Flight Experiments with Compression-Ignition Engines

Abstract

THE Air Ministry has ordered a number of “Culverin” 720 horse-power heavy oil engines from Messrs. D. Napier and Son, Ltd. It is understood that these are to be used for complete operational tests in large flying boats. Imperial Airways is also interested in the same problem for civil aircraft, and will doubtless be watching these results. The Napier engine is a horizontal water-cooled engine, built under licence from the German Junkers company. The Bristol Aeroplane Co., Ltd., has also developed a compression-ignition engine of the radial air-cooled type, which has actually gained the world's altitude record for aircraft powered with that type of engine. The Diesel type engine has a definite advantage in long-distance flight owing to its smaller oil con sumption, but as it is structurally heavier than the petrol engine this advantage is outweighed on short flights. With modern design and performance of heavier-than-aircraft, there is no gain in using it for a flight of less than about eight hours duration. Another major point in its favour is the lessened risk of fire after a crash. Although the fuel oil used is not non-inflammable, its flash point is much lower than that of petrol, and the risk of ignition from flame or hot parts is less. A minor trouble to be dealt with is the lack of facilities for the distribution of this fuel oil at the present time. The oil distributing companies will need considerable additions to their plant before fuel oil will be available upon as world wide a scale as is petrol.