Paper 3: Development of the Napier Deltic Charge Cooled Engine

This third generation of Deltic engine, of higher horsepower, is basically similar in design to the earlier units but a redesigned turbo-blower of increased efficiency has been introduced and charge-air coolers are interposed between the blower and cylinder blocks, thus enabling a greater mass of air to be trapped at a lower temperature with the charge pressure remaining unchanged. By this arrangement the power of the engine, for fast patrol boat application, has been increased to 3700 b.h.p. from 3100 b.h.p. at 2100 crankshaft rev/min.

The engine is generally of light alloy construction and for marine use includes an integral ahead and astern gearbox.

The paper gives a survey of the design changes made to the engine and the development problems encountered before a 1000-hour endurance test was satisfactorily completed.