Chenu
Chenu Motors at the 1913 Paris Air Show.
The models exhibited closely resemble the conventional car engine. The cylinders, which are in pairs of cast iron, with the jacket cast integral with the body, are placed vertically on an aluminium crank-case. They have exceptionally large inlet and exhaust valves, which are arranged on opposite sides of the engine, while ample water spaces are provided, reaching well down the cylinder barrel. The lubricating pump, driven off the centre of the camshaft, is placed in a sump formed in the base of the crank chamber, which contains sufficient oil for 10 hours running without replenishing. Bosch, double ignition is fitted, one plug in each
cylinder being at the side near the inlet valve, and the other over the exhaust valve. This form of ignition would appear to be essential on these engines, which run at extremely high speed, on account of the slow ignition of the charge due to the shape of the combustion chamber.
A double half compression device is fitted to facilitate engine starting, as this is especially necessary where the reducing gear is fitted. The weights of the reducing gears, which are supplied with any of the three smaller engines if desired, are 22 lbs. for the four-cylinder engines, and 31 lbs. for the six-cylinder 100 h. p. engine.
Two carburettors are fitted to the two six-cylinder models; whilst the standard thrust bearing provided permits the engine to be used for A tractor screw or a propeller.
This firm have introduced a new model of the same dimensions and general construction as the old four-cylinder 65 h.p. engine which was entered as a 50 h.p. last year, but which, by the use of lighter reciprocating parts, larger valves, &c, is now able to run at a much higher normal speed. The maximum revolutions of the 65 h.p. engine is 1,800 per minute, but the 90 hp engine may be run at 2,300 revolutions per minute. The torque curve is the same for both of these models, until after a speed of revolution of about 1,500 per minute is attained. The largest engine, 250 h.p., is intended for use on dirigibles and several have already been fitted to the Astra Torres VI, XIII, XV and XVI, besides other aircraft.