It is two years since we last dealt with an O.S. engine in the M.A. Tests series. During this period the O.S. range has been further expanded and with sonic thirty models on its current production list the Ogawa Model Manufacturing Company Ltd. now has the largest range of model engines produced by any manufacturer anywhere in the world. These together with O.S. radio control equipment are built in a modern well equipped factory which includes a large proportion of active model enthusiasts among its personnel including a permanent staff of two engaged solely on model engine design and experimental work.

Since our test on the Max-19 engine early in 1963 a dozen new O.S. models in six different capacities nave been announced. Moreover nearly all the then existing models have been either improved or replaced. It is. obviously quite impossible to keep up to date with all O.S. engines in the M.A. Tests series but to help cut into some of the backlog of those still awaiting test we are making the present report a double test covering the two current Max-S models namely the 5.83 c.c. S.35 (intended for CL stunt use) and the 4.86 c.c. S.30RC which is aimed at the intermediate or multi trainer RC field. Coming just within the new SMAE 10 c.c. total maximum displacement limit for twin or multi-engine models the S.30RC with its moderate weight and excellent throttling should also be a good choice for a multi-channel twin-engine model.......