International Shipbuilding Progress

Eight propeller coefficients, essential for a description of the dynamic behaviour of a ship’s propulsion system, are mentioned. The instrument for the experimental determination of these coefficients, a propeller exciter, is dealt with briefly.

Finally the results of the experiments, i.e. eight propeller coefficients, are given as a function of the blade area ratio and the pitch and are compared with theoretical results and as far as possible compared with results obtained by other investigators. It appears that the experimentally obtained coefficients are smaller than the theoretically approximated coefficients.

Starting with the status of development of RSAD76 engines described in a number of publications [1,2,3,4], work is described which has been done during the last felt years on improving the scavenging system and charging conditions with the object of raising engine ratings by a higher degree of supercharging. Detailed investigations into the scavenging process led to new and improved arrangements of the scavenging ports from which all RD-type engines have benefited. The writer then traces the further development of the supercharging system for numbers of cylinders difficult to deal with in pulse operation. Substantial advances were made by the introduction of new turbine arrangements for RD engines haring seven, eight and ten cylinders; this rendered it possible to employ to a far-reaching extent the advantages of full-admission turbines – something that had previously only been practical on engines having six, nine or twelve cylinders. Major increases in rating were thus also obtained in the case of these “difficult” numbers of cylinders, without the exhaust gas temperature being increased.

The article describes the method in use at the N.S.M.B. to calculate a well faired table of offsets, starting with measurements from a small scale lines plan.

In addition new developments and extensions of existing programs for hydrostatic calculations are described.