. The engines shown by the first three firms were of the types which were originally developed bv Mr. Clerget under the auspices of the Service des Becherches de VAeronautique. Two sizes are made, one of 100 h.p. and the other of 200 h.p., and the design in each ease is a nine- cylinder radial air-cooled engine fitted »\ith a two-valve head. Each cylinder is supplied by its own fuel pump, and the fuel is delivered to a valve situated in the centre of the cylinder head. The Panhard model, which has flown several hours, develops 100 h.p. at 1,800 r.p.m. at 500 lb. weight, the bore and stroke being 120 mm. by 130 mm. The fuel pumps are placed behind each cylinder. The 200-h,p. engine as shown by Hispano-Suiza has a bore of 130 mm. and stroke of 170 mm., a compression ratio of 10 to 1, and at 1,800 r.p.m. it develops 225 h.p. The weight is fi80 Jb., giving a weight' power ratio of 3 lb. per b.h.p. The fuel pumps are fitted in front of the cylinders in this engine and are operated directlv by a cam concentric with the engine crankshaft. The quan- tity of the fuel delivered by the pumps is controlled by a linkage connecting all the pumps to one common lever. Peugeot Aviation were showing the Junkers type of com- pression ignition^engine which is now manufactured bv them on licence. This engine, developed by the Junkers Company over many years, is a six-cylinder opposed piston engine, there being twelve pistons, two in each cylinder, and two The Hispano-Suiza heavy-oil engine. (FLIGHT Photo.) crankshafts. The crankshafts are geared together by a train of spur gearing, and the airscrew shaft is positioned on the centre line of the engine. The cylinder bore is 4 • 72 in. and the engine speed 1,500 r.p.m. As the opposed pistons move apart and towards the end of the outward stroke, exhaust and inlet ports on the cylinder walls are opened, the exhaust being at one end and the inlet the other. Thus a good through scavenge is obtained by the scavenge air which is supplied by a gear-driven centrifugal compressor at a pressure of 4 to 5 lb. per sq. inch. On compression of the new charge of air the fuel oil is sprayed into the combustion space through two fuel valves on opposite sides of the cylinder. The horse- power developed is approximately 680 at a weight/power ratio of 2f lb. Captain Swan has compiled an interesting table of data, not only of the engines shown, but of all the engines made by the various firms. Unfortunately lack of space compels us to hold this table over until next month—Ed.
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