Complex sentence: Modern light planes commonly use the flat-8 configuration instead as it is lighter and easier to air cool, in addition it can be manufactured in modular designs sharing components with flat-4 and flat-6 engines.
Split into simpler sentences: Modern light planes commonly use the flat-8 configuration instead as it is lighter and easier to air cool. In addition it can be manufactured in modular designs sharing components with flat-4 and flat-6 engines.