However, the unit sizes in RO really don't warrant air support - even the artillery support is a bit overpowered for a squad/platoon/company to command. Even today it's uncommon for ground units to directly call air-strikes during battle...usually aircraft are assigned patrol areas where they engage targets of opportunity.
It would be better to have aircraft as map elements that come in randomly or at predetermined times, just as they would have on the battlefield. Check out Aksay for a Stuka that randomly dive-bombs the Russian positions, or Kaliskov (sp?), where waves of heavy aerial bombardment occasionally sweep across the map, destroying buildings and fortifications.