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Aviation History
1949
1949 - 1397.PDF
August nth, 1949 FLIGHT 161 Hispano Suiza \2-cylinder, V-type, liquid-cooled engine with petrol injection direct to the cylinders. HISPANO SUIZA 12B New Series of Liquid-cooled Engines and a Compounded Unit DEVELOPED from the well-established 12Z series, thelatest Hispano Suiza engines have sturdier con-struction, higher charging pressure and improved performance. Three versions are scheduled for production: type 12B 00 has a single-stage, single-speed blower, 12B 20 a single-stage, two-speed blower, while 12B 40 has the single-speed blower and is compounded with an exhaust turbo-blower to produce what in France is termed a "groupe moto-propulseur." Cylinder head and coolant jackets for each row of six cylinders is a monobloc casting into which the cylinder sleeves are screwed. Twin cam- shafts on each cylinder head actuate two inlet and two exhaust valves per cylinder. Pistons of forged light alloy cany a fire ring, two compression rings and an oil scraper ring. The seven-bearing crankshaft is chromed on the journals and pins and an unusual feature is the attachment of the eight counterweights by welding. At the forward end a straight-toothed gear reduces the crankshaft speed at a ratio of 2:1 for the airscrew shaft. An alternative ratio of 3.3:1 can be arranged. The driving pinion is mounted independently on two roller bearings and receives its drive from the end of the crankshaft by means of a torsionaJly-resflient shaft. On the reduction gear casing are mounted the " Eclipse " electric starter, the forward lubricating oil scavenge pump and the two mag- netos. One magneto feeds plugs on the inlet sides of the cylinders and the other plugs on the exhaust sides. Ignition timing is automatically regulated by the charging air pressure to ensure combustion conditions and secure good cruising economy. From the rear of the crankshaft are taken the drives for the overhead camshafts and for the blower. Here also are arranged -the duplex oil pump (pressure and rear scavenging units), coolant pump, fuel feed pump and a 100 h.p. take-off for an accessories drive box. Six-unit Lavalette fuel injection pumps, mounted centrally on the sides of the crankcase outside the cylinder blocks, are also driven from the rear. Fuel injection is controlled by a* Hispano Suiza mixture regulator with corrections for the density of air delivered to the cylinder and for temperature. Direct injection to the cylinder per- mits adequate scavenging of the cylinders, involving sub- stantial valve overlap, without loss of fuel. Lubrication is effected with .high- and low-pressure Timing diagram 4eg Wet ope* 60 before TDC fuel injection commences 30 after TDC fue* injection terminates 30 before 6DC Met dam 50 after BDC '*"«««» 21-18 before TDC ***«« open* 65 before BDC txkauxt dots AS after TDC INLET FUELNJECTION COMPRES POVW3? EXHAUSTl IGNITION Power curves of piston engine with two-speed blower (left) and of the "groupe moto- propulseur" (right). 2400 22O0 2OOO 1800 16O0 ?f MOO * 12OO 1OOO ATVk 600 4OO 0 111 T/ .1 IK* — 2 OFF » . i ONI 4 k\ SIN • i &c \ G\ \ i i US s\ i TYPE i 117Omm ^ ^225O ^ 82Oi V1O III 1 i i r.pjn. nmha \Mis a T 0 • KM 4 -Of < F aWn&c 3WJISINQ ! t s - : X s ^ II1 I-- If- • TYPE4OII illII III 27OOr.fi.rtv 1 - 1" s •Orrmnhg 22$Orpn 5 1O eummiK I AUTrUDE(KM) ALTITUDE (KM)
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