A New Light Aeroplane Engine

A New Light Aeroplane Engine September, 1931 AIRCRAFT ENGINEERING 227 Th e 60-h.p. Four-Cylinder Inverted Air-Cooled Hirt h with Coil-Ignition Described OR many years, Helmut Hirth, the well-known Piston s and valves are the only parts which have pre-war pilot and engine-constructor, has friction bearings. In this way it was possible to been working on the construction and design achieve a fuel consumption of 225 g./h.p./hr. of a new cheap engine for touring aeroplanes. (0·495 lb./h.p./hr. ) and the astonishingly low oil Those who know his early engines expected to see consumption of only 0·25 to 1·1 g./h.p./hr. a high revolution, water-cooled, two-cycle engine (0·025 lb./h.p./hr. ) The low compression ratio of 5·3 : 1 permit s the use of any kind of fuel. with double pistons, something after the type of the motor-cycle engines which have run successfully Long experience in the use of roller bearings and in many races. It was a great surprise, therefore, an exact knowledge of their requirements in lubri­ when he came out about a year ago with an air- cation have led to the use of fresh oil dry-sum]) cooled, four-cylinder, four-cycle, vertical engine. lubrication, a system which allows th e roller bearings This engine resembled the well-known British to take up exactly the quantity of oil which they Cirrus engine, and developed about a 100 h.p. need. At the same time, under this system, the The type was not, however, developed further, oil is given no chance of over-heating. The dissi­ because, in the meantime, the Argas As.8 had pation of the internal heat from the crank-case, which under normal construction takes place by already flown with great success in numerous means of the oil and the casing itself to the outer machines. Fully realising the fact that a 100-h.p. air and thus sets up dangerous tensions in the light- machine for th e use of a sportsman or a club repre­ sented an expensive power reserve that could metal casing, is simplified and improved by arrang­ hardly be justified, and in view of the wide use of ing for the interior of the crank-case to be directly the French Salmson engine, Hirth turned his atten­ sprayed with fresh air. The air which is heated in tion to the construction of a lighter and smaller, th e crank-case in this manner is then mixed with four-cylinder-in-line, four-cycle, air-cooled inverted fresh air and led to the carburettors. engine, with a peak development of 65 h.p. and a Th e built up crankshaft (patented by Dr. normal development in practice of 40-50 h.p. Albert Hirth) is borne on five roller bearings and a In designing this engine, Hirth, to a certain radial bearing as journal and thrust bearings. The extent, trod new path s in th e design of aero engines. various component parts can easily be made in any well-arranged engineering shop. He decided against a continuous camshaft. Two small camshafts, situated one between each pair of The valves are actuated by two small camshafts cranks, actuate the valves by means of push-rods between the pairs of cylinder-heads, by means of running through hollow tension-rods between rocker-arms and push-rods. The latter lead cylinder-head and casing. Ignition is effected by through the hollowed-out cylinder-locking-screws a fixed-spark coil and battery. This allows of t o the rocking lever in the cylinder-head. They ar e thus protected front heat variations. The valve particularly quick starting. Twent y years' experience in flying had shown rocker-arms, as well as the valve guides and springs, The restricted development of sport and travel tha t with the present-day standard of fuselage are enclosed in dust-tight covers, and are lubricated flying in Germany, and for this reason the small design, for aerodynamic reasons an engine-power of from the crank-case through the cylinder-locking- demand for engines for light aeroplanes, necessitates a t least 40 h.p. to 60 h.p. is necessary for a two- screws. the manufacture of these engines in small quantities seater light aeroplane. Smaller engines can be with comparatively high manufacturing costs. The particular shape of the suction-pipe, which is used, but they are really insufficient to meet the th e result of exhaustive experiments, combined The funds which are available in Germany for needs of practical sport and journey flying. An with the battery ignition which has been success­ the development of flying are put up, in the main, engine of 60 h.p. for continuous load, with a peak fully incorporated in an aeroplane engine for the by the large air transport undertakings, so that capacit y of 65 h.p. , was therefore chosen. there is very little left over for sport and private first time, permits of absolutely reliable and imme­ In order to achieve favourable consumption flying. diat e starting up of the engine from cold, as well as figures with this comparatively small unit, all ensuring regular and steady running without load This consideration led to the cutting down of the rotatin g parts are arranged on roller bearings. a t about 150 r.p.m. A hand-starter simplifies manufacturing cost of the H.M.60 engine by the utilisation of components which were already being LEADIN G PARTICULARS startin g up. Length overall .. .. 775 mm. (30 in.) made in considerable numbers in other branches of The very small amount of attention necessary for Heigh t overall .. .. 688 mm. (27 in.) the works and could, therefore, be manufactured thi s engine, its low price, as well as low maintenance- Widt h overall .. .. .. 386 mm. (15 in.) cheaply. Bore .. .. .. .. 115 mm. (4½ in.) cost, its simple handling and its great reliability, Strok e .. .. .. .. 110 mm. (4⅓ in.) mak e it particularly suitable for flying-schools and Volume .. .. .. .. 3·46 litres (211 cu. in.) privat e owners. Compression ratio .. .. 5·3 : 1 Maximu m permissible power (a t 2,100 r.p.m.) .. .. 65 h.p . Norma l full power (at 2,000 r.p.m. ) .. .. .. 60 h.p. Weigh t (without oil, starter, airscrew, exhaust manifold, battery , etc.) .. .. 82·3 kg. (181 lb.) Weigh t per horse-power (at 2,100 r.p.m.) .. .. 1·265 kg./h.p. (2·8lb./h.p.) Fuel consumption .. .. 225 g/h.p./hr (0·495 lb./h.p./hr.) Oil consumption .. ., 1·1g/h.p./hr. (0·025 lb./h.p./hr. ) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

A New Light Aeroplane Engine

Aircraft Engineering and Aerospace Technology, Volume 3 (9): 1 – Sep 1, 1931

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb029449
Publisher site
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Abstract

September, 1931 AIRCRAFT ENGINEERING 227 Th e 60-h.p. Four-Cylinder Inverted Air-Cooled Hirt h with Coil-Ignition Described OR many years, Helmut Hirth, the well-known Piston s and valves are the only parts which have pre-war pilot and engine-constructor, has friction bearings. In this way it was possible to been working on the construction and design achieve a fuel consumption of 225 g./h.p./hr. of a new cheap engine for touring aeroplanes. (0·495 lb./h.p./hr. ) and the astonishingly low oil Those who know his early engines expected to see consumption of only 0·25 to 1·1 g./h.p./hr. a high revolution, water-cooled, two-cycle engine (0·025 lb./h.p./hr. ) The low compression ratio of 5·3 : 1 permit s the use of any kind of fuel. with double pistons, something after the type of the motor-cycle engines which have run successfully Long experience in the use of roller bearings and in many races. It was a great surprise, therefore, an exact knowledge of their requirements in lubri­ when he came out about a year ago with an air- cation have led to the use of fresh oil dry-sum]) cooled, four-cylinder, four-cycle, vertical engine. lubrication, a system which allows th e roller bearings This engine resembled the well-known British to take up exactly the quantity of oil which they Cirrus engine, and developed about a 100 h.p. need. At the same time, under this system, the The type was not, however, developed further, oil is given no chance of over-heating. The dissi­ because, in the meantime, the Argas As.8 had pation of the internal heat from the crank-case, which under normal construction takes place by already flown with great success in numerous means of the oil and the casing itself to the outer machines. Fully realising the fact that a 100-h.p. air and thus sets up dangerous tensions in the light- machine for th e use of a sportsman or a club repre­ sented an expensive power reserve that could metal casing, is simplified and improved by arrang­ hardly be justified, and in view of the wide use of ing for the interior of the crank-case to be directly the French Salmson engine, Hirth turned his atten­ sprayed with fresh air. The air which is heated in tion to the construction of a lighter and smaller, th e crank-case in this manner is then mixed with four-cylinder-in-line, four-cycle, air-cooled inverted fresh air and led to the carburettors. engine, with a peak development of 65 h.p. and a Th e built up crankshaft (patented by Dr. normal development in practice of 40-50 h.p. Albert Hirth) is borne on five roller bearings and a In designing this engine, Hirth, to a certain radial bearing as journal and thrust bearings. The extent, trod new path s in th e design of aero engines. various component parts can easily be made in any well-arranged engineering shop. He decided against a continuous camshaft. Two small camshafts, situated one between each pair of The valves are actuated by two small camshafts cranks, actuate the valves by means of push-rods between the pairs of cylinder-heads, by means of running through hollow tension-rods between rocker-arms and push-rods. The latter lead cylinder-head and casing. Ignition is effected by through the hollowed-out cylinder-locking-screws a fixed-spark coil and battery. This allows of t o the rocking lever in the cylinder-head. They ar e thus protected front heat variations. The valve particularly quick starting. Twent y years' experience in flying had shown rocker-arms, as well as the valve guides and springs, The restricted development of sport and travel tha t with the present-day standard of fuselage are enclosed in dust-tight covers, and are lubricated flying in Germany, and for this reason the small design, for aerodynamic reasons an engine-power of from the crank-case through the cylinder-locking- demand for engines for light aeroplanes, necessitates a t least 40 h.p. to 60 h.p. is necessary for a two- screws. the manufacture of these engines in small quantities seater light aeroplane. Smaller engines can be with comparatively high manufacturing costs. The particular shape of the suction-pipe, which is used, but they are really insufficient to meet the th e result of exhaustive experiments, combined The funds which are available in Germany for needs of practical sport and journey flying. An with the battery ignition which has been success­ the development of flying are put up, in the main, engine of 60 h.p. for continuous load, with a peak fully incorporated in an aeroplane engine for the by the large air transport undertakings, so that capacit y of 65 h.p. , was therefore chosen. there is very little left over for sport and private first time, permits of absolutely reliable and imme­ In order to achieve favourable consumption flying. diat e starting up of the engine from cold, as well as figures with this comparatively small unit, all ensuring regular and steady running without load This consideration led to the cutting down of the rotatin g parts are arranged on roller bearings. a t about 150 r.p.m. A hand-starter simplifies manufacturing cost of the H.M.60 engine by the utilisation of components which were already being LEADIN G PARTICULARS startin g up. Length overall .. .. 775 mm. (30 in.) made in considerable numbers in other branches of The very small amount of attention necessary for Heigh t overall .. .. 688 mm. (27 in.) the works and could, therefore, be manufactured thi s engine, its low price, as well as low maintenance- Widt h overall .. .. .. 386 mm. (15 in.) cheaply. Bore .. .. .. .. 115 mm. (4½ in.) cost, its simple handling and its great reliability, Strok e .. .. .. .. 110 mm. (4⅓ in.) mak e it particularly suitable for flying-schools and Volume .. .. .. .. 3·46 litres (211 cu. in.) privat e owners. Compression ratio .. .. 5·3 : 1 Maximu m permissible power (a t 2,100 r.p.m.) .. .. 65 h.p . Norma l full power (at 2,000 r.p.m. ) .. .. .. 60 h.p. Weigh t (without oil, starter, airscrew, exhaust manifold, battery , etc.) .. .. 82·3 kg. (181 lb.) Weigh t per horse-power (at 2,100 r.p.m.) .. .. 1·265 kg./h.p. (2·8lb./h.p.) Fuel consumption .. .. 225 g/h.p./hr (0·495 lb./h.p./hr.) Oil consumption .. ., 1·1g/h.p./hr. (0·025 lb./h.p./hr. )

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Sep 1, 1931

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