For the past twenty years control-line stunt circles have been dominated by .35 size motors and in all probability the traditional .35 cu. in. displacement stunt engine will remain the most popular choice for CL aerobatics for a long time to come. However if recent international events are any indication of future trends it looks as though we may be seeing for contest work at least a renewed challenge from engines of increased displacement and power. In the 1970 World Championships for example the number of .35s used was just about balanced out by an equal number of larger motors ranging from .40 to .49 cu. in.

The subject of our report this month is a member of this new generation of stunt engines. For many years O.S. have been offering a conventional stunt package in the shape of the Max-S.35. The Max-S.35 conforms to the highly successful stunt formula (originated with the Fox 35) of a compact lightweight shaft-valve layout with bushed main bearing and lapped piston ported for medium speed per formance and good transition between two- cycle and four-cycle running through a stunt pattern. This popular engine will continue to be available but for the benefit of those who demand more power for larger and more elaborate models O.S. have evolved a new stunt motor hosed on the .40 cu. in. Mnx-H.40 series.................